地磁扰动和接地极共同作用的浙西电网偏磁电流计算

Calculation of Bias Currents in Zhexi Power Grid Subjected to Combined Geomagnetic Disturbance and Ground Electrode

溪洛渡—浙西±800 kV直流输电工程试运行期间,浙西换流站受端电网的很多变压器出现了直流偏磁问题,其同时发生地磁扰动(GMD)的地磁感应电流(GIC)直流偏磁的安全风险需要研究。针对溪洛渡一浙西±800 kV直流输电工程的受端电网,建立了浙西电网和金华换流站的GIC计算模型,运用节点导纳矩阵法计算了浙西电网GIC;根据溪洛渡—浙西直流输电试运行期间-500 A接地极入地电流的测试数据,计算分析了GMD和接地极共同作用下浙西电网的偏磁电流水平。研究结果表明,目前浙西电网安装直流偏磁抑制装置的容量,不能满足消除GMD和接地极共同作用的需要,建议根据中科院和中国气象局空间天气事件的预报,避开有太阳剧烈活动的时间安排检修或调试,避免抑制装置发生过载的问题,保障浙西电网的安全。

During the operation of Xiluodu-Zhexi ±800 kV HVDC transmission project,serious DC bias problems occurred to many transformers in the receiving-end grid of Zhexi Converter station,so it is necessary to assess the DC bias risk when Geo-magnetically induced current（GIC） is driven simultaneously by a geomagnetic disturbance（GMD）.Based on the network structure of Xiluodu-Zhexi UHVDC receiving-end grid,we established the GIC calculation model of Zhexi power grid and Jinhua converter station,and calculated their GICs with node admittance method.Furthermore,with the measured value of-500 A earth-return current during the trial stage of XiluoduZhexi DC transmission project,we analyzed the bias current in Zhexi power grid subjected to the combined effect of GMD and ground electrode.The results show that the current capacity of DC bias blocking devices installed in Zhexi power grid is inadequate to deal with the combined effect of GMD and ground electrode.Therefore,in order lo avoid the overload of blocking devices and ensure the safety of Zhexi power grid,maintenance and commissioning of blocking devices should be carefully scheduled according to space weather forecast of the Chinese Academy of Sciences and China Meteorological Administration to dodge the time frame of intense solar activities.