云电送粤特高压输电网络连锁故障分析

Analysis on Cascading Outages of Yunnan-Guangdong Ultra-high Voltage Transmission Grid

近年来世界范围内发生了不少由连锁故障引发的大规模停电事故,这已成为影响电力系统安全稳定运行的一个重要因素。为此,以2010年云电送粤特高压输电网络为例,分析了当其送端云南电网重负荷线路发生扰动时,与故障线路潮流方向相同的500kV线路和与其构成电磁环网的220kV线路的距离三段保护的动作情况。通过比较监测线路的计算阻抗值和距离三段保护定值,判断该线路保护动作情况,给出是否会发生连锁故障的结论。结果表明,两回500kV线路相继发生三相永久短路故障后,系统仍然能够保持暂态稳定,且不会导致其它线路后备保护动作。提出了预防云南电网连锁故障的建议,该研究的结论已应用于云南电网生产实践当中。

Many severe cases of black outs have taken place recently among different countries, which has the significant effect on safe and stable operation of power system. Taking Yunnan-Guangdong ultra-high voltage transmission system as example, power flow diversion of 500 kV lines with the same power flow direction and 220 kV lines formed electromagnetic loop network with fault lines are analyzed when faults occur on the Yunnan power system （sending end）. Action of distance three-segment protection is obtained by comparing calculated impedance and protection setting. The results indicate that the system is stable and cascading outage will not be aroused when threephase permanent fault occurs on double circuit 500kV lines, which provides the suggestion how to prevent the cascading outage of Yunnan power grid. The conclusion has been applied on the manufacture of Yunnan power grid.