基于行波差动电流的输电线路接地故障测距
Grounding Fault Location of Transmission Line by Traveling ?Wave Differential Current

行波测距的准确性受多个因素影响．为此，分析了行波差动电流的不平衡输出，定义了经不平衡电流补偿的行波差流，推导了线路内部故障时该差流的表达式．由于行波在零模和线模上的传播速度不同，两种模量的行波差流也不相同，其幅值比和相角差与故障点位置相关，据此提出了基于行波差动电流的接地故障测距原理．该原理提取行波差动电流的工频分量进行测距，无需提取行波波头，不受线路对行波衰减及波速不确定等因素的影响，PSCAD 仿真表明，测距误差很小，测距结果准确可靠．
The precision of traveling wave fault location is influenced by multiple factors. In this paper，the unbalance output of traveling wave differential current is analyzed，a new traveling wave differential current compensated by unbalance current is defined，and the expression of the differential current at the time when internal fault occurs is deduced. The traveling wave differential currents of zero mode and aerial mode are different because of the difference between the traveling wave propagation velocity in zero mode and aerial mode. Actually，the amplitude ratio and phase contrast of the two differential currents depend on the fault location. On this basis，a principle of grounding fault location based on traveling wave differential current is proposed. With this principle the fault is located by abstracting the fundamental frequency component of traveling wave differential current，and it is not necessary to capture the traveling wave head．Therefore this method is immune to the attenuation of travelling wave and the indeterminacy of propagation velocity. The PSACD simulation proves that the error of measurement is very small and the fault locating results is accurate and reliable