Dissertations / Theses: 'Renewable energy sources Computer simulation'

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Ng, Kwok-kei Simon, and 吳國基. "Optimal planning and management of stochastic demand and renewable energy in smart power grid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434299.

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To combat global climate change, the reduction of carbon emissions in different industries, particularly the power industry, has been gradually moving towards a low-carbon profile to alleviate any irreversible damage to the planet and our future generations. Traditional fossil-fuel-based generation is slowly replaced by more renewable energy generation while it can be harnessed. However, renewables such as solar and wind are stochastic in nature and difficult to predict accurately. With the increasing content of renewables, there is also an increasing challenge to the planning and operation of the grid. With the rapid deployment of smart meters and advanced metering infrastructure (AMI), an emerging approach is to schedule controllable end-use devices to improve energy efficiency. Real-time pricing signals combined with this approach can potentially deliver more economic and environmental advantages compared with the existing common flat tariffs. Motivated by this, the thesis presents an automatic and optimal load scheduling framework to help balance intermittent renewables via the demand side. A bi-level consumer-utility optimization model is proposed to take marginal price signals and wind power into account. The impact of wind uncertainty is formulated in three different ways, namely deterministic value, scenario analysis, and cumulative distributions function, to provide a comprehensive modeling of unpredictable wind energy. To solve the problem in off-the-shelf optimization software, the proposed non-linear bi-level model is converted into an equivalent single-level mixed integer linear programming problem using the Karush-Kuhn-Tucker optimality conditions and linearization techniques. Numerical examples show that the proposed model is able to achieve the dual goals of minimizing the consumer payment as well as improving system conditions. The ultimate goal of this work is to provide a tool for utilities to consider the demand response model into their market-clearing procedure. As high penetration of distributed renewable energy resources are most likely applied to remote or stand-alone systems, planning such systems with uncertainties in both generation and demand sides is needed. As such, a three-level probabilistic sizing methodology is developed to obtain a practical sizing result for a stand-alone photovoltaic (PV) system. The first-level consists of three modules: 1) load demand, 2) renewable resources, and 3) system components, which comprise the fundamental elements of sizing the system. The second-level consists of various models, such as a Markov chain solar radiation model and a stochastic load simulator. The third-level combines reliability indices with an annualized cost of system to form a new objective function, which can simultaneously consider both system cost and reliability based on a chronological Monte Carlo simulation and particle swamp optimization approach. The simulation results are then tested and verified in a smart grid laboratory at the University of Hong Kong to demonstrate the feasibility of the proposed model. In summary, this thesis has developed a comprehensive framework of demand response on variable end-use consumptions with stochastic generation from renewables while optimizing both reliability and cost. Smart grid technologies, such as renewables, microgrid, storage, load signature, and demand response, have been extensively studied and interactively modeled to provide more intelligent planning and management for the smart grid.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

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Liu, Kai, and 劉愷. "Optimal dispatch and management for smart power grid." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46336680.

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Wren, Duncan E. "Computer simulation of intelligent building facades." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/7351.

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The economic and environmental benefits secured through the increased integration of photovoltaic (PV) technology into the built environment are undeniable and provide the principal motivation for this research. Present delays in the technology transfer of building integrated photovoltaics (BIPV) can be attributed to the following; material cost, performance guarantee, increased installation complexity and unfamiliar technology. It is well understood that the temperature of a PV material receiving solar irradiation, will increase with solar intensity, while reducing in electrical efficiency. It therefore makes economic sense to minimise the increase in PV material temperature and maximise electrical energy yield. Through the addition of a convecting fluid, flowing over the surface of heated PV material, heat transfer will be induced. With the added benefit of warm air capture from an integrated photovoltaic/thermal (PVT) collector, the economic benefits are increased. But, to ensure maximum utilisation of both thermal and electrical energy production, a significantly more complex control system has to be employed than that for a PV system on its own. Modelling the energy flows within a multifunctional PVT building facade presents a problem of considerable complexity. Previous work in this area has centred on performing finite element analysis of the system in order to find solutions to complex algorithms. It requires considerable computational power to perform these calculations and often the results produced are much more detailed than required. Within this thesis, a fully operational PVT facade model is presented, giving the potential for improved multifunctional facade design. This new model has been developed into a software program for use within the TRNSYS environment. By using the TRNSYS software, a detailed building model has been created and integrated with the new PVT facade model. Simulations were then undertaken to evaluate the energy transfers between internal and external environments and the electrical and thermal energy capturing capabilities of the facade. Simulated results have been evaluated against experimental data taken from a fully operational PVT facade. The results conclude that the presented model simulates the energy flows around, through and within the facade (radiative, conductive, convective and electrical) very well. Performance enhancing development work is due to take place on the operational facade analysed in this work, very soon. This new facade model will be used as a tool to evaluate the proposed changes to the building prior to this development work being undertaken.

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Khazaei, Javad Khazaei. "Distributed Coordination and Control of Renewable Energy Sources in Microgrids." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6274.

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Microgrid is an emerging technology in the eld of electrical engineering which employs the concept of Distributed Energy Resources (DERs) in order to generate electricity in a small sized power system. The main objectives of this dissertation are to: 1- design a new control for lower level control of DERs in microgrids, 2- implement distributed upper level control for DERs in microgrids and 3- apply analytical approaches in order to analyze DERs in microgrids. The control in each DER can be divided into two main categories: lower and upper level. Lower level control is the main objective of control in each DER. For example, the lower level control in Photovoltaic (PV) is in charge of transferring the maximum power from sun into the main grid. Unlike the lower level control, the upper level control is an additional control loop on top of the lower level controls. For example, Voltage/Frequency (VF) controllers are installed on top of Active/Reactive (PQ) power controller in energy storage devices as upper level control. In this dissertation, for the lower level control improvements, two widely used DERs are selected (PV, and oshore wind farm) and new control algorithms are developed in order to improve the performance of lower level controllers in these DERs. For the PV lower level improvement, a new control methodology is proposed in order to minimize the maximum power tracking error in PV lower level controller. Second contribution in lower level control is for the oshore wind farm applications based on Multi-Terminal High Voltage Direct Current (MTDC) transmission; a new control is designed in order to minimize the losses in transmission lines through lower level control of High Voltage Direct Current (HVDC) converters. For the upper level control, this dissertation considers the energy storage as another mostly used type of DER in microgrids. The lower level control for energy storage is in charge of controlling the PQ of the energy storage. The main contribution in the upper level control is to implement the distributed control algorithm based on consensus theory for battery energy storages in order to maximize the efficiency, energy management as well as synchronizing the performance of parallel energy storage devices in microgrids. In this case, the consensus based distributed control algorithm with limited information exchange between neighboring energy storage units is proposed and implemented to validate the claim. The third contribution of this research is to apply advanced analysis techniques to evaluate the performance of the DERs in microgrids. Two approaches are introduced for microgrid modeling in this research. Firstly, an impedance modeling technique is used to model the oshore wind farm connected to the main AC grid through HVDC transmission line. Multiple Input Multiple Output (MIMO) Nyquist analysis and singular value analysis are used to assess the interactions between HVDC converter and grid. Secondly, an unbalanced microgrid is considered and Dynamic Phasor (DP) analysis is applied in order to nd the stability limitations under different scenarios. This dissertation has led to seven journal papers (five published, one journal in revision process and one journal submitted recently) and four conference papers.

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Chen, Tianyu. "Simulation of the thermal and electrical performance of a novel PVT-PCM system." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49210/.

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This study provides an insight into the fundamentals of PV performance enhancement under different environmental conditions. The study also presents a new concept of PCM integrated PVT system which has a better performance from both electrical and thermal perspectives. The study employs both analytical and computational techniques to investigate the PV performance under the effect of different parameters such as wind speed, solar radiation level, ambient temperature and additional cooling condition. A parametric analysis of the PCM is also carried out under different solar radiation level, water inlet temperature and flow speed. Additional analysis regarding to the effects of PCM’s thermal physical properties against its thermal performance is also presented. A validation analysis is carried out prior to the parametric analysis to ascertain the reliability of the CFD models used, the prediction result of the CFD model is compared with analytical calculations as well as data from literature. The study found that the active water cooling is the best solution which can provide guaranteed performance enhancement regardless effects of ambient conditions. The novel PVT-PCM system is found to have a noticeable electrical performance enhancement over conventional PV panel as well as having the ability to store a significant amount of thermal energy. It is found that the PVT-PCM system has much lower PV cell temperature (maximum temperature reduction of 36.5°C and 38.3°C respectively) compared to conventional PV systems when used in both Nottingham and Shanghai area, hence provide up to 5.4kWh (5.7kWh in Shanghai) more energy per unit module. The stored thermal energy could be utilized to provide moderate heating to air and/or water. The air preheated by PVT-PCM system could satisfy space heating requirement during April to October in Nottingham without any additional energy consumption. On the other hand, the preheated water could reduce boiler heating energy from up to 20% and 41% respectively for Nottingham and Shanghai climate. The overall performance benefits of the proposed PVT-PCM system could be greater if used in hotter climates. Finally, a cost analysis was carried to prove the whole system is financially feasible for use in both climates of Nottingham and Shanghai with a discounted payback period of 10.67 and 12.83 years respectively.

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Duran, Serhat. "Computer-aided Design Of Horizontal-axis Wind Turbine Blades." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605790/index.pdf.

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Designing horizontal-axis wind turbine (HAWT) blades to achieve satisfactory levels of performance starts with knowledge of the aerodynamic forces acting on the blades. In this thesis, HAWT blade design is studied from the aspect of aerodynamic view and the basic principles of the aerodynamic behaviors of HAWTs are investigated. Blade-element momentum theory (BEM) known as also strip theory, which is the current mainstay of aerodynamic design and analysis of HAWT blades, is used for HAWT blade design in this thesis. Firstly, blade design procedure for an optimum rotor according to BEM theory is performed. Then designed blade shape is modified such that modified blade will be lightly loaded regarding the highly loaded of the designed blade and power prediction of modified blade is analyzed. When the designed blade shape is modified, it is seen that the power extracted from the wind is reduced about 10% and the length of modified blade is increased about 5% for the same required power. BLADESIGN which is a user-interface computer program for HAWT blade design is written. It gives blade geometry parameters (chord-length and twist distributions) and design conditions (design tip-speed ratio, design power coefficient and rotor diameter) for the following inputs
power required from a turbine, number of blades, design wind velocity and blade profile type (airfoil type). The program can be used by anyone who may not be intimately concerned with the concepts of blade design procedure and the results taken from the program can be used for further studies.

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Taylan, Onur. "Numerical Modeling And Performance Analysis Of Solar-powered Ideal Adsorption Cooling Systems." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611799/index.pdf.

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Energy consumption is continuously increasing around the world and this situation yields research to find sustainable energy solutions. Demand for cooling is one of the reasons of increasing energy demand. This research is focused on one of the sustainable ways to decrease energy demand for cooling which is the solar-powered adsorption cooling system. In this study, general theoretical performance trends of a solar-powered adsorption cooling system are investigated using TRNSYS and MATLAB. Effects of different cycle enhancements, working pairs, operating and design conditions on the performance are analyzed through a series of steady and seasonal-transient simulations. Additionally, a normalized model is presented to investigate the effects of size of the system, need for backup power, collector area and mass of adsorbent. Results are presented in terms of values and ratios of cooling capacity weighted COP. For the conditions explored, the thermal wave cycle, wet cooling towers, high evaporation temperatures and evacuated tube collectors produced the highest COP values. Moreover, the heat capacity of the adsorbent bed and its shell should be low for the simple and heat recovery cycles and the adsorbent bed should be cooled down to the condensation temperature for all cases to achieve the highest possible COP. The selection of working pair should depend on the temperature of the available heat source (solar energy in this study) since each working pair has a distinct operating temperature range. Furthermore, there is always a need for backup power for the analyzed location and the system.

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Clarke, Anne E. "Electric Water Heater Modeling for Distributed Energy Resource Aggregation and Control." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4449.

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Today's utilities face new challenges due to the continually increasing penetration of residential solar and other distributed, stochastic generation sources. In order to maintain balance and stability in the grid without building costly, large-scale generation plants, utilities are turning to distributed energy resources for use in demand response programs. Demand response is a cost-efficient way to balance grid load/generation without the need for increased capital investment in traditional generation resources. Demand response programs are excellent exploiters of end-user devices that otherwise further accentuate the daily load curve and thus, add to the difficulties created by daily load peaks. Electric water heaters are excellent candidates for use in demand response programs for a variety of reason. One, electric water heaters represent a large portion of daily household loads due to their high nominal power ratings (1.5 kW - 5.5kW), and frequent use estimated to account for approximately one third of all daily residential power demand. Two, they are composed of strictly resistive elements, which greatly simplifies modeling, aggregation and control. And third, they can be used for load "shedding" during periods of high electrical demand as well as load "absorbing" during periods of excess generation due to their thermal storage capabilities. With improved access and control, electric water heaters could become a major distributed energy resource for utilities. In order to properly control and use a distributed energy resource, it is important to know how these resources operate and their patterns of behavior in different environments. This thesis presents a single-element, single mass electric water heater model for analyzing the effectiveness of using electric water heaters as distributed energy resources and for participation in demand response programs. The CTA-2045 communication protocol was used for testing demand response signals. The electric water heater is modeled in Python and the communication pathway was built in C++ and Python.

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Munoz-Coreas, Edgard. "Stargrazer One: A New Architecture for Distributed Maximum Power Point Tracking of Solar Photovoltaic Sources." UKnowledge, 2015. http://uknowledge.uky.edu/ece_etds/76.

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The yield from a solar photovoltaic (PV) source is dependent on factors such as light and temperature. A control system called a maximum power point tracker (MPPT) ensures that the yield from a solar PV source is maximized in spite of these factors. This thesis presents a novel implementation of a perturb and observe (PO) MPPT. The implementation uses a switched capacitor step down converter and a custom digital circuit implementation of the PO algorithm. Working in tandem, the switched capacitor step down converter and the custom digital circuit implementation were able to successfully track the maximum power point of a simulated solar PV source. This implementation is free of the overhead encountered with general purpose processor based MPPT implementations. This makes this MPPT system a valid candidate for applications where general purpose processors are undesirable. This document will begin by discussing the current state of MPPT research. Afterward, this thesis will present studies done to be able to use the chosen switched capacitor step down converter. Then the digital circuit PO implementation will be discussed in detail. Simulations of the architecture will be presented. Finally, experimental validation using a hardware prototype will be shown.

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Moghadasiriseh, Amirhasan. "Analysis and Modeling of Advanced Power Control and Protection Requirements for Integrating Renewable Energy Sources in Smart Grid." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2469.

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Attempts to reduce greenhouse gas emissions are promising with the recent dramatic increase of installed renewable energy sources (RES) capacity. Integration of large intermittent renewable resources affects smart grid systems in several significant ways, such as transient and voltage stability, existing protection scheme, and power leveling and energy balancing. To protect the grid from threats related to these issues, utilities impose rigorous technical requirements, more importantly, focusing on fault ride through requirements and active/reactive power responses following disturbances. This dissertation is aimed at developing and verifying the advanced and algorithmic methods for specification of protection schemes, reactive power capability and power control requirements for interconnection of the RESs to the smart grid systems. The first findings of this dissertation verified that the integration of large RESs become more promising from the energy-saving, and downsizing perspective by introducing a resistive superconducting fault current limiter (SFCL) as a self-healing equipment. The proposed SFCL decreased the activation of the conventional control scheme for the wind power plant (WPP), such as dc braking chopper and fast pitch angle control systems, thereby increased the reliability of the system. A static synchronous compensator (STATCOM) has been proposed to assist with the uninterrupted operation of the doubly-fed induction generators (DFIGs)-based WTs during grid disturbances. The key motivation of this study was to design a new computational intelligence technique based on a multi-objective optimization problem (MOP), for the online coordinated reactive power control between the DFIG and the STATCOM in order to improve the low voltage ride-through (LVRT) capability of the WT during the fault, and to smooth low-frequency oscillations of the active power during the recovery. Furthermore, the application of a three-phase single-stage module-integrated converter (MIC) incorporated into a grid-tied photovoltaic (PV) system was investigated in this dissertation. A new current control scheme based on multivariable PI controller, with a faster dynamic and superior axis decoupling capability compared with the conventional PI control method, was developed and experimentally evaluated for three-phase PV MIC system. Finally, a study was conducted based on the framework of stochastic game theory to enable a power system to dynamically survive concurrent severe multi-failure events, before such failures turn into a full blown cascading failure. This effort provides reliable strategies in the form of insightful guidelines on how to deploy limited budgets for protecting critical components of the smart grid systems.

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Hu, Huafen. "Risk-conscious design of off-grid solar energy houses." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31814.

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Thesis (Ph.D)--Architecture, Georgia Institute of Technology, 2010.
Committee Chair: Godfried Augenbroe; Committee Member: Ellis Johnson; Committee Member: Pieter De Wilde; Committee Member: Ruchi Choudhary; Committee Member: Russell Gentry. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Lind, Philip. "A study of modelling the energy system of an ice rink sports facility : Modelling the heating and cooling of ABB arena syd and implementation of renewable energy sources using TRNSYS." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40054.

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Environmental issues are important challenges for today’s society. Lots of the energy used by humans comes from fossil energy sources resulting in the environmental threats. A considerable amount of this energy is used in the building sector. Industrial buildings and sports facilities are large users of energy and thus becomes very interesting in an optimization point of view. Modelling of the systems allows for cheap and effective optimizing of the energy usage and effectivity measures can be investigated and implemented. This study creates a model of the indoor ice rink arena of ABB arena syd in Västerås using TRNSYS as the main software for simulation. Focus is placed on the heating of the arena through heat pumps and district heating, and cooling of the ice in the arena using cooling machines. The effect of PV as well as a battery storage in the arena is also investigated as an effectiveness scenario. The results from the study revealed that it is possible to simulate the heating demand for the arena, accurately identifying the normal demand as well as the instances when the demand peaks and the magnitude of the peaks. It is also possible to simulate the cooling demand for the ice over extended time periods. However, this study could not identify the peaks for cooling demand. It is also beneficial for the system to install PV, but not a battery storage. With current price levels for electricity it is however not a very beneficial deal. With higher electricity prices the investment is preferable. The study also concludes that TRNSYS can be used for modelling an ice rink sports arena, however it leaves room for improvement on that aspect.

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Helkin, Steven Alexander. "Design and optimization of a wave energy harvester utilizing a flywheel energy storage system." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4774.

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This thesis details the design and optimization of a buoy used to collect renewable energy from ocean waves. The proposed buoy is a point absorber--a device that transforms the kinetic energy of the vertical motion of surface waves into electrical energy. The focus of the research is on the mechanical system used to collect the energy, and methods to improve it for eventual use in an actual wave energy harvester. A flywheel energy storage system was utilized in order to provide an improved power output from the system, even with the intermittent input of force exerted by ocean waves. A series of laboratory prototypes were developed to analyze parameters that are important to the success of the point absorb mechanical system. By introducing a velocity-based load control scheme in conjunction with flywheel energy storage, it was seen that the average power output by the prototype was increased. The generator load is controlled via a relay switch that removes electrical resistance from the generator--this sacrifices time during which power is drawn from the system, but also allows the buoy to move with less resistance. A simulation model was developed in order to analyze the theoretical wave absorber system and optimize the velocity threshold parameters used in the load control. Results indicate that the power output by the system can be substantially improved through the use of a flywheel energy storage control scheme that engages and disengages the electrical load based on the rotational velocity of the flywheel system. The results of the optimization are given for varying-sized generator systems input into the simulation in order to observe the associated trends.
ID: 030646228; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 111-114).
M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Computer Aided Mechanical Engineering Track

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Batalha, Tiago Peres 1986. "Projeto e simulação numérica de uma turbina hidrocinética de eixo vertical : Project and numerical simulation of a vertical axis hydrokinetic turbine." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265924.

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Orientador: Kamal Abdel Radi Ismail
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-24T19:59:29Z (GMT). No. of bitstreams: 1 Batalha_TiagoPeres_M.pdf: 29669933 bytes, checksum: 83773b03eb136ff18c60979de7ceaffe (MD5) Previous issue date: 2014
Resumo: Áreas rurais ou isoladas são geralmente abastecidas com energia baseada na queima de óleo diesel. No entanto, estratégias melhores podem ser implementadas utilizando-se recursos de energia renováveis disponíveis na região como recursos hidráulicos, biomassa entre outros. A tecnologia hidrocinética está entre as mais promissoras soluções uma vez que é relativamente barata, de fácil manufatura, confiável e adequada para a maioria das áreas amazônicas devido à grande capacidade hidráulica e predominância de assentamentos de baixa densidade populacional localizados nas margens de rios. Esta dissertação desenvolve uma metodologia de simulação numérica de dinâmica dos fluidos com aplicação das equações de RANS (Reynolds Average Navier Stokes) e malhas bi e tridimensionais para caracterização e projeto de turbinas hidrocinéticas de eixo vertical. Diferentes perfis de pá foram analisados, tais como placa plana, arco circular, NACA simétrico e assimétrico. Os efeitos de número de pás, perfil da pá e velocidade do fluxo de água sobre os coeficientes de torque e potência são apresentados e discutidos. As vantagens desse tipo de turbina incluem operação independente da direção da corrente, reversibilidade, possibilidade de agrupamento, construção barata e sistemas de transmissão simples. Um sistema de apenas uma turbina de 0,5 m de raio e 1 m de altura com sete lâminas submetida à razão de velocidade da ponta de 2,5 com velocidade de fluxo de água de 2 m/s teria potência de aproximadamente 1,6 kW, o que é suficiente para alimentar aproximadamente 7 casas de padrão de consumo médio no Brasil
Abstract: Rural and isolated areas are usually served by diesel based energy supply. However, better strategies can be implemented using renewable energy sources available in the area such as hydraulic, biomass and others. The hydrokinetic technology is among the promising technologies since it is relatively cheap, easy to manufacture, reliable and suitable for most of the Amazon areas because of the large hydraulic capacity and low density population settlements near rivers borders. This dissertation uses CFD, RANS (Reynolds Average Navier Stokes) equations and two and three-dimensional meshes to characterize and develop a methodology of numerical simulation of a vertical axis hydrokinetic turbine. In the simulations, different blade profiles were used such as flat plate, circular arc, symmetric and asymmetric NACA profiles. The effects of the number of blades, blade profile and water flow velocity on the turbine torque and power coefficients were presented and discussed. The advantages of this type of turbines include operation independent of current direction, reversibility, possibility of stacking, cheap construction and simple transmission systems. A system with only one turbine with radius of 0.5 m and height of 1 m with seven blades submitted to a tip speed ratio of 2.5 with water flow velocity of 2 m/s would have power of approximately 1.6 kW, what is enough to supply energy to 7 standard homes in Brazil
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica

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Usta, Yasemin. "Simulations Of A Large Scale Solar Thermal Power Plant In Turkey Using Concentrating Parabolic Trough Collectors." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612800/index.pdf.

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In this study, the theoretical performance of a concentrating solar thermal electric system (CSTES) using a field of parabolic trough collectors (PTC) is investigated. The commercial software TRNSYS and the Solar Thermal Electric Components (STEC) library are used to model the overall system design and for simulations. The model was constructed using data from the literature for an existing 30-MW solar electric generating system (SEGS VI) using PTC&rsquo
s in Kramer Junction, California. The CSTES consists of a PTC loop that drives a Rankine cycle with superheat and reheat, 2-stage high and 5-stage low pressure turbines, 5-feedwater heaters and a dearator. As a first approximation, the model did not include significant storage or back-up heating. The model&rsquo
s predictions were benchmarked against published data for the system in California for a summer day. Good agreement between the model&rsquo
s predictions and published data were found, with errors usually less than 10%. Annual simulations were run using weather data for both California and Antalya, Turkey. The monthly outputs for the system in California and Antalya are compared both in terms of absolute monthly outputs and in terms of ratios of minimum to maximum monthly outputs. The system in Antalya is found to produce30 % less energy annually than the system in California. The ratio of the minimum (December) to maximum (July) monthly energy produced in Antalya is 0.04.

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Adekola, Olawale Ibrahim. "Design and development of a smart inverter system." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2195.

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Thesis (MTech (Electrical, Electronic and Computer Engineering))--Cape Peninsula University of Technology, 2015.
The growing interest in the use of solar energy to mitigate climate change, reduction in the cost of PV system and other favourable factors have increased the penetration of the PV(Photovoltaic) systems in the market and increase in the worldwide energy supply. The main component in a DG is a smart inverter connected in a grid-tied mode which serves as a direct interface between the grid and the RES (Renewable Energy System). This research work presents a three phase grid-tied inverter with active and reactive power control capabilities for renewable energy sources (RES) and distributed generators (DG). The type of the inverter to be designed is a Voltage Source Inverter (VSI). The VSI is capable of supplying energy to the utility grid with a well regulated DC link at its input. The solution this project proposes is an implementation of the designed filter to effectively reduce the harmonics injected into the grid to an acceptable value according to standards and also an approach to control the real and reactive power output of the inverters to help solve the problems of instability and power quality of the distribution system. The design, modelling and simulation of the smart inverter system is performed in MATLAB/SIMULINK software environment. A 10 kW three-phase voltage source inverter system connected to the utility grid was considered for this research. Series of simulations for the grid-connected inverter (GCI) model was carried out using different step changes in active and reactive power references which was used to obtain the tracking response of the set power references. The effectiveness of the control system which was designed to track the set references and supply improved power quality with reduced current ripples has been verified from the simulation results obtained.

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Ray, Mike C. T. "Solar Data Analysis." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1078.

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The solar industry has grown considerably in the last few years. This larger scale has introduced more problems as well as possibilities. One of those possibilities is analyzing the data coming from the sites that are now being monitored, and using the information to answer a variety of questions. We have four questions which are of prime importance identified in this thesis: 1. Can data from customers be trusted? 2. Can we use data from existing sites to determine which sites need the most improvement? 3. Can we implement a location-based algorithm to reduce the amount of false positives for performance, or other alarms? 4. Can we improve upon the current predicted power algorithm? We find that not only can we answer these questions definitively, but the improvements found are of significant value. Each of these items represents an important question that either directly or indirectly translates into increased revenue and engineering improvements for the solar industry as a whole.

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Mazloomzadeh, Ali. "Development of Hardware in the Loop Real-Time Control Techniques for Hybrid Power Systems Involving Distributed Demands and Sustainable Energy Sources." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1666.

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The future power grid will effectively utilize renewable energy resources and distributed generation to respond to energy demand while incorporating information technology and communication infrastructure for their optimum operation. This dissertation contributes to the development of real-time techniques, for wide-area monitoring and secure real-time control and operation of hybrid power systems. To handle the increased level of real-time data exchange, this dissertation develops a supervisory control and data acquisition (SCADA) system that is equipped with a state estimation scheme from the real-time data. This system is verified on a specially developed laboratory-based test bed facility, as a hardware and software platform, to emulate the actual scenarios of a real hybrid power system with the highest level of similarities and capabilities to practical utility systems. It includes phasor measurements at hundreds of measurement points on the system. These measurements were obtained from especially developed laboratory based Phasor Measurement Unit (PMU) that is utilized in addition to existing commercially based PMU’s. The developed PMU was used in conjunction with the interconnected system along with the commercial PMU’s. The tested studies included a new technique for detecting the partially islanded micro grids in addition to several real-time techniques for synchronization and parameter identifications of hybrid systems. Moreover, due to numerous integration of renewable energy resources through DC microgrids, this dissertation performs several practical cases for improvement of interoperability of such systems. Moreover, increased number of small and dispersed generating stations and their need to connect fast and properly into the AC grids, urged this work to explore the challenges that arise in synchronization of generators to the grid and through introduction of a Dynamic Brake system to improve the process of connecting distributed generators to the power grid. Real time operation and control requires data communication security. A research effort in this dissertation was developed based on Trusted Sensing Base (TSB) process for data communication security. The innovative TSB approach improves the security aspect of the power grid as a cyber-physical system. It is based on available GPS synchronization technology and provides protection against confidentiality attacks in critical power system infrastructures.

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Wawerka, Robert. "Budova s téměř nulovou spotřebou energie: případová studie rekonstrukce konvenčního rodinného domu v Dánsku." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-355637.

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This doctoral thesis proposes a new method of energy retrofitting of existing residential buildings towards nearly zero-energy status. The topic of energy retrofitting of existing buildings is widely discussed and lamented within the European Union and the Member states and is enshrined in the Directive 2010/31/EU. This research is in line with the European Union strategy Europe 2020 which sets targets for climate change and energy sustainability. The thesis describes the study of building energy performance of a pilot energy retrofitted residential building towards nearly zero-energy where progressive design technologies, such as energy modelling, monitoring, building optimisation and verification were used. This case study helped to formulate the recommendations on the effectiveness of various passive and active design methods together with renewable energy systems and after the extensive research it contributes to model and verify the future expectation and energy efficiency requirements of the residential market.

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20

McFarland, Matthew Ogden. "Enhanced Cal Poly SuPER System Simulink Model." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/376.

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The Cal Poly Sustainable Power for Electrical Resources (SuPER) project is a solar power DC distribution system designed to autonomously manage and supply the energy needs of a single family off-the-grid home. The following thesis describes the improvement and re-design of a MATLAB Simulink model for the Cal Poly SuPER system. This model includes a photovoltaic (PV) array, a lead-acid gel battery with temperature effects, a wind turbine model, a re-designed DC-DC converter, a DC microgrid, and multiple loads. This thesis will also include several control algorithms such as a temperature controlled thermoelectric (T.E.) cooler, intelligent load switching, and an intelligent power source selector. Furthermore, a seven day simulation and evaluation of the results are presented. This simulation is an important tool for further system development, re-design, and long term system performance prediction.

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Mesbahi, Abdessamad. "Deterministic and Stochastic Economic Modeling of Hybrid Power Supply System with Photovoltaic Generators." Master's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/42555.

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Relevance of research. Due to the rapid deployment of the non-dispatchable (intermittent) generation sources in the smart grid, such as integration of the photovoltaic power plants and wind turbines in the distribution systems; this caused a problem of the uncertainty increase of simulation results for decision-making for power supply systems, these uncertainties of power systems are getting more and more notice. At the same time, the classical power systems models cannot give accurate simulation results. Wherein; it became necessary to define new models to represent the specific parameters of power system. wherein; this research reveals to the benefits of using probabilistic mathematical approaches to define and calculate the specific economic parameters, as well as the technical parameters for power supply system with the integration renewable energy generators, which are characterising by randomness and uncertainty due to the high penetration to the renewables. Monte Carlo Method, and Point Estimation Method are used to handle the uncertainties of renewable energy resources. The standard functions to represent the stochastic parameters of the model are analyzed with the use of three-point estimation technique for the distribution functions of their probable values. A synthetic skewed probability density function was analytically constructed basing on the standard normal distribution, which is suitable for analytic representation of the predicted and/or statistical random sampling of the uncertain model parameters of energy system with renewables, and analytical expressions were obtained to compute the moments of proposed synthetic probability function. Relationship of work with scientific programs, plans, themes. is to demonstrate the possibility of describing the input parameters of the simulation Deterministic and Stochastic Modeling by probability Density Functions by the use of three-point approximation techniques and to obtain analytical expressions for the characteristics of such distributions, suitable for non-iterative (as opposed to Monte Carlo Method) probabilistic method applications, namely the Point Estimation Method. Purpose and tasks of the research. Increasing the simulation accuracy results for estimation economic and technical parameters characterising photovoltaic power plant based on based on the life cycle model; as well as development of different algorithms based on deterministic and stochastic modeling of power system with non-dispatchable sources and minimize the computation time. Object of research. Processes of determining the estimated technical and economic parameters characterising a photovoltaic power plant located in Ukraine basing on stochastic modeling. Subject of research. Use of the Monte Carlo Method and Point Estimation Method to estimate the various economic and technical information characteristic of alternative power plants in order to obtain accurate simulation results. Practical value of the results. Practical techniques of the three-point approximation are used to construct the probability density function of the model uncertain (stochastic) parameter, which dominantly influences the modeling result: an event occurrence probability, the result attainability, whatsoever. This technique is an effective tool for the practical evaluating of an uncertain value of a technological or economic factor of material and/or economic object, and widely used for overall Levelized Energy Cost (LCOE – LEC) which is directly or indirectly engaged into analytic representation of the power systel model. Usually, the model of a kind is designed to solve technical and/or economic problem by means of Deterministic and Stochastic Modeling. Scientific novelty of the obtained results is the development of algorithms and mathematical solutions using a probabilistic approach basing Point Estimation Method instead of Monte Carlo Melthod to obtain more accurate estimation simulation results, as well as to obtain computational results in less time for useful decision-making in alternative power plant projects.

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Cáceres, Delgado Adriana. "Algoritmo para frenagem regenerativa de uma máquina síncrona de imã permanente." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263011.

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Orientador: Niederauer Mastelari
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: A proteção ambiental e o melhor uso dos recursos energéticos são áreas de pesquisa de grande atividade. Como resultado destas pesquisas o desenvolvimento de veículos elétricos (VE) e híbridos (VEH) têm se acelerado. Estes possuem problemáticas desafiadoras, como baixa autonomia, a conversão de energia, o controle do veículo, o gerenciamento e distribuição da energia dentro dele, assim como o "design" tanto estético quanto mecânico e econômico. Este conjunto de problemáticas inspirou este projeto de mestrado que tem como objetivo o estudo e elaboração de um algoritmo para frenagem regenerativa (FR) de uma máquina síncrona de imã permanente brushless (BLDC). Motivados nas características que a estratégia de FR proporciona ao VE, entre estas, o aumento na autonomia e a melhora do desempenho mecânico e eletrônico do mesmo já que quando a FR é ativada recupera-se uma parte da energia cinética durante a desaceleração através da máquina elétrica operando como gerador. Com base no anterior este trabalho foi desenvolvido em várias etapas: principalmente ao abranger os conceitos sobre frenagem regenerativa; estudar o motor BLDC desde seu modelo, acionamento e identificação das características mais relevantes com respeito a outros motores elétricos. Seguido do projeto da parte mecânica do sistema, que compreende a transmissão e a inércia, para ser envolvidos no modelo simulado. Assim como o desenvolvimento dos algoritmos para o acionamento do motor, onde serão monitoradas a velocidade e a posição do rotor, com o fim de controlar sua aceleração e desaceleração. Posteriormente um algoritmo para frenagem regenerativa, onde é monitorado o estado do motor e executam-se as decisões lógicas tanto para redirecionamento de energia, quanto para controle da frenagem. O resultado obtido foi que o algoritmo para FR regenera parte da energia cinética envolvida durante a desaceleração, além de que gerencia o funcionamento de todo o processo e subprocessos durante a aceleração, velocidade constante e desaceleração passo a passo e minimiza o consumo de energia em cada desaceleração.
Abstract: Environmental protection and optimal energy resources are great activity research areas. As a result of these researches, electric vehicles (EVs) and hybrid (HEV) developments have been accelerated. They have challenging problems such as low autonomy, power conversion, vehicle control, energy management and distribution within it, as well as the esthetic and mechanical design and also the economic issues. This set of problems inspired this master's project which is aimed to study and elaborate an algorithm for regenerative braking (RB) in a synchronous permanent magnet brushless machine (BLDC). Motivated in the RB strategy characteristics that provides to the EV, such as, autonomy increased, mechanical and electronic performance improvement just when the RB is activated and part of the kinetic energy is recovered through the electric maquine as a generator. This work was developed in several stages: mainly cover the regenerative braking concepts; study the BLDC motor from its model, driver and outstanding features identification respect others electric motors. Followed by the mechanical design of the system, which includes the transmission and inertia, to be included in the simulated model. Just as the development of the algorithms for the motor drive, where will be monitored speed and rotor position, in order to control its acceleration and deceleration. Subsequently a management regenerative braking algorithm, which monitors the engine state, and excecute the logical decisions for redirecting the energy, and for braking control. As a result it was found that when the electrical machine operates as a generator part of the kinetic energy is recovered during deceleration. And also it was able to prove that the algorithm manages the whole process operation since the acceleration, constant velocity and deceleration step by step, while minimizing energy consumption in every downturn.
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica

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23

Ptáček, Michal. "Parciální řešení hybridního systému s nízkoteplotními palivovými články a obnovitelnými zdroji." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-233620.

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The thesis deals with the principle functions of low-temperature fuel cells with proton exchange membrane (PEMFC), photovoltaic sources (PVPP) and wind energy sources (WPP), along with solving their detailed mathematical expressions. In this work, the individual sources and their simulated models are analyzed in depth. The actual simulation is preceded by familiarization with important historical milestones in the development of fuel cells. Furthermore there is a basic classification of fuel cells and the characteristics of the cells used in the energy sectors. The text also provides information on projects that address the implementation of PEMFC as a primary or supplementary source of energy. Along with outlining the options for PEMFC as a perspective hydrogen technologies in the near future, the basic methods of hydrogen production and storage options are presented for the complexity. The work is exclusively focused on improving PEMFC mathematical models that under the hybrid system cooperate with renewable energy sources (RES). Part of the theses contains a short review of run or modeled concepts of hybrid systems in the energy sector. Using these models the main deficiencies of the models or of the whole PEMFC system can be identify. Specifications of the deficiencies lead to the creation of a new advanced dynamic PEMFC model that allows an analysis of the development of electrical and non-electrical quantities using long term tests. Furthermore, the thesis presents results of the experiments of thermal and dynamic behavior PEMFC, which were obtained from the additionally extended model with a reformer and the DC/DC converter. In this text there is a model of a photovoltaic module created, which is based on the nominal values parameterization. The model is subjected to basic experiments in which measured hydrometeorological data are used. If the hybrid system utilizes renewable energy sources, it is good to know the evolution of atmospheric conditions in the installation of these resources. Specifically for PVPP, publicly available databases containing information about solar radiation levels can be used for the selected location. Public databases are often used for initial design and manufacturing options for PVPP. An evaluation of the relevancy of public databases is performed based on a long-term observation of real measured data. Furthermore, these data are used for experiments on the photovoltaic module. Partially the text addresses the issue of the wind energy sources, however, it is simulated only on a simplified model of WPP. Created models of subsystems can be generally implemented as partial inputs hybrid systems in the future work. The thesis was developed at Centre for Research and Utilization of Renewable Energy (CVVOZE) with the financial support of the National Programme for Sustainability and the Ministry of Education, Youth and Sports of the Czech Republic under the project no. LO1210 - Energy for Sustainable Development and the project no. FEKT-S-14-2520 - New Technologies for Sustainable Development of Electrical Power Systems. The thesis was also generated under the project no. TA03020523 - Dynamic model of distribution network with the financial support of Technology Agency of the Czech Republic.

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Panovec, Jan. "Uplatnění energie obnovitelných zdrojů v budovách." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227660.

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The aim of this diploma thesis is to understand the functioning of heating and cooling systems in an administrative building built in passive standard using a renewable energy source. The thesis includes theoretical findings of heat pumps and designing the heating systems. The experimental part contains an analysis of working of heating and cooling systems in selected rooms in assigned building, which includes an experimental measurement of selected quantities and a thermographic measurement. In the last part of the thesis a comparison of measured and simulated values using simulation software was done.

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25

Ferreira, Rodrigo Arruda Felício. "Controle de microrredes CC baseado em droop adaptativo de tensão – simulação em tempo real com control-hardware-in-loop." Universidade Federal de Juiz de Fora (UFJF), 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/4173.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este trabalho apresenta um estudo sobre alguns dos aspectos relacionados às microrredes em corrente contínua, uma alternativa para utilização de fontes renováveis de energia em sistemas de geração distribuída. Considerando que a manutenção da tensão no barramento principal das microrredes, no qual as fontes e as cargas são conectadas, é uma das questões mais importantes para a operação de modo satisfatório destes sistemas, um sistema de controle descentralizado de tensão integrando técnicas de controle por droop de tensão e de controle por modos deslizantes é proposto. Uma microrrede CC de 10 kW conectada à rede CA e composta por arranjos fotovoltaicos e bancos de baterias, dimensionada para atender uma parcela das cargas eletrônicas e de iluminação do Instituto Federal de Educação, Ciência e Tecnologia – Campus Juiz de Fora, é modelada e simulada em tempo real utilizando o conceito de simulação CHIL. Resultados experimentais utilizando controladores externos como dispositivos em teste são utilizados para analisar o comportamento do sistema em diferentes condições e para validação da metodologia proposta. Além disso, é apresentado um estudo das técnicas de análise de estabilidade de tensão para sistemas em corrente contínua. Por ﬁm, é apresentada uma metodologia baseada em síntese de elementos reativos utilizando conversores estáticos para estabilização ativa de sistemas CC simpliﬁcados, contendo uma fonte e uma carga do tipo potência constante.
This work presents aspects related to DC microgrids, an alternative way of using renewable energy sources in a decentralized fashion. Whereas the maintenance of the microgrid main bus voltage, in which the sources and loads are connected, is one of the most important issues for the satisfactory operation of these systems, a novel methodology for regulating DC bus voltage integrating voltage droop control and sliding mode control techniques is proposed. A grid-connected 10 kW DC microgrid containing photovoltaic arrays and a battery bank, sized to meet a portion of electronic and lighting loads of the Federal Institute of Education, Science and Technology - Campus Juiz de Fora, is modeled and simulated in real time using the concept of CHIL simulation. Experimental results using external controllers as hardware under test are used to analyze system behavior under diﬀerent conditions and to validate the proposed methodology. Furthermore, a study regarding voltage stability analysis techniques applied to DC systems is presented. Finally, a methodology based on synthesis of reactive elements using static converters for active stabilization of simpliﬁed CC systems, containing one source and one constant power load, is presented.

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Kravetz, Fábio Inocêncio. "Conversor SEPIC modificado com acoplamento magnético série e célula multiplicadora de tensão." Universidade Tecnológica Federal do Paraná, 2018. http://repositorio.utfpr.edu.br/jspui/handle/1/3201.

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As fontes renováveis de energia, em especial a energia solar fotovoltaica vem ganhando espaço nos últimos anos devido ao avanço da tecnologia, redução dos custos e redução das fontes não-renováveis. Os painéis fotovoltaicos isoladamente ou para pequenas aplicações geram uma baixa tensão de saída e a adequação dos níveis de tensão fornecidos em sua saída aos requeridos pela concessionária de energia elétrica é um desafio. Neste trabalho é apresentada uma nova estrutura modificada da topologia do conversor SEPIC que usa as técnicas de acoplamento magnético série e células multiplicadoras de tensão em conjunto, afim de obter um elevado ganho de tensão, visando a aplicação em fontes renováveis de energia. Optou-se pela solução não isolada, pois esta apresenta diversas vantagens em relação a solução isolada, como: menor peso, volume, custo e maior eficiência energética devido a menores perdas de potência nos indutores acoplados. Também, a utilização da indutância de dispersão, que é um parâmetro intrínseco de um acoplamento magnético, permite a operação com comutação suave ZCS (ZCS, do inglês Zero Current-Switching) no interruptor, aumentando a eficiência da estrutura com a redução das perdas por comutação. No decorrer do trabalho são realizadas as análises das etapas de operação de diversos conversores a partir do conversor SEPIC modificado, evolui-se pela adição de técnicas elevadoras de tensão até a estrutura proposta neste trabalho. Por fim, é realizado o controle em malha fechada utilizando um controlador PID analógico que fornece uma resposta rápida e consequente correção a possíveis mudanças na variável controlada. Os resultados teóricos e experimentais do conversor proposto são descritos neste trabalho para validar as análises desenvolvidas e demonstrar a eficiência da estrutura. O protótipo é desenvolvido para uma aplicação com potência nominal de 200 W, tensão nominal de saída igual a 450 V e uma tensão de entrada variando entre 20 V e 40 V. O rendimento obtido para o conversor proposto operando na frequência de 35 kHz na potência nominal é de 91,28% e eficiência igual a 89,04% para a potência nominal de 200 W na frequência de 90 kHz.
The renewable energy resources, in special the photovoltaic energy has been achieve more space in last years due to technology advances, cost reduction and decrease of the non-renewable energy sources. The photovoltaic panels in isolation or to small applications generate a low output voltage and to comply with of voltage levels provided in panel’s output to those required by electric power concessionaire is a challenge. In this work is presented a new structure modified of the SEPIC converter topology who uses the coupling magnetic series and voltage multiplier cell techniques together, in order to obtain a high voltage gain aiming at application in renewable energy resources. It was has been choosen non-isolated solution, because this present several advantages in relation to the isolated solution, such as: lower weight, volume, cost and high energy efficiency due to smaller power losses in the coupled inductors. The use leakage inductance, who is an intrinsic parameter of the a magnetic coupling, allows soft-switching operation ZCS in switch, increasing the structure’s efficiency with reduction of switching losses. During the work are perform the analysis of the operation steps of several converters as of the modified SEPIC converter and evolves by addition high voltage techniques until the structure proposed in this work. Finally, is performed the closed loop control using the analog PID controller who provides a fast response and consequent correction to possible changes in the controlled variable. The theoretical and experimental results of the proposed converter are described in this work to validate the developed analysis and demonstrate the structure’s efficiency. The prototype is developed to a application with nominal power of 200 W, nominal output voltage equal 450 V and an input voltage varying between 20 V and 40 V. The efficiency obtained to proposed converter operating in frequency of the 35 kHz in nominal power is 91,28% and efficiency equal 89,04% to nominal power in frequency of the 90 kHz.

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Pusha, Ayana T. "Multiple turbine wind power transfer system loss and efficiency analysis." 2013. http://hdl.handle.net/1805/3800.

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Indiana University-Purdue University Indianapolis (IUPUI)
A gearless hydraulic wind energy transfer system utilizes the hydraulic power transmission principles to integrate the energy of multiple wind turbines in a central power generation location. The gearless wind power transfer technology may replace the current energy harvesting system to reduce the cost of operation and increase the reliability of wind power generation. It also allows for the integration of multiple wind turbines to one central generation unit, unlike the traditional wind power generation with dedicated generator and gearbox. A Hydraulic Transmission (HT) can transmit high power and can operate over a wide range of torque-to-speed ratios, allowing efficient transmission of intermittent wind power. The torque to speed ratios illustrates the relationship between the torque and speed of a motor (or pump) from the moment of start to when full-load torque is reached at the manufacturer recommended rated speed. In this thesis, a gearless hydraulic wind energy harvesting and transfer system is mathematically modeled and verified by experimental results. The mathematical model is therefore required to consider the system dynamics and be used in control system development. Mathematical modeling also provided a method to determine the losses of the system as well as overall efficiency. The energy is harvested by a low speed-high torque wind turbine connected to a high fixed-displacement hydraulic pump, which is connected to hydraulic motors. Through mathematical modeling of the system, an enhanced understanding of the HTS through analysis was gained that lead to a highly efficient hydraulic energy transmission system. It was determined which factors significantly influenced the system operation and its efficiency more. It was also established how the overall system operated in a multiple wind turbine configuration. The quality of transferred power from the wind turbine to the generator is important to maintaining the systems power balance, frequency droop control in grid-connected applications, and to ensure that the maximum output power is obtained. A hydraulic transmission system can transfer large amounts of power and has more flexibility than a mechanical and electrical system. However high-pressure hydraulic systems have shown low efficiency in wind power transfer when interfaced with a single turbine to a ground-level generator. HT’s generally have acceptable efficiency at full load and drop efficiency as the loading changes, typically having a peak around 60%. The efficiency of a HT is dependent on several parameters including volumetric flow rate, rotational speed and torque at the pump shaft, and the pressure difference across the inlet and outlet of the hydraulic pump and motor. It has been demonstrated that using a central generation unit for a group of wind turbines and transferring the power of each turbine through hydraulic system increases the efficiency of the overall system versus one turbine to one central generation unit. The efficiency enhancement depends on the rotational speed of the hydraulic pumps. Therefore, it is proven that the multiple-turbine hydraulic power transfer system reaches higher efficiencies at lower rotational speeds. This suggests that the gearbox can be eliminated from the wind powertrains if multiple turbines are connected to the central generation unit. Computer simulations and experimental results are provided to quantify the efficiency enhancements obtained by adding the second wind turbine hydraulic pump to the system.

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Προδρομίδης, Γεώργιος. "Mathematical simulation and optimization of a stand alone zero emissions hybrid system based on renewable energy sources." Thesis, 2014. http://hdl.handle.net/10889/7938.

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Renewable Energy Sources (RES) are the most promising resources of energy production for everyday life. Therefore, the precise combination of RES based technologies into hybrid systems could provide the solution to several energy problems facing the planet. The motivation of the present research study is the total understanding of the prevailing phenomena by using RES equipment in several projects. This thesis will focus on standalone hybrid RES based systems. By presenting the RES systems the necessity of buffering systems will become apparent as the most crucial parts of off-grid systems. Therefore, the most well-established buffering technologies will be analytically presented in order to be subsequently embodied into the simulated RES applications. Following the above theoretical approach of RES based equipment and hybrid systems in general, this thesis will focus on a more applied research study comprising the energetic and economical simulation and optimization of a RES based stand alone system that is already installed in Leicestershire, UK. Based on local meteorological data, an optimization strategy has been developed to identify the most economical and efficient scenarios for electricity generation to cover the desirable load on an annual basis. Furthermore, the environmentally-friendly character of the system was highly concerned with emissions reduction; therefore the capability of an off-grid system was also investigated. The feasibility of RES based systems for electricity supply will then be presented for four different Greek Islands. Three specific typical loads have been selected to be covered and the grid connection was considered optional. Up to this point the simulation and optimization procedures were applied by using the HOMER software tool in order to investigate the most suitable well-established platform in the world. After the theoretical research study on the most well-known platform of HOMER an innovative optimization theory based on the energy part of a hybrid system will be presented in order to select the most efficient system according to the desired requirements and the location of a RES based project. This thesis will then focus on the design and operation of an autonomous hybrid system under real-life meteorological conditions which is capable of simulating several loads assumed to cover the electricity demands of small buildings. The specific hybrid system embodies technologies that use photovoltaic and wind energy in combination with an electrochemical storage bank. Experiments on the coverage of annual loads regarding a typical house, a typical country house and a small company were also performed to prove the feasibility of the stand-alone system. The same established RES project was then simulated on a yearly basis using the HOMER software platform to determine real-time results. The above analysis revealed that HOMER software cannot successfully simulate the operation of such a system, therefore the design of a new mathematical model to produce results similar to those of the experimental process was considered essential based on a new optimization strategy.
Οι Ανανεώσιμες Πηγές Ενέργειας (ΑΠΕ) αποτελούν τις πιο πολλά υποσχόμενες πηγές στον τομέα της παραγωγής της ηλεκτρικής ενέργειας μέσα στην ανθρώπινη καθημερινότητα. Έτσι ο ακριβής συνδυασμός των ΑΠΕ σε υβριδικά συστήματα θα μπορούσε να αποτελέσει τη λύση στο μεγάλο ενεργειακό πρόβλημα που αντιμετωπίζει ο πλανήτης τα τελευταία χρόνια και όσο περνάει ο καιρός αυτό φαίνεται να διογκώνεται. Το κίνητρο για την εκπόνηση της παρούσας διδακτορικής διατριβής στηρίζεται στην ανάγκη για απόλυτη κατανόηση των φαινομένων που λαμβάνουν χώρα κατά τη χρήση των ΑΠΕ σε διάφορα συστήματα για την παραγωγή ηλεκτρικής ενέργειας. Επιπλέον, μέσα από αυτή την έρευνα θα φανεί πως οι καιρικές συνθήκες επηρεάζουν τη συμπεριφορά ενός υβριδικού συστήματος και σε ποιό ποσοστό. Ακόμα περιμένουμε να γίνει φανερό το πόσο σημαντική είναι η σωστή επιλογή των τεχνολογιών σύμφωνα με τις ηλεκτρικές ανάγκες που πρέπει να καλυφθούν από ένα εγκατεστημένο σύστημα. Στη συνέχεια της παρούσας εργασίας μελετήθηκε κάτω από ποιες συνθήκες ένα αυτόνομο υβριδικό σύστημα μπορεί να είναι εφικτό καθώς και πόσο ακριβή αποτελέσματα μπορούν αν δώσουν τα θεωρητικά μαθηματικά μοντέλα επάνω στην πρόβλεψη της λειτουργίας ενός συστήματος. Τέλος, παρουσιάστηκε πως μπορεί να ενισχυθεί ο οικολογικός χαρακτήρας ενός συστήματος ενώ την ίδια στιγμή αποκαλύφθηκε η κύρια αδυναμία του κατά τη λειτουργία καθώς και πως αυτή μπορεί να λυθεί με τη χρήση καινοτόμων συσκευών για την αποθήκευση ενέργειας. Μέσω της παρούσας διδακτορικής διατριβής αποδείχθηκε πως ένα υβριδικό σύστημα υποστηριζόμενο από ΑΠΕ μπορεί να μετατραπεί σε εντελώς αυτόνομο με ενισχυμένο τον οικολογικό του χαρακτήρα και με την οικονομική και ενεργειακή βιωσιμότητά του να κυμαίνεται σε υψηλά επίπεδα. Το παραπάνω συμπέρασμα προέκυψε μέσω θεωρητικών αλλά και πειραματικών προσομοιώσεων διάφορων υβριδικών μονάδων. Αυτό αποτελεί ίσως το πιο ενθαρρυντικό στοιχείο για πλήρη αξιοποίηση των ΑΠΕ προκειμένου να καλυφθούν οι παγκόσμιες ενεργειακές ανάγκες με τρόπους εντελώς φιλικούς προς το περιβάλλον στο άμεσο μέλλον.

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29

Dusetty, Venkatakrishna. "Numerical Simulation of Thermoelectric Transport in Bulk and Nanostructured SiSn Alloys." 2020. https://scholarworks.umass.edu/masters_theses_2/935.

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Abstract:

The current high demand for sustainable and renewable energy sources to solve world energy crisis has enormously increased interest in looking at alternative sources of energy. All the machines used in manufacturing process, electricity generation, residential applications, transportation etc., rejects energy in the form of heat into environment. Thermoelectric materials can convert thermal-to-electrical and electrical-to-thermal energy and can be utilized in waste-heat harvesting, more efficient cooling to reduce energy usage and CO2 emissions. Significant research efforts have been devoted over the past decade to thermoelectric materials, with particular emphasis being placed on combining materials selection with nanostructuring. The overarching goal was to reduce thermal conductivity through selective phonon scattering and thus boost the thermoelectric figure-of-merit (ZT). SiGe alloys, as well as superlattices and nanocomposites made from them, showed significant improvements upon nanostructuring and ZT exceeding one at high temperatures. Other group IV alloys were not studied in the context of thermoelectrics. However, SiSn alloys are widely studied for their optoelectronic properties because they were predicted to become direct-gap materials when Sn composition increased beyond about 50%. To address this gap, we study the thermoelectric properties of SiSn alloys. Furthermore, we develop an iterative full-band solver for the electron Boltzmann transport equation and use it to compute the electron and hole mobility and Seebeck coeffcient in SiSn alloys. The electronic structure of SiSn alloys was computed in the virtual crystal approximation from non-local empirical pseudopotentials, while the application of strain allowed us to extract the electron-phonon coupling deformation potentials for each alloy composition. We benchmark our code against available mobility data for Si and SiGe alloys and find that it accurately reproduces the measured values. Full phonon dispersion was computed from the adiabatic bond charge model, which was shown to accurately reproduce measured dispersion, and used in our phonon BTE solver to compute lattice thermal conductivities. Scattering rates include anharmonic phonon-phonon, impurity, isotope, alloy, and boundary mechanisms. The lowest thermal conductivity was obtained in SiSn alloys, which have been experimentally demonstrated with up to 18% Sn composition. This carries through when combined with calculations of electronic power factor, where mobilities and Seebeck coeffcients of SiSn alloys are comparable to those of SiGe. Furthermore, ZT is optimized through doping for every composition. The ZT improves dramatically at higher temperatures, reaching ZT of 1.9, 2.36 is obtained for Sn composition of 10% and 50% in a n-doped bulk SiSn alloys at a temperature of 1480 K. However, such high Sn composition of 50% is unlikely to be synthesized due to low solid solubility of Sn in Si. Lastly, we study the impact of nanostructuring in thin films on the ZT. We also establish the limits on how much the ZT can be improved through nanostructuring by studying thin films of SiSn alloys across temperature from room temperature up to 1500 K. We conclude that in bulk SiSn alloys, even at modest Sn concentration of 10%, ZT can reach 1.9, while in 20 nm thin films of n-type SiSn alloys, it can reach the long-sought target of ZT>3 and ZT of 2.16 is obtained in p-type nanostructured SiSn alloys.

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30

Sharma, Prashant Kumar. "Optimal Location of Distributed Generation to Reduce Loss in Radial Distribution Networks." Thesis, 2015. http://etd.iisc.ernet.in/2005/3772.

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Abstract:

Power losses are always a cause of worry for any power grid. In India, the situation is even worse. Though recent reports by Ministry of Power shows that Aggregate Technical and Commercial losses (AT &C losses) have come down from 36.64% in 2002-03 to 27% in 2011-12, yet they are much higher than the losses seen in many of the developed nations. The reduction shown in power loss is because of the Electricity Act, 2003 and the amendments made to it in 2007 which controlled the commercial losses rather than the technical losses. According to Ministry of Power, technical losses (Transmission & Distribution losses or T&D losses) in India are reported to be 23.65% in 2011-12. However, according to the study done by EPRI, for systems deployed in developed countries, these losses are estimated to be in the range of 7-15.5%. T & D losses occur in four system components namely step-up transformers and high voltage transmission (0.5-1%), step down to in intermediate voltage, transmission and step down to sub transmission voltage level (1.5-3%), sub-transmission system and step down to low voltage for distribution (2-4.5%), and distribution lines (3-7%). 1% of power loss is approximately equivalent to annual loss of Rs 600 million for a single state. Hence, in a year, loss in distribution line alone causes approximate loss of Rs 1.8-4.2 billion per state. Understanding and reducing power losses in distribution lines which contribute nearly 50% of the total T&D losses assume significance and has formed the motivation for the work reported in the thesis. In recent years, the trend has been to encourage users to generate solar power predominantly at residential complexes and captive power plants at industrial complexes. It has been suggested in the literature that Distributed Generation (DG) can not only reduce the load demanded from the power grid but also the power loss. In this thesis, it has been shown that by the choice of proper size and location of DG, the power loss can be reduced substantially as compared to unplanned deployment of DGs. The objective of the thesis is to design strategy for location of distributed user generated power to maximize the reduction in power loss. The thesis begins with a study of distributed generation in primary distribution networks and proceeds to problem formulation, with the aim being to develop an algorithm that can find out the optimal locations for DG allocation in a network. A greedy approximation algorithm, named OPLODER (i.e. Optimal Locations for Distributed Energy Resources), is proposed for the same and its performance on a benchmark data set is observed, which is found to be satisfactory. The thesis then moves on to describe the actual data of 101,881 commercial, residential and industrial consumers of Bangalore metropolitan area. A loss model is discussed and is used to calculate the line losses in LV part of the grid and loss is estimated for the said actual data. The detailed analysis of the losses in the distribution network shows that in most cases the losses are correlated with the sanctioned load. However there are also some outliers indicating otherwise. The analysis concludes that the distributed generated sources need to be optimally located in order to benefit fully. Also presented thereafter is a study about the impact of electrical properties and the structure of the network on power loss. In the second part of the thesis, OPLODER was again used to process the BESCOM data of 101,881 consumers by modeling them to be connected in three topologies namely Bus (i.e. linear structure), Star (i.e. directly connected) and Hybrid (i.e. tree structure). In case of Bus topology, when DG capacity available is 5% of the demand in substation, OPLODER reduced the loss from 14.65% to 10.75%, from 11.63% to 7.71% and from 13.33% to 9.24% for IISc, Brindavan, and Gokula substations respectively. Similarly, for the same amount of DG in case of star topology, OPLODER reduced loss from 1.75% to 1.26%, from 3.39% to 2.59% and from 2.96% to 1.99% for IISc, Brindavan, and Gokula substations respectively. Thereafter, the available real world data is re-modeled as a tree-type structure which is closer to the real world distribution network and OPLODER is run on it. The results obtained are similar to those presented above and are highly encouraging. When applied to the three substations viz. IISc, Brindavan and Gokula, the power loss dips from 9.95% to 7.42%, from 6.01% to 4.44% and from 8.07% to 5.95%, in case of DG used is 5% of the demand in substation. For the optimal strategies worked out in the thesis, additional overheads will be present. These overheads are studied and it has been found that the present infrastructure and technologies will be sufficient to handle the smart distribution network and the optimal strategy for distributed sources.

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31

Γκόπης, Χρήστος, and Βάιος Βαϊνάς. "Ανάλυση υβριδικού συστήματος ηλεκτροπαραγωγής με ΑΠΕ." Thesis, 2012. http://hdl.handle.net/10889/5240.

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Abstract:

Η διπλωματική εργασία που ακολουθεί, παρουσιάζει τη μελέτη και μοντελοποιήση ενός αυτόνομου υβριδικού συστήματος. Το αυτόνομο σύστημα που εξετάζεται είναι ένα υβριδικό σύστημα ηλεκτροπαραγωγής που αποτελείται από ένα φωτοβολταϊκό πάρκο, μία ανεμογεννήτρια, μία μονάδα υδρογόνου και δύο γεννήτριες βιομάζας και φυσικού αερίου. Για την μοντελοποίηση του συστήματος χρησιμοποιείται το πρόγραμμα σχεδιάσης και προσομοίωσης ηλεκτρικών συστημάτων PSCAD. Στην εργασία αυτή το ενδιαφέρον εστιάζεται στη συμπεριφορά του συστήματος στη μόνιμη κατάσταση λειτουργίας και στη συμπεριφορά σε κάποια μεταβατικά φαινόμενα. Τα μεταβατικά φαινόμενα που εξετάζονται είναι τα εξής: - Βραχυκύκλωμα των τριών φάσεων ως προς γη στο ζυγό της σύγχρονης γεννήτριας φυσικού αερίου - Συμπεριφορά συστήματος σε απότομη αποσύνδεση της ανεμογεννήτριας - Συμπεριφορά συστήματος σε διακοπή παροχής ρεύματος στην μονάδα υδρογόνου από το Φ/Β πάρκο Στο Κεφάλαιο 1 γίνεται μία γενικότερη αναφορά στο Φ/Β σύστημα. Στο Κεφαλαιο 2 γίνεται μία γενικότερη αναφορά στην αιολική ενέργεια. Στο Κεφάλαιο 3 γίνεται μία γενικότερη αναφορά στο υδρογόνο. Στο Κεφάλαιο 4 γίνεται μία γενικότερη αναφορά στην βιομάζα. Στο Κεφάλαιο 5 γίνεται μία γενικότερη αναφορά στο φυσικό αέριο. Στο Κεφάλαιο 6 γίνεται μία γενικότερη αναφορά στις σύγχρονες μηχανές και στο μαθηματικό τους υπόβαθρο. Στο Κεφάλαιο 7 περιγράφεται η δομή και τα στοιχεία που αποτελούν το αυτόνομο υβριδικό δίκτυο ηλεκτροπαραγωγής στο περιβάλλον του προγράμμματος μοντελοποιήσης, του PSCAD και παρουσιάζονται τα μοντέλα που απαρτίζουν το συνολικό σύστημα. Στο Κεφάλαιο 8 εξετάζεται η συμπεριφορά του συστήματος στη μόνιμη κατάσταση λειτουργίας. Στο Κεφάλαιο 9 εξετάζεται η συμπεριφορά του συστήματος στα τρία μεταβατικά φαινόμενα που έχουν προαναφερθεί, στο βραχυκύκλωμα των τριών φάσεων ως προς γη στο ζυγό της σύγχρονης γεννήτριας φυσικού αερίου, στην απότομη αποσύνδεση της ανεμογεννήτριας και στην διακόπη παροχής ρεύματος στην μονάδα υδρογόνου.
The thesis that follows, presents the study and the modelling of an autonomous hybrid system. The autonomous system that is examined is an electricity generating hybrid system that constists of a photovoltaic system, a wind generator, a hydrogen unit, a biomass generator and a natural gas generator. For the modelling of the system a designing and simulation program is used known as PSCAD. The main course of the current subject is the behavior of the system in the permanent situation of operation and the behavior of it in certain transient states. The transient states that are examined are the following: - Short-circuit of the three phases as for the ground on the natural gas generator bus. - Behavior of system in abrupt detachment of wind generator. - Behavior of system in abrupt detachment of the hydrogen unit. In Chapter 1 follows a theoretical analysis of the PV system. In Chapter 2 follows a theoretical analysis of the wind generator. In Chapter 3 follows a theoretical analysis of the hydrogen unit. In Chapter 4 follows a theoretical analysis of the biomass. In Chapter 5 follows a theoretical analysis of the natural gas. In Chapter 6 follows a theoretical and mathematical analysis of the synchronous machines. In Chapter 7 we describe the structure and the elements that constitute the autonomous hybrid system of electric generation in the environment of PSCAD. Also, the models that compose the total system are shown. In Chapter 8 is examined the reaction of system in the permanent situation of operation. In Chapter 9 is examined the reaction of system in the three transient states that have been mentioned before.

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32

(8083571), Veeraraghava Raju Hasti. "HIGH-PERFORMANCE COMPUTING MODEL FOR A BIO-FUEL COMBUSTION PREDICTION WITH ARTIFICIAL INTELLIGENCE." Thesis, 2019.

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Abstract:

The main accomplishments of this research are

(1) developed a high fidelity computational methodology based on large eddy simulation to capture lean blowout (LBO) behaviors of different fuels;

(2) developed fundamental insights into the combustion processes leading to the flame blowout and fuel composition effects on the lean blowout limits;

(3) developed artificial intelligence-based models for early detection of the onset of the lean blowout in a realistic complex combustor.

The methodologies are demonstrated by performing the lean blowout (LBO) calculations and statistical analysis for a conventional (A-2) and an alternative bio-jet fuel (C-1).

High-performance computing methodology is developed based on the large eddy simulation (LES) turbulence models, detailed chemistry and flamelet based combustion models. This methodology is employed for predicting the combustion characteristics of the conventional fuels and bio-derived alternative jet fuels in a realistic gas turbine engine. The uniqueness of this methodology is the inclusion of as-it-is combustor hardware details such as complex hybrid-airblast fuel injector, thousands of tiny effusion holes, primary and secondary dilution holes on the liners, and the use of highly automated on the fly meshing with adaptive mesh refinement. The flow split and mesh sensitivity study are performed under non-reacting conditions. The reacting LES simulations are performed with two combustion models (finite rate chemistry and flamelet generated manifold models) and four different chemical kinetic mechanisms. The reacting spray characteristics and flame shape are compared with the experiment at the near lean blowout stable condition for both the combustion models. The LES simulations are performed by a gradual reduction in the fuel flow rate in a stepwise manner until a lean blowout is reached. The computational methodology has predicted the fuel sensitivity to lean blowout accurately with correct trends between the conventional and alternative bio-jet fuels. The flamelet generated manifold (FGM) model showed 60% reduction in the computational time compared to the finite rate chemistry model.

The statistical analyses of the results from the high fidelity LES simulations are performed to gain fundamental insights into the LBO process and identify the key markers to predict the incipient LBO condition in swirl-stabilized spray combustion. The bio-jet fuel (C-1) exhibits significantly larger CH₂O concentrations in the fuel-rich regions compared to the conventional petroleum fuel (A-2) at the same equivalence ratio. It is observed from the analysis that the concentration of formaldehyde increases significantly in the primary zone indicating partial oxidation as we approach the LBO limit. The analysis also showed that the temperature of the recirculating hot gases is also an important parameter for maintaining a stable flame. If this temperature falls below a certain threshold value for a given fuel, the evaporation rates and heat release rated decreases significantly and consequently leading to the global extinction phenomena called lean blowout. The present study established the minimum recirculating gas temperature needed to maintain a stable flame for the A-2 and C-1 fuels.

The artificial intelligence (AI) models are developed based on high fidelity LES data for early identification of the incipient LBO condition in a realistic gas turbine combustor under engine relevant conditions. The first approach is based on the sensor-based monitoring at the optimal probe locations within a realistic gas turbine engine combustor for quantities of interest using the Support Vector Machine (SVM). Optimal sensor locations are found to be in the flame root region and were effective in detecting the onset of LBO ~20ms ahead of the event. The second approach is based on the spatiotemporal features in the primary zone of the combustor. A convolutional autoencoder is trained for feature extraction from the mass fraction of the OH ( data for all time-steps resulting in significant dimensionality reduction. The extracted features along with the ground truth labels are used to train the support vector machine (SVM) model for binary classification. The LBO indicator is defined as the output of the SVM model, 1 for unstable and 0 for stable. The LBO indicator stabilized to the value of 1 approximately 30 ms before complete blowout.

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Dissertations / Theses on the topic 'Renewable energy sources Computer simulation'

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