To evaluate the strategy of reliability enhancement for an existing industrial power system , the Benefit-Cost ratio of all possible improvement scenarios have to be investigated . This thesis presents a quantitative and systematic method to solve the Benefit-Cost ratio of network restructure for reliability enhancement . This method can provide a simple and effective tool for planning reliability improvement in the industry power systems. Up to now , many methodologies have been developed to solve the service reliability for distribution power systems . In this thesis , the reliability indices of industrial power systems are calculated to evaluate the service quality . According to the result of reliability analysis and the corresponding cost of loss of load for each load bus , the annual power outage cost is derived for each scenario of system restructure. By integrating the power outage cost and the corresponding investment cost , the optimal reliability enhancement is determined by the best strategy with the Benefit-Cost ratio.

This paper is to investigate the impact of temperature sensitivity to the load profiles of power system by artificial neural networks (ANN). The load survey study is performed to derive the typical load patterns of the residential, commercial, and industrial customers respectively. By executing the training process of customer power consumption and temperature, the ANN model is created to derive the temperature sensitivity of power consumption for each customer class, which is then used to solve the impact of temperature rise to system power profiles. According to the system load composition and temperature sensitivity of power consumption by each customer class, the hourly increase of system power loading due to 1¢J temperature rise is solved. To study the temperature effect to the system reliability, the ¡§IEEE Reliability Test System¡¨ is selected as test system for power system reliability analysis. Based on the temperature sensitivity of power consumption for each customer class and load composition of each load bus. The power demand is updated with the temperature rise. The temperature sensitivity of commercial customers is very significant because of the high air conditioner loading. When the system load composition is most composed of commercial customers, the power demand are due to temperature rise will have very critical impact to system reliability. On the other hand, the tempearture rise will have less impact of reliability analysis for the system which serves high percentage of industrial customers. It is concluded that the research of temperature sensitivity on power consumption can provide important information for system reliability analysis. Better substation planning and system capacity expansion can be obtained to meet system reliability criterion by taking into account the temperature effect to system loading.

Instrument transformers are a crucial component of power system protection. They supply the protection system with scaled-down replicas of current and voltage signals present in a power network to the levels which are safe and practical to op- erate with. The conventional instrument transformers are based on electromagnetic coupling between the power network on the primary side and protective devices on the secondary. Due to such a design, instrument transformers insert distortions in the mentioned signal replicas. Protective devices may be sensitive to these distortions. The inuence of distortions may lead to disastrous misoperations of protective devices. To overcome this problem, a new instrument transformer design has been devised: optical sensing of currents and voltages. In the theory, novel instrument transform- ers promise a distortion-free replication of the primary signals. Since the mentioned novel design has not been widely used in practice so far, its superior performance needs to be evaluated. This poses a question: how can the new technology (design) be evaluated, and compared to the existing instrument transformer technology? The importance of this question lies in its consequence: is there a necessity to upgrade the protection system, i.e. to replace the conventional instrument transformers with the novel ones, which would be quite expensive and time-consuming? The posed question can be answered by comparing inuences of both the novel and the conventional instrument transformers on the protection system. At present, there is no systematic approach to this evaluation. Since the evaluation could lead to an improvement of the overall protection system, this thesis proposes a comprehensive and systematic methodology for the evaluation. The thesis also proposes a complete solution for the evaluation, in the form of a simulation environment. Finally, the thesis presents results of evaluation, along with their interpretation.

The electric power systems in U.S. Navy ships supply energy to sophisticated systems for weapons, communications, navigation and operation. The reliability and survivability of a Shipboard Power System (SPS) are critical to the mission of a Navy ship, especially under battle conditions. When a weapon hits the ship in the event of battle, it can cause severe damage to the electrical systems on the ship. Researchers in the Power System Automation Laboratory (PSAL) at Texas A&M University have developed methods for performing reconfiguration of SPS before or after a weapon hit to reduce the damage to SPS. Reconfiguration operations change the topology of an SPS. When a system is stressed, these topology changes and induced dynamics of equipment due to reconfiguration might cause voltage instability, such as progressive voltage decreases or voltage oscillations. SPS stability thus should be assessed to ensure the stable operation of a system during reconfiguration. In this dissertation, time frames of SPS dynamics are presented. Stability problems during SPS reconfiguration are classified as long-term stability problems. Since angle stability is strongly maintained in SPS, voltage stability is studied in this dissertation for SPS stability during reconfiguration. A test SPS computer model, whose simulation results were used for stability studies, is presented in this dissertation. The model used a new generalized methodology for modeling and simulating ungrounded stiffly grounded power systems. This dissertation presents two new indices, a static voltage stability index (SVSILji) and a dynamic voltage stability index (DVSI), for assessing the voltage stability in static and dynamic analysis. SVSILji assesses system stability by all lines in SPS. DVSI detects local bifurcations in SPS. SVSILji was found to be a better index in comparison with some indices in the literature for a study on a two-bus power system. Also, results of DVSI were similar to the results of conventional bifurcation analysis software when applied to a small power system. Using SVSILji and DVSI on the test SPS computer model, three of four factors affection voltage stability during SPS reconfiguration were verified. During reconfiguration, SVSILji and DVSI are used together to assess SPS stability.

Modern power systems are now stepping into the post-restructuring era, in which utility industries as well as ISOs (Independent System Operators) are involved. Attention needs to be paid to the reliability study of power systems by both the utility companies and the ISOs. An uninterrupted and high quality power is required for the sustainable development of a technological society. Power system blackouts generally result from cascading outages. Protection system hidden failures remain dormant when everything is normal and are exposed as a result of other system disturbances. This dissertation provides new methods for power system vulnerability analysis including protection failures. Both adequacy and security aspects are included. The power system vulnerability analysis covers the following issues: 1) Protection system failure analysis and modeling based on protection failure features; 2) New methodology for reliability evaluation to incorporate protection system failure modes; and, 3) Application of variance reduction techniques and evaluation. A new model of current-carrying component paired with its associated protection system has been proposed. The model differentiates two protection failure modes, and it is the foundation of the proposed research. Detailed stochastic features of system contingencies and corresponding responses are considered. Both adequacy and security reliability indices are computed. Moreover, a new reliability index ISV (Integrated System Vulnerability) is introduced to represent the integrated reliability performance with consideration of protection system failures. According to these indices, we can locate the weakest point or link in a power system. The whole analysis procedure is based on a non-sequential Monte Carlo simulation method. In reliability analysis, especially with Monte Carlo simulation, computation time is a function not only of a large number of simulations, but also time-consuming system state evaluation, such as OPF (Optimal Power Flow) and stability assessment. Theoretical and practical analysis is conducted for the application of variance reduction techniques. The dissertation also proposes a comprehensive approach for a TTC (Total Transfer Capability) calculation with consideration of thermal, voltage and transient stability limits. Both steady state and dynamic security assessments are included in the process of obtaining total transfer capability. Particularly, the effect of FACTS (Flexible AC Transmission Systems) devices on TTC is examined. FACTS devices have been shown to have both positive and negative effects on system stability depending on their location. Furthermore, this dissertation proposes a probabilistic method which gives a new framework for analyzing total transfer capability with actual operational conditions.

This dissertation studies the causes and mechanism of power system cascading outages and develops new methods and new tools to help detect, prevent and mitigate the outages. Three effective solutions: a steady state control scheme, a transient stability control scheme, and an interactive system-wide and local scheme have been proposed using those new methods and tools. A steady state control scheme can help detect and prevent the possible cascading outage at its initial slow steady state progress stage. It uses new methods and new tools to solve the line overload, congestion or bus high/low voltage problems. New methods, such as vulnerability index (VI), margin index (MI), network contribution factor (NCF), topology processing and selected minimum load shedding (SMLS), and new tools, such as transmission network control based on a network contribution factor (NCF) method, generator control based on a generator distribution factor (GDF) method, and load control based on a load distribution factor (LDF) method have been proposed and developed. A transient stability control scheme can help prevent and mitigate the possible cascading outage at its transient progress stage if there is enough time to take action. It uses one Lyapunov direct method, potential energy boundary surface (PEBS) method, and sensitivity analysis of transient energy margin for fast stabilizing control. The results are verified by the accurate time-domain transient stability analysis method. The interactive scheme takes advantage of accurate system-wide and local information and analysis results, uses some techniques from both steady state control and transient stability control, works at both the system-wide level and local substation level, monitors the system all the time, and takes actions when needed to help detect, prevent and mitigate the possible cascading outage. Comprehensive simulation studies have been implemented using the IEEE 14- bus, 24-bus, 39-bus and 118-bus systems and promising results show the ability of the proposed solutions to help detect, prevent and mitigate cascading outages.

Power System Deregulation is a trend, and it takes place when the government, reduces unnecessary intervention and relaxes the control of capacity and price for the electricity market. It can establish the market mechanism and create rules that facilitate competition. The intention is to raise the market efficiency, introducing various types of production technologies and marketing management. As a result, it should create higher added value and ensure customer rights and interests to reach a win-win situation from both parties. In this thesis, a maximum profit will be pursued in the security market by the use of the Enhanced Immune Algorithm and Signal-to-Noise Ratio search under deregulated environment. Participation of generator companies and distribution companies are determined by ISO depending on their individual contributions to join the security market. The monetary influence is also discussed by using the social welfare. In this thesis, optimization will be considered when a line trip could lead to system congestion under security analysis. Tracing was used to find GenCos and DisCos¡¦s contributions to the transmission lines. ISO determines the participants to join the security market according to the tracing results. For the same fault type, various dispatch fees of the bids from participants will have various impacts on ISO¡¦s dispatch in terms of social welfare in the security market. Various fault types will also be discussed for the impacts of dispatch fees over ISO. This research could also provide a solid foundation for power system deregulation in the future. ISO can forecast the cost for a fault, and maximizes social welfare.

Thesis (Ph.D.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on Feb. 9, 2010). Includes bibliographical references.

Thesis (Ph.D.) -- McGill University. / Written for the Dept. of Electrical Engineering. Typewritten MS. Bibliography: leaves 283-299.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains viii, 73 p. : ill. Includes abstract. Includes bibliographical references (p. 71-73).