Dissertations / Theses: 'Electirc Power System'

1

Papalexopoulos, Alexis D. "Modeling techniques for power system grounding systems." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/13529.

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Zhou, Ning. "Subspace methods of system identification applied to power systems." Laramie, Wyo. : University of Wyoming, 2005. http://proquest.umi.com/pqdweb?did=1095432761&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Valirad, sina, and Mahyar Parsasirat. "Iran's electric power system." Thesis, Blekinge Tekniska Högskola, Avdelningen för elektroteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11227.

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Abstract Iran is a very vast country with about 80 million population that they are really fragmented. Providing electricitypower for all the society which is duty of power ministry of Iran according to the resources and facilities. The thesis gives an overview of production of electrical energy in Iran and how the production is divided ondifferent energy sources. At the present time there are 197 power plants are producing electricity to supportthe country that they are combination of 8 kind of different power plants which are thermal power plants, gaspower stations, combined cycles, hydro power plants, biogas plants, wind power stations, solar plants andnuclear power stations. During the last decade Iran took care of renewable energy sources to produce electricitythat cause wind power plants and solar power plants can take a small share from the total production. Althoughthey are not play a serious role yet but the policy of the country is improving these kind of power plants. Foreach source the production principle is described briefly by help of a diagram and also there is a table of allpower plants which are included details of each power plant like: name of power plant, state (location) , year ofinstallation, nominal power, gross power, efficiency, consumption (fuel, water,…) and so on. For each kind ofpower plants there is a bar chart which compares the nominal power of all power plants at a glance and alsothere is a map that the location of each station has been marked on. Total data for production in a year has been presented. Also there is a list of power plants which they are underconstruction and will be ready in future. For transmitting electricity power in the country there are four kind of transmission lines which are: 400 KV, 230KV, 132 KV and 66 KV. The development of each kind of transmission lines since 1963 is presented in a table anda chart. Also Iran has export and import electricity with 8 neighbor countries like: Iraq, Afghanistan, Azerbaijan,Turkmenistan, Turkey, Pakistan, Armenia and Nakhjavan. The range of exchange since 1993 is shown in a tableand a chart.

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Zhang, Yi. "Adaptive remedial action schemes for transient instability." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/y_zhang_112707.pdf.

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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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6

Wang, Min. "Pattern recognition methodology for network-based diagnostics of power quality problems /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6099.

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Hong, Mingguo. "Controllability and diagnosis in electric power systems /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6088.

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8

Ebrahimpour, Mohammad Reza. "An analytical study of the power flow equations with applications to systems with multiple close solutions." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/15746.

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9

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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10

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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11

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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12

Liu, Guoping. "Oscillation monitoring system based on wide area phasor measurements in power systems." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Summer2010/g_liu_060110.pdf.

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Thesis (Ph. D.)--Washington State University, August 2010.
Title from PDF title page (viewed on July 23, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 76-81).

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13

Parsons, Antony Cozart. "Automatic location of transient power quality disturbances /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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14

Manmek, Thip Electrical Engineering &amp 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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Wu, Qiang. "Tap changing dynamic modeling and its effects on power system voltage behavior." Thesis, The University of Sydney, 1998. https://hdl.handle.net/2123/27640.

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This thesis presents research results on the effects of tap changing dynamic modeling on power system mid-to-long term voltage behavior. The modeling of tap changing dynamics in voltage stability studies is first addressed. The dynamic operation of an on-load-tap—changing transformer is represented by a highly nonlinear, discrete and time—delay embedded model, which is suitable to mid-to—long term voltage stability studies. Different discrete tap models and their continuous approximations with respect to time and tap position are introduced. The initial emphasis is on studying the influences of different discrete and continuous tap models on voltage stability properties. Combining the tap changer dynamics with the detailed load dynamics, the impacts of different tap models on system voltage behavior are illustrated via theoretical analysis and simulation. It is shown that different stability regions are associated with different continuous tap models and significantly influence the system/voltage behavior, especially under heavily loaded system conditions. The Lyapunov stability method is used to predict the stability region. Limit cycle phenomena are observed in systems with discrete tap models due to the inherent nonlinearities present in these models, the tap dynamics and its interaction with the load dynamics. Conditions for existence of limit cycles are derived via the describing function method. Cases when discrete tap models and their corresponding continuous approximations result in different and / or similar system behavior are also illustrated. Further, a detailed study is given on. the voltage oscillation phenomenon in power systems with on-load—tap—changers. Two kinds of oscillations are considered, namely the well-known voltage oscillations due to tap hunting and oscillations due to tap— load interactions. The focus is on the limit cycle caused by the tap-load interaction. The effects of tap deadband and other parameters such as tap delay time and load recovery time on the existence of system cyclic behavior are carefully investigated. It. is shown that whether or not the limit cycle can be avoided by adjusting the tap deadband depends mainly on the load characteristics. Trajectory sensitivity analysis offers useful information on the influence of parameters on system cyclic behavior. Next, consideration is given to the coordination of a tap changer, as a voltage control device, with other controls, such as a switching capacitor. Using the results of voltage stability analysis as a framework, a new approach for the coordination of dissimilar control actions is derived for arresting voltage collapse. The benefits of coordination of tap locking and capacitor switching are demonstrated foi two possible situations. Firstly, prior capacitor switching at some buses is shown to expand the stability regioh and provide sufficient time for successful tap locking. Secondly, locking taps at some buses can slow the system deterioration and provides time for capacitor switching. The results obtained not only highlight the importance of tap dynamics modeling in voltage behavior studies, but also give an insight into system voltage stability evaluatiofi and control involving on—load-tap—changer dynamics.

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Wu, Qiang. "Dynamics and coordinated control of voltage behavior in power systems." Thesis, The University of Sydney, 2000. https://hdl.handle.net/2123/27766.

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This thesis presents results on the dynamics and coordinated control of voltage behavior in power systems. The first part of the thesis is on dynamic modeling, with emphasis on tap-changing transformers and load dynamics. For both, highly simplified models are used in voltage stability analysis, despite the complex nature of the devices involved, i.e. tap changing operation and aggregate load. The operating conditions, under which the stability results based on these simplified models are reliable need to be clarified. A study is carried out on the influence of diiferent discrete and continuous tap models on voltage stability properties, particularly when combined with load dynamics. It has been found that small disturbance analysis, especially if based on the common continuous tap model with fixed time constant, is often an unreliable indicator of system stability. Some important differences in system responses with continuous and discrete tap models are highlighted along with the conditions under which they occur. Limit cycles are shown to characterize the system responses with discrete tap models. The limit cycles originate from the deadband nonlinearity embedded in the discrete tap operation and tap-load interactions. Describing functions for the nonlinearity of the discrete tap operation are derived and used to predict the existence of limit cycles. Furthermore, the feasibility of avoiding the limit cycles through adjusting deadband size is investigated. It has been shown that whether or not increasing deadband can always eliminate the existing limit cycle depends on the associated load dynamics. Following this, attention is given to load dynamics modeling. The focus is on use of generic dynamic load models. A simulation study is given on system behavior with generic dynamic loads as compared with the detailed physically based load models which they ap— proximate. Several simple and a more complicated load structures are considered, which include lower voltage tap changers, induction motors, thermostatically controlled heating and static load. It has been shown, for simple load structures, generic dynamic load models, if the parameters are properly identified, provide fairly accurate prediction of system stability behavior in all cases except the one with high percentage of induction motors. On the other hand, for a load structure with diverse compositions, generic dynamic load models have practically useful accuracy for representing the load. This suggests that ap— plying generic dynamic load models will be practically useful in reducing the complexity of system modeling and give reliable stability analysis results. The second part of the thesis is devoted to coordinated voltage control. A general frame work for coordinating optimally a diverse set of control actions is established. The benefit of control coordination is illustrated through a case study on coordination of capacitor switching and tap locking. By careful coordination of these controls, voltage collapse can be arrested with less overall control effort and less impact on the voltage profile than by either acting along. An analytical framework for coordinated voltage control based on coordination of dissimilar control actions is then presented. A 4-stage optimal control scheme is proposed along with detailed formulations. In the first three stages, a security constrained steady—state approach is used to define the optimal control direction for providing stability and adequate security margin. An algorithm based on differential dynamic programming based is then used to optimally schedule controls with different response time and dynamics. Finally, the dynamic sensitivity-based method is employed to refine the obtained control sequence; in terms of finding the optimal switching times for the control actions identified in earlier stages. In the final study of the thesis, application is made of the stability analysis and coordinated control techniques to a substantial physical power system, namely the New South Wales power grid. The algorithm and techniques proposed in previous chapters is tested in a more practical situation.

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17

Sayler, Kent Alexander Halpin S. Mark. "Predicting generator coupling using power system impedance matrices." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/SAYLER_KENT_33.pdf.

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18

Schooley, David C. "Unit commitment and system reliability in electric utility systems with independent wind and solar generation." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12917.

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Hiskens, Ian A. "Energy functions, transient stability and voltage behaviour /." Online version, 1990. http://bibpurl.oclc.org/web/30417.

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20

Amy, John Victor. "Composite system stability methods applied to advanced shipboard electric power systems." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/10945/23576.

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CIVINS
Large increases in the complexity of shipboard electric loads as well as development of electric drive, integrated electric drive and pulsed power systems make manifest the present and future importance of naval electric power systems. The most crucial attribute of these systems is their ability to fulfill their function in the presence of "large-signal" perturbations. Fundamental differences between shipboard and commercial electric power systems make all but the most general nonlinear, "large-signal" stability analyses inappropriate for the design and assessment of naval electric power systems. The tightly coupled and compact nature of shipboard systems are best accommodated by composite system stability analyses. Composite system methods, based upon Lyapunov's direct method, require that each component's stability be represented by a Lyapunov function. A new Lyapunov function which is based upon coenergy is developed for 3-phase synchronous machines. This use of coenergy is generalizable to all electromechanical energy conversion devices. The coenergy-based Lyapunov function is implemented as a "stability organ" which generates waveforms at information teirninals of a "device object" in the object oriented simulation environment of WAVESIM. Single generator simulation results are used to acquire a measure of the "over sufficiency" of the coenergy-based Lyapunov function. Some means of combining the components' Lyapunov functions is necessary with composite system stability criterions. To provide the largest stability region in a Lyapunov function convective derivative space, thereby reducing "over sufficiency", a "timevariant weighted-sum" composite system criterion is developed. This criterion is implemented as a "stability demon" "device object" within the WAVESIM environment. The "stability demon" is tested through RLC circuit simulations and a two-generator simulation. The output of the "stability demon" is suitable for use within an overall system stabilising controller.

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21

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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22

Yu, Qiuli. "Multi-agent systems for reconfiguration of shipboard integrated power system including AC-DC zonal distribution system." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-11072008-122943.

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23

Sotomayor, Martínez Rodrigo. "System theoretic process analysis of electric power steering for automotive applications." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/105318.

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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 101-103).
The automotive industry is constantly challenged with meeting and exceeding customer expectations while reducing time to market of new products in order to remain competitive. Providing new features and functionality into vehicles for customer satisfaction is becoming more challenging and driving design complexity to a higher level. Although traditional methods of Product Development Failure Mode identification such as FMEA (Failure Mode and Effect Analysis) or FTA (Fault Three Analysis) have been used to analyze failures in automotive systems, there are limitations when it comes to design errors, flawed requirements, human factors implications, and component interaction accidents in which all components operated as required but the system behavior was not as expected. In order to determine if there is room for improvement in current automotive product development process, this thesis applies Dr. Nancy Leveson's Systems-Theoretic Process Analysis (STPA) technique to compare and contrast with a Failure Modes and Effects Analysis (FMEA) approach as used in the automotive industry through a case study. A formal method of comparing results is proposed. This study found limitations with FMEA in terms of identifying unsafe interactions between systems, anticipating human error and other behaviors dependent on human interaction, identifying engineering design flaws, and producing requirements. STPA was able to find causes that had a direct relationship with those found in FMEA while also finding a portion of causes related to a higher level of abstraction of those in FMEA. STPA also found a subset of causes that FMEA was not able to find, which relate mainly to engineering design flaws and system interaction.
by Rodrigo Sotomayor Martínez.
S.M. in Engineering and Management

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Gnanam, Gnanaprabhu. "Optimal power flow including voltage stability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq25844.pdf.

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Wei, Zhen. "Electro-mechanical braking system development and hybrid electric vehicle power management for urban driving." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49417/.

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As the energy and environment crisis increase severely, developing cleaner and more fuel efficient vehicles have become a research hot spot of automobile industry. In recent years HEV (hybrid electric vehicle) and EV (electric vehicle) are widely considered as two of the most viable solutions to the world’s need for cleaner and more fuel-efficient vehicles. This project aims to further improve the performance and fuel efficiency of EVs/HEVs for real application of urban driving. The thesis can be divided in to two major studies: EMB (Electro-Mechanical Brake) system development and HEV power management, which are two hot topics in the latest researches of EVs/HEVs. The brake system plays an important role in vehicles. As the X-by-wire technology develops, EMB can realize individual control of braking force on each wheel; which makes it very suitable for electrified vehicles. In this thesis a compact design of EMB actuator is proposed. To investigate the control of EMB system, a down scaled EMB test rig has been set up and an EMB motor control system has been developed. In the section of clamping force control of EMB system, in order to achieve fully control of braking force, a low cost sensor less clamping force control method is proposed. It is noted that in real applications of EVs/HEVs the EMB system is normally cooperated with regenerative braking system during braking process, in this thesis the co-operative control of hybrid brake system is investigated as well to improve the braking performance and regenerative braking efficiency. In order to overcome the drawbacks of the conventional gasoline vehicles, HEVs encompass two power sources (internal combustion engine and electric motor) to drive the vehicle. Due to existence of the double power sources, HEVs normally have multiple operation modes. The objective of HEV power management is to find the optimal power distribution on each power source to meet the power requirement with minimum fuel consumption. In this thesis to improve the fuel efficiency and keep the balance of battery SOC (state of charge) simultaneously during urban driving, a revised dynamic programming (DP)-optimized HEV power management control strategy is proposed. The DP algorithm is applied to obtain the optimal engine/motor power distribution and utilized for the design of the fuzzy control strategy. The traditional DP algorithm is modified with the consideration of SOC balance for HEVs. In the analysis of DP simulation results, rules of torque slip behaviors have been found, which are directly utilized in the design of fuzzy control strategy. In order to improve the practicality of the control strategy to meet the diversities of city driving patterns, an urban driving pattern recognition method is presented. To evaluate the control performance, the proposed control strategy is also compared with the conventional rule-based strategy. The simulation results indicate that by adopting the proposed strategy the fuel efficiency of HEV is improved, and the SOC of the battery is kept in balance during different urban driving cycles.

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Leelardcharoen, Kanoknart. "Interdependent response of telecommunication and electric power systems to seismic hazard." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42742.

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Infrastructure systems are essential to the functioning of contemporary societies and economies. A major disruption to the built environment can lead to severe public safety issues and economic losses. Within the past few decades, modern control and information technologies have been rapidly developed in an attempt to improve the reliability of individual utility systems by exchanging technologies across them. One of the major ramifications is the emergence of interdependencies among these critical infrastructure systems, especially when facing major disruptions. Failure of an individual system becomes more likely to affect the functionality of other interconnected infrastructure systems. In order to mitigate such consequences, the mechanics of interdependencies and failure propagation among the systems must be understood. This research focuses on the development of a framework for probabilistically quantifying interdependent responses of two essential infrastructure systems - telecommunication and electric power systems - subjected to seismic hazards, which are one of the most powerful and geographically extensive threats. The study explores the effects of seismic hazards beyond the obvious seismic-induced physical damage to utility system facilities. In particular, the seismic evaluation of telecommunication systems considers the degradation of system performance due to physical damage and the abnormally high usage demands in telecommunication systems expected after catastrophic earthquakes. Specifically, a newly developed seismic-induced congestion model is proposed, and the probabilistic formulations of the critical interdependencies across telecommunication and power systems are presented in a probabilistic framework. The study illustrates the procedure for fragility analysis of interdependent systems and presents a practical application through a test bed implementation in Shelby County, TN. From this study, telecommunication systems are found to be very vulnerable to seismic-induced congestion. The electric power interdependencies amplify the degradation in telecommunication systems up to 50% in their vulnerability while electric power operations are heavily dependent upon telecommunication infrastructures and the fragility median of electric power system observability can decrease by 30%. The study also indicates up to 100% overestimation of the independent fragility analysis and the results reveal the relationship between system topology and the sensitivity of system performance to the intensity of interdependencies. The proposed methodology is expected to be a valuable tool for decision making in evaluating seismic mitigation strategies and also to provide the foundation for future studies on interdependent responses of other critical infrastructures.

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Zitouni, Salah. "An expert system for electric power system management." Thesis, University of Dundee, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338200.

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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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Gossman, Stephanie Mizzell. "A new proposed method of contingency ranking." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34667.

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Security analysis of a power system requires a process called contingency analysis that analyzes results from all possible single contingencies (i.e. outages) in the system. The process of contingency analysis requires the definition of a parameter that is used to monitor a certain aspect of the system, which is called a performance index. The performance index definitions used traditionally have been highly nonlinear, and the results have not accurately predicted the outcome of the performance index in some cases. These incorrect results are referred to as misrankings since the contingency results are usually placed in order of severity so that the most severe cases are evident. This thesis considers a new definition of contingency ranking using a more linearized definition of the performance index. The construction of both the new, proposed definition and the classic definition both consider the current loading of circuits in the system as compared to their rated values. Specifically, the parameter measured by the proposed definition measures the difference, while the more nonlinear definition uses a ratio of the two quantities, which is then raised to a higher power. A small, four bus test system is used to demonstrate the benefits of the new, more linearized definition. The average percent error for all single line contingencies of the system decreased by over 9.5% using the proposed definition as compared to the previous one. This decrease in error allows this performance index to monitor a similar parameter (comparing current loading and current rating of the lines) and achieve a higher degree of accuracy. Further linearization of this proposed definition also shows a reduction in the average percent error by an additional 22% so that when compared to the original, highly nonlinear definition, the average error is reduced by almost 30%. By linearizing the definition of the performance index, the results are more accurate and misrankings are less likely to occur from the security analysis process.

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30

Setréus, Johan. "On Reliability Methods Quantifying Risks to Transfer Capability in Electric Power Transmission Systems." Licentiate thesis, KTH, Electromagnetic Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10258.

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In the operation, planning and design of the transmission system it is of greatest concern to quantify the reliability security margin to unwanted conditions. The deterministic N-1 criterion has traditionally provided this security margin to reduce the consequences of severe conditions such as widespread blackouts. However, a deterministic criterion does not include the likelihood of different outage events. Moreover, experience from blackouts shows, e.g. in Sweden-Denmark September 2003, that the outages were not captured by the N-1 criterion. The question addressed in this thesis is how this system security margin can be quantified with probabilistic methods. A quantitative measure provides one valuable input to the decision-making process of selecting e.g. system expansions alternatives and maintenance actions in the planning and design phases. It is also beneficial for the operators in the control room to assess the associated security margin of existing and future network conditions.

This thesis presents a method that assesses each component's risk to an insufficient transfer capability in the transmission system. This shows on each component's importance to the system security margin. It provides a systematic analysis and ranking of outage events' risk of overloading critical transfer sections (CTS) in the system. The severity of each critical event is quantified in a risk index based on the likelihood of the event and the consequence of the section's transmission capacity. This enables a comparison of the risk of a frequent outage event with small CTS consequences, with a rare event with large consequences.

The developed approach has been applied for the generally known Roy Billinton Test System (RBTS). The result shows that the ranking of the components is highly dependent on the substation modelling and the studied system load level.

With the restriction of only evaluating the risks to the transfer capability in a few CTSs, the method provides a quantitative ranking of the potential risks to the system security margin at different load levels. Consequently, the developed reliability based approach provides information which could improve the deterministic criterion for transmission system planning.

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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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32

Godart, Thierry F. "An expert system approach to voltage control design and operation in power systems." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/15787.

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33

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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34

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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35

Stefopoulos, Georgios Konstantinos. "Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Ahmad, M. Masood. "Sensitivity estimates via perturbation analysis in power system simulations." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15408.

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37

Troullinos, George. "Estimating order reduction for dynamic systems with applications to power system equivalents." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/13449.

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38

Park, Jaewook. "An integrated approach to lifeline performance evaluation /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/10196.

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Liu, Xinghua. "Power system operation integrating clean energy and environmental considerations." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085866.

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Fletcher, Robert Henry. "Optimal distribution system horizon planning /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/6018.

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41

Arunachalam, Suresh. "Expansion of an existing power system - a study." Diss., Rolla, Mo. : University of Missouri--Rolla, 1989. http://scholarsmine.mst.edu/thesis/pdf/Arunachalam_09007dcc805881ce.pdf.

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Thesis (M.S.)--University of Missouri--Rolla, 1989.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed October 7, 2008) Includes bibliographical references (p. 89).

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42

Novik, Frode Karstein. "Power system for electric heating of pipelines." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8936.

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Direct electrical heating (DEH) of pipelines is a flow assurance method that has proven to be a good and reliable solution for preventing the formation of hydrates and wax in multiphase flow lines. The technology is installed on several pipelines in the North Sea and has become StatoilHydros preferred method for flow assurance. Tyrihans is the newest installation with 10 MW DEH for a 43 km pipline. However, the pipeline represents a considerable single-phase load which makes the power system dependent on a balancing unit for providing symmetrical conditions. This limits the step out distance and is not suitable for subsea installation. Aker Solutions has proposed several specially connected transformers for subsea power supply of DEH systems, Scott-T being one of them. The Scott-T transformer is a three-to-two-phase transformer which provides balanced electrical power between the two systems when the two secondary one-phase loads are equal. By implementing this transformer, it can be possible to install the power supply subsea as there is no need for a balancing unit. In addition, the system may be applicable for long step out distances. This is because the pipeline is inductive and can use the reactive power produced by the long cable which also can increase the critical cable length. There are however some limitations on this system using the Scott-T transformer. There is a large variation in the magnetic permeability between individual joints of the pipeline. This can result in different load impedance of the two pipe sections connected to the Scott-T transformer. The result is unbalance in the power system. The method of symmetrical components is applied to investigate the behavior during unbalanced loading of the Scott-transformer. The relationship between the negative- and the positive sequence component of the current is used to express the degree of unsymmetry. For the simulations in SIMPOW, the Scott-T transformer is modelled by the use of Dynamic Simulation Language. The simulations on the DSL model give correct and reliable results for analysing the the degree of unsymmetry in the Scott-T transformer. When the load impedance of one pipe section is varied, simulation proves that it can change between 0.75 and 1.34 per unit of the other pipe impedance. The Scott-T transformer does still provide electrical power between the two systems which is below the limit for the degree of unsymmetry (15%). Case 1 and Case 2 introduce two possible configurations for a subsea DEH system with the Scott-T transformer implemented. The configurations include an onshore power supply which is connected to a subsea power system for direct electrical heating and a subsea load at the far end of the subsea cable. The pipeline in Case 1 is 100 km long and is divided into two pipe sections of 50 km which are connected to a Scott-T transformer. The pipeline in Case 2 is 200 km long and is divided into four pipe sections of 50 km each. There are two Scott-T transformers in Case 2. For normal operation of the subsea load (50 MW, cosfi=0.9) and heating the pipe content from the ambient sea emperature, the results indicate that tap changers are necessary to keep the Scott-T transformers secondary terminal voltage at 25 kV. This meets the requirement in both cases for heating the pipe content from 4 to 25 degrees celsius within 48 hours after a shutdown of the process. The degree of unsymmetry is zero for both cases when the system is operated as normal. However, all system simulations indicate that reactive power compensation has to be included for Case 1 as well as for Case 2 in order to have a power factor of unity at the onshore grid connection. The fault scenarios indicate that the degree of unsymmetry is dependent on both the type of fault and the power supply in the system. For Case 1, the relationship (I-/I+) is only of 3.3% in the subsea cable when there is a short-circuit at DEHBUS3, but as much as 87% at the grid connection. The degree of unsymmetry in the Scott-T transformer is then 67%. This is far beyond the limit for maximum negative sequence component of 15%. The significant unsymmetry in the line between the grid and BUS1 is most likely due to the large power delivered to the fault. During the fault, the reactive power delivered to the system increases from 10.6 Mvar to 131.9 Mvar after the fault, but the active power increases only from 75.2 MW to 87.1 MW. This means that it is most likely the reactive power that contributes to the consequent unsymmetry and negative sequence component of the current. There are two Scott-T transformers installed in Case 2. If the DEH system is only heating the pipe section closest to shore (at DEHBUS33), simulations show that the three-phase power system becomes unsymmetric which results in different phase currents. The degree of unsymmetry at the grid connection is 32% when only the pipe section at DEHBUS33 is heated. In addition, the unbalance in the three-phase system caused by SCOTT1 involves unbalance in the SCOTT2 transformer as well. The load voltages are not equal in magnitude and dephased of 90 degrees for this mode, but are 32 kV and 35 kV respectively and dephased of 88 degrees. This concludes a very important behavior of the Scott-T transformer. The simulations conclude that the Scott-T transformer provides symmetrical conditions for both configurations when the two load impedances are equal. However, Case 2 shows an important result when installing two Scott-T transformers in the same system. Unbalanced loading of one of the specially connected transformers gives unsymmetrical conditions in the three-phase system which results in unbalanced load voltages for the other Scott-T transformer. The analysis is limited to the configurations given for Case 1 and Case 2, but shows typical results when an alternative transformer connection is implemented in a DEH system.

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43

Singhavilai, Thamvarit. "Identification of electric power system dynamic equivalent." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=15647.

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WU, YINGJUN. "Contributions to Secure Electric Power System Operation." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2507525.

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Electric power system is a fundamental infrastructure of modern society. A magnicent property of electric power system { security, is achieved by keeping it operated in a secure state at most of the time. Security means the ability to withstand imminent disturbances or contingencies, such as electric short circuits or unanticipated loss of system elements, without interruption of customer service. This thesis proposes methods to secure power system operation from classifying threat origins to power system security, analyzing power system steady-state security, splitting power system network intentionally to increase power system transient stability. Maintaining electric power system secure is a very challenging interdisciplinary multidimensional problem, which is impacted by a large amount of factors, such as extreme weather conditions and unexpected disturbances. In order to achieve keeping the system secure, pursuing a better understanding of all kinds of origins of threats to electric power system is meaningful. Identifying and classifying potential threats to electric power system help to design corresponding measures to tackle them. Moreover, due to impossibility of considering countless threats with nite resource, quantifying and ranking the risks of threats contribute to level up eciency and eectiveness. When power system in a normal, alert, or emergency state, steady-state security analysis, as a branch of power system security analysis, is an eective tool to provide information for operators to design control to mitigate power system progressing into a extremis state. Conventionally, most analysis methods for steady-state security are "point-wised", which means that they considering operational points by checking all components' electrical quantities. However, this sort of method has obvious disadvantages, such as heavy numerical computation and lacking global information. Therefore, "region-wised" method, such as nodal power injections security region and interface power ow security region, with the ability to provide global security information to operators, is promising. Normal, preventive and emergency control measures are eective tools to keep power system security. However, if these measures fail, power system will be placed into a extremis state. Extremely, a cascading spreading of system components outages would result in partial or systemwide blackout (loss of supplied load). In this case, intentional islanding, the ultimate control to preserve as many stable areas as possible, is an eective and promised measure to prevent blackout. In designing a islanding scheme, fast and eectively searching out the optimal MC (minimum cut-set) to split power system network is a conundrum. Moreover, for the large-scale power system, it is even impossible to nd out the best scheme but surrender to suboptimum ones. Genetic algorithm, with excellent optimization capacity, is suitable in this optimization problem to search the optimal MC from the collection of possible cut-sets. However, a considerable portion of meaningless individuals would be produced at the stages of population initialization and genetic operation in the original algorithm, some supplementary modications must be employed to improve its eciency and eectiveness. For each survived island, resynchronization, one aspect of restoration, is a prior issue should be considered. A threat to jeopardize the resynchronization of the survived island is power system 1 transient instability. The mechanism of transient instability can be described as a part of generators in power system deviating from the remaining ones. The deviation of the group from the remaining groups causing power system instable is called critical pattern. The strategy of designing controllers to increase the coherency between the two groups of generators is promising to reduce, even eliminate in some case, the risk of the threat to power system transient stability. In order to implement the control strategy, Lyapunov trajectory tracking control is eective to calculate the mechanical torque to track power system's desired state.

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45

Sarawgi, Sanjoy Kumar. "A simulation tool for studying the effects of special protection systems and communications on power system stability." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Summer2004/s%5Fsarawgi%5F072604.pdf.

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46

Gubba, Ravikumar Krishnanjan. "Distributed simulation of power systems using real time digital simulator." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-06152009-222641.

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47

Thapa, Ravi Chandra. "Damping Interarea Oscillations in Power Systems with DFIG." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29173.

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With rapid depletion of fossil fuels and increasing environmental concerns, the trend to capture renewable energy, especially through wind energy resources, is increasing. The doubly fed induction generator (DFIG) is the most widely used generator for wind energy conversion because of its various advantages over other types of generators. In a DFIG, the rotor is fed through back to back converters via slip rings. The converters enable the generation control. This control property can be used to support reliable operation of a grid network system. Interarea oscillation has been a major factor in limiting power transfers in interconnected power systems. Poorly damped modes can trigger oscillatory instability, potentially leading to cascading blackouts in such systems. We consider a two-area system where DFIG based wind generation is integrated with conventional synchronous generators. A simple controller is proposed for the DFIG to improve damping of interarca oscillations. To support the proposition, case studies are conducted in Matlab/Simulink. The effectiveness of the proposed controller is then analyzed by eigenvalue analysis and verified with time domain simulation results. The results show that a properly tuned controller can increase the damping of dominant oscillatory mode by nearly 5% while improving the area transfer by about 200 MW of wind power. The results further show that with the proposed control strategy, damping of dominant oscillatory mode increased by more than 10%.
North Dakota State University. Graduate School
North Dakota State University. Department of Electrical and Computer Engineering

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48

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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Nguyen, Van Liem. "Modeling and control coordination of power systems with FACTS devices in steady-state operating mode." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0036.

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This thesis is devoted to the development of new models for a recently-implemented FACTS (flexible alternating current transmission system) device, the unified power flow controller (UPFC), and the control coordination of power systems with FACTS devices in steady-state operating mode. The key objectives of the research reported in the thesis are, through online control coordination based on the models of power systems having FACTS devices, those of maximising the network operational benefit and restoring system static security following a disturbance or contingency. Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) power-flow analysis as dynamic variables, the thesis first develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with the discrete time variable replaced by the NR iterative step in the power-flow analysis. The key advantage of the model developed is that of facilitating the process of UPFC constraint resolution during the NR solution sequence. Any relative priority in control functions pre-set in the UPFC controllers is automatically represented in the power-flow formulation. Although the developed UPFC model based on the dynamic simulation of series and shunt converter controllers is flexible and general, the number of NR iterations required for convergence can be large. Therefore, the model is suitable mainly for power system planning and design studies. For online control coordination, the thesis develops the second UPFC model based on nodal voltages. The model retains all of the flexibility and generality of the dynamic simulation-based approach while the number of iterations required for solution convergence is independent of the UPFC controller dynamic responses. Drawing on the constrained optimisation based on Newtons method together with the new UPFC model expressed in terms of nodal voltages, a systematic and general method for determining optimal reference inputs to UPFCs in steady-state operation is developed. The method is directly applicable to UPFCs operation with a high-level line optimisation control (LOC) for maximising the network operational benefit. By using a new continuation technique with adaptive parameter, the algorithm for solving the constrained optimisation problem extends substantially the region of convergence achieved with the conventional Newtons method. Having established the foundation provided by the comprehensive models developed for representing power systems with FACTS devices including the UPFC, the research, in the second part, focuses on real-time control coordination of power system controllers, with the main purpose of restoring power system static security following a disturbance or contingency. At present, as the cost of phasor measurement units (PMUs) and wide-area communication network is on the decrease, the research proposes and develops a new secondary voltage control where voltages at all of the load nodes are directly controlled, using measured voltages.

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50

Altamirano, Chavez Armando. "An efficient algorithm using Householder's formulas for the solution of faulted power systems." Thesis, Kansas State University, 1986. http://hdl.handle.net/2097/9896.

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Dissertations / Theses on the topic 'Electirc Power System'

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