基于正序突变量相轨迹辨识的可再生能源配电网电流保护

Renewable Energy Distribution Network Overcurrent Protection Based on Positive-Sequence Sudden-Change Component Locus Identification

【目的】随着可再生能源的大量接入,中性点经小电阻接地的配电网潮流不确定性使得传统三段式电流保护的整定变得日趋复杂,其灵敏性和可靠性都有所降低。为了解决上述问题,提出了一种基于正序突变量电流相轨迹辨识的新型电流保护方法予以应对。【方法】首先,分析了故障点上游、下游的正序突变量电流大小及其分布特征;其次,利用亲和力聚类算法,根据聚类结果识别定义的主故障路径;最后,提出一种搜索方法,将搜索得到的正序突变量产生源头,即位于主故障路径上的最后一级馈线视为故障馈线。【结果】基于PSCAD的仿真研究表明,所提出的保护方法能够适应各种故障工况,不受分布式电源加入的影响,具有较高的灵敏度和可靠性。【结论】研究结果有助于提升中性点经小电阻接地的配电网运行安全性,同时提升故障排查效率。

[Objectives]With the widespread integration of renewable energy,the uncertainty of power flow in distribution networks with neutral points grounded through small resistors has made the setting of traditional three-stage current protection increasingly complex,and reduced its sensitivity and reliability.To solve the above issues,a new type of current protection based on positive sequence sudden�change variable current phasor trajectory identification was proposed.[Methods]Firstly,the magnitude and distribution characteristics of the positive sequence sudden-change variable current upstream and downstream of the fault point were analyzed.Secondly,using the affinity clustering algorithm,the defined“main fault path”based on the clustering results was identified.Finally,a novel searching method was proposed to identify the source of the positive sequence sudden-change variable,which was the last level feeder located on the main fault path,as the faulted feeder.[Results]Simulation research based on PSCAD shows that the proposed protection method can adapt to various fault conditions,is immune to the integration of renewable energy,and has high sensitivity and reliability.[Conclusions]The research findings are helpful to enhance the operational safety of distribution networks with neutral points grounded through small resistors,and improve the efficiency of fault detection.