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Dissertations / Theses on the topic 'Power system stability control'
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1
Manansala, Edgardo Celestino. "Adaptive power system control." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54391.
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This work presents a centralized control scheme applied to a power system. The scheme has adaptive characteristics which allow the controller to keep track of the changing power system operating point and to control nonlinear functions of state variables. Feedback to the controller is obtained from phasor measurements at chosen power system buses, generator field voltage measurements, and state estimators. Control effort is aimed at minimizing the oscillations and influencing the power system state trajectory through the control of linear and nonlinear functions of state variables during a power system disturbance.
The main contributions of this dissertation are the simultaneous introduction and utilization of measurement based terms in the state and output equations in the derivation and implementation of the control law, the study of limits on controller performance as the state residual vector becomes very large, and the simulation of the performance of local state estimators to prove the need for faster phasor measurement systems.
The test system is a hypothetical 39-Bus AC power system consisting of typical components which have been sufficiently modelled for the simulation of power system performance in a dynamic stability study.Ph. D.
2
Cheung, Siu-pan. "Direct transient stability margin assessment of power system with excitation control and SVC control /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1753706X.
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張小彬 and Siu-pan Cheung. "Direct transient stability margin assessment of power system with excitation control and SVC control." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31212979.
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Anderson, Sharon Lee. "Reduced order power system models for transient stability studies." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09052009-040743/.
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Song, Yang. "Design of secondary voltage and stability controls with multiple control objectives." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29714.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Begovic, Miroslav; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Lambert, Frank; Committee Member: Shamma, Jeff. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Oukati, Sadegh Mahmoud. "Control of power electronic devices (FACTS) to enhance power system stability." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275177.
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Farsangi, Malihe Maghfouri. "Robust control of flexible AC transmission systems for damping power system oscillations." Thesis, Brunel University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269400.
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Falkner, Catherine M. "Robust output feedback controllers for power system stabilization." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/14802.
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He, Fangpo. "Nonlinear adaptive control in the design of power system stabilisers /." Title page, contents and introduction only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09phh431.pdf.
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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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Chapman, Jeffrey W. (Jeffrey Wayne). "Feedback linearizing generator excitation control for enhanced power system stability." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/117237.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Title as it appears in the M.I.T. Graduate List, June 1992: Nonlinear control strategies for power system stability enhancement.
Includes bibliographical references (leaves 104-107).
by Jeffrey W. Chapman.
M.S.
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Silveira, e. Silva Aguinaldo. "Placement and control of static compensators for power system stability." reponame:Repositório Institucional da UFSC, 1990. http://repositorio.ufsc.br/xmlui/handle/123456789/75626.
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曾坤明 and Kwan-ming Tsang. "Decoupling and stabilizing control of multi-machine power systems withstatic VAr compensators." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31211008.
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Zhang, Yang. "Design of wide-area damping control systems for power system low-frequency inter-area oscillations." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/y_zhang_112007.pdf.
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Thandi, Gurjit Singh. "Modeling, Control and Stability Analysis of a PEBB Based DC Distribution Power System." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36788.
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Power Electronic Building Block (PEBB) concept is to provide generic building blocks for power conversion, regulation and distribution with control intelligence and autonomy. A comprehensive modeling and analysis of a PEBB based DC distributed power system (DPS), comprising of a front end power factor correction (PFC) boost rectifier, a DC-DC converter and a three phase four leg inverter is performed. All the sub-systems of the DC DPS are modeled and analyzed for stability and good transient performance.
A comprehensive stability analysis of a PEBB based DC DPS is performed. The effect of impedance overlap on the system and individual sub-systems is examined. Ability of a PEBB based converter to stabilize the integrated system by actively changing the system bandwidth is presented. The fault tolerance capability in a PEBB based rectifier is established by ensuring stable system operation, with one leg of the rectifier failed open-circuited.
Master of Science
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Sreenivasachar, Kannan. "Unified power flow controller, modeling, stability analysis, control strategy and control system design." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60570.pdf.
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Chandrasekharan, Santhosh. "Development of a tractor-semitrailer roll stability control model." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196260360.
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Almutairi, Abdulaziz. "Enhancement of power system stability using wide area measurement system based damping controller." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/enhancement-of-power-system-stability-using-wide-area-measurement-system-based-damping-controller(7d98d164-8051-4662-ad18-374620d28a00).html.
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Contemporary power networks are gradually expanding incorporating new sources of electrical energy and power electronic based devices. The major stability issue in large interconnected power systems is the lightly damped interarea oscillations. In the light of growth of their incidents there are increased concerns about the effectiveness of current control devices and control systems in maintaining power system stability. This thesis presents a Wide Area Measurement System (WAMS) based control scheme to enhance power system stability. The control scheme has a hierarchical (two-level) structure comprising a Supplementary Wide-Area Controller (SWAC) built on top of existing Power System Stabilisers (PSSs). The SWAC's focus is on stabilising the critical interarea oscillations in the system while leaving local modes to be controlled entirely by local PSSs. Both control systems in the two levels work together to maintain system stability. The scheme relies on synchronised measurements supplied by Phasor Measurement Units (PMUs) through the WAMS and the only cost requirement is for the communication infrastructure which is already available, or it will be in the near future. A novel linear quadratic Gaussian (LQG) control design approach which targets the interarea modes directly is introduced in this thesis. Its features are demonstrated through a comparison with the conventional method commonly used in power system damping applications. The modal LQG approach offers simplicity and flexibility when targeting multiple interarea modes without affecting local modes and local controllers, thus making it highly suitable to hierarchical WAMS based control schemes. Applicability of the approach to large power systems is demonstrated using different scenarios of model order reduction. The design approach incorporates time delays experienced in the transmission of the SWAC's input/output signals. Issues regarding values of time delays and required level of detail in modelling time delays are thoroughly discussed. Three methods for selection of input/output signals for WAMS based damping controllers are presented and reviewed. The first method uses modal observability/controllability factors. The second method is based on the Sequential Orthogonalisation (SO) algorithm, a tool for the optimal placement of measurement devices. Its application is extended and generalised in this thesis to handle the problem of input/output signal selection. The third method combines clustering techniques and modal factor analysis. The clustering method uses advanced Principal Component Analysis (PCA) where its draw backs and limitations, in the context of power system dynamics' applications, are overcome. The methods for signal selection are compared using both small signal and transient stability analysis to determine the best optimal set of signals. Enhancement of power system stability is demonstrated by applying the proposed WAMS based control scheme on the New England test system. The multi-input multi-output (MIMO) WAMS based damping controller uses a reduced set of input/output signals and is designed using the modal LQG approach. Effectiveness of the control scheme is comprehensively assessed using both small signal and transient stability analysis for different case studies including small and large disturbances, changes in network topology and operating condition, variations in time delays, and failure of communication links.
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Gu, Qun. "Flexible control of electrical power system to enhance small signal stability /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Parsi-Feraidoonian, Raiomand. "Application of catastrophe theory to transient stability analysis of multimachine power systems." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29723.
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Transient stability analysis is an important part of power planning and operation. For large power systems, such analysis is very time consuming and expensive. Therefore, an online
transient stability assessment will be required as these large power systems are operated close to their maximum limits. In this thesis swallowtail catastrophe is used to determine the transient stability regions. The bifurcation set represents the transient stability region in terms of power system transient parameters bounded by the transient stability limits. The system modelling is generalized in such, that the analysis could handle either one or any number of critical machines. This generalized model is then tested on a three-machine as well as a seven-machine system. The results of the stability analysis done with the generalized method is compared with the time solution and the results were satisfactory. The transient stability regions determined are valid for any changes in loading conditions and fault location. This method is a good candidate for on-line assessment of transient stability of power systems.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Zhang, Xiaorui. "Voltage stability analysis and control in power systems." Thesis, University of Strathclyde, 2007. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21656.
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Under the title of Voltage Stability Analysis and Control, three major subjects have been examined in this PhD project: the fundamental study of voltage stability, the on-line prediction method for voltage collapse, and secondary voltage control systems. The fundamental study was aimed to lay a theoretical foundation for the rest of research in this project. The on-line prediction method and secondary voltage control systems are particularly targeting on the "early prediction and prevention" strategy to tackle the rapid and "uncontrollable" nature of the voltage collapse phenomenon. The work on the fundamental study was presented in chapter 3 of this thesis. The basic characteristics of voltage collapse were examined, the theory concerning the voltage stability determining factors (VSDFs) was established. Based on this fundamental study, a knowledge based system for the on-line prediction of voltage collapse was proposed in chapter 4. The pattern recognition technique was used in this prediction system, and the design and development of such a system were intensively discussed in this chapter. As a well recognised prevention measure to voltage collapse, secondary voltage control systems were systematically investigated in chapter 5,6, and 7 of this thesis. Chapter 5 deals with the principle of secondary voltage control, and the design and analysis of such a system by classic and optimal control were presented in chapter 6 and 7 respectively. As a further study, improving voltage stability through generation dispatch was also briefly discussed at the end of this thesis. An algorithm aimed at this purpose was proposed to determine the generation participation pattern upon system load increase. All the studies in this project were simulated on the standard IEEE test power systems, some of the study results have been published in the different international conferences or academic forums.
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Restrepo, Jaime Quintero. "A real-time wide-area control for mitigating small-signal instability in large electric power systems." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Spring2005/j%5Fquintero%5F011905.pdf.
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Molina, Diogenes. "Intelligent control and system aggregation techniques for improving rotor-angle stability of large-scale power systems." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50291.
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A variety of factors such as increasing electrical energy demand, slow expansion of transmission infrastructures, and electric energy market deregulation, are forcing utilities and system operators to operate power systems closer to their design limits. Operating under stressed regimes can have a detrimental effect on the rotor-angle stability of the system. This stability reduction is often reflected by the emergence or worsening of poorly damped low-frequency electromechanical oscillations. Without appropriate measures these can lead to costly blackouts. To guarantee system security, operators are sometimes forced to limit power transfers that are economically beneficial but that can result in poorly damped oscillations. Controllers that damp these oscillations can improve system reliability by preventing blackouts and provide long term economic gains by enabling more extensive utilization of the transmission infrastructure.
Previous research in the use of artificial neural network-based intelligent controllers for power system damping control has shown promise when tested in small power system models. However, these controllers do not scale-up well enough to be deployed in realistically-sized power systems. The work in this dissertation focuses on improving the scalability of intelligent power system stabilizing controls so that they can significantly improve the rotor-angle stability of large-scale power systems.
A framework for designing effective and robust intelligent controllers capable of scaling-up to large scale power systems is proposed. Extensive simulation results on a large-scale power system simulation model demonstrate the rotor-angle stability improvements attained by controllers designed using this framework.
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Kong, Dechao. "Advanced HVDC systems for renewable energy integration and power transmission : modelling and control for power system transient stability." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4217/.
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The first part is concerned with dynamic aggregated modelling of large offshore wind farms and their integration into power systems via VSC-HVDC links. The dynamic aggregated modelling of offshore wind farms including WT-DFIGs and WT-PMSGs are proposed to achieve effective representations of wind farms in terms of computational time and simulation accuracy for transient stability analysis. Modelling and control of VSC-HVDC systems for integration of offshore wind farms are investigated. Comparisons of two control schemes of rectifier-side converter are carried out to evaluate their dynamic performance for integration of these offshore wind farms in terms of transient stability. The second part is to address the advanced transmission systems with innovative HVDC configurations. Feasibility studies of updated schemes of monoplolar CSC-HVDC link with support of monopolar VSC-HVDC link as the hybrid bipolar CSC/I{VDC system is carried out to deal with two key issues of CSC-HVDC. Small-signal modelling of MTDC grids is investigated and parameter optimisation of PI controller of converters in MTDC grids is carried out using PSO method based on small-signal models of the system at multiple operating points to obtain optimised parameters of PI controllers to improve dynamic performance of MTDC grids at multiple operating points.
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Young, Derek W. G. "Design, simulation and practical implementation of optimal excitation controllers for synchronous generators." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010652.
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This thesis describes the design of multivariable excitation controllers for synchronous generators, and their practical implementation on a laboratory machine system. The main objectives of the investigation were aimed at extending the steady-state stability limit of the generator and improving its general controllability. The present work is principally concerned with the implementation and test of the designs. Instrumentation has been developed to measure and combine feedback signals; this instrumentation and the laboratory generator system are described in detail. The performances of the controllers are predicted by computer simulation and evaluated by practical testing; attention is focussed on comparison of predicted and experimental performances. The theoretical basis of the design strategy is described, in which an optimal control algorithm applies the system states as feedback signals to the open-loop system, thereby shifting certain of the system eigenvalues to more desirable, predetermined locations. The state variables are selected as physically measurable quantities which obviates the need for implementing state estimation techniques.
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Soltani, Amirmasoud. "Low cost integration of Electric Power-Assisted Steering (EPAS) with Enhanced Stability Program (ESP)." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/8829.
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Vehicle Dynamics Control (VDC) systems (also known as Active Chassis systems) are mechatronic systems developed for improving vehicle comfort, handling and/or stability. Traditionally, most of these systems have been individually developed and manufactured by various suppliers and utilised by automotive manufacturers. These decentralised control systems usually improve one aspect of vehicle performance and in some cases even worsen some other features of the vehicle. Although the benefit of the stand-alone VDC systems has been proven, however, by increasing the number of the active systems in vehicles, the importance of controlling them in a coordinated and integrated manner to reduce the system complexity, eliminate the possible conflicts as well as expand the system operational envelope, has become predominant. The subject of Integrated Vehicle Dynamics Control (IVDC) for improving the overall vehicle performance in the existence of several VDC active systems has recently become the topic of many research and development activities in both academia and industries Several approaches have been proposed for integration of vehicle control systems, which range from the simple and obvious solution of networking the sensors, actuators and processors signals through different protocols like CAN or FlexRay, to some sort of complicated multi-layered, multi-variable control architectures. In fact, development of an integrated control system is a challenging multidisciplinary task and should be able to reduce the complexity, increase the flexibility and improve the overall performance of the vehicle. The aim of this thesis is to develop a low-cost control scheme for integration of Electric Power-Assisted Steering (EPAS) system with Enhanced Stability Program (ESP) system to improve driver comfort as well as vehicle safety. In this dissertation, a systematic approach toward a modular, flexible and reconfigurable control architecture for integrated vehicle dynamics control systems is proposed which can be implemented in real time environment with low computational cost. The proposed control architecture, so named “Integrated Vehicle Control System (IVCS)”, is customised for integration of EPAS and ESP control systems. IVCS architecture consists of three cascade control loops, including high-level vehicle control, low-level (steering torque and brake slip) control and smart actuator (EPAS and EHB) control systems. The controllers are designed based on Youla parameterisation (closed-loop shaping) method. A fast, adaptive and reconfigurable control allocation scheme is proposed to coordinate the control of EPAS and ESP systems. An integrated ESP & ESP HiL/RCP system including the real EPAS and Electro Hydraulic Brake (EHB) smart actuators integrated with a virtual vehicle model (using CarMaker/HiL®) with driver in the loop capability is designed and utilised as a rapid control development platform to verify and validate the developed control systems in real time environment. Integrated Vehicle Dynamic Control is one of the most promising and challenging research and development topics. A general architecture and control logic of the IVDC system based on a modular and reconfigurable control allocation scheme for redundant systems is presented in this research. The proposed fault tolerant configuration is applicable for not only integrated control of EPAS and ESP system but also for integration of other types of the vehicle active systems which could be the subject of future works.
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Baldwin, Thomas L. "Real-time phasor measurements for improved monitoring and control of power system stability." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170758/.
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Chan, Teck-Wai. "Proximity-to-Separation Based Energy Function Control Strategy for Power System Stability." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15840/.
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The issue of angle instability has been widely discussed in the power engineering literature. Many control techniques have been proposed to provide the complementary synchronizing and damping torques through generators and/or network connected power apparatus such as FACTs, braking resistors and DC links. The synchronizing torque component keeps all generators in synchronism while damping torque reduces oscillations and returns the power system to its pre-fault operating condition. One of the main factors limiting the transfer capacity of the electrical transmission network is the separation of the power system at weak links which can be understood by analogy with a large spring-mass system. However, this weak-links related problem is not dealt with in existing control designs because it is non-trivial during transient period to determine credible weak links in a large power system which may consist of hundreds of strong and weak links. The difficulty of identifying weak links has limited the performance of existing controls when it comes to the synchronization of generators and damping of oscillations. Such circumstances also restrict the operation of power systems close to its transient stability limits. These considerations have led to the primary research question in this thesis, "To what extent can the synchronization of generators and damping of oscillations be maximized to fully extend the transient stability limits of power systems and to improve the transfer capacity of the network?" With the recent advances in power electronics technology, the extension of transfer capacity is becoming more readily achievable. Complementary to the use of power electronics technology to improve transfer capacity, this research develops an improved control strategy by examining the dynamics of the modes of separation associated with the strong and weak links of the reduced transmission network. The theoretical framework of the control strategy is based on Energy Decomposition and Unstable Equilibrium Points. This thesis recognizes that under extreme loadings of the transmission network containing strong and weak links, weak-links are most likely to dictate the transient stability limits of the power system. We conclude that in order to fully extend the transient stability limits of power system while maximizing the value of control resources, it is crucial for the control strategy to aim its control effort at the energy component that is most likely to cause a separation. The improvement in the synchronization amongst generators remains the most important step in the improvement of the transfer capacity of the power system network.
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Chapman, Jeffrey W. (Jeffrey Wayne). "Power system control for large-disturbance stability : security, robustness and transient energy." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39393.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 223-228).
by Jeffrey Wayne Chapman.
Ph.D.
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Adewole, Adeyemi Charles. "Voltage stability assessment and wide area protection/control using synchrophasor measurements." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2380.
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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Electric power systems are being operated closer to their designed stability limits due to the constraints caused by the continuous increase in system loading, and the lack of new power stations and transmission network infrastructure to support this increase in system loading. This coupled with the practice of long distance bulk power transmission and cascading contingencies, makes system instability and consequently blackouts inevitable. In such scenarios, system instabilities like voltage instability becomes a serious threat to the secure operation of the power system, and voltage collapse (system-wide blackouts) are prone to occur. This is often compounded by the unavailability of real-time system measurements for situational awareness from the existing Supervisory Control and Data Acquisition (SCADA)/Energy Management System (EMS) platforms which are usually based on unsynchronized SCADA measurements with a slow reporting rate of 1 measurement every 2-10 seconds. This Doctoral thesis proposes non-iterative algorithms and methods of solution based on the IEEE C37.118 synchrophasor measurements from Phasor Measurement Units (PMUs) with a high reporting rate of up to 200 measurements every second (200 fps) for voltage stability assessment and automated wide area Centralised Protection/Control (CPC) against catastrophic voltage instabilities/blackouts in power systems. Extended formulations are proposed for the Optimal Placement of PMUs (OPP) in power systems with respect to voltage stability assessment. The impact of zero injection buses, critical buses, and PMU redundancy is considered in the formulation of the OPP problem solution. The extended formulations made use of Binary Integer programming (BIP) and Modal Participation Factors (MPFs) derived from the eigenvalues of the power flow Jacobian.
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Lammert, Gustav [Verfasser]. "Modelling, Control and Stability Analysis of Photovoltaic Systems in Power System Dynamic Studies / Gustav Lammert." Kassel : Kassel University Press, 2019. http://d-nb.info/1196034125/34.
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Begovic, Miroslav M. "Analysis, monitoring and control of voltage stability in electric power systems." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54490.
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The work presented in this text concentrates on three aspects of voltage stability studies: analysis and determination of suitable proximity indicators, design of an effective real-time monitoring system, and determination of appropriate emergency control techniques. A simulation model of voltage collapse was built as analytical tool on 39-bus, 10-generator power system model. Voltage collapse was modeled as a saddle-node bifurcation of the system dynamic model reached by increasing the system loading. Suitable indicators for real-time monitoring were found to be the minimum singular value of power flow Jacobian matrix and generated reactive powers. A study of possibilities for reducing the number of measurements of voltage phasors needed for voltage stability monitoring was also made. The idea of load bus coherency with respect to voltage dynamics was introduced. An algorithm was presented which determines the coherent clusters of load buses in a power system based on an arbitrary criterion function, and the analysis completed with two proposed coherency criteria. Very good agreement was obtained by simulation between the results based on accurate and approximate measurements of the state vector. An algorithm was presented for identification of critical sets of loads in a voltage unstable power system, defined as a subset of loads whose changes have the most pronounced effect on the changes of minimum singular value of load flow Jacobian or generated reactive powers. Effects of load shedding of critical loads were investigated by simulation and favorable results obtained. An investigation was also done by sensitivity analysis of proximity indicators of the effects that locations and amounts of static var compensation have on the stability margin of the system. Static compensation was found to be of limited help when voltage instabilities due to heavy system loading occur in power systems. The feasibility of implementation of the analyses and algorithms presented in this text relies on development of a feasible integrated monitoring and control hardware. The phasor measurement system which was designed at Virginia Polytechnic institute and State University represents an excellent candidate for implementation of real-time monitoring and control procedures.Ph. D.
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Tavahodi, Mana. "Mixed model predictive control with energy function design for power system." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16374/.
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For reliable service, a power system must remain stable and capable of withstanding a wide range of disturbances especially for the large interconnected systems. In the last decade and a half and in particular after the famous blackout in N.Y. U.S.A. 1965, considerable research effort has gone in to the stability investigation of power systems. To deal with the requirements of real power systems, various stabilizing control techniques were being developed over the last decade. Conventional control engineering approaches are unable to effectively deal with system complexity, nonlinearities, parameters variations and uncertainties. This dissertation presents a non-linear control technique which relies on prediction of the large power system behaviour. One example of a large modern power system formed by interconnecting the power systems of various states is the South-Eastern Australian power network made up of the power systems of Queensland, New South Wales, Victoria and South Australia. The Model Predictive Control (MPC) for the total power system has been shown to be successful in addressing many large scale nonlinear control problems. However, for application to the high order problems of power systems and given the fast control response required, total MPC is still expensive and is structured for centralized control. This thesis develops a MPC algorithm to control the field currents of generators incorporating them in a decentralized overall control scheme. MPC decisions are based on optimizing the control action in accordance with the predictions of an identified power system model so that the desired response is obtained. Energy Function based design provides good control for direct influence items such as SVC (Static Var Compensators), FACTS (Flexible AC Transmission System) or series compensators and can be used to define the desired flux for generator. The approach in this thesis is to use the design flux for best system control as a reference for MPC. Given even a simple model of the relation between input control signal and the resulting machine flux, the MPC can be used to find the control sequence which will start the correct tracking. The continual recalculation of short time optimal control and then using only the initial control value provides a form of feedback control for the system in the desired tracking task but in a manner which retains the nonlinearity of the model.
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Peppas, Dimitris. "Development and Analysis of Nordic32 Power System Model in PowerFactory." Thesis, KTH, Elektriska energisystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118948.
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The present work deals with the implementation of the test system Nordic32 proposed by Cigre task force 38-02-08. This test system which consists of 32 buses is a representation of the Swedish transmission and is suitable for the simulation of transient stability and long term dynamics. This work provides a detailed description about the steps followed to create both the static part of the system for load flow calculations and the controllers that the generators are equipped with. Furthermore, the thesis closes with a basic study concerning the modal analysis and the voltage stability of the system revealing some weaknesses that need further examination.
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Newman, Michael John 1976. "Design and control of a Universal Custom Power Conditioner (UCPC)." Monash University, Dept. of Electrical and Computer Systems Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5651.
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Kasis, Andreas. "Distributed schemes for stability and optimality in power networks." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/270819.
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The generation, transmission and distribution of electricity underpins modern technology and constitutes a necessary element for our development and economic functionality. In the recent years, as a result of environmental concerns and technological advances, private and public investment have been steadily turning towards renewable sources of energy, resulting in a growing penetration of those in the power network. This poses additional challenges in the control of power networks, since renewable generation is in general intermittent, and a large penetration may cause frequent deviations between generation and demand, which can harm power quality and even cause blackouts. Load side participation in the power grid is considered by many a means to counterbalance intermittent generation, due to its ability to provide fast response at urgencies. Industrial loads as well as household appliances, may respond to frequency deviations by adjusting their demand in order to support the network. This is backed by the development of relevant sensing and computation technologies. The increasing numbers of local renewable sources of generation along the introduction of controllable loads dramatically increases the number of active elements in the power network, making traditionally implemented, centralised control dicult and costly. This demonstrates the need for the employment of highly distributed schemes in the control of generation and demand. Such schemes need to ensure the smooth and stable operation of the network. Furthermore, an issue of fairness among controllable loads needs to be considered, such that it is ensured that all loads share the burden to support the network evenly and with minimum disruption. We study the dynamic behaviour of power networks within the primary and secondary frequency control timeframes. Using tools from non-linear control and optimisation, we present methods to design distributed control schemes for generation and demand that guarantee stability and fairness in power allocation. Our analysis provides relaxed stability conditions in comparison with current literature and allows the inclusion of practically relevant classes of generation and demand dynamics that have not been considered within this setting, such as of higher order dynamics. Furthermore, fairness in the power allocation between loads is guaranteed by ensuring that the equilibria of the system are solutions to appropriately constructed optimisation problems. It is evident that a synchronising variable is required for optimality to be achieved and frequency is used as such in primary control schemes whereas for secondary frequency control a dierent synchronising variable is adopted. For the latter case, the requirements of the synchronising feedback scheme have been relaxed with the use of an appropriate observer, showing that stability and optimality guarantees are retained. The problem of secondary frequency regulation where ancillary services are provided from switching loads is also considered. Such loads switch on and off when some prescribed frequency threshold is reached in order to support the power network at urgencies. We show that the presence of switching loads does not compromise the stability of the power network and reduces the frequency overshoot, potentially saving the network from collapsing. Furthermore, we explain that when the on and o switching frequencies are equivalent, then arbitrarily fast switching phenomena might occur, something undesirable in practical implementations. As a solution to this problem, hysteresis schemes where the switch on and off frequencies differ are proposed and stability guarantees are provided within this setting.
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Zhang, Pei. "Co-ordination and control of power system damping controllers to enhance small signal stability." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321949.
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Slay, Tylor. "Adoption of an Internet of Things Framework for Distributed Energy Resource Coordination and Control." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4464.
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Increasing penetration of non-dispatchable renewable energy resources and greater peak power demand present growing challenges to Bulk Power System (BPS) reliability and resilience. This research investigates the use of an Internet of Things (IoT) framework for large scale Distributed Energy Resource (DER) aggregation and control to reduce energy imbalance caused by stochastic renewable generation. The aggregator developed for this research is Distributed Energy Resource Aggregation System (DERAS). DERAS comprises two AllJoyn applications written in C++. The first application is the Energy Management System (EMS), which aggregates, emulates, and controls connected DERs. The second application is the Distributed Management System (DMS), which is the interface between AllJoyn and the physical DER. The EMS runs on a cloud-based server with an allocated 8 GB of memory and an 8 thread, 2 GHz processor. Raspberry Pis host the simulated Battery Energy Storage System (BESS) or electric water heater (EWH) DMSs. Five Raspberry Pis were used to simulate 250 DMSs.
The EMS used PJM's regulation control signals, RegA and RegD, to determine DERAS performance metrics. PJM is a regional transmission organization (RTO). Their regulation control signals direct power resources to negate load and generation imbalances within the BPS.
DERAS's performance was measured by the EMS server resource usage, network data transfer, and signal delay. The regulation capability of aggregated DER was measured using PJM's resource performance assessment criteria. We found the use of an IoT framework for DER aggregation and control to be inadequate in the current network implementation. However, the emulated modes and aggregation response to the regulated control signal demonstrates an excellent opportunity for DER to benefit the BPS.
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Alshogeathri, Ali Mofleh Ali. "Vehicle-to-Grid (V2G) integration with the power grid using a fuzzy logic controller." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20606.
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Master of ScienceDepartment of Electrical and Computer Engineering
Shelli K. Starrett
This thesis introduces a Vehicle to Grid (V2G) system which coordinates the charging, and discharging among the Electric Vehicles (EVs) and two-test systems, to help with peak power shaving and voltage stability of the system. Allowing EVs to charge and discharge without any control may lead to voltage variations and disturbance to the grid, but if the charging and discharging of the EVs is done in a smart manner, they can help the power network. In this thesis, fuzzy logic controllers (FLC) are used to control the flow of power between the grid and the electric vehicles. The presented work in this thesis mainly focuses on the control architecture for a V2G station that allows for using EVs batteries to help the grid’s voltage stability. The designed controllers sustain the node voltage, and thus also achieve peak shaving. The proposed architectures are tested on 16 -generator and 6-generator test systems to examine the effectiveness of the proposed designs. Five fuzzy logic schemes are tested to illustrate the V2G system’s ability to influence system voltage stability. The major contributions of this thesis are as follows: • FLC based control tool for V2G station present at a weak bus in the system. • Investigate the effect of the station location and voltage sensitivity. • Comparison of chargers providing real power versus reactive power. • Simulation of controller and system interactions in a daily load curve cycle. Keywords: State of Charge (SOC), Electric Vehicle (EV), Fuzzy Logic Controller (FLC), Vehicle to grid (V2G), and Power System Voltage Stability.
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Zonetti, Daniele. "Energy-based modelling and control of electric power systems with guaranteed stability properties." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS118/document.
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Pour traiter les systèmes non linéaires, à grande échelle, multi-domaine tels que les systèmes électriques de puissance, nous avons remarqué dans les dernières années un intérêt croissant pour les techniques de modélisation, analyse et contrôle basées sur la notion d'énergie. L'énergie est en fait un concept fondamental en science et en ingénierie, où typiquement les systèmes dynamiques sont regardés comme des dispositifs de transformation d'énergie. Cette perspective est particulièrement utile pour étudier des systèmes non linéaires assez complexes, qui peuvent être décomposés en sous-systèmes plus simples, caractérisés au niveau énergétique, et qui, à travers leurs interconnexions, déterminent le comportement global du système tout entier. Il représente bien évidemment le langage le plus naturel et intuitif pour représenter les systèmes électriques de puissance. En particulier, l'utilisation de systèmes Hamiltoniens à Ports a eu un impact très fort dans différentes applications, plus précisément dans le cas de systèmes mécaniques, électriques et électromécaniques. Dans ce contexte alors, l'approche Hamiltonien à Ports représentent sans doute une base solide qui montre une nouvelle fac{c}on d'aborder les problèmes d'analyse et contrôle de systèmes électriques de puissance. Basée sur cette approche, la thèse est structurée en trois étapes fondamentales:1 - Modélisation d'une classe très générale de systèmes électriques de puissance, basée sur la théorie des graphes et la formulation en Systèmes Hamiltoniens à Ports des composantes.2 - Modélisation, analyse et commande de systèmes de transmission de courant continu haute tension. Avec l'intention de construire un pont entre la théorie et les éventuelles applications, un des objectifs fondamentaux consiste à établir des relations évidentes entre les solutions adoptées dans la pratique et les solutions obtenues à travers une analyse mathématique précise.3 - Travaux apparentés de l'auteur, dans différents domaines des systèmes électriques de puissance: systèmes ac conventionnels et micro réseauxTo deal with nonlinear, large scale, multidomain, systems, as power systems are, we have witnessed in the last few years an increasing interest in energy–based modeling, analysis and controller design techniques. Energy is one of the fundamental concepts in science and engineering practice, where it is common to view dynamical systems as energy-transformation devices. This perspective is particularly useful in studying complex nonlinear systems by decomposing them into simpler subsystems which, upon interconnection, add up their energies to determine the full systems behavior. This is obviously the most natural and intuitive language to represent power systems. In particular, the use of port–Hamiltonian (pH) systems has been already proven highly successful in many applications, namely for mechanical, electrical and electromechanical systems. The port-Hamiltonian systems paradigm theremore provides a solid foundation, which suggests new ways to look at power systems analysis and control problems.Based on this framework, this thesis is structured in three main steps.1 - Modelling of a generalized class of electric power systems, based on graph theory and port-Hamiltonian representation of the individual components.2 - Modelling, analysis and control of multiterminal hvdc transmission systems. With the intention to bridge the gap between theory and applications, one of the main concerns is to establish connections between existing engineering solutions, usually derived via ad hoc considerations, and the solutions stemming from theoretical analysis.3 - Additional contributions of the author in other fields of electric power systems, including traditional ac power systems an microgrids
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Shukla, Srivats. "Hierarchical Decentralized Control for Enhanced Stability of Large-Scale Power Systems." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/84224.
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Due to the ever-increasing penetration of distributed generation units connected to the power distribution system, electric power systems, worldwide, are undergoing a paradigm shift with regards to system monitoring, operation and control. We envision that with the emergence of `active' distribution systems consisting of `prosumers' and localized energy markets, decentralized control methods in power systems are gaining a growing attention among power researchers. Traditionally, two main types of control schemes have been implemented in power systems: (a) wide-area monitoring based centralized control, and (b) local measurement based primary (machine) level control. By contrast, decentralized control schemes based on local monitoring and control of strategically-determined subsystems (or `areas') of a large-scale power system are not used. The latter control schemes offer several advantages over the former, which include more flexibility, simplicity, economy and scalability for large-scale systems. In this dissertation, we summarize our research work on hierarchical and decentralized control techniques for the enhancement in a unified manner of voltage and rotor angle stability in large-scale power systems subject to large (e.g., short circuits) and small (e.g., small load changes) disturbances. We study system robustness by calculating local stability margins. We derive decentralized control laws that guaranty global asymptotic stability by applying Lyapunov's second method for interconnected systems. Furthermore, we argue that the current centralized control structure must only play a supervisory control role at a higher (tertiary) hierarchical level by processing the decisions taken by the regional control entities regarding the stability/instability of the system. This ensures system-wide situational awareness while minimizing the communication bandwidth requirements. We also develop a multi-agent based framework for this hierarchical control scheme. Finally, we compare different communication protocols using simulation models and propose an efficient communication network design for decentralized control schemes. This work, in principle, motivates the development of fast stability analysis which, in the future, may also account for the non-linear coupling that exist between machine rotor angles and bus voltages in power system models. As a future work, we propose the use of statistical techniques like random-effects regression and saddlepoint approximation method to reliably estimate the type-I and type-II probability errors in the proposed hierarchical, decentralized control decision process.Ph. D.
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Athanasius, Germane Information Technology & Electrical Engineering Australian Defence Force Academy UNSW. "Robust decentralised output feedback control of interconnected grid system." Awarded by:University of New South Wales - Australian Defence Force Academy, 2008. http://handle.unsw.edu.au/1959.4/39591.
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The novel contribution of the thesis is the design and implementation of decentralised output feedback power system controllers for power oscillation damping (POD) over the entire operating regime of the power system. The POD controllers are designed for the linearised models of the nonlinear power system dynamics. The linearised models are combined and treated as parameter varying switched systems. The thesis contains novel results for the controller design, bumpless switching and stability analysis of such switched systems. Use of switched controllers against the present trend of having single controller helps to reduce the conservatism and to increase the uncertainty handling capability of the power system controller design. Minimax-LQG control design method is used for the controller design. Minimax-LQG control combines the advantages of both LQG and H control methods with respect to robustness and the inclusion of uncertainty and noise in the controller design. Also, minimax-LQG control allows the use of multiple integral quadratic constraints to bound the different types of uncertainties in the power system application. During switching between controllers, switching stability of the system is guaranteed by constraining the minimum time between two consecutive switchings. An expression is developed to compute the minimum time required between switchings including the effect of jumps in the states. Bumpless switching scheme is used to minimise the switching transients which occur when the controllers are switched. Another contribution of the thesis is to include the effect of on load tap changing transformers in the power system controller design. A simplified power system model linking generator and tap changing transformer dynamics is developed for this purpose and included in the controller design. The performance of the proposed linear controllers are validated by nonlinear computer simulations and through real time digital simulations. The designed controllers improve power system damping and provide uniform performance over the entire operating regime of the generator.
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Du, Zhaobin. "Area COI-based slow frequency dynamics modeling, analysis and emergency control for interconnected power systems." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B4175783X.
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Auer, Sabine. "The Stability and Control of Power Grids with High Renewable Energy Share." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/18978.
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Die vorliegende Dissertation untersucht die Stabilität und Regelung von Stromnetzen mit hohem Anteil Erneuerbarer Energien (EE). Dabei stehen drei Forschungsfragen, zu den neuartigen Herausforderungen für die zukünftige Stromnetzstabilität im Zuge der Energiewende, im Vordergrund.
Erstens soll untersucht werden wie die Resilienz von Stromnetzen gemessen und im zweiten Schritt auch verbessert werden kann. Dabei zeige ich den notwendigen Detailgrad für transiente Stabilitätsuntersuchungen auf.
Die zweite Frage lautet wie, trotz des zunehmenden Ausbaus von EE in Verteilnetzen, die statische Spannungsstabilität garantiert und Leitungsüberlastungen verhindert werden können. Hierfür analysiere ich mit einem konzeptionellen hierarchischen Verteilnetzmodell das zukünftige Potential für die Erzeugung von Blindleistung aus dezentralen Ressourcen am Beispiel Deutschlands.
Die dritte Frage, wie eine dynamisch-stabile Integration von EE möglich ist, bildet den Hauptfokus meiner Dissertation. Dabei untersuche ich wie neuartige dynamische Aspekte EE, wie intermittente Fluktuationen oder auch Mess- und Reaktionszeiten von Leistungselektronik, die dynamische Netzstabilität beeinflussen und wie mögliche Instabilitäten durch Konzepte der Nachfragesteuerung behoben werden können. Dabei stoße ich bei der Analyse lokaler intermittenter Fluktuationen in ohmschen Verteilnetzen auf ein bemerkenswertes Wechselspiel zwischen Eigenschaften der Netzdynamik und -topologie. Als Zweites zeige ich wie mit der Einführung von Leistungselektronik und den damit verbundenen Mess- und Reaktionszeiten Resonanzkatastrophen hervorrufen werden können. Schließlich präsentiere ich wie die dezentrale Nachfragesteuerung von Elektroautos dynamische Instabilitäten, hervorgerufen durch Fluktuationen von EE, bereinigen kann.
Zusammenfassend behandelt diese Arbeit verschiedene Aspekt zur Stabilität zukünftiger Stromnetze und integriert dabei sukzessive neuartige dynamische Aspekte von EE.This PhD thesis is centered around the "Stability and Control of Power Grids with high Renewable Energy Share". With a conceptual modelers approach, I tackle three overarching questions related to the novel challenges the energy transition poses for the stability of future power grids. The first question focuses on how to measure and subsequently improve the resilience of a power grid. Here, I contribute important insights on the necessary model detail for transient stability assessments. The second question concerns how to ensure static voltage stability and avoid capacity overloading while the deployment of Renewable Energy Sources (RES) in the distribution grid layers is massively increasing. As a possible solution to this problem I analyze the future technical potential of reactive power provision from decentral resources in Germany. The third question, and main focus of this thesis, is on how to integrate renewable energies in a dynamically stable way. Specifically, I investigate the influence of intermittent RES and measurement delays from power electronic resources on frequency stability and how the latter can be restored by concepts of demand control. First, for local intermittent fluctuations in lossy distribution grids I find a remarkable and subtle but robust interplay of dynamical and topological properties, which is largely absent for lossless grids. Second, I show how delays may induce resonance catastrophes and how the existence of critical delays sets an upper limit for measurement times. Third and last, I present how the right parameterization of decentral electric vehicle control can completely overcome issues of short-term dynamic instability related to RES fluctuations. This control avoids demand synchronization and high battery stress. Altogether, this thesis investigates the stability of future power grids moving towards integrating more aspects of renewable energy dynamics. Finally, I point out open questions to encourage further research.
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Gianto, Rudy. "Coordination of power system controllers for optimal damping of electromechanical oscillations." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0056.
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This thesis is devoted to the development of new approaches for control coordination of PSSs (power system stabilisers) and FACTS (flexible alternating current transmission system) devices for achieving and enhancing small-disturbance stability in multi-machine power systems. The key objectives of the research reported in the thesis are, through optimal control coordination of PSSs and/or FACTS devices, those of maintaining satisfactory power oscillation damping and secure system operation when the power system is subject to persisting disturbances in the form of load demand fluctuations and switching control. Although occurring less frequently, fault disturbances are also considered in the assessment of the control coordination performance. Based on the constrained optimisation method in which the eigenvalue-based objective function is minimised to identify the optimal parameters of power system damping controllers, the thesis first develops a procedure for designing the control coordination of PSSs and FACTS devices controllers. The eigenvalue-eigenvector equations associated with the selected electromechanical modes form a set of equality constraints in the optimisation. The key advance of the procedure is that there is no need for any special software system for eigenvalue calculations, and the use of sparse Jacobian matrix for forming the eigenvalue-eigenvector equations leads to the sparsity formulation which is essential for large power systems. Inequality constraints include those for imposing bounds on the controller parameters. Constraints which guarantee that the modes are distinct ones are derived and incorporated in the control coordination formulation, using the property that eigenvectors associated with distinct modes are linearly independent. The robustness of the controllers is achieved very directly through extending the sets of equality constraints and inequality constraints in relation to selected eigenvalues and eigenvectors associated with the state matrices of power systems with loading conditions and/or network configurations different from that of the base case. On recognising that the fixed-parameter controllers, even when designed with optimal control coordination, have an inherent limitation which precludes optimal system damping for each and every possible system operating condition, the second part of ii the research has a focus on adaptive control techniques and their applications to power system controllers. In this context, the thesis reports the development of a new design procedure for online control coordination which leads to adaptive PSSs and/or supplementary damping controllers (SDCs) of FACTS devices for enhancing the stability of the electromechanical modes in a multi-machine power system. The controller parameters are adaptive to the changes in system operating condition and/or configuration. Central to the design is the use of a neural network synthesised to give in its output layer the optimal controller parameters adaptive to system operating condition and configuration. A novel feature of the neural adaptive controller is that of representing the system configuration by a reduced nodal impedance matrix which is input to the neural network.
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Chompoobutrgool, Yuwa. "Concepts for Power System Small Signal Stability Analysis and Feedback Control Design Considering Synchrophasor Measurements." Licentiate thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103032.
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In the Nordic power network, the existence of poorly damped low-frequency inter-area oscillations (LFIOs) has long affected stability constraints, and thereby, limited power transfer capacity. Adequate damping of inter-area modes is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) is a prevalent means to enhance the damping of such modes. With the advent of phasor measurement units (PMUs), it is expected that wide-area damping control (WADC), that is, PSS control using wide-area measurements obtained from PMUs, would effectively improve damping performance in the Nordic grid, as well as other synchronous interconnected systems. Numerous research has investigated one ``branch'' of the problem, that is, PSS design using various control schemes. Before addressing the issue of controller design, it is important to focus on developing proper understanding of the ``root'' of the problem: system-wide oscillations, their nature, behavior and consequences. This understanding must provide new insight on the use of PMUs for feedback control of LFIOs. The aim of this thesis is, therefore, to lay important concepts necessary for the study of power system small signal stability analysis that considers the availability of synchrophasors as a solid foundation for further development and implementation of ideas and related applications. Particularly in this study, the focus is on the application addressed damping controller design and implementation. After a literature review on the important elements for wide-area damping control (WADC), the thesis continues with classical small signal stability analysis of an equivalent Nordic model; namely, the KTH-NORDIC32 which is used as a test system throughout the thesis. The system's inter-area oscillations are identified and a sensitivity analysis of the network variables directly measured by synchrophasors is evaluated. The concept of network modeshapes, which is used to relate the dynamical behavior of power systems to the features of inter-area modes, is elaborated. Furthermore, this network modeshape concept is used to determine dominant inter-area oscillation paths, the passageways containing the highest content of the inter-area oscillations. The dominant inter-area paths are illustrated with the test system. The degree of persistence of dominant paths in the study system is determined through contingency studies. The properties of the dominant paths are used to construct feedback signals as input to the PSS. Finally, to exemplify the use of the dominant inter-area path concept for damping control, the constructed feedback signals are implemented in a PSS modulating the AVR error signal of a generator on an equivalent two-area model, and compared with that of conventional speed signals.
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Li, Xiawen. "Power System Stability Improvement with Decommissioned Synchronous Machine Using Koopman Operator Based Model Predictive Control." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102503.
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Traditional generators have been decommissioned or replaced by renewable energy generation due to utility long-standing goals. However, instead of flattening the entire plant, the rotating mass of generator can be utilized as a storage unit (inertia resource) to mitigate the frequency swings during transient caused by the renewables. The goal of this work is to design a control strategy utilizing the decommissioned generator interfaced with power grid via a back-to-back converter to provide inertia support. This is referred to as decoupled synchronous machine system (DSMS). On top of that, the grid-side converter is capable of providing reactive power as an auxiliary voltage controller. However, in a practical setting, for power utilities, the detailed state equations of such device as well as the complicated nonlinear power system are usually unobtainable making the controller design a challenging problem. Therefore, a model free, purely data-driven strategy for the nonlinear controller design using Koopman operator-based framework is proposed. Besides, the time delay embedding technique is adopted together with Koopman operator theory for the nonlinear system identification. Koopman operator provides a linear representation of the system and thereby the classical linear control algorithms can be applied. In this work, model predictive control is adopted to cope with the constraints of the control signals. The effectiveness and robustness of the proposed system are demonstrated in Kundur two-area system and IEEE 39-bus system.Doctor of Philosophy
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Cvetkovic, Milos. "Power-Electronics-Enabled Transient Stabilization of Power Systems." Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/344.
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Transient stability of electric energy grids is defined as the ability of the power system to remain in synchronism during large disturbances. If the grid is not equipped with controllers capable of transiently stabilizing system dynamics, large disturbances could cause protection to trigger disconnecting the equipment and leading further to cascading system-wide blackouts. Today’s practice of tuning controllers generally does not guarantee a transiently stable response because it does not use a model for representing system-wide dynamic interactions. To overcome this problem, in this thesis we propose a new systems modeling and control design for provable transient stabilization of power systems against a given set of disturbances. Of particular interest are fast power-electronically-controlled Flexible Alternating Current Transmission System (FACTS) devices which have become a new major option for achieving transient stabilization. The first major contribution of this thesis is a framework for modeling of general interconnected power systems for very fast transient stabilization using FACTS devices. We recognize that a dynamic model for transient stabilization of power systems has to capture fast electromagnetic dynamics of the transmission grid and FACTS, in addition to the commonly-modeled generator dynamics. To meet this need, a nonlinear dynamic model of general interconnected electric power systems is derived using time-varying phasors associated with states of all dynamic components. The second major contribution of this thesis is a two-level approach to modeling and control which exploits the unique network structure and enables preserving only relevant dynamics in the nonlinear system model. This approach is fundamentally based on separating: a) internal dynamics model for ensuring stable local response of components; b) system-level model in terms of interaction variables for ensuring stability of the system when the components are interconnected. The two levels can be controlled separately which minimizes the need for communication between controllers. Both distributed and cooperative ectropy-based controllers are proposed to control the interaction-level of system dynamics. Proof of concept simulations are presented to illustrate and compare the promising performance of the derived controllers. Some of the most advanced FACTS industry installations are modeled and further generalized using our approach.
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Manmek, Thip Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Real-time power system disturbance identification and its mitigation using an enhanced least squares algorithm." Awarded by:University of New South Wales. Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/26233.
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This thesis proposes, analyses and implements a fast and accurate real-time power system disturbances identification method based on an enhanced linear least squares algorithm for mitigation and monitoring of various power quality problems such as current harmonics, grid unbalances and voltage dips. The enhanced algorithm imposes less real-time computational burden on processing the system and is thus called ???efficient least squares algorithm???. The proposed efficient least squares algorithm does not require matrix inversion operation and contains only real numbers. The number of required real-time matrix multiplications is also reduced in the proposed method by pre-performing some of the matrix multiplications to form a constant matrix. The proposed efficient least squares algorithm extracts instantaneous sine and cosine terms of the fundamental and harmonic components by simply multiplying a set of sampled input data by the pre-calculated constant matrix. A power signal processing system based on the proposed efficient least squares algorithm is presented in this thesis. This power signal processing system derives various power system quantities that are used for real-time monitoring and disturbance mitigation. These power system quantities include constituent components, symmetrical components and various power measurements. The properties of the proposed power signal processing system was studied using modelling and practical implementation in a digital signal processor. These studies demonstrated that the proposed method is capable of extracting time varying power system quantities quickly and accurately. The dynamic response time of the proposed method was less than half that of a fundamental cycle. Moreover, the proposed method showed less sensitivity to noise pollution and small variations in fundamental frequency. The performance of the proposed power signal processing system was compared to that of the popular DFT/FFT methods using computer simulations. The simulation results confirmed the superior performance of the proposed method under both transient and steady-state conditions. In order to investigate the practicability of the method, the proposed power signal processing system was applied to two real-life disturbance mitigation applications namely, an active power filter (APF) and a distribution synchronous static compensator (D-STATCOM). The validity and performance of the proposed signal processing system in both disturbance mitigations applications were investigated by simulation and experimental studies. The extensive modelling and experimental studies confirmed that the proposed signal processing system can be used for practical real-time applications which require fast disturbance identification such as mitigation control and power quality monitoring of power systems
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Elkington, Katherine. "Modelling and Control of Doubly Fed Induction Generators in Power Systems : Towards understanding the impact of large wind parks on power system stability." Licentiate thesis, KTH, Electric Power Systems, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10206.
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The rapid development of wind power technology is reshaping conventional power grids in many countries across the world. As the installed capacity of wind power increases, its impact on power grids is becoming more important. To ensure the reliable operation of a power system which is significantly fed by wind power, the dynamics of the power system must be understood, and the purpose of this study is to develop suitable analytical tools for analysing the dynamic impact of large-scale wind parks on the stability of a power grid, and to investigate the possibility of improving the stabilisation and damping of the grid by smart control strategies for wind turbines.Many of the newer, larger turbines now being produced are variable speed turbines, which use doubly fed induction generators (DFIGs). These are induction generators which have their stator and rotor independently excited. When unconventional generators of this type are used in a power system, the system behaves differently under abnormal dynamic events. For example, new types of generators cause different modes of oscillation in the power system, not only because of their dynamic characteristics, but also because they load the system differently.Very large power oscillations can occur in a power system as a result of internal disturbances. Ordinarily these oscillations are slow and, in principle, it is possible to damp them with the help of wind power. This leads to the idea of using a power system stabiliser (PSS) for a DFIG. In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods to optimally damp the oscillations.Voltage stability is another important aspect of the safe operation of a power system. It has been shown that the voltage stability of a power system is affected by induction generators. The voltage stability must therefore be carefully analysed in order to guard against a power system collapse.By using modal analysis and dynamic simulations, we show that the presence of a wind farm in the vicinity of a power system will improve the angular behaviour of the power system under small disturbances, but may decrease voltage stability under larger disturbances. We compare the performance of wind turbines to that of conventional synchronous generator power plants, and we show that a wind park consisting of DFIGs, which are equipped with PSSs, may be used as a positive contribution to power system damping.