±800 kV泰州换流站接地极入地电流对交流电网的直流偏磁影响

DC Bias Influence of ±800 kV Taizhou Earth Electrode Grounding Current on AC Power Grid

针对换流站直流接地极入地电流对交流电网的直流偏磁影响问题,以±800 kV泰州换流站接地极为例,分析了接地极直流电流对交流电网影响机理,对泰州换流站接地极土壤电阻率进行了实测,对电阻率实测结果进行了分层反演,并在此基础上建模仿真研究了锡盟—泰州±800 kV特高压直流输电工程受端换流站接地极对受端电网的直流偏磁影响。通过分析比较换流站试运行期间变电站偏磁情况,验证了建模分析的准确性和有效性,并得到部分站点变压器将存在严重的直流偏磁风险的结论,最后对偏磁电流超标站点进行了隔直治理,从而提升了电网整体安全稳定运行水平。

Aiming at the influence of DC earth electrode grounding current of converter station on DC bias of AC power grid, the influence mechanism of earth electrode DC current on AC power grid is analyzed with the grounding example of ±800 kV Taizhou converter station. The earth resistivity of the earth electrode of Taizhou converter station was measured, and the measured resistivity results were layered inversion. Based on this, the DC bias effect of the earth electrode of the receiving converter station on the receiving grid of Ximeng-Taizhou ±800 kV UHVDC transmission project was studied by modeling and simulation. The accuracy and effectiveness of the modeling analysis are verified by analyzing and comparing the transformer bias during the trial operation of converter stations, and the conclusion that some station transformers have serious DC bias risks is obtained. In the end, the site with over-standard bias current is directly isolated, thus improving the overall safe and stable operation level of the power grid.