Currently, major power systems almost invariably operate under interconnected conditions to transfer power in a stable and reliable manner. Multi-area reliability evaluation has thus become an invaluable tool in the planning and operation of such systems. Multi - area reliability evaluation is typically done by considering equivalent tie lines between different areas in an integrated power system. It gives approximate results for the reliability indices of a power system as it models each of the areas as a single node to which are connected the entire area generation and loads. The intratransmission lines are only indirectly modeled during the calculation of equivalent tie lines' capacities. This method is very widely used in the power industry, but the influence of the various approximations and assumptions, which are incorporated in this method, on reliability calculations has not been explored. The objective of the research work presented in this thesis is the development of a new method called Composite system based multi - area reliability model, which does multi - area reliability evaluation considering the whole composite system. It models the transmission system in detail and also takes into account the loss sharing policy within an area and no - load loss sharing policy among the areas. The proposed method is applied to standard IEEE 24 bus Reliability Test System (RTS) and the traditional equivalent tie-line method is applied to the multi-area configuration of the same test system. The results obtained by both the methods are analyzed and compared. It is found that the traditional model, although having some advantages, may not give accurate results.

This dissertation studies the performance of synchrophasor measurement obtained using substation Intelligent Electronic Devices (IEDs) and proposes new algorithms and test methodology to improve and verify their performance when used in power system applications. To improve the dynamic performance when exposed to sinusoidal waveform distortions, such as modulation, frequency drift, abrupt change in magnitude, etc, an adaptive approach for accurately estimating phasors while eliminating the effect of various transient disturbances on voltages and currents is proposed. The algorithm pre-analyzes the waveform spanning the window of observation to identify and localize the discontinuities which affect the accuracy of phasor computation. A quadratic polynomial signal model is used to improve the accuracy of phasor estimates during power oscillations. Extensive experimental results demonstrate the advantages. This algorithm can also be used as reference algorithm for testing the performance of the devices extracting synchronized phasor measurements. A novel approach for estimating the phasor parameters, namely frequency, magnitude and angle in real time based on a newly constructed recursive wavelet transform is developed. This algorithm is capable of estimating the phasor parameters in a quarter cycle of an input signal. It features fast response and achieves high accuracy over a wide range of frequency deviations. The signal sampling rate and data window size can be selected to meet desirable application requirements, such as fast response, high accuracy and low computational burden. In addition, an approach for eliminating a decaying DC component, which has significant impact on estimating phasors, is proposed using recursive wavelet transform. This dissertation develops test methodology and tools for evaluating the conformance to standard-define performance for synchrophasor measurements. An interleaving technique applied on output phasors can equivalently increase the reporting rate and can precisely depict the transient behavior of a synchrophasor unit under the step input. A reference phasor estimator is developed and implemented. Various types of Phasor Measurement Units (PMUs) and PMU-enabled IEDs (Intelligent Electronic Devices) and time synchronization options have been tested against the standards using the proposed algorithm. Test results demonstrate the effectiveness and advantages.

This dissertation studies the causes and mechanism of power system cascading outages and proposes the improved interactive scheme between system-wide and local levels of monitoring and control to quickly detect, classify and mitigate the cascading outages in power system. A novel method for evaluating the vulnerability of individual components as well as the whole power system, which is named as weighted vulnerability analysis, is developed. Betweenness centrality is used to measure the importance of each bus and transmission line in the modeled power system network, which is in turn used to determine the weights for the weighted vulnerability index. It features fast reaction time and achieves higher accuracy when dealing with the cascading outage detection, classification and mitigation over the traditional methods. The overload problem due to power flow redistribution after one line tripped is a critical factor contributing to the cascading outages. A parallel corridor searching method is proposed to quickly identify the most vulnerable components after tripping a transmission line. The power system topology model can be simplified into state graph after searching the domains for each generator, the commons for each bus, and links between the commons. The parallel corridor will be determined by searching the links and commons in system topology graph for the given state of power system operation. During stressed operating state, either stable or unstable power swing may have impacts on distance relay judgment and lead to relay misoperation, which will result in the power system lines being tripped and as a consequence power system operating state becoming even more stressful. At the local level, an enhanced fault detection tool during power system swing is developed to reduce the chance of relay misoperation. Comprehensive simulation studies have been implemented by using the IEEE 39-bus and 118-bus test systems. The results are promising because: The results from weighted vulnerability analysis could provide better system situational awareness and accurate information about the disturbance; The results form parallel corridor search method could identify the most vulnerable lines after power re-distribution, which will give operator time to take remedial actions; The results from new travelling wave and wavelet transform based fault detection could reduce the impact of relay misoperation.

This dissertation studied new transmission line fault diagnosis approaches using new technologies and proposed a scheme to apply those techniques in preventing and mitigating cascading blackouts. The new fault diagnosis approaches are based on two time-domain techniques: neural network based, and synchronized sampling based. For a neural network based fault diagnosis approach, a specially designed fuzzy Adaptive Resonance Theory (ART) neural network algorithm was used. Several ap- plication issues were solved by coordinating multiple neural networks and improving the feature extraction method. A new boundary protection scheme was designed by using a wavelet transform and fuzzy ART neural network. By extracting the fault gen- erated high frequency signal, the new scheme can solve the difficulty of the traditional method to differentiate the internal faults from the external using one end transmis- sion line data only. The fault diagnosis based on synchronized sampling utilizes the Global Positioning System of satellites to synchronize data samples from the two ends of the transmission line. The effort has been made to extend the fault location scheme to a complete fault detection, classification and location scheme. Without an extra data requirement, the new approach enhances the functions of fault diagnosis and improves the performance. Two fault diagnosis techniques using neural network and synchronized sampling are combined as an integrated real time fault analysis tool to be used as a reference of traditional protective relay. They work with an event analysis tool based on event tree analysis (ETA) in a proposed local relay monitoring tool. An interactive monitoring and control scheme for preventing and mitigating cascading blackouts is proposed. The local relay monitoring tool was coordinated with the system-wide monitoring and control tool to enable a better understanding of the system disturbances. Case studies were presented to demonstrate the proposed scheme. An improved simulation software using MATLAB and EMTP/ATP was devel- oped to study the proposed fault diagnosis techniques. Comprehensive performance studies were implemented and the test results validated the enhanced performance of the proposed approaches over the traditional fault diagnosis performed by the transmission line distance relay.

The main purpose of this thesis is to study the emergency power-supply system analysis for red and orange lines of Kaohsiung Mass Rapid Transit(KMRT). First of all, the configurations of KMRT power-supply were introduced. Then the traction power required and station substation demand were analyzed by computer program. The suitability of planning and the power-supply system were examined by considering their target year requirements based on the headways of both 2 and 3 minutes. The dispatch strategic is investigated when one of Bulk Supply Substation(BSS) was outaged. To analyze the system transient stability for the islanding operation of KMRT system when all 161kV circuits tripped, the mathematical models of the standby diesel generators with excitation system and governor system as well as the loads are considered in the computer simulation. The Ferranti effect due to 22.8kV cables for the transmission of energy backup power to send the critical loads in the train station is investigated, it is found that the shunt reactors is required for the mitigation of over voltage problem introduced by the Ferranti effect.

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Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 253-261). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 116-119.

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.