特高压直流接地极线路过电压研究

Study on Overvoltage of UHV DC Grounding Line

针对±800 kV宾金直流工程发生的＂7.13＂直流接地极线路烧毁故障,使用电力系统分析软件MATLAB Sim Power Systems建立电磁暂态仿真模型,对直流系统不同运行方式下高压侧接地引起的直流接地极线路内部过电压特征及分布进行了分析,量化了接地极线路内部过电压水平。分析表明特高压接地极线路内部过电压与接地极线路长度、直流系统运行方式、出线避雷器参数有关;宾金直流工程宜宾侧接地极线路最大内部过电压幅值为278 kV,金华侧接地线路最大内部过电压幅值为60 kV;宜宾侧接地极线路绝缘子并联间隙干弧距离设计为20 cm,在故障时刻绝缘配合失效是引起＂7.13＂故障的原因。

Taking the ＂7.13＂ fault of ± 800 kV Yibin-Jinhua DC project as an analysis object, we established a simulation model by using the power system analysis software MATLAB Sim Power Systems. The internal overvoltage characteristics and distribution of the grounding circuit of the UHVDC system were analyzed and the grounding line internal overvoltage level was quantitatively calculated. The analysis shows that the overvoltage inside the UHV grounding circuit depends on the grounding line length, system operation mode, and outgoing arrester parameters. The maximum internal overvoltage amplitude of grounding line is 278 kV on Yibin station side and 60 kV on Jinhua station side. The dry arc distance of grounding line shunt protective gap on Yibin station side was set to 20 cm, which causes failure of insulation coordination at ＂7.13＂ accident.