Browsing by Subject "fault location"
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Item Improving Distribution System Reliability Through Risk-base Doptimization of Fault Management and Improved Computer-based Fault Location(2013-11-07) Dong, YimaiUtilities of distribution systems now are under the pressure of improving the reliability of power supply, not only from the urge to increase revenue, but also from requirements of their customers and the Independent Service Organization (ISO)?s regulation on power quality. Optimization in fault management tasks has the potential of improving system reliability by reducing the duration and scale of outages caused by faults through fast fault isolation and service restoration. The research reported by this dissertation aims at improving distribution system reliability through optimized fault management. Three questions are explored and answered: 1) how to establish the cause-and-effect relationship between fault management and system reliability; 2) how can individual fault management tasks benefit from the newly emerged smart grid technologies; and 3) how to improve the overall performance of fault management under new operation condition. Optimization of the fault management is done through minimizing a risk function representing system reliability. The improvement in system reliability is approached in following steps: 1) a risk function consists of distribution reliability indices is defined as the criterion for system reliability; 2) a new fault location method is proposed first that can accurately locate the faults with the assistance of voltage-sag-measurements from system-wide Intelligent Electronics Devices (IEDs); 3) the fault management task of field inspection is optimized using the risk function and the probability model of the true fault location established using results from fault location; 4) the decision making on the execution of during-fault service restoration is optimized through Monte Carlo simulation; 5) the optimized fault management is utilized in processing the faults and the improvement in system reliability is assessed by reduction of costs associated with these faults. The proposed optimization is demonstrated on a realistic distribution system. The stochastic model of faults in the system is built with consideration of normal and extreme weather conditions. Results show that the proposed optimization is capable of improving system reliability by reducing the mean and variance of outage cost calculated over the simulated years.Item Methodology for designing the fuzzy resolver for a radial distribution system fault locator(Texas A&M University, 2006-04-12) Li, JunThe Power System Automation Lab at Texas A&M University developed a fault location scheme that can be used for radial distribution systems. When a fault occurs, the scheme executes three stages. In the first stage, all data measurements and system information is gathered and processed into suitable formats. In the second stage, three fault location methods are used to assign possibility values to each line section of a feeder. In the last stage, a fuzzy resolver is used to aggregate the outputs of the three fault location methods and assign a final possibility value to each line section of a feeder. By aggregating the outputs of the three fault location methods, the fuzzy resolver aims to obtain a smaller subset of line sections as potential faulted sections than the individual fault location methods. Fuzzy aggregation operators are used to implement fuzzy resolvers. This dissertation reports on a methodology that was developed utilizing fuzzy aggregation operators in the fuzzy resolver. Three fuzzy aggregation operators, the min, OWA, and uninorm, and two objective functions were used to design the fuzzy resolver. The methodologies to design fuzzy resolvers with respect to a single objective function and with respect to two objective functions were presented. A detailed illustration of the design process was presented. Performance studies of designed fuzzy resolvers were also performed. In order to design and validate the fuzzy resolver methodology, data were needed. Due to the lack of real field data, simulating a distribution feeder was a feasible alternative to generate data. The IEEE 34 node test feeder was modeled. Time current characteristics (TCC) based protective devices were added to this feeder. Faults were simulated on this feeder to generate data. Based on the performance studies of designed fuzzy resolvers, the fuzzy resolver designed using the uninorm operator without weights is the first choice. For this fuzzy resolver, no optimal weights are needed. In addition, fuzzy resolvers using the min operator and OWA operator can be used to design fuzzy resolvers. For these two operators, the methodology for designing fuzzy resolvers with respect to two objective functions was the appropriate choice.Item Novel techniques for fault location, voltage profile calculation and visualization of transients(2009-05-15) Evrenosoglu, Cansin YamanThis dissertation addresses three different problems in power systems. The first problem is related to the fault location in complex topologies such as three terminal circuits with series compensation and mutually coupled line sections and distribution networks with distributed generation. Novel methods are presented by using traveling wave approach and wavelet transformation technique to overcome the difficulties introduced by the discontinuities and integrated components such as Metal Oxide Varistor (MOV) protected series capacitors and distributed generation in complex topologies. Simulation results show good correlation between the actual and estimated fault locations for all the studied cases. The second problem concerns the calculation techniques of voltage profiles along transmission lines. A simple yet effective approach to accurately and rapidly obtain the voltage profile along a transmission line during fault transients is presented. The objective of the presented method is to eliminate the need to use wave equations and line parameters provided that an electromagnetic Transients Program (EMTP) type transients simulator is available for generating bus voltage transients for a given fault. This is accomplished by developing a time series model to estimate the voltage at an intermediate point along the transmission line. The model is formed for each intermediate point separately. Once the model is obtained it can be used to predict the transient voltage at that point along the line during any fault in the system. The approach can potentially be useful as a post processor to a transient simulator and can be used by developers of transient animations and movies for illustrating fault-initiated propagation of traveling waves in power systems. The third problem is the lack of powerful visualization and animation methods, which can help understanding the complex behavior of power systems during transients. The goal of this part of the dissertation is to develop new animation and visualization methods for power system electromagnetic transients for both educational and research purposes. Proposed approaches are implemented in different environments such as MATLAB and Microsoft Visual Studio to show the effectiveness of two and three-dimensional visualization of power system transients. The implementations of the proposed methods provide better understanding of the power systems during transient phenomena due to the faults or switchings.Item Optimal fault location(Texas A&M University, 2008-10-10) Knezev, MajaBasic goal of power system is to continuously provide electrical energy to the users. Like with any other system, failures in power system can occur. In those situations it is critical that correct remedial actions are applied as soon as possible after the accurate fault condition and location are detected. This thesis has been focusing on automated fault location procedure. Different fault location algorithms, classified according to the spatial placement of physical measurements on single ended, multiple ended and sparse system-wide, are investigated. As outcome of this review, methods are listed as function of different parameters that influence their accuracy. This comparison is than used for generating procedure for optimal fault location algorithm selection. According to available data, and position of the fault with respect to the data, proposed procedure decides between different algorithms and selects an optimal one. A new approach is developed by utilizing different data structures such as binary tree and serialization in order to efficiently implement algorithm decision engine. After accuracy of algorithms is strongly influenced by available input data, different data sources are recommended in proposed architecture such as the digital fault recorders, circuit breaker monitoring, SCADA, power system model and etc. Algorithm for determining faulted section is proposed based on the data from circuit breaker monitoring devices. This algorithm works in real time by recognizing to which sequence of events newly obtained recording belongs. Software prototype of the proposed automated fault location analysis is developed using Java programming language. Fault location analysis is automatically triggered by appearance of new event files in a specific folder. The tests were carried out using the real life transmission system as an example.Item Optimal fault location(2009-05-15) Knezev, MajaBasic goal of power system is to continuously provide electrical energy to the users. Like with any other system, failures in power system can occur. In those situations it is critical that correct remedial actions are applied as soon as possible after the accurate fault condition and location are detected. This thesis has been focusing on automated fault location procedure. Different fault location algorithms, classified according to the spatial placement of physical measurements on single ended, multiple ended and sparse system-wide, are investigated. As outcome of this review, methods are listed as function of different parameters that influence their accuracy. This comparison is than used for generating procedure for optimal fault location algorithm selection. According to available data, and position of the fault with respect to the data, proposed procedure decides between different algorithms and selects an optimal one. A new approach is developed by utilizing different data structures such as binary tree and serialization in order to efficiently implement algorithm decision engine. After accuracy of algorithms is strongly influenced by available input data, different data sources are recommended in proposed architecture such as the digital fault recorders, circuit breaker monitoring, SCADA, power system model and etc. Algorithm for determining faulted section is proposed based on the data from circuit breaker monitoring devices. This algorithm works in real time by recognizing to which sequence of events newly obtained recording belongs. Software prototype of the proposed automated fault location analysis is developed using Java programming language. Fault location analysis is automatically triggered by appearance of new event files in a specific folder. The tests were carried out using the real life transmission system as an example.