基于HHT小电流接地故障选线与在线故障定位方法

小电流接地系统发生单相接地故障,系统仍可运行1~2小时,要求在不断电的情况下,实现故障选线,并对故障进行定位。提出一种基于HHT小电流接地故障选线与在线故障定位的方法,利用奇异性检测法判断各线路在故障时刻的极性,实现故障选线,在线路参数未知的情况下,采用合闸时产生的操作过电压行波在线测量行波波速,单相接地故障发生后,利用HHT寻找电压行波瞬时频率突变时刻,并运用单端测距法实现对架空线、电缆和电缆-架空线混合线路故障定位。最后,对算例进行数值仿真,仿真结果验证了该方法的可行性和实用性。

A Method of Fault Line Selection and Fault Location Online in Neutral Point Ineffectively Grounded Power System Based on HHT

Power cable for power transmission has been gradually extended. The outlet lines in distribution system therefore are more constituted with overhead lines, cables and hybrid lines. The system can be still running 1-2 hours when single phase to earth fault occurs, which requires the location of the fault is detected in the case of UPS. A method of power cable fault location online in neutral point ineffectively grounded power system based on HHT is proposed in this paper. Singularity detection method by which fault line selection can be achieved is used to determine the polar of each line at fault time. Under the condition that the parameters of lines are unknown, the velocity of traveling wave in cable can be measured by the use of switching overvoltage wave which is generated when the closing occurs. The modulus can be obtained by the method of phase-mode transformation when single phase to earth fault happens. HHT, which has a strong completeness and adaptability, is used to process the non-stationary modulus and find the mutations moments of instantaneous frequency. Then the location of line fault is determined by one-terminal fault location method. Finally, the digital simulation results of an example show the effectiveness and practicability of this method.