多个特高压直流系统送端共用接地极的内过电压研究

根据向家坝—南汇±800 kV直流输电工程的具体参数，利用电磁暂态仿真软件EMTP-RV对3个特高压直流输电系统送端采用共用接地极方案进行了详细的仿真研究；通过模拟直流系统不同运行方式下几种直流侧故障的暂态过程，深入分析了共用接地极方案对直流系统内过电压的影响。仿真结果表明，直流系统发生故障时，均未造成与其共用接地极的非故障系统各避雷器动作，非故障系统直流运行电压和电流均无明显扰动。采用共用接地极方案并未对直流系统的内过电压产生较大影响。

Research on Inner Overvolatage of Multi-UHVDC Systems With Sharing Earth Electrode at Sending End

Using the concrete parameters of UHVDC transmission project from Xiangjiaba to Nanhui and by use of electromagnetic transient calculation software EMTP-RV,the detailed simulation research on the scheme of sharing earth electrode by three UHVDC transmission systems at sending end is conducted.By means of simulating the transient processes of several faults occurred at DC side under various operating modes of UHVDC systems,the impact of the sharing earth electrode scheme on overvoltage within UHVDC systems are analyzed in detail.Simulation results show that when a UHVDC system is faulty,the lightning arresters in non-faulty UHVDC systems that sharing earth electrode with the faulty UHVDC system do not act,and there are not evident disturbances in the DC operating voltages and currents in non-faulty UHVDC systems,therefore,it is shown that the application of sharing earth electrode scheme does not make evident impact on the inner overvoltage in UHVDC systems.