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1
Ruckdaschel, James David. "Harmonic Analysis of a Static VAR Compensated Mixed Load System." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/82.
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As power electronic based controllers and loads become more prevalent in power systems, there is a growing concern about how the harmonics generated by these controllers and loads affect the power quality of the system. One widely used power electronic based load is the Variable Frequency Drive (VFDs) used to vary the speed of an induction motor; whereas a common example of a power electronic based controller used in power systems is the Static VAR Compensator (SVC) for improving a system’s power factor. In this thesis, the harmonic content and overall performance of a system including both a VFD and a SVC will be studied and analyzed. Specifically, the cases of no compensation, static capacitor compensation, and power electronic based static VAR compensation are examined.
A small-scale model of a system for study was constructed in lab. Several cases were then performed and tested to simulate a system which contained both fixed and power electronic based harmonic generating loads. The performance of each case was determined by total harmonic current and voltage distortions, true power factor, and RMS current levels at different points in the system.
2
Silva, Aguinaldo Silveira e. "Placement and control of static compensators for power system stability." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311620.
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Mandali, Anusree. "Voltage Regulation Control on a Power System with Static Var Compensator." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1504863882578828.
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Zhang, Zhengwen. "Fast response static var generator for improving the power system performance of an electric arc furnace (EAF)." Thesis, Aston University, 2002. http://publications.aston.ac.uk/11836/.
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Cascaded multilevel inverters-based Static Var Generators (SVGs) are FACTS equipment introduced for active and reactive power flow control. They eliminate the need for zigzag transformers and give a fast response. However, with regard to their application for flicker reduction in using Electric Arc Furnace (EAF), the existing multilevel inverter-based SVGs suffer from the following disadvantages. (1) To control the reactive power, an off-line calculation of Modulation Index (MI) is required to adjust the SVG output voltage. This slows down the transient response to the changes of reactive power; and (2) Random active power exchange may cause unbalance to the voltage of the d.c. link (HBI) capacitor when the reactive power control is done by adjusting the power angle d alone. To resolve these problems, a mathematical model of 11-level cascaded SVG, was developed. A new control strategy involving both MI (modulation index) and power angle (d) is proposed. A selected harmonics elimination method (SHEM) is taken for switching pattern calculations. To shorten the response time and simplify the controls system, feed forward neural networks are used for on-line computation of the switching patterns instead of using look-up tables. The proposed controller updates the MI and switching patterns once each line-cycle according to the sampled reactive power Qs. Meanwhile, the remainder reactive power (compensated by the MI) and the reactive power variations during the line-cycle will be continuously compensated by adjusting the power angles, d. The scheme senses both variables MI and d, and takes action through the inverter switching angle, qi. As a result, the proposed SVG is expected to give a faster and more accurate response than present designs allow. In support of the proposal there is a mathematical model for reactive powered distribution and a sensitivity matrix for voltage regulation assessment, MATLAB simulation results are provided to validate the proposed schemes. The performance with non-linear time varying loads is analysed and refers to a general review of flicker, of methods for measuring flickers due to arc furnace and means for mitigation.
5
Habtay, Yehdego Tekeste. "Advanced static VAr compensator for direct on line starting of induction motors in an interconnected offshore power system." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/371.
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Ahmed, Sheikh. "PMU based PSS and SVC fuzzy controller design for angular stability analysis." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20547.
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Master of Science<br>Department of Electrical and Computer Engineering<br>Shelli Starrett<br>Variability in power systems is increasing due to pushing the system to limits for economic purposes, the inclusion of new energy sources like wind turbines and photovoltaic, and the introduction of new types of loads such as electric vehicle chargers. In this new environment, system monitoring and control must keep pace to insure system stability and reliability on a wide area scale. Phasor measurement unit technology implementation is growing and can be used to provide input signals to new types of control. Fuzzy logic based power system stabilizer (PSS) controllers have also been shown effective in various studies. This thesis considers several choices of input signals, composed assuming phasor measurement availability, for fuzzy logic-based controllers. The purpose of the controller is to damp power systems’ low frequency oscillations. Nonlinear transient simulation results for a 4-machine two-area system and 50 machine system are used to compare the effects of input choice and controller type on damping of system oscillations.
Reactive power in the system affects voltage, which in turn affects system damping and dynamic stability. System stability and damping can be enhanced by deploying SVC controllers properly. Different types of power system variables play critical role to damp power swings using SVC controller. A fuzzy logic based static var compensator (SVC) was used near a generator to damp these electromechanical oscillations using different PMU-acquired inputs. The goal was again improve dynamic stability and damping performance of the system at local and global level. Nonlinear simulations were run to compare the damping performance of different inputs on the 50 machine system.
7
Banejad, Mahdi. "Identification of damping contribution from power system controllers." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15851/1/Mahdi_Banejad_Thesis.pdf.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
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Banejad, Mahdi. "Identification of Damping Contribution from Power System Controllers." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15851/.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
9
Goldoost, Soloot Reza. "Wide-area damping control through inverse filtering technique." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/95937/4/Reza%20Goldoost%20Soloot_Thesis.pdf.
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This thesis proposes a new wide-area controller for enhancing the stability of power systems by damping inter-area oscillations. The obtained controller is a new nonlinear controller that accomplishes the task by using data from PMUs employed throughout the network. The controller improves the damping of inter-area oscillations by providing a supplementary control input for several controllable devices such as excitation systems of synchronous generators and Static Var Compensators. The novel nonlinear inverse filtering controller is developed and investigated in different network configurations in the thesis.
10
Davies, Mark. "Control systems for static VAR compensators." Thesis, Staffordshire University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361648.
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Li, Tianya. "Electromechanical wave propagation phenomenon and its control implications in power systems." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/95962/1/Tianya_Li_Thesis.pdf.
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This thesis investigates advanced control methods and strategies to enhance the transient stability of a power system which is affected by the electromechanical wave propagation phenomenon. The characteristics of the travelling wave phenomenon and its impact on system separation during first swing are investigated in detail. This thesis identifies four innovative control implications for power system stability and proposes an improved method to enhance power system transient stability. By designing better control of existing equipment, this research achieves increased maximum power transfer under contingencies in a cost efficient and readily implemented way.
12
Fernando, Warnakulasuriya A. M. "Power quality improvement in power systems using a static VAR compensator." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10638886.
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<p> The primary purpose of a power system is to transform energy from one of its naturally obtainable forms into electricity, and then supply it through grids to points of consumption. With the increasing demand for electricity, more reliable methods are required to keep the quality of power in the desired range. This paper focuses on the impacts that a static var compensator (SVC) has on power quality. A two-area power system was used to demonstrate the power quality enhancements of a SVC, and simulations were done on the Real Time Digital Simulator (RTDS) and Electrical Transients Analyzer Program (ETAP). Simulations were performed for both steady-state and transient conditions to exhibit the dynamic capabilities of a SVC. Also, two different types of SVC controls were used and their effectiveness was analyzed. Simulations showed that the steady-state voltage, namely at bus 8 where the SVC was installed, improved from 0.94pu to 1.0pu. In addition, the voltage recovery time of bus 8 was improved from over 40s to approximately 2s.</p><p>
13
Liu, Zhiqiang. "Static synchronous parallel compensation of var flow in power distribution systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/MQ55264.pdf.
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Subsingha, Wanchai. "Analysis and control of the advanced static var compensator for normal and abnormal operating conditions in power systems." Thesis, Northumbria University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416348.
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Tukur, Ahmed Gidado. "Reducing Airflow Energy Use in Multiple Zone VAV Systems." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1467872641.
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Hadjikypris, Melios. "Supervisory control scheme for FACTS and HVDC based damping of inter-area power oscillations in hybrid AC-DC power systems." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/supervisory-control-scheme-for-facts-and-hvdc-based-damping-of-interarea-power-oscillations-in-hybrid-acdc-power-systems(cc03b44a-97f9-44ec-839f-5dcbcf2801f1).html.
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Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.
17
Jen, Ching Kuo, and 任慶國. "A Study of Control System for Static Var Compensators." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/48254840057757833788.
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LIU, CHUAN-SHANG, and 劉傳聖. "Design of power system stabilizers and static VAR compensators." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/08314311556450270702.
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CHANG, TIEN CHIA, and 張添嘉. "Stability Analysis of the Cogeneration System with Static Var Compensators." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/47446261941857811320.
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碩士<br>國立中山大學<br>電機工程研究所<br>83<br>This thesis develops the control strategy, proper installation
location and parameter setting of the SVC to improve the
stability of the cogeneration facility. In this thesis, the
China Steel Corporation (CSC) with many cogeneration units is
selected for the stability problems study. The power system of
CSC always suffers a great voltage fluctuation due to the
operation of rolling mills. To solve this problem, the SVC with
voltage as a feedback signal is assumed to be installed on the
bus which connects to the rolling mill facility. Transient
stability program is then executed to verify the performance of
the SVC. Besides, the load shedding scheme is designed for the
cogeneration to prevent the power system from breakdown after
the tie line is tripped due to external system fault. The SVC
will be used and designed to improve the power system transient
stability and achieve the stable operation during the emergency
state. Furthermore, the system will suffer a voltage
disturbance when a large induction motor is started in the
stable isolated system. According to the computer simulation,
it is concluded that the SVC should be installed at the same
bus as the induction motor to achieve the best enhancement of
system dynamic stability.
20
ZHEN, JIN-XING, and 鄭進興. "Design of adaptive power system stabilizers and static VAR compensators." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/05680691572422469991.
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Chen, Chun-Kai, and 陳淳楷. "Static Var Compensator for Improving Shipboard Electric Power System Stability." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/16029838310927628562.
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碩士<br>國立海洋大學<br>電機工程學系<br>91<br>The shipboard electric power system is an independent system of which the required reliability is higher than that of the seashore power system. Because of the frequent load variation, the generating unit shall have fast and stable responding capability. Proper application of compensating devices will improve the damping of electromechanical oscillations and thus the stability of the system.
This thesis studies a practical shipboard electric power system, with emphasis placed on investigating the effect of the static var compensator (SVC) on the system dynamic behaviors by using the method of eigenanalysis. Time-domain simulations of the system under different disturbances are performed for verification.
22
WU, GI-RUI, and 吳啟瑞. "Design of adaptive power system stabilizers and static var controllers." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/85673715315215964419.
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Shih-Wei, Sun, and 孫士偉. "Ehancement of Transmission System Stability by Applying Static Var Compensator." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/36911736827233227208.
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碩士<br>南台科技大學<br>電機工程系<br>98<br>ABSTRACT
The main purpose of this thesis is to investigate the power system voltage stability and transient stability analysis. In the thesis, the Taiwan power system is selected for study. Based on the peak operation condition of Taiwan power system, the P-V and Q-V curves can be obtained by executing the voltage stability analysis in various N-1 and N-2 transmission line tripping contingencies. The P-V curve can denote the voltage collapse point and transfer power limit while the Q-V curve can identify the reactive power margin of the transmission lines. By the way, transient stability analysis is also performed to verify the system can be recovered to stable or not by examining the bus voltage and transmission line power flow after the contingency. In addition, the static var compensator are considered to be installed at the critical buses with different capacities to enhance the system stability and to avoid system from collapse.
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陳俊昌. "Static Var Compensator and Battery Energy Storage System for Shipboard Electirc Power System Stability." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/80152075190708545361.
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碩士<br>國立海洋大學<br>電機工程學系<br>90<br>The shipboard electric power system is an independent system of which the required reliability is higher than that of the seashore power system. Because of the frequent load variation, the generating unit shall have fast and stable response. Equipped with properly tuned additional Static Var Compensator will improve the damping of electromechanical oscillations in power system. Battery Energy storage system can provide simultaneously control of both its active and reactive power to improve power system operation and control.
The main purpose of this thesis is to study the stability of the shipboard electric power system on analyzing the effect of the Static Var Compensator and Battery Energy Storage System on overall system dynamic behaviors. A sample shipboard electric power system is taken as the study system. Based on the results analyzed and verified from the time-domain simulations, this paper shows that Battery Energy Storage System and Static Var Compensator can offer an important resource for improving shipboard electric power system operation.
25
Lee, maw ming, and 李茂銘. "The Effect of Load Models on Static Var Compensators in Taiwan Power System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/15016883956890909500.
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碩士<br>國立臺北科技大學<br>電機工程系碩士班<br>90<br>The Taiwan power system is an isolating power system and unable to get support from other systems when the electrical power supply is insufficient. In the past few years, the Taiwan Power Corporation has dedicated to build the third extra voltage transmission lines to solve the insufficient problem of power supply. However, for the location of field unavailability that result in the construction delaying, the expansion of power flow capacity sluggish and the network jam condition is more serious than before. Only improving the existing power generators and the transmission facilities can solve those problems. One of efficient instruments is to adopt the high quality Static Var Compensator (SVC). It is helpful to improve the power factor, enhance the capacity of the power system, stabilize the voltage and increase the power flow efficiency. The SVC is also useful for reducing lines loss and operation cost.
The aim of the thesis is to study the effect of load models on the SVC in Taiwan power system. Firstly, the definition, type, mathematical model and the method of setting load models are described. The Taipower system adapting load models and parameters are also introduced. Secondly, the principle, application, mathematical model and type of the SVC are further introduced. Finally, Three load models; Static ZIP Load Model, Dynamic Motor Load Model and Composite load Model are adopted in the Power System Analysis Software Package (PSASP) simulation, so that the system characters of steady state and the effect of load models on the system oscillation damping could be observed and compared when the 345KV bus is applied in the SVC and the three phases grounded fault occurred. It is expected that the results could be useful reference for the Taiwan Power Corporation in improving the power systems stability and facilities security.
26
BANSAL, ANKITA. "A COMPARITIVE STUDY OF AUXILIARY SIGNALS OF STATIC VAR SYSTEM FOR DAMPING SUBSYNCHRONOUS RESONANCE." Thesis, 2013. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15767.
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Transmission systems are being restructured to provide increased power transfer capability to accommodate a much wider range of possible generation patterns, due to the present pace of power system. The power transfer in the integrated power system is impeded by transient stability, voltage stability, and small signal stability. To enhance the power transfer capability, Series compensation has been widely used. The fast acting power electronic converters, Flexible AC Transmission System (FACTS) devices with their equally fast and efficient controlling capabilities are becoming the pillars of support of such a highly integrated power systems. FACTS devices are very effective and capable for increasing loadability, reducing system loss, improved stability of network and reduced cost of production.
However, presence of series compensation gives rise to the problems of dynamic instability and sub synchronous resonance (SSR). SSR is basically an electrical power system condition where the electrical network exchanges energy with the turbine generator at one more natural frequencies of the combined system below the synchronous frequency of the system. A number of power electronic devices have been proposed for dynamic compensation, improving system stability, directing power flows, etc. One of the power electronic devices used for reactive power compensation is a Static VAR Compensator (SVC). Such a system when connected in shunt with a power system is referred to as a static VAR System.
An idea of the thesis is to damp SSR by adding static var compensator (SVC). This thesis shows that by using different auxiliary controllers of SVC, damping performance is enhanced. The major objective is to compare various auxiliary controllers of SVC. The results are obtained by modelling a linearized system in MATLAB.
A detailed system model has been developed. The study system consists of a generator supplying power to an infinite bus over a long transmission line. IEEE type-1 excitation system is considered for the generator. The SVC of switched capacitor-thyristor controller reactor (SC-TCR) type provides dynamic voltage support at the midpoint of line. A lumped parameter T-circuit represents the network. The SVC and series compensation are located at the centre of transmission line in order to optimize the performance of these devices.
Different SVC auxiliary controllers are compared and evaluated for enhancement of dynamic stability of a series compensated power system by computing the eigenvalues of linearized system model.
The performance of combined reactive power frequency controller (CRPF) and combined voltage angle and reactive power controller (VARP) has been compared and it is found that the combined voltage angle and reactive power (VARP), SVC auxiliary controller is the most effective for system damping at a given operating point.
27
Huang, Jian-Long, and 黃健龍. "Design of a Grey Decision Prediction Controller for Induction Generator System with Static VAR Compensator." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/ysv63d.
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碩士<br>國立臺北科技大學<br>電機工程系所<br>93<br>This thesis integrates the inverting power supply system and the Static VAR Compensator (SVC) to form an inverting power supply system for induction generator with SVC. The advantages of induction generator includes lower cost, simple structure, high power-weight ratio, protection ability of over load and short circuit, so that the induction generators are widely used in smaller capacity power station.
However, there are drawbacks of the conventional induction generators, the output voltage and frequency are easily and instantaneously affected by rotational speed of rotor, system load, and the power factor. It leads that the output frequency at the generator terminal is irritable and the voltage regulation is deteriorated. To solve the problems, this thesis proposes a novel induction generator system, which combines the inverting power supply system and SVC, to restrain voltage fluctuation due to the change load of induction generator system. As a result, the output voltage will steadily remain at the set point and increase the quality of output voltage of induction generator.
For the inverting power supply system, the output voltage of the generator is converted by a three-phase converter, filtered by an L-C filter, and then supplied to inverter as the DC input. As a result, the output frequency is independent of generator’s rotor speed, and the output frequency can be dynamically regulated to the set-point frequency by adjust the inverter. In addition, SVC can effectively improve the voltage regulation performance of induction generator system in the conditions of high voltage, loading, and unloading. Furthermore, Grey Decision Prediction Controller (GDPC) is embedded into the two modules of induction generator system. The grey prediction function can predict the trend of the system response and proactively compensate the considered system. In addition, the grey decision function can dynamically regulate steps of grey prediction to enhance the performance of dynamic behaviors of the inverting power supply system and SVC.
Experiment results show that the proposed induction generator system has quick and excellent dynamic response in the variations of voltage and rotor’s speed. The designed system can dramatically improve the supply quality of elf-excited induction-generator and the stability of output voltage.
28
展子傑. "Time-Frequency and Power-Voltage Curve Analyses for Voltage Stability of Power System with Static Var Compensation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/48512002949101537670.
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Kashyap, Ravi Bhushan. "Design of controllers associated with static VAR compensators for damping of low frequency oscillations in a power system." Thesis, 1993. http://spectrum.library.concordia.ca/2961/1/MM84663.pdf.
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This thesis is concerned with the development of a supplementary controller associated with a Static Var Compensator for damping of low-frequency oscillations (0.05-2.0 Hz) which are normally present in power systems. The objective of this thesis is to demonstrate that with the use of load modulation, damping of intermachine and system oscillation can be increased. The development of supplementary controllers requires that a simplified model of the system be available. In large systems this can be a difficult process. In this thesis a simplified approach is presented. It is based on fast fourier transform analysis of the response of the system in time domain from which a reduced order transfer function is determined. This analysis is carried out on a system similar to that of Hydro-Quebec. Classical control system design methods (root locus and bode plot) are then used to design the controller, limiting the analysis to the linear region. The extent of this region is defined in the thesis. The design of this controller is carried out and its effectiveness demonstrated in the environment of Matrix$\sb{\rm x},$ a mathematical software package. It is then confirmed for the detailed system using in-house transient stability program. The simulation results show the effectiveness of these controllers to damp the oscillations with the use of locally available variables. It is also shown that these controllers can be used to damp out the oscillations which may not be locally observable on the bus but are made available through the use of remote communication
30
Mazur, Ronald Wayne. "Damping of power system harmonic resonances using firing angle modulation of the thyristor controlled reactor of a static var compensator." 1989. http://hdl.handle.net/1993/16969.
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Chen, Zhao Hong, and 陳昭浤. "Application of static var compensators to distribution systems." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/67470986394600731059.
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Santosh, Kumar A. "Voltage Stability Analysis of Unbalanced Power Systems." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3065.
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The modern day power system is witnessing a tremendous change. There has been a rapid rise in the distributed generation, along with this the deregulation has resulted in a more complex system. The power demand is on a rise, the generation and trans-mission infrastructure hasn't yet adapted to this growing demand. The economic and operational constraints have forced the system to be operated close to its design limits, making the system vulnerable to disturbances and possible grid failure. This makes the study of voltage stability of the system important more than ever.
Generally, voltage stability studies are carried on a single phase equivalent system assuming that the system is perfectly balanced. However, the three phase power system is not always in balanced state. There are a number of untransposed lines, single phase and double phase lines. This thesis deals with three phase voltage stability analysis, in particular the voltage stability index known as L-Index. The equivalent single phase analysis for voltage stability fails to work in case of any unbalance in the system or in presence of asymmetrical contingency. Moreover, as the system operators are giving importance to synchrophasor measurements, PMUs are being installed throughout the system. Hence, the three phase voltages can be obtained, making three phase analysis easier.
To study the effect of unbalanced system on voltage stability a three phase L-Index based on traditional L-Index has been proposed. The proposed index takes into consideration the unbalance resulting due to untransposed transmission lines and unbalanced
loads in the system. This index can handle any unbalance in the system and is much more realistic. To obtain bus voltages during unbalanced operation of the system a three phase decoupled Newton Raphson load ow was used.
Reactive power distribution in a system can be altered using generators voltage set-ting, transformers OLTC settings and SVC settings. All these settings are usually in balanced mode i.e. all the phases have the same setting. Based on this reactive power optimization using LP technique on an equivalent single phase system is proposed. This method takes into account generator voltage settings, OLTC settings of transformers and SVC settings. The optimal settings so obtained are applied to corresponding three phase system. The effectiveness of the optimal settings during unbalanced scenario is studied. This method ensures better voltage pro les and decrease in power loss.
Case studies of the proposed methods are carried on 12 bus and 24 bus EHV systems of southern Indian grid and a modified IEEE 30 bus system. Both balanced and unbalanced systems are studied and the results are compared.
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Santosh, Kumar A. "Voltage Stability Analysis of Unbalanced Power Systems." Thesis, 2016. http://hdl.handle.net/2005/3065.
Pełny tekst źródłaStreszczenie:
The modern day power system is witnessing a tremendous change. There has been a rapid rise in the distributed generation, along with this the deregulation has resulted in a more complex system. The power demand is on a rise, the generation and trans-mission infrastructure hasn't yet adapted to this growing demand. The economic and operational constraints have forced the system to be operated close to its design limits, making the system vulnerable to disturbances and possible grid failure. This makes the study of voltage stability of the system important more than ever.
Generally, voltage stability studies are carried on a single phase equivalent system assuming that the system is perfectly balanced. However, the three phase power system is not always in balanced state. There are a number of untransposed lines, single phase and double phase lines. This thesis deals with three phase voltage stability analysis, in particular the voltage stability index known as L-Index. The equivalent single phase analysis for voltage stability fails to work in case of any unbalance in the system or in presence of asymmetrical contingency. Moreover, as the system operators are giving importance to synchrophasor measurements, PMUs are being installed throughout the system. Hence, the three phase voltages can be obtained, making three phase analysis easier.
To study the effect of unbalanced system on voltage stability a three phase L-Index based on traditional L-Index has been proposed. The proposed index takes into consideration the unbalance resulting due to untransposed transmission lines and unbalanced
loads in the system. This index can handle any unbalance in the system and is much more realistic. To obtain bus voltages during unbalanced operation of the system a three phase decoupled Newton Raphson load ow was used.
Reactive power distribution in a system can be altered using generators voltage set-ting, transformers OLTC settings and SVC settings. All these settings are usually in balanced mode i.e. all the phases have the same setting. Based on this reactive power optimization using LP technique on an equivalent single phase system is proposed. This method takes into account generator voltage settings, OLTC settings of transformers and SVC settings. The optimal settings so obtained are applied to corresponding three phase system. The effectiveness of the optimal settings during unbalanced scenario is studied. This method ensures better voltage pro les and decrease in power loss.
Case studies of the proposed methods are carried on 12 bus and 24 bus EHV systems of southern Indian grid and a modified IEEE 30 bus system. Both balanced and unbalanced systems are studied and the results are compared.
34
Kimla, John. "Optimized Fan Control In Variable Air Volume HVAC Systems Using Static Pressure Resets: Strategy Selection and Savings Analysis." Thesis, 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7332.
Pełny tekst źródłaStreszczenie:
The potential of static pressure reset (SPR) control to save fan energy in variable air
volume HVAC systems has been well documented. Current research has focused on the creation
of reset strategies depending on specific system features. As the commissioning process has
begun to require the prediction of savings, knowledge of the extent to which various SPR control
strategies impact fan energy has become increasingly important. This research aims to document
existing SPR control strategies and utilize building data and simulation to estimate fan energy
use.
A comprehensive review of the literature pertaining to SPR control was performed and
the results were organized into a top-down flow chart tool. Based on the type of feedback
available from a particular system, or lack thereof, this tool will facilitate the selection of a SPR
control strategy. A field experiment was conducted on a single duct variable air volume system
with fixed discharge air temperature and static pressure setpoints. Finally, an air-side model of
the experimental system was created using detailed building design information and calibrated
using field measurements. This model was used to estimate the fan energy required to supply
the trended airflow data using fixed static pressure (FSP) and SPR control based on zone
demand, system demand, and outside air temperature.
While utilizing trend data from November 1, 2008 to February 12, 2009, the FSP control
of the experimental system was used as the baseline for ranking the energy savings potential of
nine different forms of duct static pressure control. The highest savings (73-74%) were achieved
using zonal demand based SPR control. System demand based SPR control yielded savings
ranging from 59 to 76%, which increased when the duct sensor was positioned near the fan
discharge and under similar zone load conditions. The outside air temperature based SPR
control yielded savings of 65% since the experimental system supplied primarily perimeter
zones. Finally, increasing the FSP setpoint from 2 to 3 inWG increased fan energy by 45%,
while decreasing the setpoint from 2 to 1 inWG decreased fan energy by 41%.
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Ravi, Kumar B. "Development Of Algorithms For Power Quality Improvements In Distribution Systems." Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1170.
Pełny tekst źródła
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Ravi, Kumar B. "Development Of Algorithms For Power Quality Improvements In Distribution Systems." Thesis, 2004. http://etd.iisc.ernet.in/handle/2005/1170.
Pełny tekst źródła
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Von, Landsberg John Lodewyk. "'n Ontwikkelingsperspektief van vakleerlingskappe in Suid-Afrika : implikasies vir die onderwysstelsel." Diss., 2014. http://hdl.handle.net/10500/18698.
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Text in Afrikaans<br>Hierdie navorsing getiteld 'n Ontwikkelingsperspektief van vakleerlingskappe in Suid-Afrika: implikasies vir die onderwysstelsel ondersoek die wortels van die vakleerlingskap
stelsel sedert antieke tye, deur die koloniale tydperk in Suid-Afrika, die "armblankevraagstuk"1922-1960, voor-demokrasie 1950-1980, 1980-1993 en post-demokrasie
1994-2014. Die studie konsentreer op die kronologiese verloop van gebeure wat gelei
het tot die formalisering van die vakleerlingskapstelsel in Suid-Afrika in 1922 asook die
evolusie tot in sy huidige vorm. Spesifieke aandag is geskenk aan wetgewing, beide
provinsiaal en nasionaal, wat bygedra het tot die vorming van die stelsels.
Die vakleerlingskapstelsel van Amerika is ook ondersoek vanaf sy wortels tot die
huidige era met al sy vorme van tegniese beroepsonderwys asook vakleerlingopleiding.
Daar is gekyk na al die verskillende Amerikaanse kolleges en tegniese skoolstelsel.
‘n Vergelykende studie tussen Amerika en Suid-Afrika se vakleerlingskapstelsel is
gemaak met spesifieke aanbevelings vir die Suid-Afrikaanse stelsel.<br>This research, entitled A developmental perspective of apprenticeships in South Africa:
Implications for the education system, examined the origins of the apprenticeship
system from its roots in pre-history, through colonial time in South Africa, the "armblanke-vraagstuk" 1922-1960, pre-democracy 1950-1980, 1980-1993 and postdemocracy
1994-2014. This study concentrated on chronicling the events leading to the
establishment of formalized apprenticeship training in South Africa in 1922 and its
evolution to its present form. Particular attention was paid to the legislation, both
provincial and national, that provided for the establishment of the present system.
The apprenticeship system of the USA was also examined from its roots up to the
present time in all its forms of technical, vocational and artisan training. Looking at the
different college systems and technical training schools of the USA.
Comparisons between USA and South Africa‘s apprenticeship systems was made with
specific recommendations for South Africa‘s system.<br>Educational Foundations<br>M. Ed. (Vergelykende Opvoedkunde)
38
Garbers, Rachel. "An e-learning instructional design framework for mobile devices in Africa." Diss., 2018. http://hdl.handle.net/10500/25531.
Pełny tekst źródłaStreszczenie:
English text, with summaries in English, Afrikaans and Zulu<br>This study aims to propose an e-learning framework for mobile devices in Africa to help improve enrolment rates and education standards in the FET (Further Education and Training) phase. The study is qualitative in nature and employs document analysis as main research method. An overview of the South African education context with supporting statistical data to motivate why an e-learning alternative is crucial for improving South African and African education is provided. The literature review includes a descriptive analysis of 7 existing e- and m-learning frameworks, with key features highlighted for possible adaptation or incorporation into an e-learning framework for Africa. Behaviourism, Constructivism and Connectivism are discussed as applicable learning theories to pedagogically underpin this proposed e-learning framework. Thereafter, a critical evaluation of current South African education policy documents (White Papers, the Norms and Standards for Educators and the Draft Policy for the Provision and Management of Learning Teaching and Support Materials) is conducted to determine whether these policies support and enable e-learning effectively. Part 2 of Chapter 5 comprises a critical analysis and comparison of education systems and applicable legislation in the USA, Finland and Malawi to establish how education is structured and how e-learning is administered in these countries to make relevant recommendations for South Africa and to inform the design of an e-learning framework for Africa. Research findings are presented as answers to the research questions posed and the proposed e-learning framework with further recommendations are presented to the South African Department of Basic Education, teachers and researchers.<br>Die doel van hierdie studie is om ‘n e-onderrig-en-leer raamwerk vir mobiele toestelle vir Afrika voor te stel, sodat inskrywingsgetalle en onderrig- en leerstandaarde in die Verdere Onderrig en Opleidings (VOO) fase verbeter kan word. Dit is ‘n kwalitatiewe studie en dokumentanalise word as navorsingsmetode toegepas. ‘n Oorsig van die huidige Suid-Afrikaanse onderwysstelsel en konteks met ondersteunende statistiese bevindinge word verduidelik om e-onderrig-en-leer as noodsaaklike alternatief vir Suid-Afrika en Afrika te motiveer. Die literatuuroorsig sluit ‘n beskrywende analise van sewe bestaande e- en m-onderrig-en-leer (mobiele-onderrig-en-leer) raamwerke in. Hoofkenmerke van elke raamwerk word uitgelig vir moontlike aanpassing en inkorporering in ‘n e-onderrig-en-leer raamwerk vir die Afrika-konteks. Leerteorië, nl Behaviourisme, Konstruktivisme en Konnektivisme (Connectivism) word in diepte bespreek as pedagogies fundamenteel om die e-onderrig-en-leer raamwerk te onderbou en te ondersteun. ‘n Kritiese evaluasie van Suid-Afrikaanse onderwysbeleid (d.w.s. Witskrifte, die Norme and Standaarde vir Onderwysers en die konsepdokument oor die Voorsiening en Bestuur van Onderrig-, Leer- en Ondersteuningsmateriaal) is gedoen om vas te stel of die beleid wel e-onderrig-en-leer effektief ondersteun en prakties moontlik maak. ‘n Krities analitiese en vergelykende studie van die VSA (Verenigde State van Amerika), Finland en Malawi se onderwysstelsels- en wetgewing is gedoen in hoofstuk 5 deel 2 om te bepaal hoe dié lande onderwys struktureer en hoe e-onderrig-en–leer geadministreer word, sodat relevante voorstelle vir Suid-Afrika gemaak kan word en om insae te lewer in die ontwerp van ‘n e-onderrig-en-leer raamwerk toepaslik vir die Afrika-kontinent. Navorsingsbevindinge word voorgelê aan die Suid-Afrikaanse Departement van Basiese Onderwys, onderwysers sowel as aan navorsers.<br>Lolu cwaningo luhlose ukuphakamisa uhlaka lwe-e-learning lamadivaysi eselula e-Afrika ukusiza ukuthuthukisa izinga lokubhalisa nezindinganiso zemfundo kwiSigaba se-FET (Further Education and Training). Ucwaningo luyimfanelo enemvelo futhi lusebenzisa ukuhlaziywa kwedokhumenti njengendlela yokucwaninga eyinhloko. Ukuhlolisisa umongo wezemfundo waseNingizimu Afrika ngokusekela imniningwane yezibalo ukugqugquzela ukuthi kungani enye yokufunda email ibalulekile ekuthuthukiseni imfundo yaseNingizimu Afrika ne-Afrika. Ukubuyekezwa kwezincwadi kuhlanganisa ukuhlaziywa okuchazayo kwezinhlaka eziyisikhombisa ezisekhona ze-e- e-m-learning, nezici eziyinhloko eziqokonyiswe ukukhishwa kwe-adaption noma ukufakwa kwisakhiwo se-e-learning se-Afrika. Ukuzikhethela, Ukwakhiwa kwe-Constructivism (Kwe Zokwakha) kanye ne-Connectivism (Kwe Zokuxhumana) kuxoxwa njengezifundo ezifanele zokufunda ukusekela lolu hlelo oluhlongozwayo lwe-e-learning. Ngemuva kwaloko, ukuhlolwa okubalulekile kwemibhalo yamanje yemfundo yaseNingizimu Afrika (Amaphepha Asemhlophe, Imigomo Nemigomo Yabafundisi kanye neNqubomgomo Yohlaka Lokufundiswa Nezifundo Nokusekela) kwenziwa ukuze kutholakale ukuthi lezi zinqubomgomo zisekela futhi zikwazi yini ukufundisa nge-e-ephumelelayo. Ingxenye yesibili yeSahluko sesihlanu iqukethe ukuhlaziywa okubucayi kanye nokuqhathaniswa kwezinhlelo zemfundo kanye nemithetho esebenzayo eMelika, eFinland nase Malawi ukuqinisekisa ukuthi imfundo ihlelwe kanjani nokuthi i-e-learning inikezwa kanjani ukwenza izincomo ezifanele eNingizimu Afrika nokwazisa ukuklama uhlaka lwe-e-learning lwe-Afrika. Imiphumela yokucwaninga inikezwa njengezimpendulo zemibuzo yokucwaninga ephakanyisiwe kanye nohlaka oluhlongozwayo lwe-e-learning kanye nezincomo ezengeziwe ezethulwa eMnyangweni wezemfundo Eyisisekelo, othisha nabacwaningi baseNingizimu Afrika.<br>Curriculum and Instructional Studies<br>M. Ed. (Curriculum Studies)