直流输电换相失败对交流侧继电保护的影响

Analysis on Influence of HVDC Commutation Failure on AC Relay Protection

为验证换相失败期间交流侧突变量方向保护元件误动的原因,以广东电网发生的一起直流换流站换相失败引起高压交流电网继电保护不正确动作事件为例,用PSCAD/EMTDC软件做辅助分析,改进和仿真了CIGRE直流输电标准测试模型。仿真结果表明:因换相失败引起的非特征谐波与非周期分量较严重,对交流侧继电保护运行有一定影响,针对这些保护元件逻辑与算法分别提出了相应的改进措施。

The main reasons that cause the commutation failure are voltage decrease of commutation bus and commutating voltage zero-crossing phase shift during AC system fault. The interaction between AC system and DC system during the period of the fault will probably cause protection component incorrect action at the AC system side. The incorrect action of protection caused by commutation failure in DC converter station happened in Guangdong power grid is an example. Simulation and verification are carried out on the improved CIGRE Benchmark Model by PSCAD/EMTDC. The result verified the reason of incorrect action of AC protection during commutation failure. And meanwhile the result also shows non-characteristic harmonic and non-periodic component are serious resulted from commutation failure,which have some influence on AC relay protection. Some improved advices are given on algorithm of these protection components.