一种T形高压输电线路故障测距新方法

对T形线路的故障测距,现有方法都是先判断故障支路,再将3端线路等效成2端线路进行测距。但在T节点附近短路,尤其是经高阻短路时,现有的测距方法由于无法正确判别故障支路而存在一定范围的测距死区。针对上述缺陷,分别假设故障发生在某一支路,由假定正常的2段支路端的电压、电流推算求得T节点电压和注入假定故障支路的电流,从而分别求得3个故障距离。经证明,求得的3个故障距离有且仅有1个在0和对应支路总长度之间,该距离就是真实的故障距离,故障发生在对应支路上。该方法无需事先判别故障支路即可测距,在T节点附近经高阻故障时无测距死区。其测距精度理论上不受过渡电阻和故障类型影响,无需故障前数据,且对滤波无高要求。EMTP仿真结果表明该方法正确、有效,测距精度高。

New Fault Location Method for HV T-connection Transmission Lines

In the conventional fault location method,the fault section is first identified,and then,three-terminal lines are converted into two-terminal to calculate the fault location.However,when the fault occurs nearby the T-connection point,particularly in the case of high resistance grounding,the method cannot identify the fault section precisely and has a dead band.To overcome the shortcoming,this paper presents a new fault location method for teed lines,assuming the fault occurs at each of the three branches respectively,then calculating the teed node voltage and current flowing to the assumed fault branch.In the three fault distances calculated,the only one greater than zero and less than the corresponding branch length is for the real faulty branch.The proposed method can locate faults without having to identify the fault section first and can accurately locate the faults occurring near the teed node through large resistance.The fault location accuracy is independent of the fault resistance and fault type in theory.In addition,pre-fault data or filter is not required.Simulation results with EMTP indicate that the method is correct and accurate.