接地极偏磁治理对电网GIC的影响

Influence of DC Bias Suppression of Grounding Electrodes on Power Grid GIC

超/特高压直流工程建设用电容隔离装置治理电网的接地极直流偏磁,改变电网地磁感应电流（geomagnetically inducedcurrent,GIC）的自然分布,使地磁暴电网灾害的风险增加。针对哈密电网接地极直流偏磁治理,建立了计算新疆电网的GIC模型,采用1V/km地电场和MATLAB计算了电容隔离装置投入前后的电网GIC,分析比较了哈密电网偏磁治理对新疆750kV及哈密220kV电网GIC的影响。结果表明,采用电容隔离方法治理接地极的直流偏磁,会使包括换流站在内的一些站点的GIC量值增大,增大变压器GIC故障以及地磁暴电网灾害的风险。研究方法及结论对接地极偏磁治理与评估也同样有效。

Capacitor blocking device are used in UHV DC engineering construction to control DC bias of grounding electrodes of power grid, changing natural distribution of geomagnetically induced current（GIC） of the grid and causing increase of geomagnetic storm risk. For DC bias suppression of grounding electrodes of Hami power grid, a GIC model for Xinjiang grid is established, and 1 V/km electric field and MATLAB programming are used to calculate grid GIC before and after capacitor blocking device putting into operation. Effect of DC bias suppression in Hami grid of Xinjiang 750 kV grid and Hami 220 kV grid was analyzed and compared. Results showed that the method using capacitor blocking devices to control DC bias current of grounding electrodes would cause GIC increase in some stations, including converter station, possibly leading to GIC fault of substation and increasing risk of geomagnetic storm disaster of power grid. The research method and conclusions are equally effective to DC bias suppression and evaluation of grounding electrodes.