含分布式电源的配电网保护影响机理及故障定位

Influence Mechanism and Fault Location of Distribution Network Protection with Distributed Generation

针对分布式电源(distributed generation,DG)接入配电网使得传统的电流保护方法无法适用的问题,本文以双馈线配电网线路作为研究对象,首先分析了在线路不同位置发生三相短路故障时,DG分别接入馈线末端母线、非末端母线以及馈线首端母线时,对线路中流经各个保护的短路电流大小影响,在PSCAD软件建立配电网模型进行仿真分析,因含DG的配电网发生短路故障动作值难以整定,提出了一种基于智能电子设备(intelligent electronic device,IED)上传故障信息的矩阵算法,并通过算例验证了该算法的准确性.结果表明,DG接入馈线末端母线和非末端母线时,故障发生在DG下游会造成故障区段保护误动作,上游区段保护可能会拒动,不利于故障定位与切除,所提的矩阵算法适用于含DG的配电网,无论单一故障或者多重故障,都可实现故障区域的精准定位,保证配电网安全可靠运行.

In view of the problem that the traditional current protection method cannot be applied when distributed generation(DG)is connected to the distribution network,this paper takes the double-feeder distribution network line as the research object.Firstly,when three-phase short-circuit faults occur at different locations of the line,the influence of DG connected to a busbar of feeder ends or a non-end busbar on the short-circuit current flowing through each protection device in the line is analyzed.Then,a distribution network model is built by PSCAD software for simulation analysis.Since it is difficult to set the action value of short-circuit faults in the distribution network containing DG,a matrix algorithm based on intelligent electronic devices(IEDs)for fault information uploading is proposed,and the accuracy of the algorithm is verified by an example.The results reveal that when DG is connected to a busbar of feeder ends or a nonend busbar,the fault that occurs in the downstream of DG will cause maloperation of the protection device in the fault section,and the protection device in the upstream section may encounter operation failure,which is not conducive to fault positioning and removal.The proposed matrix algorithm is applicable to the distribution network with DG,and regardless of single or multiple faults,the fault area can be accurately located to ensure the safe and reliable operation of the distribution network.