Three aspects of Subsynchronous Resonance (SSR) related problems in power systems are addressed in this dissertation which aims at contributing to a better understanding of these problems. Subsynchronous Resonance (SSR) problems in series compensated steam-turbine power systems co-exist with the beneficial effects provided by the series capacitors. Since the early 1930s, numerous researchers have addressed issues relating to these problems. The development of a generalized frequency scan method for analyzing SSR in a Single-Machine Infinite-Bus (SMIB) power system equipped with fixed series capacitor compensation is presented. This method overcomes shortcomings present in the traditional frequency scan technique which is widely used in power system analysis. It has been noticed that there are nonlinear dynamic phenomena in power systems which can not be explained by linear system theory. This includes limited oscillations in a power system when it experiences SSR at a frequency close to one of the system modes. The phenomenon can be explained by Hopf bifurcations. This dissertation presents an analysis for a high dimensional model of a SMIB power system equipped with fixed series capacitor compensation. The results obtained can lead to a more precise understanding of this phenomenon than those available to date which use perturbation methods and highly simplified second-order power system models. Compared with fixed series capacitor compensation in power systems, the newly developed Thyristor Controlled Series Compensation (TCSC) scheme has some well known advantages with regard to flexible power system control. It has been noted that vernier mode TCSC operation can provide for SSR mitigation. In this thesis, such beneficial effect is demonstrated and analyzed for a simplified North-Western American Power System (NWAPS) model, based on EMTP simulations. Issues relating to modelling and simulation of power system and TCSC are addressed. / Graduation date: 1995

The design of the electric platform in military vehicles requires the ability to determine the best combination of power system components that support the desired operational abilities, while minimizing the size, weight, cost, and impact of the overall power system. Because prototypes are both time consuming, rigid, and costly, they have become inadequate for verifying system performance. By using simulations, engineers can best plan for and observe the associations between missions (including modes of operation and system scenarios) and system performance in a dynamic, realistic environment. This thesis proposes a new tool to analyze and design military vehicle platforms: the Advanced Mobile Integrated Power System (AMPS). This tool is useful for design and design verification of military vehicles due to its unique incorporation of mission-specific functionality. It allows the user ease of design with the ability to customize the vehicle power system architecture and components, while permitting full control over source and load input parameters. Simulation of programmed mission sequences allows the user to ensure that the chosen vehicle architecture can provide all of the electrical power and energy needed to support the mission, thus providing adequate design verification. The present thesis includes an introduction to vehicle power systems and an outline of the need for simulation, a description of the AMPS project and vehicle specifications, analytical and numerical models of the simulated vehicle, explanation of the power management system, description of the graphical user interface, and a simulation performed with the AMPS tool.

State estimation plays an essential role in the monitoring and control of power transmission systems. In modern, highly inter-connected power systems the state estimation should be performed in a distributed fashion and requires information exchange between the control centers of directly connected systems. Motivated by recent reportson trojans targeting industrial control systems, in this paper we investigate how a single compromised control center can affect the outcome of distributed state estimation. We describe five attack strategies, and evaluate their impact on the IEEE 118 benchmark power system. We show that that even if the state estimation converges despite the attack, the estimate can have up to 30% of error, and bad data detection cannot locate theattack. We also show that if powerful enough, the attack can impede the convergence of the state estimation, and thus it can blind the system operators. Our results show that it is important to provide confidentiality for the measurement data in order to prevent the most powerful attacks. Finally, we discuss a possible way to detect and to mitigate these attacks. / <p>QC 20130522</p>

A physical control/protection platform needs to be tested and its functionality verified prior to installation and commissioning. Closed-loop testing of a physical control/protection platform, in a real-time simulator environment is practically the only option to safely and thoroughly verify the design integrity and evaluate its functionality and performance. Moreover, a real-time simulator is also required to conduct statistical switching studies, as it substantially reduces the total run time of the study. This thesis proposes and develops a generalized methodology for implementation of the power system equations in the FPGA environment. The developed methodology enables real-time operation, for closed-loop testing of physical control/protection platforms in hardware-in-the-loop (HIL) configuration, and even faster-than-real-time operation, for statistical switching studies. Based on the developed methodology, an FPGA-based simulator is developed and tested. The salient features of the proposed implementation are: ² It enables the use of a nanosecond range simulation time-step to simulate large systems in real-time, in contrast to the us range time-steps used in the existing simulators. Thus it is also able to provide a wide frequency bandwidth for the simulation results. ² It retains the calculation time, within each simulation time-step, nearly fixed irrespective of the size of the system. ² It eliminates the need for the corrective measures, adopted in the existing real-time simulators, to reduce error due to the lack of synchronization between the simulation time-grid and the output signals of the control/protection platform under test. As an integral part of this work, this thesis proposes and develops the modified two-layer network equivalent (M-TLNE). The salient feature of the M-TLNE is its computational efficiency, as compared to the existing network equivalents, which makes it a prime choice for statistical switching studies and real-time simulation of electromagnetic transients. This thesis also proposes a generalized methodology, applicable to both single and multi-port network equivalents for both single- and multi-phase systems, for developing the proposed M-TLNE. The developed methodology ensures the stability and passivity of the M-TLNE.

In recent years, considerable attention has been focused on the application of orthogonal expansions to system analysis, parameter identification, model reduction and control system design. However, little research has been done in applying their useful properties to Power System analysis and control. This research attempts to make some inroads in applying the so called " orthogonal expansion approach " to analysis and control of Power systems, especially the latter. A set of orthogonal functions commonly called Walsh functions in system science after it's discoverer J.L. Walsh [1923] have been successfully used for parameter identification in the presence of severe nonlinearities. The classical optimal control problem is applied to a synchronous machine infinite bus system via the orthogonal expansion approach and a convenient method outlined for designing PID controllers which can achieve prespecified closed loop response characteristics. The latter is then applied for designing a dynamic series capacitor controller for a single machine infinite bus system. / Graduation date: 1993

A physical control/protection platform needs to be tested and its functionality verified prior to installation and commissioning. Closed-loop testing of a physical control/protection platform, in a real-time simulator environment is practically the only option to safely and thoroughly verify the design integrity and evaluate its functionality and performance. Moreover, a real-time simulator is also required to conduct statistical switching studies, as it substantially reduces the total run time of the study. This thesis proposes and develops a generalized methodology for implementation of the power system equations in the FPGA environment. The developed methodology enables real-time operation, for closed-loop testing of physical control/protection platforms in hardware-in-the-loop (HIL) configuration, and even faster-than-real-time operation, for statistical switching studies. Based on the developed methodology, an FPGA-based simulator is developed and tested. The salient features of the proposed implementation are: ² It enables the use of a nanosecond range simulation time-step to simulate large systems in real-time, in contrast to the us range time-steps used in the existing simulators. Thus it is also able to provide a wide frequency bandwidth for the simulation results. ² It retains the calculation time, within each simulation time-step, nearly fixed irrespective of the size of the system. ² It eliminates the need for the corrective measures, adopted in the existing real-time simulators, to reduce error due to the lack of synchronization between the simulation time-grid and the output signals of the control/protection platform under test. As an integral part of this work, this thesis proposes and develops the modified two-layer network equivalent (M-TLNE). The salient feature of the M-TLNE is its computational efficiency, as compared to the existing network equivalents, which makes it a prime choice for statistical switching studies and real-time simulation of electromagnetic transients. This thesis also proposes a generalized methodology, applicable to both single and multi-port network equivalents for both single- and multi-phase systems, for developing the proposed M-TLNE. The developed methodology ensures the stability and passivity of the M-TLNE.

In this thesis, a demand elasticity model is developed and tested for the dispatch of high voltage power systems and microgrids. The price obtained from dispatching a network in a base-case scenario is used as input to a price-elastic demand model. This demand model is then used to determine the price-responsive demand for the next iteration, assuming that the load schedule is defined a day-ahead. Using this scheme, trends for demand, hourly prices, and total operation costs for a system can be obtained to study the impact of demand response on unit commitment and dispatch of distributed energy resources. This way, the effect on the scheduling of dispatchable generators and energy storage systems can be analyzed with respect to price-elastic loads. The results for a test power system and a benchmark microgrid show that as the demand is more elastic, the longer it takes for the dispatch to converge to a final condition. The 24-hour model eventually converges to a steady state, with prices and costs at their lowest values for different scenarios, which is good for most system participants and desirable in a market environment, thus highlighting the importance of price-responsive loads in electricity markets.

The design of the electric platform in military vehicles requires the ability to determine the best combination of power system components that support the desired operational abilities, while minimizing the size, weight, cost, and impact of the overall power system. Because prototypes are both time consuming, rigid, and costly, they have become inadequate for verifying system performance. By using simulations, engineers can best plan for and observe the associations between missions (including modes of operation and system scenarios) and system performance in a dynamic, realistic environment. This thesis proposes a new tool to analyze and design military vehicle platforms: the Advanced Mobile Integrated Power System (AMPS). This tool is useful for design and design verification of military vehicles due to its unique incorporation of mission-specific functionality. It allows the user ease of design with the ability to customize the vehicle power system architecture and components, while permitting full control over source and load input parameters. Simulation of programmed mission sequences allows the user to ensure that the chosen vehicle architecture can provide all of the electrical power and energy needed to support the mission, thus providing adequate design verification. The present thesis includes an introduction to vehicle power systems and an outline of the need for simulation, a description of the AMPS project and vehicle specifications, analytical and numerical models of the simulated vehicle, explanation of the power management system, description of the graphical user interface, and a simulation performed with the AMPS tool.

Thesis (Ph.D.)--Drexel University, 2008. / Vita. Includes bibliographical references (leaves 204-209). Online version available

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 129 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 122-129).