交流1000kV特高压线路三相故障暂态过程分析

摘要

The transient current and voltage of UHV AC transmission lines under three-phase fault are theoretically analyzed and simulated. There are HF(High Frequency) components and decaying DC components in fault current,while there are only HF components in fault voltage. The initial value of fault HF component is related to fault POW(Point On Wave) and it is the highest when POW is 90°. The frequency of HF component is related to fault location and system operating mode. The smaller the system short circuit capacity is and the farther the fault location is,the closer the harmonic frequency will be to the fundamental one. The farther the fault location is,the larger the HF component will be. The HF harmonics of fault voltage are more serious than those of fault current under the same fault condition. Shunt reactors can reduce the steady capacitive current but have unobvious effect on fault transient current.%通过理论分析和仿真验证得到特高压线路三相故障后相关暂态电气量的特点:特高压线路故障电流中除有一很大的衰减直流分量外还存在高频分量:故障电压中也含有较大的高频分量但没有直流分量;故障高频分量的初始值与短路角(以电压角为基准)有关.当故障角为90°时.高频分量的初始值最大:高频谐波的频率与故障距离和系统运行方式有关.系统方式越小,故障距离越大,高频谐波频率越接近于工频;故障距离越远.电流、电压中的谐波含量对基波分量的影响越大;相同的故障条件下,故障电压中的高次谐波要比故障电流更加严重:并联电抗器可以降低线路的稳态电容电流,但对故障暂态电容电流的作用不明显.