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Analysis Of Reliability Non-coherence In Distribution Power Systems

Posted on:2011-05-26Degree:MasterType:Thesis
Country:ChinaCandidate:W N LiFull Text:PDF
GTID:2132360308958730Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
Reliability and economy of power system influences and restricts each other. Based on the graph of reliability cost-benefit analysis, the reliability of power system improves while investing more. However, a particular phenomenon in power system called reliability non-coherence,which means the reliability of power system does not get better but probably worse when adding a new component in it,may be a special case against this classic theory.For the reason of a comparatively high failure rate of switching devices in distribution power systems (DPS), a section algorithm is presented to evaluate the DPS reliability considering the failures of switching devices. The impact of switching devices failures on the system reliability is analyzed when computing the reliability of DPS to get a more accurate value. Case studies show that the impact of failures on switching devices can not be ignored in DPS, Which laid the foundation for identification of non-coherence phenomena in DPS.The reasons of resulting in the non-coherence phenomena and the candidate non-coherence components in DPS are discussed according to the definition of non-coherence in power system reliability. Switching devices are the most possible non-coherence components in DPS. A method of non-coherence components identification is presented based on the section algorithm which considering the failures of switching devices. A comprehensive model considering the capital cost, maintenance and operating cost is proposed to analyze the impacts of non-coherence components on the system economy. According to the qualitative analysis on the impact of circuit breaker to the system reliability, a circuit breaker reliability model based on the energy not supplied index (ENS) is proposed.Parameter analysis of non-coherence components caused by the circuit breaker is presented based on the ENS index, which consists of reliability parameters of circuit breaker and other components, loads and system structure. Case studies shows non-coherence phenomenon can be influenced by all this factors. This conclusion is agree with the one received by the qualitative analysis.The characters of non-coherence phenomenon are analyzed based on different reliability index. Case study shows different non-coherence identification results can be reached based on different system reliability index. Study shows non-coherence phenomenon can probable exist in DPS. Analysis on non-coherence components will improve the reliability of DPS while cutting down the cost.This thesis was supported by the National Natural Science Foundation of China ("Study on the reliability non-coherence theory and application for power system", No. 50777072).
Keywords/Search Tags:Reliability Non-coherence, Non-coherence Identification, Parameter Analysis, Failures of Switching Devices, Section Algorithm
PDF Full Text Request
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