基于主动注入的柔性直流配电网故障定位

An active converter injection-based fault location method for a flexible DC distribution network

柔性直流配电网中换流站难以耐受双极短路冲击电流,在1~2 ms内闭锁,提供给故障定位的有效信息少,定位精度差。因此,提出了一种基于DC/DC主动注入的柔性直流配电网的故障定位方法。在换流站均闭锁的情况下,金属性故障解锁配网首端DC/DC换流站,非金属型故障先后解锁首末两端DC/DC换流站,然后提取电压电流数据进行故障定位。该故障定位方法考虑了换流站因快速闭锁无法提供有效暂态信息的问题。利用DC/DC换流站高压侧支撑电容对注入信号的电气特征响应,即可实现故障区段区别。此外,该方法不需要额外的注入设备且适用于单一MMC换流站的网络,原理简单可靠且定位精度高。最后在PSCAD/EMTDC仿真软件中搭建柔性直流配电网,验证了所提故障定位方法的可行性。

The converter station in a flexible DC distribution network finds it difficult to withstand the impulse current caused by a bipolar short-circuit fault,and is locked for 1~2 ms.There is little transient effective information for fault treatment,and it has poor location accuracy.Therefore,this paper proposes a fault treatment method of flexible DC distribution network based on DC/DC active injection.When the converter stations are locked,the DC/DC converter at the head of the distribution network will be unlocked in the case of a metal fault,and the DC/DC converter at the head and end will be unlocked successively in the case of a non-metal fault.Then the voltage and current data will be extracted for fault location.The fault location method has considered effective transient information which cannot be provided by the converter station because of fast locking.Based on the electrical characteristic response of the high-voltage side support capacitor of the DC/DC converter to the injection signal,the fault section can be distinguished.Also the method suitable for a network with single MMC converter station does not need additional injection equipment,and the principle is simple and reliable with high positioning accuracy.Finally,the flexible DC distribution network is built in PSCAD/EMTDC to verify the feasibility of the proposed fault location method.