Dissertations / Theses on the topic 'Distribution network reliability'

The need of water and the limited sources, force the researchers to find the most economical and feasible solution in the design of a water distribution network. In this study, reliability and optimization of a water distribution network are taken into account together in the design stage of the network. The relationship between reliability of a water distribution network and its cost is examined during the design of a water distribution network. A methodology for deciding the reliability level of the selected design is proposed by examining the reliability-cost relationship. The design alternatives for the case study area are obtained by the aid of a commercially available software WADISO employing partial enumeration optimization technique. The reliability value for each of the design alternative is calculated according to Misirdali (2003)&rsquo
s adaptation based on the methodology proposed by Bao and Mays (1990) by the aid of a hydraulic network solver program HapMam prepared by Nohutç
u (2002). For purposes of illustration, the skeletonized form of Ankara Water Distribution Network subpressure zone (N8-1) is taken as the case study area. The methodology in this study, covering the relation between the reliability and the cost of a water distribution network and the proposed reliability level can be used in the design of new systems.

Power distribution networks are recognized as the constituent part of power systems with the highest concentration of failure events. Even though the faults in distribution networks have a local effect when compared to the generation and transmission sides, major contingency escalation events are being more frequently reported from this section. The various aspects regarding the reliability and performance of distribution networks are identified as an important topic. Integration of new technologies, automation and increased penetration of distributed generation is expected to make improving and even sustaining high reliability standards a complex task.   This thesis presents developed approaches to quantify and analyze the complex correlated failure probabilities of different failure modes in distribution networks. A theoretical simulation model that relates to real world data to measure false tripping probabilities is developed and tested. More simplified approaches that utilities can exercise with readily available data in fault registers are also established.  Optimal configurations that could improve system performance and respective investment costs are analyzed and savings in system reliability at the cost of grid investments are modelled. The optimization helps in prioritizing the most critical investments by considering the system impact of reconfigurations focusing on meeting customer demands and respecting transfer capacities of weak links. The value of existing networks and willingness of the grid owner in investing can be integrated into suggestive alterations to assist decision making in planning and maintenance allocation.   The thesis makes both system specific and generalizable observations from detailed data collection from power utilities. The observations and results have potential in aiding future research by giving important understanding of the reliability impacts of network structures and of control and protection equipment.
Eldistributionsnätet är den del av elnäten som leder till flest kundarbrott trots att felhändelserna oftast är mycket lokala jämfört med händelse på genererings och transmissions sidan. Alltså identifieras de olika aspekterna beträffande pålitlighet och prestanda för distributionssystem som viktiga ämnen. Integration av ny teknik, automatisering och ökad penetration av distribuerad produktion förväntas göra förbättringar och rent av upprätthållande av höga tillförlitlighetskrav till en komplex uppgift.   Denna avhandling presenterar metoder för att kvantifiera och analysera de komplexa och korrelerade sannolikheterna för olika fellägen i distributionsnätet. En teoretisk simuleringsmodell baserrad på verkliga data för att mäta sannolikheter för felaktiga brytarkommandon utvecklas och testas. Mer förenklade tillvägagångssätt där elnätsföretag kan använda lättillgängliga data i felregister presenteras också. Optimala konfigurationer som kan förbättra systemprestandan och investeringskostnader analyseras och minskningar i systemets tillförlitlighet genom minskade kostnader för nätinvesteringar modelleras. Optimeringen bidrar till att prioritera kritiska investeringar genom att påvisa systemets inverkan av omkonfigurationer. Optimeringen tär hänsyn till kundernas krav och att bevara överföringsförmågan hos svaga länkar. Värdet av befintliga nät och villigheten hos nätägaren att investera kan undersökas som förslag, till ändringar, som stöd detta för beslut om planering och underhåll.   Avhandlingen gör både systemspecifika och generaliserbara observationer från en detaljerad datainsamling från elnätägare. Observationerna och resultaten har potential att hjälpa framtida forskning genom att ge en viktig förståelse för tillförlitlighetseffekter från nätverksstrukturen och från kontroll- och skyddsutrustning.

QC 20171004

Over the past decades, the concepts and methods for reliability assessment have evolved from analysing the ability of individual components to operate without faults and as intended during their lifetime, into the comprehensive approaches for evaluating various engineering strategies for system planning, operation and maintenance studies. The conventional reliability assessment procedures now receive different perspectives in different engineering applications and this thesis aims to improve existing approaches by incorporating in the analysis: a) a more detailed and accurate models of LV and MV networks and their reliability equivalents, which are important for the analysis of transmission and sub-transmission networks, b) the variations in characteristics and parameters of LV and MV networks in different areas, specified as “generic” UK/Scottish highly-urban, urban, sub-urban and rural network models, c) the relevant requirements for network reliability performance imposed by Regulators on network operators, d) the actual aggregate load profiles of supplied customers and their correlation with typical daily variations of fault probabilities and repair times of considered network components, and e) some of the expected “smart grid” functionalities, e.g., increased use of network automation and reconfiguration schemes, as well as the higher penetration levels of distributed generation/storage resources. The conventional reliability assessment procedures typically do not include, or only partially include the abovementioned important factors and aspects in the analysis. In order to demonstrate their importance, the analysis presented in the thesis implements both analytical and probabilistic reliability assessment methods in a number of scenarios and study cases with improved and more detailed “generic” LV and MV network models and their reliability equivalents. Their impact on network reliability performance is analysed and quantified in terms of the frequency and duration of long and short supply interruptions (SAIFI and SAIDI), as well as energy not supplied (ENS). This thesis addresses another important aspect of conventional approaches, which often, if not always, provide separate indicators for the assessment of system-based reliability performance and for the assessment of customer-based reliability performance. The presented analysis attempts to more closely relate system reliability performance indicators, which generally correspond to a fictitious “average customer”, to the actual “best-served” and “worst-served” customers in the considered networks. Here, it is shown that a more complex metric than individual reliability indicators should be used for the analysis, as there are different best-served and worst-served customers in terms of the frequency and duration of supply interruptions, as well as amounts of not supplied energy. Finally, the analysis in the thesis considers some aspects of the anticipated transformation of existing networks into the future smart grids, which effectively require to re-evaluate the ways in which network reliability is approached at both planning and operational stages. Smart grids will feature significantly higher penetration levels of variable renewable-based distributed generation technologies (with or without energy storage), as well as the increased operational flexibility, automation and remote control facilities. In this context, the thesis evaluates some of the considered smart grid capabilities and functionalities, showing that improved system reliability performance might result in a deterioration of power quality performance. This is illustrated through the analysis of applied automation, reconfiguration and automatic reclosing/remote switching schemes, which are shown to reduce frequency and duration of long supply interruptions, but will ultimately result in more frequent and/or longer voltage sags and short interruptions. Similarly, distributed generation/storage resources might have strong positive impact on system reliability performance through the reduced power flows in local networks and provision of alternative supply points, even allowing for a fully independent off-grid operation in microgrids, but this may also result in the reduced power quality levels within the microgrids, or elsewhere in the network, e.g. due to a higher number of switching transfers and transients.

We live in a time where society put a high demand for the quality performanceof the electricity network. At the same time the electricity companiesneed to operate their businesses with an increasing need for cost-effectiveness.An approach for electricity companies - especially grid owners - to make theiroperations more cost-effective could be to focus on the design of the networkitself, for instance structuring the network so that the total length of cable isreduced.This thesis targets the configuration of the primary feeders, based on thestructure of an existing distribution network and the minimization of the totalamount of cable in the network. The goal with the thesis - apart from studyingif cable minimization improves reliability - is to find a method that could designdistribution networks not only retroactively but also in a planning stage.The objective function of the optimisation problem is to minimize the totalcable length in the network. The constraints are based on keeping powerbalance over each load point and no cable capacity violations. If it weren’t forthe fact that the objective function and the constraints have different units,the problem could have been solved with ordinary linear programming. Now,mixed integer linear programming is utilized instead, which uses heuristics as asolver. Dividing the substations into clusters and studying different scenariosof willingness to invest into the network, two radial network structures werederived by the proposed algorithm.Results from comparing the existing network with the two derived networksshows that reliability indices may in fact improve when the total cable lengthis reduced. Although more tests are necessary.Calculated values and discussions about the results are documented in thethesis report.
Vi lever i en tid där samhället ställer höga krav på elnätets prestanda ochtillförlitlighet. Samtidigt har elnätsföretagen ett ökat behov av att kostnadseffektiviserasin verksamhet. Ett sätt för dem - speciellt elnätsägarna - att blimer kostnadseffektiva skulle kunna vara att fokusera på elnätets design. Exempelvisatt bygga upp nätverket på ett sätt så att den totala kabellängdenminimeras.Det här mastersexamensarbetet studerar konfigurationen av de primäramatarledningarna, baserat på ett nuvarande distributionselnäts utseende ochen minimering av den totala kabellängden. Målet med arbetet är - förutomatt undersöka om den minskade kabellängden förbättrar elnätets tillförlitlighet- att hitta en metod som kan designa elnätet både retroaktivt och i ettplaneringsstadium.Optimeringsproblemets målfunktion är att minimera den totala kabellängdeni nätverket. Bivillkoren är grundade på att hålla kraftbalansen i systemetoch att inte överskrida kabelkapaciteten. Om det inte vore för att målfunktionenoch bivillkoren har olika enheter skulle problemet kunnat lösas med vanliglinjär programmering. Nu modelleras det istället som ett MILP-problem, vilketanvänder sig av heuristik för att hitta en lösning. Efter att ha delat upp lastnodernai kluster och studerat olika scenarion av investeringsvilja i nätverket,lyckades den föreslagna algoritmen ta fram två radiella nätverk.Resultaten av att ha jämfört det nuvarande elnätet med de två föreslagnaalternativen visar att olika tillförlitlighetsindex kan förbättras när kabellängdenminskar. Fler tester är dock nödvändiga.Beräknade värden och närmre diskussioner kring resultatet är dokumenteradei rapporten.

In this research, the impacts of installing DG on a residential distribution circuit are explored. The work is focused on analyzing the impact of DG installation on distribution network operation including voltage analysis, electric losses and reliability of the system. First, various DG penetration levels and the impact of distributing the DG across several locations are explored. Secondly, the impacts of installing DG on any one phase on the voltage profiles of the unbalanced three-phase distribution network are investigated. Thirdly, the losses of the system are analyzed. Next, the reliability analysis (SAIDI, CAIDI, ENS, and AENS) of the system is performed by installing DGs as backup generators. Different DG penetration levels, locations and the impacts of installing one large-scale DG on the main distribution line vs. several small-scale randomly distributed DGs are explored. A residential distribution circuit in Blacksburg, VA was built using its one-line diagram in DEW (Distributed Engineering Workstation) to perform detailed analysis. The research involves several case studies that explore the impacts of installing distributed generation (DG) on residential distribution network operation including the voltage profile, losses, and reliability indices of the system.
Master of Science

Asset management and automation are acknowledged by distribution utilities as a useful strategy to improve service quality and reliability. However, the major challenge faced by decision makers in distribution utilities is how to achieve long-term return on the projects while minimising investment and operation costs. Distribution automation (DA) in terms of transformer economic operation (TEO), distribution network reconfiguration (DNR), and sectionalising switch placement (SSP) is recognised as the most effective way for distribution network operators (DNOs) to increase operation efficiency and reliability. Automated tie-switches and sectionalising switches play a fundamental role in distribution networks. A method based on the Monte Carlo simulation is discussed for transformer loss reduction, which comprises of profile generators of residential demand and a distribution network model. The ant colony optimisation (ACO) algorithm is then developed for optimal DNR and TEO to minimise network loss. An ACO algorithm based on a fuzzy multi-objective approach is proposed to solve SSP problem, which considers reliability indices and switch costs. Finally, a multi-objective ant colony optimisation (MOACO) and an artificial immune systems-ant colony optimisation (AIS-ACO) algorithm are developed to solve the reconfiguration problem, which is formulated within a multi-objective framework using the concept of Pareto optimality. The performance of the optimisation techniques has been assessed and illustrated by various case studies on three distribution networks. The obtained optimum network configurations indicate the effectiveness of the proposed methods for optimal DA.

The problem of optimum restoration after occurrence the outages in a distribution network is an important issue in smart grids. In this kind of networks remote-controlled switches, alternative sources and grid-connected distributed generators (DG) are employed. Therefore, the reliability of the system (corresponding to the frequency of failures and the duration of interruptions) is improved by operating the switches to resupply a part of interrupted system during the repair time. To evaluate the reliability indices in smart grids, neglecting the restoration during the repair time causes the wrong assessment of the network. Thus, considering the rerouting the power during the interruptions seems necessary to calculate the reliability indices. The problem of restoration is formulated as a non-linear integer programming problem with the assistance of the network graph. The circuit graph method is also used to pre-evaluate the feasible interchanging operations to enhance the efficiency of the computations. The topological and operational constraints in this formulation can be found and resolved with the assistance of fundamental cut-set matrix. The optimum restoration schemes is obtained by considering the optimal islanded mode of operation of the DGs which implies maximizing the loading of DGs while not violating their generation capacities. The optimum restoration policies lead us to find the optimum number and location of those manual switches that should be upgraded to the remote-controlled switches. This is a multi-objective problem that contains the contribution of each restoration policy in the reliability improvement and the cost of those switching operations. The proposed algorithm is applied to different standard test systems and the results are compared to the results obtained from other methods and algorithms.

Resilience is widely interpreted as the capacity of a system to resist (preparation phase), absorb and withstand (responding phase), and rapidly recover from (restoration phase) exceptional conditions. During this study, a mixed variety of calculations were assessed in order to find the best solution for determination of resilience and reliability of a simple network. Then, Todini’s formula and failure index was applied to estimate reliability of system in different scenarios as constant demands in period of 24 hours, constant demands in period of 72 hours when tank will be empty (failure of tank), variable demands in period of 24 hours. At first hydraulic simulation of those scenarios was done by EPANET and validated by MATLAB-TOOLKIT. Then, Resilience index (RI), Failure Index (FI) and reliability (R) of system were measured. Finally, an optimization procedure was done to make a water distribution network with highest resilience and lowest failure probability. All these procedures have been applied on a real network as WDS of Modena. It concluded that this method can be used for every water system without considering the type of failure. As a result, first scenario has a constant decreased and increased trend of RI and FI respectively because of diminishing of water level in tank. During second scenario, there is significant change after the tank will be empty (or it is broke). Third scenario is more like a real network with variable demand during a day. It was concluded that there is a minimum resilience parameter during day when a peak time of water demand expected. It can be justified that the reservoir and pump system had to sustain more pressure to satisfy the demands of junctions. Maximum resilience is related to night during a day with less demands and providing water by tank to other junctions. This modelling could be useful to optimize the dimensions and features of instruments to increase availability and reliability of system.

ABSTRACT DESIGN OF WATER DISTRIBUTION SYSTEM BY OPTIMIZATION USING RELIABILITY CONSIDERATIONS Akdogan, Tevfik Department of Civil Engineering Supervisor : Assoc. Prof. Dr. Nuri Merzi April 2005, 91 pages In spite of a wide research, design of water distribution networks are not realized using optimization techniques. One reason for this fact is, design of water distribution networks is evaluated, mostly, as a least-cost optimization problem where pipe diameters being the only decision variables. The other motivation for preferring the traditional modeling practice is that, existing optimization algorithms are not presented to the user as friendly as it should be. In fact, water distribution systems are very complex systems such that it is not easy to obtain least-cost design systems considering other constraints such as reliability, in addition to classical constraints related to hydraulic feasibility, satisfaction of nodal demands and requirement of nodal pressures. This study presents a user-friendly package concerning the design of water distribution networks by optimization using reliability considerations
this works employs the algorithm proposed by Goulter and Coals (1986). At the end, a skeletonized network design is offered
various costs are estimated in regard to the degree of reliability.

When designing urban water systems (i.e. water distribution and sewer systems) it is imperative that uncertainty is taken into consideration. However, this is a challenging problem due to the inherent uncertainty associated with both system loading requirements and the potential for physical components failure. It is therefore desirable to improve the reliability of each system in order to account for these uncertainties. Although it is possible to directly evaluate the reliability of a water distribution systems (WDS) (using reliability measures), the calculation processes involved are computationally intensive and therefore unsuitable for some state-of-the-art, iterative design approaches (such as optimisation). Consequently, interest has recently grown in the use of reliability indicators, which are simpler and faster to evaluate than conventional direct reliability methods. In this thesis, a novel measure (the RUF) is developed to quantify reliability in urban water systems with a view to enhance their robustness under a range of future scenarios (Policy Reform, Market Forces, Fortress World and New-Sustainability Paradigm). The considered four future scenarios were synthesized in the EPSRC supported multidisciplinary 4 year project: Urban Futures. Each investigated urban future scenario is characterised by a distinct household water demand and local demand distribution (emerging due to different urban forms evolving in future scenarios). In order to assess the impact of urban futures, RUF has been incorporated into Urban Water System (UWS) dynamic simulations for both WDSs and Foul Sewer Systems (FSSs) using open source codes of EPANET and SWMM. Additionally, in order to overcome extensive computational effort, resulting from the use of traditional reliability measures, a new holistic reliability indicator, the hydraulic power entropy (IHPE) has been developed and compared to existing reliability indicators. Additionally, the relationship between the new reliability indicator and the above mentioned RUF reliability measure is investigated. Results suggest that the magnitude of the IHPE in network solutions provides a holistic indication of the hydraulic performance and reliability for a WDS. However, the performance of optimal solutions under some Urban Futures indicates that additional design interventions are required in order to achieve desired future operation. This thesis also proposes a new holistic foul sewer system (FSS) reliability indicator (the IFSR). The IFSR represents sewer performance as a function of excess pipe capacity (in terms of available increase and also decrease in inflow). The indicator has been tested for two case studies (i.e. different sewer network layouts). Results suggest that the magnitude of IFSR has positive correlations with a number of identified key performance indicators (i.e. relating to capacity, velocity, blockages). Finally, an Integrated Design Approach (IDA) has been developed in order to assess the implications of applying design interventions on both a WDS and downstream FSS. The approach holistically considers present and future operation of each interconnected system. The approach was subsequently demonstrated using two proposed design interventions. Results suggest that, for the considered design interventions, there is trade-off between the simultaneous improvement of both WDS and FSS operation and reliability.

Recent technological developments are bringing about substantial changes that are converting traditional distribution networks into "smart" distribution networks. In particular, it is possible to observe seamless integration of Information and Communication Technologies (ICTs), including the widespread installation of automatic equipment, smart meters, etc. The increased automation facilitates active network management, interaction between market actors and demand side participation. If we also consider the increasing penetration of distributed generation, renewables and various emerging technologies such as storage and dynamic rating, it can be argued that the capacity of distribution networks should not only depend on conventional asset. In this context, taking into account uncertain load growth and ageing infrastructure, which trigger network investments, the above-mentioned advancements could alter and be used to improve the network design philosophy adopted so far. Hitherto, in fact, networks have been planned according to deterministic and conservative standards, being typically underutilised, in order for capacity to be available during emergencies. This practice could be replaced by a corrective philosophy, where existing infrastructure could be fully unlocked for normal conditions and distributed energy resources could be used for post fault capacity services. Nonetheless, to thoroughly evaluate the contribution of the resources and also to properly model emergency conditions, a probabilistic analysis should be carried out, which captures the stochasticity of some technologies, the randomness of faults and, thus, the risk profile of smart distribution networks. The research work in this thesis proposes a variety of post fault capacity services to increase distribution network utilisation but also to provide reliability support during emergency conditions. In particular, a demand response (DR) scheme is proposed where DR customers are optimally disconnected during contingencies from the operator depending on their cost of interruption. Additionally, time-limited thermal ratings have been used to increase network utilisation and support higher loading levels. Besides that, a collaborative operation of wind farms and electrical energy storage is proposed and evaluated, and their capacity contribution is calculated through the effective load carrying capability. Furthermore, the microgrid concept is examined, where multi-generation technologies collaborate to provide capacity services to internal customers but also to the remaining network. Finally, a distributed software infrastructure is examined which could be effectively used to support services in smart grids. The underlying framework for the reliability analysis is based on Sequential Monte Carlo Simulations, capturing inter-temporal constraints of the resources (payback effects, dynamic rating, DR profile, storage remaining available capacity) and the stochasticity of electrical and ICT equipment. The comprehensive distribution network reliability analysis includes network reconfiguration, restoration process, and ac power flow calculations, supporting a full risk analysis and building the risk profile for the arising smart distribution networks. Real case studies from ongoing project in England North West demonstrate the concepts and tools developed and provide noteworthy conclusions to network planners, including to inform design of DR contracts.

This dissertation is a systematic study of the 22kV Nelson Mandela Bay Municipality (NMBM) electricity power distribution network reliability evaluation and improvements to be applied. Reliability evaluation of electric power systems has traditionally been an integral part of planning and operation. Changes in the electricity utility, coupled with aging electrical apparatus, create a need for more realistic techniques for power system reliability modelling. This work presents a reliability evaluation technique that combines set literature and evaluation criteria. In analysing system reliability, this research takes into account the reasons for many outages and voltage dips and seeks to find mitigating approaches that are financially justified. The study analyses the power system in terms of the methodology developed, using power system reliability techniques, power quality evaluation, protection analyses and evaluating the network against maintenance interventions and programs, manpower availability and weather conditions contributing to the outages. In evaluating the power system various techniques are used to determine if the power network operates within the NRS standards, namely, reliability calculations, testing of protection equipment, interrogation of power quality instruments and modeling the network on Digsilent. This study will look at all the important factors influencing power system reliability, analysing the network in terms of the methodology and recommend improvements.

In this dissertation, we consider two specific types of problems over networks. In the first problem, we explore systematic methods to address some of the challenges in largescale maintenance planning in integrated chemical sites. In the second problem, we investigate different optimization model formulations for the design of flow distribution networks where the flow is potential-driven and nonlinearly related to the potential loss. Maintenance turnaround in the processing industry is a complex asset renewal project that includes huge capital expenditures and downtime losses. The option of deferring or rescheduling a turnaround project typically provides immediate financial relief from capital expenditure. However, the risk of running into site-wide disruptions in the form of unplanned events, yield, and reliability losses is not straightforward to assess. We propose mathematical optimization models to evaluate the risk of loss from turnaround deferrals in integrated sites and provide alternatives to reliably operate the site in a medium-term horizon. In the first chapter, we introduce the turnaround planning problem and the challenges it poses in integrated sites. We also introduce the background for the network design problem. In the second chapter, we study the financial impact of rescheduling turnarounds and the associated risk under unplanned outages. We compare the risk profiles presented by different production planning strategies. We propose a stochastic programming model for production planning that optimally builds up inventory ahead of time to hedge against production losses during unplanned outages. In the third chapter, we extend the stochastic optimization to handle a large set of scenarios and propose a Lagrangean decomposition method that improves a myopic production plan. The fourth chapter proposes a mixed-integer linear programming model that prescribes turnaround schedules when the underlying assets undergo yield loses and selectivity degradation. Here, we also study the impact of deferrals over a long-term horizon. The penultimate chapter addresses the nonlinear network design problem.The closing chapter summarizes the work and provides a few future directions. In the spirit of advancing manufacturing paradigms, the thesis supports investment in modeling efforts that address enterprise-wide planning problems.

The interruption cost for one hour of a petrochemical plant is 33 times higher than that of the average interruption cost for industrial plants across all industries. In addition to the high cost of loss of production, interruptions to the operations of petrochemical and gas-toliquid plants pose safety and environmental hazards. Thus it is necessary to better understand the reliability requirements of petrochemical and gas-to-liquid plants. This study investigated the reliability of electrical distribution networks used in petrochemical and gas-to-liquid plants compared to those used in other industrial plants. A model was developed that can be used to establish the adequacy of the reliability of a distribution network in terms of the components and network topologies used. This model was validated against data that had been collected by the IEEE and applied to an actual petrochemical plant. Over 19 years’ worth of data regarding the trips that have occurred on the distribution network of an existing petrochemical plant was collected and manipulated in order to calculate the reliability indices associated with the equipment used to make up thisRecommended Practice for the Design of Reliable Industrial and Commercial Power Systems. The cost of loss of production and the capital costs associated with increased reliability were calculated for a section of the existing petrochemical plant. The reliability associated with different network topologies that could possibly be used to supply power to this section of the plant were modelled using an appropriate software package. The resulting total cost of ownership over the life of the plant associated with each topology was then calculated in order to establish which network topology is the most appropriate for petrochemical and gas-to-liquid plants. It was concluded the components that affect the reliability of an industrial distribution network are different to those that affect a utility distribution network. These components were listed and compared. It was found that the reliability indices that were calculated for the components that affect the reliability of a petrochemical plant were similar to those provided by the IEEE. 17 out of 20 of the indices that were calculated were within the required factor of deviation. Generally the failure rates of components used in petrochemical plants were very similar to those given in the IEEE Gold Book, while the MTTR’s for the components used in petrochemical plants were found to be slightly better than those given in the IEEE Gold Book. The effect of network topology was found to be significant, with small changes in the topology of a network resulting in large variations in the reliability of the network. It was also found that the most appropriate type of network topology to use in the design of the electrical distribution network of a petrochemical plant is the dual radial network. This is the most conservative of the commonly used network topologies and is the one that is currently used in the existing plant that was studied. Due to the high cost of loss of production in petrochemical plants it was established that any incremental improvement in the reliability of the dual radial network would be beneficial to the total cost of ownership of such a plant. Such incremental improvement of the reliability of the distribution network could be cost effectively achieved by adopting a conservative maintenance strategy and the establishment of a conservative spares inventory. Before this study was undertaken, there was no literature around the reliability of electrical distribution networks that focused specifically on petrochemical and gas-to-liquid plants. This study produced a set of reliability indices and a model that electrical engineers can use in the reliability analysis of petrochemical and gas-to-liquid plants. Furthermore it shows that, because the cost of loss of production in petrochemical plants is so high, the most conservative distribution network design and maintenance philosophies should always be used. distribution network. These reliability indices were compared to those given by the IEEE
Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted

A stable and reliable electrical power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customer’s reliability requirements are met and that the regulators requirements are satisfied at the lowest possible cost. It is known fact around the world that 90% of the customer service interruptions are caused due to failure in distribution system. Therefore, it is worth considering reliability assessments as it provides an opportunity to incorporate the cost or losses incurred by the utilities customer as a result of power failure. This must be considered in the planning and operating practices. The system modelling and simulation study is carried out on one of the district’s distribution system which consists of 132 kV, 66 kV and 22 kV network in Aliwal North Sector ECOU. The reliability assessment is done on the 22, 66 and 132 kV system to assess the performance of the present system and also predictive reliability analysis for the future system considering load growth and system expansion. The alternative which gives low SAIDI, SAIFI and minimum breakeven costs is being assessed and considered. The reliability of 132 kV system could be further improved by constructing a new 132 kV line from a different source of supply and connecting with line coming from another district (reserve) at reasonable break even cost. The decision base could be further improved by having Aliwal North Sector context interruption cost. However, the historical data which may be used in Aliwal North Sector to acquire interruption costs from the customers are being proposed. The focus should be on improving the power quality on constrained networks first, then the reliability. Therefore for the Aliwal North power system network it is imperative that Eskom invest on the reliability of this network. This dissertation also analysed load reflected economic benefit versus performance expectations that should be optimized through achieving a balance between network performance (SAIDI) improvement, and total life cycle cost (to Eskom as well as the economy). Reliability analysis conducted in this dissertation used Aliwal North power system network as a case study; the results proved that the system is vulnerable to faults, planned and unplanned outages. Reliability evaluation studies were conducted on the system using DigSilent software in conjunction with FME. These two models gave accurate results with acceptable variance in most indices except for the ENS where the variance was quite significant. It can be concluded that DigSilent results are the most accurate results in all three reliability evaluation scenarios for the Aliwal North Power System, best interpretation being that of DigSilent.

Tools and algorithms are proposed that are useful for planning, designing, and operating a distribution network with a significant penetration of distributed generation (DG). In Task 1, a PV system simulation program is developed, which incorporates the most rigorous models for the calculation of insolation, module temperature, and DC and AC power output of a PV system. The effect of random inverter failures is incorporated in the model of a PV system, and a novel performance-derating coefficient is introduced. Furthermore, a novel inverter control algorithm is presented for systems with multiple inverters. The algorithm is designed to increase overall DC/AC conversion efficiency by selectively shutting down some of the inverters during periods of low insolation, thus forcing the remaining inverters to operate at higher efficiency. In Task 2, a procedure is developed to incorporate the uncertainties imposed by stochastic, renewable DG into the conventional tools for analysis of distribution systems. A clustering algorithm is proposed to reduce large input data sets that result from the interaction of stochastic processes that drive DG output with field measurements of feeder load profiles. In addition, a procedure is proposed to determine the boundary points of the original data set, which yield feeder extreme operating conditions. Finally, a Monte Carlo analysis using a reduced data set is presented, to determine the effects of deploying a large number of renewable DG systems on a distribution feeder. In Task 3, the reliability model of an asymmetric, three--phase, non-radial distribution feeder equipped with capacity-constrained DGs is developed and used to quantify the potential reliability improvements due to the intentional islanded operation of parts of the feeder. A procedure for finding optimal positions for DG and protection devices is presented using a custom-tailored adaptive genetic algorithm.

Detta examensarbete handlar om hur ett beredningsarbete genomförs från avtal och tillståndssökning till nätplanering och dimensionering av ett landsbygdsnät. Kraven på bra driftsäkerhet ökar eftersom elanvändning är en såpass viktig del av vårt samhälle. Stora störningar medför omfattande kostnader för eldistributionsföretag och kunder. För att öka driftsäkerheten och vädersäkra distributionsnät strävar eldistributionsföretagen att förlägga luftledningsnät till markkabel i landsbygden. Beredningen på ledningsnätet utförs i området Restenäs-Andorra utanför Ljungskile i Uddevalla kommun. Arbetet kommer att genomföras i samband med utbyggnation av kommunalt vatten- och avloppsnät för att minska kostnaderna på schakt samt påverkan på kund. Resultatet av beredningen omfattar en ny 10/0,4 kV nätstation, fyra nya kabelskåp samt 1200 meter 10 kV högspänningskabel och cirka 800 meter 400 V lågspänningskabel. Ledningsnätet har till största delen planerats så att samförläggning i samma schakt för vatten och avlopp sker så långt det har varit möjligt. Kabelskåp och nätstation är strategiskt utsatta för att skapa en bra nätstruktur och för att vara lättåtkomliga vid underhåll. En P2 kalkyl är upprättad för att få en överskådlig kostnad av projektet.
This thesis is about how preparation work is accomplished by contracts and permit search to network planning and dimensions. The requirement for reliable electric power increases because electricity is such an important part of our society. Large disruptions cause significant costs for electric distribution companies and customers. . To increase reliability and make the power grid weather secured, overhead lines are replaced with underground power cable. The preparation work is preformed to weatherproof the electric power grid in Restenäs-Andorra outside Ljungskile in the municipality of Uddevalla, by placing power cable in the ground instead of overhead power lines. The project will be implemented in connection with the development of communal water and sewer to reduce the cost of excavation. The result of this preparation work includes a new 10/0,4 kV substation, four cable boxes together with 1200 m of high voltage power cable and 800 m of low voltage power cable. The electric transmission network has been placed in the same excavation as water and sewer as long as possible. The substation and cable boxes are placed for easy access and to create a good mesh. A P2-calculation has been created to get an overview of the costs of the project.

U disertaciji je predstavljen pristup zasnovan na algoritmu mešovitog celobrojnog linearnog programiranja (MILP) za određivanje optimalnog broja, tipa i lokacije uređaja za automatizaciju distributivne mreže. Ugradnja različitih tipova nove opreme (daljinski kontrolisani reklozeri, sekcioneri i indikatori prolaska struje kvara) kao i relokacija postojeće opreme su istovremeno razmatrani. Prilikom određivanja optimalnog scenarija za automatizaciju, predloženi pristup uvažava troškove ispada potrošača/proizvođača usled trenutnih, kratkotrajnih i dugotrajnih ispada, najčešće korišćene pokazatelje pouzdanosti (SAIFI, SAIDI, MAIFI, i ASIDI) kao i troškove distributivnog preduzeća, asocirane uređajima za automatizaciju i ekipama koje su uključene u proces rešavanja prekida napajanja.Dakle, osnovni cilj ove disertacije je, da se napravi model zasnovan na mešovitom celobrojnom linearnom programiranju koji će omogućiti određivanje najboljeg scenarija za automatizaciju distributivne mreže u slučajevima kada se ocena kvaliteta isporuke definiše preko pokazatelja pouzdanosti, preko troškova usled prekida napajanja ili kombinacijom ova dva pokazatelja.
The dissertation presents a mixed integer linear programming (MILP) based approach for determining the optimal number, type and location of automation devices to be installed in the network by considering different types of devices simultaneously (remotely controlled circuit breakers/reclosers, sectionalizing switches, remotely supervised fault passage indicators). Simultaneously, it determines the new (optimal) locations of the automation devices that already exist in the network. In determining the most effective network automation scenario, the proposed approach takes into account the outage cost of consumers/producers due to momentary, short-term, and long-term interruptions, the commonly used network reliability indices (SAIFI, SAIDI, MAIFI, and ASIDI) as well as the cost of automation devices and the cost of crews. It provides the best network automation scenario in distribution systems if the network reliability indices are used for measuring the distribution system reliability, if cost of interruptions is defined to all consumers/producers, and if both approaches (criteria) are used.

The Swedish electricity market was de-regulated in 1996, followed by new laws and a new regulation applied to the natural monopolies of electrical distribution systems (EDS). These circumstances have motivated distribution systems operators (DSOs) to introduce more comprehensive analysis methods. The laws, the regulation and additional incentives have been investigated within this work and results from this study can be valuable when developing risk methods or other quantitative methods applied to EDS. This tendency is not unique for Sweden, the results from a comparative study of customer outage compensation laws between Sweden and UK is for example included.

As a part of investigating these incentives, studies of the Swedish regulation of customer network tariffs have been performed which provide valuable learning when developing regulation models in different countries. The Swedish regulatory model, referred to as the Network Performance Assessment Model (NPAM), was created for one of the first de-regulated electricity markets in the world and has a unique and novel approach. For the first time, an overall presentation of the NPAM has been performed including description of the underlying theory as a part of this work. However, the model has been met by difficulties and the future usage of the model is uncertain. Furthermore, the robustness of the NPAM has been evaluated in two studies with the main conclusion that the NPAM is sensitive toward small variations in input data. Results from these studies are explained theoretically investigating algorithms of the NPAM.

A pre-study of a project on developing international test systems is presented and this ongoing project aims to be a useful input when developing risk methods. An application study is included with the approach to systematically describe the overall risk management process at a DSO including an evaluation and ideas of future developments. The main objective is to support DSOs in the development of risk management, and to give academic reference material to utilize industry experience. An idea of a risk management classification has been concluded from this application study. The study provides an input to the final objective of a quantitative risk method.

Over the last several decades, electricity consumption and generation have continually grown. Investment in the Transmission and Distribution (T&D) infrastructure has been minimal and it has become increasingly difficult and expensive to permit and build new power lines. At the same time, a growing increase in the penetration of renewable energy resources is causing an unprecedented level of dynamics on the grid. Consequently, the power grid is congested and under stress. To compound the situation, the utilities do not possess detailed information on the status and operating margins on their assets in order to use them optimally. The task of monitoring asset status and optimizing asset utilization for the electric power industry seems particularly challenging, given millions of assets and hundreds of thousands of miles of power lines distributed geographically over millions of square miles. The lack of situational awareness compromises system reliability, and raises the possibility of power outages and even cascading blackouts. To address this problem, a conceptual Power Line Sensor Network (PLSN) is proposed in this research. The main objective of this research is to develop a distributed PLSN to provide continuous on-line monitoring of the geographically dispersed power grid by using hundreds of thousands of low-cost, autonomous, smart, and communication-enabled Power Line Sensor (PLS) modules thus to improve the utilization and reliability of the existing power system. The proposed PLSN specifically targets the use of passive sensing techniques, focusing on monitoring the real-time dynamic capacity of a specific span of a power line under present weather conditions by using computational intelligence technologies. An ancillary function is to detect the presence of incipient failures along overhead power lines via monitoring and characterizing the electromagnetic fields around overhead conductors. This research integrates detailed modeling of the power lines and the physical manifestations of the parameters being sensed, with pattern recognition technologies. Key issues of this research also include design of a prototype PLS module with integrated sensing, power and communication functions, and validation of the Wireless Sensor Network (WSN) technology integrated to this proposed PLSN.

This work deals with simulation of the urban distribution network reliability. For the evaluation of these networks are used indicators of reliability which are described in the first part. Next methods of analysis and posibilities for capabilities reliability simulation of distribution network are described. The third part deals with the real value of the reliability of electricity distribution in Italy. These values are presented in tables and graphs. The last part is a simulation of the urban network. Effect of different configurations on the reliability of electricity supply are studied. Sensitivity analysis is done for failure rate and proportional of the number of sampling points; the simulated values are fiven in tables and graphically.

Recently, the environmental impact of aircraft and rising fuel prices have become an increasing concern in the aviation industry. To address these problems, organizations such as NASA have set demanding goals for reducing aircraft emissions, fuel burn, and noise. In an effort to reach the goals, a movement toward more-electric aircraft and electric propulsion has emerged. With this movement, the number of critical electrical loads on an aircraft is increasing causing power system reliability to be a point of concern. Currently, power system reliability is maintained through the use of back-up power supplies such as batteries and ram-air-turbines (RATs). However, the increasing power requirements for critical loads will quickly outgrow the capacity of the emergency devices. Therefore, reliability needs to be addressed when designing the primary power distribution system. Power system reliability is a function of component reliability and redundancy. Component reliability is often not determined until detailed component design has occurred; however, the amount of redundancy in the system is often set during the system architecting phase. In order to meet the capacity and reliability requirements of future power distribution systems, a method for redundancy allocation during the system architecting phase is needed. This thesis presents an aircraft power system design methodology that is based upon the engineering decision process. The methodology provides a redundancy allocation strategy and quantitative trade-off environment to compare architecture and technology combinations based upon system capacity, weight, and reliability criteria. The methodology is demonstrated by architecting the power distribution system of an aircraft using turboelectric propulsion. The first step in the process is determining the design criteria which includes a 40 MW capacity requirement, a 20 MW capacity requirement for the an engine-out scenario, and a maximum catastrophic failure rate of one failure per billion flight hours. The next step is determining gaps between the performance of current power distribution systems and the requirements of the turboelectric system. A baseline architecture is analyzed by sizing the system using the turboelectric system power requirements and by calculating reliability using a stochastic flow network. To overcome the deficiencies discovered, new technologies and architectures are considered. Global optimization methods are used to find technology and architecture combinations that meet the system objectives and requirements. Lastly, a dynamic modeling environment is constructed to study the performance and stability of the candidate architectures. The combination of the optimization process and dynamic modeling facilitates the selection of a power system architecture that meets the system requirements and objectives.

Os avanços observados em Sistemas de Distribuição de Água vêm surgindo da necessidade de aumentar a eficiência, a qualidade e segurança do abastecimento de água aos consumidores. Dois desses avanços recentes que podem ser citados são a setorização e a quantificação da confiabilidade. O processo de setorização de um sistema de distribuição de água favorece a sua gestão, uma vez que possibilita maior controle da vazão distribuída e dos limites de fornecimento do serviço, entretanto pode implicar em restrições no abastecimento durante eventos de falhas ou emergências, sendo necessária a avaliação da confiabilidade. Diversos pesquisadores têm buscado uma metodologia coerente e adequada para quantificar a confiabilidade em sistemas de distribuição de água, muitos deles desenvolvendo métricas alternativas que visam simplificar esta definição. O presente trabalho visou investigar métricas alternativas de confiabilidade, propostas na literatura especializada, aplicando-as a estudos de caso para a rede original e após a setorização. Os resultados sugerem a viabilidade de utilização das métricas de confiabilidade como forma de avaliar diferentes níveis de setorização, no que diz respeito à vulnerabilidade do sistema.
Improvements upon Water Distribution Systems have been made under the urge of increasing efficiency, quality and security of water supply to its customers. A couple of recent breakthroughs on Water Distribution Network are partitioning and reliability. Water network partitioning enhances operational management, once it enables higher control of supplied flow and awareness of boundaries regarding each partition. Nevertheless, it can lead to supply restrictions under emergency and failure events, what may require reliability assessment. Several researchers have pursued consistent approach to quantify reliability of Water Distribution Network, many of them proposed surrogate measures which focused on simplifying its measurement. The aim of this work is to look into surrogate reliability measures proposed in the literature and applying them on case studies for its original layout and after proposed partitioning. The results implies the usage feasibility for the reliability measures as a way of evaluating different stages of partitioning, regarding system\'s vulnerability.

У дипломній роботі вирішено практичну проблему підвищення надійності системи електропостачання водогрійної котельні підприємства за рахунок застосування технічних і організаційних заходів на основі модернізації електричного обладнання та встановлення системи автоматичного введення резерву. Проведені розрахунки електричних навантажень силового та освітлювального обладнання водогрійної котельні підприємства для вибору технічних заходів забезпечення надійності роботи. Проведені розрахунки розподільної мережі та здійснено вибір комутаційного обладнання водогрійної котельні для забезпечення надійності. Встановлено пристрій автоматичного введення резерву, що дозволить спростити настроювання релейного захисту та забезпечити надійність. Запропоновані організаційно-технічні заходи підвищення надійності роботи водогрійної котельні.
In diploma thesis solved the practical problem of increasing the reliability of the power supply system of the boiler room due to the application of technical and organizational measures based on the modernization of electrical equipment and the installation of automatic reserve system. Performed calculations the electrical loads of power and lighting equipment of the boiler room for choice the technical measures to ensure the reliability of work. Performed calculations of the distribution network were made and the switching equipment of the boiler room was selected to ensure the reliability. Installed the automatic backup input device to simplify the relay protection setting and ensure reliability. The organizational and technical measures of increasing the reliability of the boiler room operation are offered.
Вступ …………………………………………………………………………….. 7 1 АНАЛІТИЧНА ЧАСТИНА .………………………………………..…….. 9 1.1 Аналіз системи електропостачання підприємства та технологічного процесу ……….……………………………………… ……………………….… 9 1.2 Аналіз технічних заходів підвищення надійності електропостачання промислових підприємств ……………………………............................……… 13 1.3 Висновки до першого розділу …………………………………………….... 17 2 НАУКОВО-ДОСЛІДНА ЧАСТИНА ………………………………………. 18 2.1 Методика оцінки показників надійності з врахуванням якості електроенергії …………………………………………………………………… 18 2.2 Формалізація методики комплексної оцінки ……………………………… 22 2.3 Аналіз алгоритму комплексної оцінки надійності електропостачання та якості електроенергії ……………………………………………………………. 25 2.4 Висновки до другого розділу ………………………………………………. 29 3 ТЕХНОЛОГІЧНА ЧАСТИНА ………..……………………………………. 30 3.1 Розрахунок навантаження котельні підприємства ….………………….…. 30 3.2 Розрахунок освітлення котельні ……………...………………...……..…... 36 3.3 Висновки до третього розділу ……………………………………………… 43 4 ПРОЕКТНО-КОНСТРУКТОРСЬКА ЧАСТИНА ………………..……… 45 4.1 Розрахунок розподільної мережі та вибір комутаційного обладнання водогрійної котельні …………………………….……………………………… 45 4.2 Вибір захисту мережі водогрійної котельні ……………………..………… 49 4.3 Вибір автоматичного контролю загазованості ………………………..…... 54 4.4 Захист ліній робочого живлення водогрійної котельні …...……...………. 56 4.5 Висновки до четвертого розділу ……………………………………....…… 58 5. СПЕЦІАЛЬНА ЧАСТИНА ………………………………………………… 59 5.1 Аналіз системи автоматичного введення резерву на підприємствах ……. 59 5.2 Вибір схеми автоматичного ввімкнення резерву …………………………. 63 5.3 Автоматичне регулювання коефіцієнта трансформації …………..………. 67 5.4 Висновки до п’ятого розділу ………………...…………………..…....…… 69 6 ОБГРУНТУВАННЯ ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ …………..… 71 6.1 Планування системи планово-попереджувальних ремонтів ……..……… 71 6.2 Планування чисельності ремонтно-експлуатаційного персоналу…...…… 73 6.3 Планування кошторису експлуатаційних витрат …………………………. 75 6.4 Планування собівартості передачі і розподілу електроенергії …………... 76 6.5 Заходи щодо зменшення затрат ……………………………………………. 77 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 79 7.1 Аналіз потенційних небезпек і шкідливих виробничих факторів ……….. 79 7.2 Забезпечення нормальних умов праці на підприємстві …………………... 80 7.3 забезпечення техногенної безпеки на підприємстві ……………………… 85 8 Екологія ……………………………………………………………………….. 90 8.1 Вплив переробки молочної сировини на навколишнє середовище ….…. 90 8.2 Основні методи очищення стічних вод в молочній промисловості …...... 92 ЗАГАЛЬНІ ВИСНОВКИ ДО ДИПЛОМНОЇ РОБОТИ ………...……….... 95 ПЕРЕЛІК ПОСИЛАНЬ …………………………..…..………………………. 96

Актуальність теми. Зважаючи на політику закладену в стратегії розвитку електроенергетичного сектору України, а саме інтеграцію до ENTSO-E, виникає значна кількість питань, які мають бути вирішені до моменту інтеграції. Одним з таких питання є підвищення надійності електричних мереж. Це питання частково може бути вирішено, за рахунок оптимального секціонування повітряних розподільчих мереж 6 - 20 кВ в умовах застосування Smart Grid. У магістерській дисертації представлено варіант визначення оптимального секціонування розподільчих мереж 6 - 20 кВ, за допомогою покрашеної методики розрахунку на основі «жадібного» алгоритму, представлений аналіз комерціалізації запропонованої методики та проаналізовані соціально – економічні вигоди від його впровадження. Метою дисертаційної роботи є: проведення аналізу оптимального секціонування повітряних розподільчих мереж 6 - 20 кВ в умовах застосування Smart Grid технологій. Для досягнення мети були поставлені та вирішені такі питання: • проведений аналіз особливостей та шляхів підвищення надійності функціонування розподільних мереж напругою 6 - 20 кВ в України та світі; • розглянуті перспективи впровадження технологій Smart Grid з метою підвищення надійності розподільчих мереж; • вдосконалена методика оптимального секціонування розподільчих мереж 6 - 20 кВ; • розроблені пропозиції практичної реалізації (комерціалізації) розробленої методики та перспективи її подальшого розвитку. Об’єктом дослідження є процеси функціонування повітряних розподільчих мереж напругою 6 - 20 кВ в умовах застосування Smart Grid технологій. Предметом дослідження є особливості впливу Smart Grid технологій на надійність електропостачання споживачів. Метод дослідження. Для вирішення поставлених завдань у дисертаційній роботі було застосовано методи оптимального секціонування повітряних розподільчих мереж в умовах врахування нормування показників надійності. За основу для розрахунку оптимального секціонування розподільчих мереж був використаний «жадібний алгоритм». Основні наукові результати роботи включають в себе: - набула подальшого розвитку методика оптимального секціонування повітряних розподільних мереж, що дозволило вирішувати задачу в умовах широкого використання засобів розосередженої генерації та узгодження роботи окремих комутаційно-захисних апаратів, що дозволяє підвищити надійність роботи інтегрованих систем електропостачання, які при цьому утворюються; - вперше здійснено аналіз можливості та доцільності впровадження технології SOP в розподільних мережах в плані підвищення надійності їх роботи, що надає можливість більш широкого й ефективного використання розосередженої генерації; - удосконалено структуру управління РМ на базі OMS, що поряд з підвищенням надійності електропостачання надає можливість одночасного зменшення втрат електричної енергії. Практичне значення одержаних результатів полягає в: - розробці програмного забезпечення для вирішення задачі оптимального секціонування розподільних мереж з інтегрованими в них джерелами розосередженої генерації та при можливості використання широкого спектру комутаційно-захисних пристроїв; - використанні, так званого, «жадібного» алгоритму, що без втрати ефективності отриманого результату в декілька разів скоротити час на вирішення задачі оптимального секціонування розподільних мереж.
Relevance of the topic. Given the policy set out in Ukraine's electricity sector development strategy, namely integration into ENTSO-E, a number of issues arise that need to be addressed by the time of integration. One such issue is to increase the reliability of electrical networks, which can be partially solved via the optimal sectionalizing of overhead distribution networks 6 - 20 kV in terms of Smart Grid. The master's dissertation presents a way of determining the optimal sectionalizing of 6 - 20 kV distribution networks, using an improved calculation method based on the "greedy" algorithm, presents an analysis of the commercialization of the proposed method and analyzes the socio-economic benefits of its implementation. The purpose of the work: analysis of the optimal sectionalizing of overhead distribution networks 6 - 20 kV in terms of Smart Grid technologies. To achieve this goal, the following issues were considered and resolved: • the analysis of features and ways to increase the reliability of functioning of distribution networks with a voltage of 6 - 20 kV in Ukraine and the world was carried out; • the prospects of introduction of Smart Grid technologies in order to increase the reliability of distribution networks were considered; • the method of optimal sectionalizing of 6 - 20 kV distribution networks was improved; • a proposal of practical realization (commercialization) of the developed technique and prospects of its further development was made. The object of the study is the processes of functioning of overhead distribution networks with a voltage of 6 - 20 kV in the conditions of application of Smart Grid technologies. The subject of the study is the features of the influence of Smart Grid technologies on the reliability of electricity supply to consumers. Research methods. To solve the set tasks, the methods of optimal sectioning of overhead distribution networks were applied, taking into account the standardization of reliability indicators. The “greedy algorithm” was used as a basis for calculation of the optimal partitioning of distribution networks. The main scientific results of the work include: • the technique of optimal sectioning of overhead distribution networks was further developed, which made it possible to solve the problem in the conditions of widespread use of distributed generation means and coordination of the operation of individual switching-protective devices, which makes it possible to increase the reliability of the integrated power supply systems, which are formed in this case; • for the first time, an analysis was made of the possibility and feasibility of introducing SOP technology in distribution networks in terms of increasing the reliability of their operation, it makes it possible to use more widely and efficiently distributed generation; • improved control structure of distribution network based on OMS, which, along with increasing the reliability of power supply, provides an opportunity to simultaneously reduce losses of electrical energy. The practical significance of the results obtained is: • development of software for solving the problem of optimal sectionalizing of distribution networks with integrated sources of distributed generation and, if possible, using a wide range of switching protection devices; • using the so-called "greedy" algorithm, without losing the effectiveness of the result obtained, to reduce several times the time for solving the problem of optimal partitioning of distribution networks.

This diploma thesis aims to briefly interpret problems relating to continuity of distribution of electrical energy in a distribution network of low voltage. It also mentions methods of calculation of a distribution system´s reliability which are the most used in practice. Next, there is a chapter dedicated to how distribution networks are projected and operated in the Czech Republic and in the United Kingdom. Based on experiences with meshed networks operation this thesis designs protection of meshed distribution network of low voltage. In the end, a non-sequential method of Monte Carlo is used to calculate System Average Interruption Index (SAIDI) and System Average Interruption Frequency index (SAIFI).

The aim of this master’s thesis is calculation and analysis of reliability indicators of the company E.ON Česká republika, s.r.o. distribution network in the south Moravia territory (area of former Jihomoravská energetika) for the period of one year, from 1st November 2008 to 31st October 2009. We consider events incurred on overhead or underground lines of level of high voltage or directly connected with these lines. Events originated from extensive disaster interruption of electric energy supply caused by particularly unfavourable external effects are not considered, because network components can not be efficiently dimensioned on those influences. Known aspects of the events are time of origin, time duration, place and cause of failure inception. Analysis of reliability indicators is accomplished according to different point of view. The first aspect is the hours of day, during which the event lasted. The second aspect is the hours of day, during which the event incurred. The third one focuses component pointed as reliable for the origin of the event. The last standpoint is percentage load of the line outlet, on which the event occurred. We can ordain this load as the proportion of current flowing through the line outlet in the time of event inception and of the value of maximum current set up on the protection of the line outlet. Indications mentioned in the last sentence were searched in the dispatcher centre thanks to graphical interface of application RIS JME Brno. In the theoretical part of the work there is described the structure of distribution network and its fundamental influence on the continuity of electric energy supply, the ways of evaluation and increasing of electric energy supply reliability, regulation of continuity of electric energy supply with emphasis on regulation in the Czech Republic valid until 26th February 2010 and since 27th February 2010. The last theoretical part focuses on definition of failure and differentiation of failures according to various aspects.

In recent years, water utilities have placed a greater emphasis on the reliability and resilience of their water distribution networks. This focus has increased due to the continuing aging of such infrastructure and the potential threat of natural or man-made disruptions. As a result, water utilities continue to look for ways to evaluate the resiliency of their systems with a goal of identifying critical elements that need to be reinforced or replaced. The simulation of pipe breaks in water reliability studies is traditionally modeled as the loss of a single pipe element. This assumes that each pipe has an isolation valve on both ends of the pipe that can be readily located and operated under emergency conditions. This is seldom the case. The proposed methodology takes into account that multiple pipes may be impacted during a single failure as a result of the necessity to close multiple isolation valves in order to isolate the “segment” of pipes necessary to contain the leak. This document presents a simple graphical metric for use in evaluating the performance of a system in response to a pipe failure. The metrics are applied to three different water distribution systems in an attempt to illustrate the fact that different pipe segments may impact system performance in different ways. This information is critical for use by system managers in deciding which segments to prioritize for upgrades or replacement.

The overall aim of this research has been to develop new algorithms and computer software that may be used to assess the reliability of water distribution systems. Such a tool can be used by design engineers to create systems which are both economical in total cost commensurate with meeting targets for a specified level of reliability. The introduction describes how water supply and distribution systems are normally designed, what they comprise and problems associated with failure or lack of availability of an adequate supply to the end user. This is followed by a resume of current methods and algorithms for the analysis of networks and a detailed examination of the previous work on network optimisation and reliability. Three main algorithms exist for the analysis of water networks. These are the Hardy-Cross methods, the Newton-Raphson methods and the Linear method. A computer program based on the Linear method, which is known to be the most reliable, is proposed for the hydraulic analysis part of the present work. With respect to reliability, a full discussion of the topic, including all the various factors which influence it such as the stochastic nature of customer demands, the apparently random occurrence of pipe breakages and the concept of repair time, is presented. A reliability analysis model, that incorporates simultaneously the three reliability factors mentioned, for the assessment of nodal and system availabilities, is proposed, from which an efficient computer program has been developed and tested. Two models for the design of optimal water distribution systems, based on reliability criteria, have been developed, programmed and tested. The first model makes use of the entropy principle for producing 'reliable' distributions of flow and the Linear Programming technique is used for computation of the least cost design. In the second model, however, a Genetic Algorithm procedure, that incorporates the new reliability analysis model and which is superior to other models has been formulated. The thesis concludes with a comparison between the two methods formulated as a result of this research and applied to realistic practical systems, plus suggestions for further work to improve the optimisation of water distribution networks.

A completely satisfactory water distribution network should fulfill its basic requirements such as providing the expected quality and quantity of water with the desired residual pressures during its lifetime. A water distribution network should accommodate the abnormal conditions caused by failures. These types of failures can be classified into two groups
mechanical failures and hydraulic failures. Mechanical failure is caused due to malfunctioning of the network elements such as pipe breakage, power outage and pump failure. On the other hand, hydraulic failure, considers system failure due to distributed flow and pressure head which are inadequate at one or more demand points.This study deals with the calculation of the hydraulic system reliability of an existing water distribution network regarding the Modified Chandapillai model while calculating the partially satisfied nodes. A case study was carried out on a part of Ankara Water Distribution Network, N8-1. After the modeling of the network, skeletonization and determination of nodal service areas were carried out. The daily demand curves for the area were drawn using the data that were taken from SCADA of the water utility. The daily demand curves of different days were joined and one representative mean daily demand curve together with the standard deviation values was obtained. The friction coefficient values of the pipes and storage tank water elevation were taken as other uncertainty parameters for the model. Bao and Mays (1990) approach were carried together with the hydraulic network solver program prepared by Nohutcu (2002) based on Modified Chandapillai model. The sensitivity analysis for the effects of system characteristics and model assumptions were carried out to see the effects of the parameters on the calculations and to investigate the way of improving the hydraulic reliability of the network. The storage tank should be located at a higher level for improving the reliability of the network. Also having the storage tank water level nearly full level helps in improving the reliability in daily management. Moreover, the hydraulic system reliability is highly dependent on the pumps as the lowest reliability factors were the ones with the no pump scenarios. Determining the required pressures for nodes are very important since they are the dominant factors that effects the reliability calculations. On the other hand, friction coefficient parameters and type of probability distribution function do not have dominant effect on the results. Results of this study were helpful to see the effects of different parameters on the hydraulic reliability calculations and for assessment of the methods for improving the reliability for the network.

The complexity of many failure mechanisms and variations in component manufacture often make standard probability distributions inadequate for reliability modeling. Finite mixture distributions provide the necessary flexibility for modeling such complex phenomena but add considerable difficulty to the inference. This difficulty is overcome by drawing an analogy to neural networks. With appropropriate modifications, a neural network can represent a finite mixture CDF or PDF exactly. Training with Bayesian Regularization gives an efficient empirical Bayesian inference of the failure time distribution. Training also yields an effective number of parameters from which the number of components in the mixture can be estimated. Credible sets for functions of the model parameters can be estimated using a simple closed-form expression. Complete, censored, and inpection samples can be considered by appropriate choice of the likelihood function. In this work, architectures for Exponential, Weibull, Normal, and Log-Normal mixture networks have been derived. The capabilities of mixture networks have been demonstrated for complete, censored, and inspection samples from Weibull and Log-Normal mixtures. Furthermore, mixture networks' ability to model arbitrary failure distributions has been demonstrated. A sensitivity analysis has been performed to determine how mixture network estimator errors are affected my mixture component spacing and sample size. It is shown that mixture network estimators are asymptotically unbiased and that errors decay with sample size at least as well as with MLE.

This thesis presents the RF and mechanical design of a metal-to-metal contact RF MEMS switch. Metal-to-metal contact RF MEMS switches are especially preferred in low frequency bands where capacitive switches suffer from isolation due to the limited reactance. Frequency band of operation of the designed switch is from DC to beyond X-band. Measured insertion loss of the structure is less than 0.2 dB, return loss is better than 30 dB, and isolation is better than 20 dB up to 20 GHz. Isolation is greater than 25 dB below 10 GHz. Hence, for wideband applications, this switch offers very low loss and high isolation. Time domain measurement is necessary for the investigation of the dynamic behavior of the devices, determination of the &lsquo
pull in&rsquo
and &lsquo
pull out&rsquo
voltages of the membranes, switching time and power handling of the devices. Also, failure and degradation of the switches can be monitored using the time domain setup. For these purposes a time domain setup is constructed. Moreover, failure mechanisms of the RF MEMS devices are investigated and a power electronic circuitry is constructed for the biasing of RF MEMS switches. Advantage of the biasing circuitry over the direct DC biasing is the multi-shape, high voltage output waveform capability. Lifetimes of the RF MEMS devices are investigated under different bias configurations. Finally, for measurement of complicated RF MEMS structures composed of large number of switches, a bias waveform distribution network is constructed where conventional systems are not adequate because of the high voltage levels. By this way, the necessary instrumentation is completed for controlling a large scale RF MEMS system.

Reliability of power system depends on the up to date knowledge of the system state for operation and control. Shifting from large conventional production units to small and/or renewable DG connected in the distribution network means more control and monitoring system require for the Distributed System operator caused by active generation and reactive power consumption by DG. Therefore it is interesting to explore concepts in fast and scalable topology processors for monitoring and controlling applications such as state estimation, OPF and static and dynamic stability assessment in electrical distribution network the need is evident to validate with meshed network to analyze the overall performance of the proposed methodology\Decentralized Topology Inference of Electrical Distribution Networks". The topology inference processor is require minimal prior knowledge of electrical network structure by taking a series of time-stamped process measurements from each bays of each substation in the network and distinguished between connected and unconnected bays. This master thesis project has implemented an IEEE reference electric power distribution network in Simulink platform , integrating the reference electrical network with the Java-based multi agent topology inference application as well as having investigated. This project has included work in the real time simulation of a standard IEEE reference distribution network, OPC server interfacing between reference model and the topology inference application, testing and analysis of the application. The reference model is selected to provide a sucient case to analyses and validate the methodology.

Although power system reliability analysis is a mature research area, there is a renewed interest in updating available network models and formulating improved reliability assessment procedures. The main driver of this interest is the current transition to a new flexible and actively controlled power supply system with a high penetration of distributed generation (DG) and energy storage (ES) technologies, wider implementation of demand-side management (DSM) and application of automated control, monitoring, protection and communication infrastructures. One of the aims of this new electricity supply network (’the smart grid’) is an improved reliability and power quality performance, realised through the delivery of an uninterrupted and high-quality supply of electrical energy. However, there is currently no integrated methodology to measure the effects of these changes on the overall system reliability performance. This PhD research aims to update the standard power system simulation engine with improved numerical software models offering new capabilities for the correct assessment of quality of supply in future electricity networks. The standard reliability analysis is extended to integrate some relevant power quality aspects, enabling the classification of short and long supply interruptions by the correct modelling of network protection and reconfiguration schemes. In addition, the work investigates the formulation and analysis of updated reliability indicators for a more accurate validation and benchmarking of both system and end-user performance. A detailed database with typical configurations and parameters of UK/European power systems is established, providing a set of generic models that can correctly represent actual distribution networks supplying a mix of residential, commercial and industrial demand for different load sectors. A general methodology for reducing system complexity by calculating both electrical and reliability equivalent models of LV and MV distribution networks is also presented. These equivalent models, based on the aggregation of individual component models, help to reduce calculation times while preserving the accuracy assessment of network’s reliability performance at bulk supply points. In addition, the aggregated counterparts (same and mixed-type) of different ’smart’ component models (DG, ES and DSM) are also included in the analysis, showing how their co-ordinated implementation and control could improve quality of supply. Conventional reliability assessment procedures are also extended in this thesis to include accurate reliability equivalent models, network contingency statistics, actual load profiles and empirical fault probability distributions, which are employed to assess the frequency and duration of interruptions in the supply system for different scenarios. Both analytical and probabilistic simulation techniques (Monte Carlo method) are developed to include up-to-date security of supply legislation, introducing a new methodology for calculating the standard set of indices reported annually to energy regulators.

The deregulation of UK power distribution market started in 1990. Due to the drivers from the regulator, DNOs need to invest appropriately and optimise network operation by innovations to satisfy the targets set by the industry regulator, the Office of Gas and Electricity Markets (Ofgem). Reduction of network losses and improvement of reliability of supply to customers are extremely important for distribution network operators (DNOs) to take into account when designing and operating their networks. They are important because of the need to minimise wasted energy and carbon emissions and to provide customers with an adequate level of service. Moreover, in Great Britain, Ofgem has implemented financial incentives with respect to these things. This thesis describes an investigation of methods these have been developed to help DNOs improve their performance with respect to two particular incentives. The first relates to network losses; the second relates to reliability of supp ly to consumers. A new loss optimisation algorithm by feeder reconfiguration based on graph theory and topology search techniques is developed in this thesis. By means of a directed exhaustive search of network configurations (and unlike a number of previous methods in the literature that rely on heuristics), this algorithm can find the global optimal result. In addition the results of the algorithm can be readily used in the solution of a multiobjective optimisation problem (optimisation both of P loss and reliability in this thesis). A new reliability evaluation and optimisation algorithm developed in this thesis is based on topology search techniques. This algorithm can not only calculate the reliability indices but, unlike previous approaches emerging from the academic literature, also determines the restoration method of each fault affected bus for a specific fault which is critical to determining the restoration time following a fault. The loss and reliability optimisation is developed to optimise both network's P loss and reliability performance. It can also provide a number of options regarding the configuration of the network, and suggests which are optimal with respect to either incentive or to both of them combined. An analytical tool developed to perform these algorithms is described. Case studies are presented to illustrate how DNOs can use the analytical methods and tool developed in this thesis to accurately calculate the impacts of design or operation decisions on losses and reliability and thereby help in the identification of cost-effective network operation actions and longer-term investments.

The goal of this thesis is to design measures of the distribution network in Brno to ensure a supply of electricity to its consumers in required quantity, quality and reliability. This project will be solved in the program called PAS DAISY Off-Line v.4.00 Bizon. At first we make an analysis of the steady state of the distribution network. We check load of transformer stations 110/22 kV, overhead and cable lines if they operate in allowed limits. Then we complete or correct reserved power drains of big consumers of electricity in the model of distribution system. From the calculation of the steady state of the distribution network we will probably find out that some parts of the system are overloaded. Therefore we suggest changes for it (like switching over circuits, installation of new transformer stations and circuits), which should ensure safety and reliability of operations in the distribution system.

Aujourd’hui les réseaux électriques sont exploités dans un marché dérégulé. Les gestionnaires des réseaux électriques sont tenus d’assurer un certain nombre de critères de fiabilité et de continuité du service, tout en minimisant le coût total consacré aux efforts effectués pour maintenir la fiabilité des installations. Il s’agit de trouver une stratégie, qui répond à plusieurs exigences, comme :le coût, les performances, la législation, les exigences du régulateur, etc. Cependant, le processus de prise de décision est subjectif, car chaque participant ramène sa contribution sur base de sa propre expérience. Bien que ce processus permette de trouver la « meilleure » stratégie, cette dernière n’est pas forcément la stratégie « optimale ». Ce compromis technico-économique a sensibilisé les gestionnaires des réseaux électriques à la nécessité d’un recours à des outils d’aide à la décision, qui doivent se baser sur des nouvelles approches quantitatives et une modélisation plus proches de la réalité physique.

Cette thèse rentre dans le cadre d’un projet de recherche lancé par ELIA, et dénommé COMPRIMa (Cost-Optimization Models for the Planning of the Renewal, Inspection, and Maintenance of Belgian power system facilities). Ce projet vise à développer une méthodologie qui permet de modéliser une partie du réseau électrique de transport (par les réseaux de Petri stochastiques) et de simuler son comportement dynamique sur un horizon donné (simulation de Monte Carlo). L’évaluation des indices de fiabilité permet de comparer les différents scénarios qui tentent d’améliorer les performances de l’installation. L’approche proposée est basée sur la stratégie RCM (Reliability-Centered Maintenance).

La méthodologie développée dans cette thèse permet une modélisation plus réaliste du réseau qui tient compte, entre autres, des aspects suivants :

- La corrélation quantitative entre le processus de maintenance et le processus de vieillissement des composants (par un modèle d’âge virtuel) ;

- Les dépendances liées à l’aspect multi-composant du système, qui tient compte des modes de défaillance spécifiques des systèmes de protection ;

- L’aspect économique lié à la stratégie de maintenance (inspection, entretien, réparation, remplacement), aux coupures (programmées et forcées) et aux événements à risque (refus disjoncteur, perte d’un client, perte d’un jeu de barres, perte d’une sous-station, etc.).
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017. Дисертація присвячена дослідженню проблемних питань, пов'язаних із розробкою інформаційних систем моніторингу стану повітряних ліній в умовах ожеледоутворення, що забезпечують зниження відмов у електропостачанні шляхом надання електротехнічному персоналу завчасної інформації про момент ожеледоутворення. У роботі представлено критичний аналіз існуючих систем моніторингу ожеледоутворення. З метою усунення їх недоліків, запропоновано нові первинний інформативний параметр і вимірювальний перетворювач ожеледоутворення. Для цього вдосконалено нестаціонарну теплову модель ділянки проводу, на основі якої, для заданих умов, досліджено інформативний параметр. Розроблено модель прогнозування динамічного ряду інформативного параметра, що дозволяє оцінити надійність отриманого прогнозу. Проведено необхідні експериментальні дослідження. Обґрунтовано архітектуру системи моніторингу стану повітряних ліній електропередавання. Для технічної реалізації системи моніторингу стану обґрунтовано структуру та будову вимірювального перетворювача блоку збору даних. Розроблено чисельну модель вимірювального перетворювача у програмному комплексі SolidWorks, що поєднує в собі розв'язок гідродинамічної та теплової задач. Також розроблено макет пристрою блоку збору даних системи моніторингу.
Thesis for getting scientific degree of the Candidate of technical science on the specialty 05.14.02 – electric power stations, network and system. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2017. The thesis is devoted to the study of problematic issues related to the development of information systems for monitoring the state of overhead power lines in icing conditions, ensuring reduction of failures in the power supply, through the provision of electrical engineering personnel advance information about the icing point. The work presents a critical analysis of existing ice formation monitoring systems. In order to correct their deficiencies, proposed a new primary informative parameter and an ice accretion measuring transducer. To this end, the transient thermal model of the wire section of overhead power lines was improved. And based on this improved model, for the given conditions, an informative parameter was researched. The developed model for forecasting the time series of the informative parameter let to estimate the reliability of the obtained forecast. The necessary experimental studies were carried out. Architecture of the monitoring system of overhead power lines was justified. For the technical implementation of information monitoring system is justified the structure and a design of the measurement transducer of data collection unit. In this work were developed the numerical model in the SolidWorks software package, which combines the solution of the hydrodynamic and thermal problems. Also, was developed the device layout for the data acquisition unit of the monitoring system.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.14.02 – електричні станції, мережі і системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017. Дисертація присвячена дослідженню проблемних питань, пов'язаних із розробкою інформаційних систем моніторингу стану повітряних ліній в умовах ожеледоутворення, що забезпечують зниження відмов у електропостачанні шляхом надання електротехнічному персоналу завчасної інформації про момент ожеледоутворення. У роботі представлено критичний аналіз існуючих систем моніторингу ожеледоутворення. З метою усунення їх недоліків, запропоновано нові первинний інформативний параметр і вимірювальний перетворювач ожеледоутворення. Для цього вдосконалено нестаціонарну теплову модель ділянки проводу, на основі якої, для заданих умов, досліджено інформативний параметр. Розроблено модель прогнозування динамічного ряду інформативного параметра, що дозволяє оцінити надійність отриманого прогнозу. Проведено необхідні експериментальні дослідження. Обґрунтовано архітектуру системи моніторингу стану повітряних ліній електропередавання. Для технічної реалізації системи моніторингу стану обґрунтовано структуру та будову вимірювального перетворювача блоку збору даних. Розроблено чисельну модель вимірювального перетворювача у програмному комплексі SolidWorks, що поєднує в собі розв'язок гідродинамічної та теплової задач. Також розроблено макет пристрою блоку збору даних системи моніторингу.
Thesis for getting scientific degree of the Candidate of technical science on the specialty 05.14.02 – electric power stations, network and system. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2017. The thesis is devoted to the study of problematic issues related to the development of information systems for monitoring the state of overhead power lines in icing conditions, ensuring reduction of failures in the power supply, through the provision of electrical engineering personnel advance information about the icing point. The work presents a critical analysis of existing ice formation monitoring systems. In order to correct their deficiencies, proposed a new primary informative parameter and an ice accretion measuring transducer. To this end, the transient thermal model of the wire section of overhead power lines was improved. And based on this improved model, for the given conditions, an informative parameter was researched. The developed model for forecasting the time series of the informative parameter let to estimate the reliability of the obtained forecast. The necessary experimental studies were carried out. Architecture of the monitoring system of overhead power lines was justified. For the technical implementation of information monitoring system is justified the structure and a design of the measurement transducer of data collection unit. In this work were developed the numerical model in the SolidWorks software package, which combines the solution of the hydrodynamic and thermal problems. Also, was developed the device layout for the data acquisition unit of the monitoring system.

Maintaining and operating manual main distribution frames is labour-intensive. As a result, Automated Main Distribution Frames (AMDFs) have been developed to alleviate the task of maintaining subscriber loops. Commercial AMDFs are currently employed in telephone exchanges in some parts of the world. However, the most significant factors limiting their widespread adoption are costeffective scalability and reliability. Therefore, an impelling incentive is provided to create a simulation framework in order to explore typical implementations and scenarios. Such a framework will allow the evaluation and optimisation of a design in terms of both internal and external redundancies. One of the approaches to improve system performance, such as system reliability, is to allocate the optimal redundancy to all or some components in a system. Redundancy at the system or component levels can be implemented in one of two schemes: parallel redundancy or standby redundancy. It is also possible to mix these schemes for various components. Moreover, the redundant elements may or may not be of the same type. If all the redundant elements are of different types, the redundancy optimisation model is implemented with component mixing. Conversely, if all the redundant components are identical, the model is implemented without component mixing. The developed framework can be used both to develop new AMDF architectures and to evaluate existing AMDF architectures in terms of expected lifetimes, reliability and service availability. Two simulation models are presented. The first simulation model is concerned with optimising central office equipment within a telephone exchange and entails an environment of clients utilising services. Currently, such a model does not exist. The second model is a mathematical model incorporating stochastic simulation and a hybrid intelligent evolutionary algorithm to solve redundancy allocation problems. For the first model, the optimal partitioning of the model is determined to speed up the simulation run efficiently. For the second model, the hybrid intelligent algorithm is used to solve the redundancy allocation problem under various constraints. Finally, a candidate concept design of an AMDF is presented and evaluated with both simulation models.
Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted

Актуальність теми. Проблема надійного забезпечення споживачів електричною енергією є однією з найважливіших при вирішенні задач проектування та експлуатації систем електропостачання (СЕП) міст, промислових підприємств та окремих об’єктів. Вимоги з питань надійного електропостачання визначаються відповідними нормативними документами і мають бути беззаперечно враховані і виконані. І споживачам, і підприємствам електричних мереж завдається істотна шкода внаслідок вимушених перерв живлення. На будь-якому рівні інфраструктури електроенергетики забезпечення надійності електропостачання споживачів завжди було важливою науково-технічною проблемою, дослідженню і вирішенню якої присвячено численні роботи вчених та науководослідних і проектних організацій (КПІ, ТГУ, МЕІ та ін.). Основні напрямки досліджень: отримання, систематизація та опрацювання статистичної інформації, оцінювання її достовірності; розроблення адекватних розрахункових моделей з оцінювання та оптимізації надійності елементів, схем та системи електропостачання вцілому; визначення ефективних системних показників надійності та методів їх розрахунку і прийняття оптимальних рішень; економічні показники втрат споживачів та електропостачальних організацій від недоотримання та недовідпуску електричної енергії. Загальний аналіз роботи електричних мереж на даний момент показує, що технічний їх стан є незадовільним, спостерігається старіння обладнання, що прогресує, та, відповідно, зниження показників надійності елементів та систем електропостачання. Більш того, постійне ускладнення структури та поява нових елементів мереж потребує розвитку теорії вирішення задач оцінювання і підвищення надійності енергозабезпечення. Відповідно, з’являється необхідність розробки методології прийняття рішень на стадіях будівництва, реконструкції та експлуатації розподільних електричних мереж (РЕМ). При оцінюванні надійності систем електрозабезпечення споживачів зазвичай розглядають такі показники, як ймовірність випадкової події перерви в електропостачанні, випадкова величина недовідпуску електричної енергії споживачам (що мала місце за результатами подій, що відбулися, або прогнозована, розрахункова), реальні або прогнозовані збитки споживачів або електропостачальної організації. Проведений аналіз свідчить про те, що показники пошкоджуваності елементів розподільних мереж та значення збитків, що несуть споживачі, практично завжди залежать від конкретних умов. Більш того, навіть для одних і тих же умов експлуатації мають місце коливання інтегрованих за рік показників пошкоджуваності елементів мереж в рази, тобто більш ніж на 100 відсотків. Це свідчить про те, що в умовах кожної системи необхідно проводити аналіз даних аварійної статистики з визначенням реальних факторів впливу на вихідні розрахункові показники (довжин ліній, схемних рішень, кількості вузлів та інші) Так само має розглядатись і враховуватись при визначені збитків (що мали місце або прогнозованих) їх суттєва залежність від сезону, часу доби, а також в значній мірі – від того, скільки часу тривала перерва в живленні споживача. Аналіз статистичної інформації свідчить про суттєву нестабільність, нестаціонарність показників, що використовуються при формуванні розрахункових моделей, оцінюванні надійності схем. Системний підхід до питання розроблення більш ефективних моделей та методів оцінки надійності розподільних мереж є як ніколи актуальним. Мета та завдання дослідження. Метою роботи є формування методології оцінювання достовірності вихідних параметрів надійності РЕМ, що визначаються по обмеженим обсягам даних аварійної статистики, та впливу прийнятих розрахункових моделей на результати обчислення показників надійності мережі. Відповідно до мети, в роботі вирішувались наступні завдання:  аналіз інформації щодо функціонування розподільних електричних мереж;  оцінка достовірності вихідних показників надійності, визначення і урахування впливових факторів, законів розподілу випадкових величин;  вибір та порівняння розрахункових моделей оцінювання надійності розподільних електричних мереж напругою 6-10 кВ на підставі опрацювання отриманих даних аварійної статистики;  послідовність реалізації системного підходу до аналізу статистичної інформації та здійсненню оцінювання надійності електропостачання. Об’єкт дослідження – розподільні мережі систем електропостачання міст. Предмет дослідження - математичні моделі та методи оцінки надійності систем електропостачання, з урахуванням особливості умов експлуатації та обсягів отримуваної вихідної інформації. Методи дослідження. Основу виконаних досліджень склали такі методи: – нелінійне програмування – метод дискретного покоординатного спуску для прийняття рішень з оптимізації точок розмикання мережі; – теорія ймовірності – використовується для оцінки впливу похибок вихідної інформації на точність визначення втрат потужності і значення ймовірного недовідпуску електричної енергії споживачам при розрахунках показників надійності; – математична статистика – для побудови гістограм розподілу згідно даних аварійної статистики, а також визначення законів розподілу та їх параметрів; для опису кривих, що показують залежність можливої похибки розрахунку значень від об’єму статистичних даних що стосуються показників надійності; – метод статистичних випробувань (Монте-Карло) – для визначення впливу похибок вихідної інформації на прийняття рішень за умови мінімізації недовідпуску електричної енергії споживачам. Елементи наукової новизни одержаних результатів. 1. Реалізовано комплексний підхід при вирішенні питань оцінки похибок вихідної інформації та їх впливу на розрахункові моделі, а саме на достовірність. 2. Запропонована методологія оцінювання впливу достовірності вихідної інформації на значення розрахункових показників надійності розподільних мереж при використанні заходів та методів уточнення показників, які визначаються. 3. Проведено згладжування статистичних розподілів даних аварійної статистики та порівняльний аналіз розрахункових моделей, що враховують індивідуальні фактори. 4. Оцінено вплив прийнятих розрахункових моделей на результати оптимізації режимів розподільних мереж виходячи з мінімізації втрат потужності і врахування надійності забезпечення споживачів електричною енергією. Практичне значення одержаних результатів. У магістерській дисертації отримано наукові результати, що мають цінність для підприємств електричних мереж у питаннях збору, систематизації інформації для її подальшої обробки для отримання параметрів розрахункових моделей. Завдяки цьому значно підвищується достовірність вихідної інформації, розрахункових моделей, а також безпосередньо розрахунків показників надійності розподільних мереж.
Actuality of theme. The problem of reliable supply of electricity to consumers is one of the most important in solving the problems of designing and operating power systems (EPS) of cities, industrial enterprises and individual objects. Requirements for reliable electricity supply are defined by the relevant regulatory documents and must be clearly considered and implemented. Both consumers and businesses are seriously harmed by forced power outages. At any level of electricity infrastructure, ensuring the reliability of electricity supply to consumers has always been an important scientific and technical problem, the research and solution of which is devoted to the numerous works of scientists and research and design organizations (KPI, TSU, MEI, etc.). Main directions of research: obtaining, systematization and processing of statistical information, evaluation of its reliability; development of adequate calculation models for evaluation and optimization of reliability of elements, circuits and power supply system as a whole; determination of effective systemic reliability indicators and methods of their calculation and making optimal decisions; economic indicators of losses of consumers and power supply organizations from under-receipt and under-release of electricity. General analysis of the operation of electrical networks at the moment shows that their technical condition is unsatisfactory, there is an aging equipment, progressing, and, consequently, a decrease in the reliability of the elements and power systems. Moreover, the constant complexity of the structure and the emergence of new network elements requires the development of a theory of solving the problems of estimating and improving the reliability of energy supply. Accordingly, there is a need to develop a decision-making methodology at the stages of construction, reconstruction and operation of distribution grids (DG). In assessing the reliability of consumer electricity systems, such indicators as the probability of an accidental event of a power outage, the accidental magnitude of unavailability of electricity to consumers (which occurred as a result of events that have occurred or are predicted, calculated) are usually considered, real or projected losses of consumers or electricity supply organization. The analysis shows that the damage rates of the elements of distribution networks and the value of losses borne by consumers almost always depend on the specific conditions. Moreover, even for the same operating conditions, fluctuations in the integrity indicators of network elements are occasionally fluctuated, by more than 100 percent. This indicates that in the conditions of each system it is necessary to analyze the data of the accident statistics with the determination of the real factors of influence on the original design indicators (lengths of lines, circuit decisions, number of nodes, etc.) It should also be considered and taken into account when determining the losses (which occurred or projected) their essential dependence on the season, time of day, and also - to a large extent - on how long the break in the power supply of the consumer. The analysis of statistical information indicates a significant instability, non-stationarity of indicators used in the formation of calculation models, evaluation of the reliability of schemes. The systematic approach to developing more efficient models and methods of assessing the reliability of distribution networks is more relevant than ever. The purpose and tasks of the study. The purpose of the work is to develop a methodology for evaluating the reliability of the original parameters of the reliability of the SEM, which are determined by the limited amount of data of the accident statistics, and the influence of the adopted calculation models on the results of calculating the network reliability indicators. Research objectives:  analysis of information on the functioning of distribution electric networks;  assessment of reliability of baseline reliability indicators, determination and consideration of influential factors, laws of distribution of random variables;  selection and comparison of calculation models of reliability estimation of distribution electric networks with voltage of 6-10 kV on the basis of processing of received data of emergency statistics;  sequence of implementation of the systematic approach to statistical analysis information and assessing the reliability of electricity supply. Object of research - Distribution networks of power supply systems of cities. Subject of research - Mathematical models, methods for assessing the reliability of power supply systems, taking into account the peculiarities of operating conditions and the amount of received information. Research methods. The basis of the performed research was the following methods:  nonlinear programming - a method of discrete coordinate descent for making decisions on the optimization of network breakpoints;  probability theory - is used to estimate the effect of initial information errors on the accuracy of determining power losses and the value of the probable non-release of electricity to consumers when calculating reliability indicators;  mathematical statistics - for plotting distribution histograms according to emergency statistics, as well as determining distribution laws and their parameters; to describe the curves showing the dependence of a possible error in the calculation of values on the volume of statistics relating to reliability indicators;  statistical test method (Monte Carlo) - to determine the impact of errors of initial information on decision making, while minimizing the lack of electricity to consumers. Elements of scientific novelty of the obtained results. 1. A comprehensive approach was implemented in addressing the issues of estimation of source information errors and their impact on the calculation models, namely reliability. 2. A methodology for estimating the impact of the reliability of the source information on the value of the calculated reliability indicators of the distribution networks when using measures and methods of refining the indicators that are determined is proposed. 3. Smoothing of statistical distributions of data of emergency statistics and comparative analysis of calculation models taking into account individual factors is carried out. 4. The influence of the adopted calculation models on the results of the optimization of the modes of distribution networks is estimated, based on the minimization of power losses and taking into account the reliability of providing consumers with electricity. The practical value of the results. In the master's thesis the scientific results are obtained that are of value for the enterprises of electric networks in the issues of collection, systematization of information for its further processing in order to obtain the parameters of the calculation models. This significantly increases the reliability of the source information, the calculation models, as well as directly calculating the reliability of distribution networks.

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After the restructuring of the electric sector, the distribution utilities must maximize the reliability to avoid violation in the reliability targets at the minimal cost. This agreement between cost and reliability can be satisfied with the application of Predictive Reliability Analysis (PRA) in the planning of distribution networks. The PRA estimates the future performance of distribution networks, with regarding to energy supply interruptions, based on the failure data of the components and network topology. The PRA can delivery estimates for the following statistical reliability indices used in the distribution utilities: System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Indices (SAIDI), Connection Point Interruption Frequency Index (CPIFI), and Connection Point Interruption Duration Index (CPIDI). However, the PRA is rarely used by engineers during the planning of the distribution utilities. This fact is due to the existence of discrepancies between the indices estimated by the PRA and those measured by distribution utilities. These discrepancies are due to the lack of historical data to estimate the reliability parameters of the components: failure rates and repair times. In spite of the distribution utilities do not have a large amount of historical data associated with failures in their equipment, these utilities store historical data on system reliability indices (SAIDI, SAIFI, CPIFI and CPIDI). This information can be used to adjust the failure data of the components (failure rates and repair times) such that the reliability indices evaluated by the ACP models have nearly the same values as those measured by distribution utilities. This adjustment process of the reliability data in ACP models is named Data Calibration. Usually, the reliability data calibration is carried out through optimization techniques. However, the most of the existing methodologies ignores the nodal reliability indices (CPIFI and CPIDI) in the calibration of failure rates and repair times. Only the CPIFI index has been considered in the data calibration. Furthermore, it is not possible to assure that the SAIFI has the same value as its measured value when the calibration considers the CPIFI index. Nevertheless, the Brazilian Electricity Regulatory Agency (ANEEL) has established penalties for violations in the indices CPIFI and CPIDI. Due to this, the PRA models must accurately estimate the nodal reliability indices CPIFI and CPIDI. The main objective of this dissertation is to develop a calibration methodology of reliability data oriented to nodal reliability indices CPIFI and CPIDI. The proposed methodology uses nonlinear and quadratic programming models to calibrate the failure rates and repair times, respectively, in a decoupled structure. This decoupled structure allows the calibration of failure rates and repair times be carried out separately. Additionally, the utilization of equality constraints in the calibration models assures that the evaluated values of SAIFI and SAIDI indices are identical to their measured values. Furthermore, the proposed calibration model for the failure rates considers the equipment condition information obtained from inspection activities. The calibration models proposed in this dissertation were tested in a feeder of the power distribution utility of Maranhão (CEMAR). The tests results demonstrate that the proposed calibration models can significantly reduce the errors between the measured and evaluated values of the CPIFI and CPIDI indices
Após a reestruturação do setor elétrico, as empresas de distribuição devem maximizar a confiabilidade do fornecimento para evitar violações nas metas de confiabilidade com o menor custo possível. Este compromisso entre custo e confiabilidade pode ser atendido com a aplicação da Análise de Confiabilidade Preditiva (ACP) no processo de planejamento de redes de distribuição. A ACP estima o desempenho futuro da rede de distribuição, com relação a interrupções no fornecimento de energia, com base nos dados de falha dos componentes e na sua topologia. A ACP pode fornecer estimativas para os seguintes indicadores de continuidade estatísticos usados pelas empresas de distribuição: Freqüência Equivalente de Interrupção por Unidade Consumidora (FEC), Duração Equivalente de Interrupção por Unidade Consumidora (DEC), Freqüência de Interrupção individual por Unidade Consumidora ou por Ponto de Conexão (FIC), Duração de Interrupção Individual por Unidade Consumidora ou por Ponto de Conexão (DIC) e Duração Máxima de Interrupção Contínua por Unidade Consumidora ou por Ponto de Conexão (DMIC). Entretanto, a ACP é raramente usada pelos engenheiros de planejamento das empresas de distribuição. Este fato é devido à existência de discrepâncias entre os índices estimados pela ACP e aqueles apurados pelas empresas de distribuição. Estas discrepâncias são causadas pela falta de dados históricos para estimar os parâmetros de confiabilidade dos componentes, isto é: taxas de falha, tempos de reparo e chaveamento. Apesar das empresas de distribuição não possuírem uma grande quantidade de dados históricos associados com as falhas dos seus equipamentos, estas empresas armazenam dados históricos sobre índices de continuidade do sistema (FEC, DEC, DIC e FIC). Esta informação pode ser utilizada para ajustar os dados de falha dos componentes (taxas de falha e os tempos de reparo) tal que os índices calculados pelo modelo de ACP sejam próximos dos índices medidos pelas empresas de distribuição. Este processo de ajuste dos dados de falha dos modelos de ACP é denominado de Calibração de Dados. Geralmente, a calibração de dados de confiabilidade é realizada através de técnicas de otimização. Contudo, a maioria das metodologias existentes desconsidera os índices de confiabilidade nodais (FIC e DIC) na calibração das taxas de falha e tempos de reparo. Apenas o índice nodal FIC tem sido considerado na calibração de dados. Além disso, não é possível garantir que o índice FEC seja igual ao seu valor apurado quando a calibração considera o índice FIC. Contudo, a ANEEL (Agência Nacional de Energia Elétrica) estabeleceu penalidades para violações nos índices FIC e DIC. Devido a isto, os modelos de ACP devem estimar precisamente os índices de confiabilidade nodais FIC e DIC. O principal objetivo desta dissertação é desenvolver uma metodologia de calibração de dados de confiabilidade orientada para os índices nodais FIC e DIC. A metodologia proposta utiliza modelos de programação não-linear e quadrática para calibrar as taxas de falha e os tempos de reparo, respectivamente, em uma estrutura desacoplada. Isto é, a calibração das taxas de falha e dos tempos de reparo é realizada separadamente. Adicionalmente, a utilização de restrições de igualdade nos modelos de calibração assegura que os valores calculados dos índices FEC e DEC sejam idênticos aos seus valores medidos. Além disso, o modelo de calibração proposto para as taxas de falha considera a informação de condição dos equipamentos obtida a partir de atividades de inspeção. Os modelos de calibração propostos nesta dissertação foram testados em um alimentador da Companhia Energética do Maranhão (CEMAR). Os resultados dos testes demonstraram que os modelos de calibração propostos podem reduzir significativamente os erros entre os valores medidos e calculados dos índices FIC e DIC.

The new regulations of the electricity sector have requested from the power utilities great performance efficiency on their distribution systems, requiring more rigorous quality and continuity energy levels. In Brazil, the privatization of the power utility companies has been allowing the adoption of new planning and operation policies, that necessarily consider the system reliability and its economic constraints. Regarding this the companies are looking for objectively estimate all the necessary system investments in order to achieve safe and economic continuity for its consumers. At planning level, there are several alternatives, such as complex systems of larger flexibility, new feeders allowing several possibilities of load transfer, isolating permanent faults confining outages to smaller sections of line, remote operated maneuver and protection equipment and supervised substations featuring devices to help fault location. However, these alternatives normally mean large sums of investment which results are not always easy to measure, due to the difficulty of identifying its benefits from those produced by other accomplished actions. At operational level, it is possible to achieve results on medium and short term through the efficient dimension of emergency dispatching crews, maneuver and maintenance plans, contingency studies, protection devices readjustment, strategic use of protection and maneuvers devices and so forth. The power utility companies have planning areas that define the best practices through its professionals' experiences associated to computing tools. Traditionally, these tools help the professionals with power flow and short circuit simulation, losses calculation, protection coordinating diagrams, etc. Some tools and methods capable to proceed reliability simulations through several criteria have been proposed recently. For example, through continuity indicators such as SAIDI and SAIFI, through network topology and equipment alternatives, as developed by Violin and Martinez [2004], through the number of customers or non-supplied energy helping the decision of inserting or removing equipment, as demonstrated by Abaide [2005], or even through reduction of interrupted customers number by the network reconfiguration due to contingency events as described by Bernardon [2007]. However during the studies of these alternatives many simplifications are usually assumed, mostly on the protection devices models. Due to that, they are considered as completely stable and it is just verified the overload operation possibility. The unsuitable protection devices interruptions caused by coordination problems are totally unconsidered. This thesis aims at presenting the algorithms developed to help determining the best distribution resources alternatives in order to increase the network reliability according to basic continuity criteria and the dynamic relationship among protection and maneuver devices. The developed computing tool can also automatically determine all the protection devices adjustments along the distribution network in order to achieve the best technical and economical application. To check the efficiency of the proposed methods, real case studies are presented with data from power utility companies.
As novas regulamentações do setor elétrico têm solicitado das concessionárias de distribuição de energia elétrica uma maior eficiência no desempenho de seus sistemas, exigindo níveis de qualidade e de continuidade de energia cada vez mais rigorosos. No que se refere ao Brasil, a privatização das empresas distribuidoras está conduzindo à incorporação de novas políticas de planejamento e operação, que necessariamente levam em consideração a confiabilidade do sistema e suas restrições econômicas. Desta forma as empresas estão buscando responder objetivamente o quanto é necessário investir em seus sistemas visando uma continuidade segura e econômica para seus consumidores. Em nível de planejamento existem diversas alternativas, tais como sistemas cada vez mais complexos e de maior flexibilidade, novos alimentadores que permitem diversas possibilidades de transferência de carga, seccionamento de trechos defeituosos, equipamentos de manobra e proteção telecomandados e subestações supervisionadas dotadas de dispositivos de auxílio à localização de falhas. Entretanto, essas alternativas geralmente implicam em investimentos de grande magnitude e nem sempre de fácil mensuração dos resultados, pois os benefícios acabam agregando-se a outras ações realizadas. Já em nível operacional, é possível almejar resultados em médio e curto prazos, através do dimensionamento eficiente das equipes de emergência, planos de manobra e manutenção, estudos de contingência, reajuste dos dispositivos de proteção e utilização estratégica de dispositivos de proteção e manobra entre outros. As empresas distribuidoras de energia possuem áreas de planejamento e operação, as quais definem as melhores práticas através da experiência dos profissionais associadas à utilização de ferramentas computacionais. Tradicionalmente, essas ferramentas auxiliam os profissionais através da realização de simulações de fluxo de potência, curto-circuito, cálculos de perda, cordenogramas de proteção, entre outros. Mais recentemente, surgiram algumas propostas de ferramentas e métodos capazes de realizar simulações de confiabilidade, sendo através dos indicadores de continuidade tais como DIC, FIC, DEC e FEC mediante alternativas de topologia e equipamentos da rede, conforme desenvolvido por Violin e Martinez [2004], do número de consumidores ou energia não fornecida mediante a inserção ou remoção de equipamentos, demonstrado por Abaide [2005], ou até mesmo reduzindo o número de consumidores interrompidos através da reconfiguração emergencial de rede descrita por Bernardon [2007]. Mas, normalmente, simplificações são assumidas na elaboração destas alternativas, principalmente ao que se refere aos dispositivos de proteção, sendo considerados completamente estáveis, verificando-se apenas a possibilidade da operação por sobrecarga e desconsiderando interrupções indevidas mediante a descoordenação dos dispositivos de proteção. Esta tese visa apresentar os algoritmos desenvolvidos aliados a uma ferramenta computacional, a qual possibilita determinar as melhores alternativas de distribuição de recursos visando o aumento da confiabilidade das redes de distribuição, segundo os critérios básicos de continuidade incluindo o relacionamento dinâmico entre dispositivos de proteção e manobra. A ferramenta desenvolvida também é capaz de determinar automaticamente os ajustes de todos os dispositivos de proteção tradicionalmente utilizados nas redes de distribuição de energia de modo a obter a melhor aplicação técnica e econômica. Como resultados, são apresentados estudos de casos com dados reais das concessionárias de energia elétrica, com o objetivo de comprovar a eficiência dos métodos propostos.

O dimensionamento otimizado de sistemas de distribuição de águas tem originado centenas de trabalhos científicos nas últimas quatro décadas. Vários pesquisadores têm buscado encontrar uma metodologia capaz de dimensionar essas redes considerando diversos aspectos e incertezas características desse tipo de projeto. No entanto, os resultados da maioria das metodologias desenvolvidas não podem ser aplicados na prática. O objetivo deste trabalho é elaborar uma metodologia de dimensionamento de redes de distribuição de água considerando um enfoque multiobjetivo. A metodologia desenvolvida considera três aspectos referentes ao projeto desses sistemas: custo; confiabilidade e perdas por vazamentos. Para tanto, empregou-se um método de otimização multiobjetivo baseado em algoritmos genéticos para a geração do conjunto de soluções não-dominadas e um método multicriterial para escolha da alternativa final. Para representar os objetivos do problema, foram testadas nove funções: custo, vazamentos, entropia, resiliência, tolerância à falha, expansibilidade, efeito do envelhecimento e resilientropia, sendo que sete destas são específicas para a representação da confiabilidade. Para se avaliar as alternativas geradas foi desenvolvido um modelo de análise hidráulica que fosse capaz de trabalhar com vazamentos e com demandas dependente da pressão. Os métodos escolhidos foram o Híbrido de Nielsen e o Gradiente. Das funções testadas, a resilientropia, proposta originalmente neste trabalho, foi a que melhor se ajustou ao conceito formal de confiabilidade, representado pela função tolerância. Os resultados encontrados pela metodologia mostraram-se promissores, uma vez esta foi capaz de encontrar redes eficientes ao final das simulações.
The topic \"Optimized design of water distribution systems\" has generated hundreds of scientific publications in the last four decades. Several researchers have searched for a technology which would take into account a variety of aspects and uncertainties innate to the design of such networks. However, the results of most methodologies developed are not practical. The objective of this work is to develop a methodology for water distribution systems design that has a multi-objective focus. The methodology developed focuses in three aspects of the design of such systems: cost, reliability and losses by leaking. A multiobjective optimization method based on generic algorithms, generating a set of non-defined solutions, and a multi-criteria method for choosing the final alternative, was employed. Nine functions representing the objectives of the problem (method) were tested: cost, leakages, entropy, resilience, failure tolerance, expansibility, aging effect and resilienthropy, seven of which are specific to representing reliability. In order to evaluate the generated alternatives, a hydraulic analysis model, that could handle leakages and pressure dependent demands, was developed. The chosen methods were Nielsen\'s Hybrid, and the Gradient. Of all tested functions, resilientropy, originally proposed in this work, proved to be the one best adjusted to the formal concept of reliability, represented by the tolerance function. The results obtained by this methodology are promising, as they produced efficient distribution networks at the end of the simulations performed.

Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.03 – "Електротехнічні комплекси та системи". – Державний виший навчальний заклад "Національний гірничий університет", Дніпропетровськ, 2012.
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.09.03 – "Электротехнические комплексы и системы". – Государственное высшее учебное заведение "Национальный горный университет", Днепропетровск, 2012.
Thesis for a candidate of technical science degree by speciality 05.09.03 – "Electrotechnical complexes and systems". State institution of higher education “National Mining University” subject to the Ministry of Education and Science, Youth and Sports of Ukraine, Dnipropetrovs’k, 2012.
Дисертація присвячена розробці принципів і технічних засобів підвищення рівня експлуатаційної надійності і поліпшенню умов електробезпеки в системах електропостачання кар'єрів. Дана характеристика системам електропостачання сучасних залізорудних кар’єрів, розглянуто особливості експлуатації електричних розподільних мереж, виконано аналіз методів контролю ізоляції та засобів захисту. Представлені результати досліджень впливу режиму нейтралі кар'єрних розподільних мереж на якісні та кількісні параметри усталеного і перехідних процесів при замиканнях на землю. З порівняння варіантів заземлення нейтралі встановлено, що найбільш висока експлуатаційна надійність забезпечується в розподільних мережах з резистором в нейтралі. Дано теоретичне обґрунтування методу непрямої оцінки параметрів провідності ізоляції розподільних мереж напругою 6 кВ без зняття робочої напруги. Подані результати дослідження впливу параметрів режиму заземлення нейтралі на працездатність захистів від замикань на землю і на умови електробезпеки. Наведені технічні рішення та рекомендації, що забезпечують підвищення рівня безаварійності та електробезпеки розподільних і живлячих мереж кар'єрів.
Диссертация посвящена разработке принципов и технических средств повышения уровня эксплуатационной надежности и улучшению условий электробезопасности в системах электроснабжения карьеров. Данная характеристика системам электроснабжения современных железорудных карьеров, рассмотрена особенности эксплуатации электрических распределительных сетей, выполнен анализ методов контроля изоляции и средств защиты. Представлены результаты исследований влияния режима заземления нейтрали карьерных распределительных сетей на качественные и количественные параметры установившихся и переходных процессов при замыканиях на землю. Из сравнения вариантов заземления нейтрали установлено, что наиболее высокая эксплуатационная надежность обеспечивается в распределительных сетях с резистором в нейтрали. Дано теоретическое обоснование метода косвенной оценки параметров проводимости изоляции распределительных сетей напряжением 6 кВ без снятия рабочего напряжения, основанного на искусственном изменении величины напряжения смещения нейтрали путем последовательного включения дополнительных тарированных активных проводимостей во все три фазы электроустановки в заданной последовательности. Представлены результаты исследования влияния параметров режима заземления нейтрали на работоспособность защит от замыканий на землю и на условия электробезопасности. Для компенсированных сетей при отсутствии автоматической резонансной настройки режима компенсации рекомендован комбинированный режим заземления нейтрали, который обеспечивает эксплуатационные показатели адекватные системам электроснабжения только с резистором в нейтрали даже при расстройках дугогасящего реактора до 50% от резонансного режима. Показано, что по степени косвенной опасности электрических сетей, работающих с разными режимами нейтрали, предпочтение следует отдать электрическим сетям с резистором в нейтрали. Приведены разработанные технические решения и рекомендации, которые обеспечивают повышение уровня безаварийности и электробезопасности распределительных и живящих сетей карьеров: структура и алгоритм автоматизации процесса косвенного определения полных проводимостей изоляции фаз и их составляющих в трехфазных электрических сетях с изолированной нейтралью напряжением 6-35 кВ с любой степенью несимметрии изоляции; рекомендации по обеспечению селективности защит от замыканий на землю на питающих КРП линиях при двухступенчатой структуре карьерных распределительных сетей; функциональная схема системы избирательной защиты для разветвленных распределительных сетей с компенсированной нейтралью.
The thesis is devoted to development of principles and technical means of increase of an operational reliability level and improvement of electrical safety conditions in power supply systems of open cast mines. The characteristic of power supply systems of modern open cast iron mines is given, the peculiarities of electrical distributive networks operation are considered, the analysis of insulation control methods and protection means are performed. The investigation results of neutral mode influence of open cast mining distributive networks on qualitative and quantitative parameters of steady and transient process in the time of ground fault are presented. From the comparison of neutral grounding options it is determined that highest operational reliability is ensured in distributive networks with resistor in neutral. The theoretical justification of indirect estimation method of insulation conductivity parameters of distributive networks by a voltage 6 kV without switching-off of a working voltage is given. The investigation results of grounding neutral mode parameters influence on the operability of ground fault protection and electrical safety conditions are given. The technical solutions and recommendations that provide the level increase of trouble-free operation and electrical safety of distributive and supplying networks of open cast mines are presented.