多直流外送电网直流偏磁影响及治理研究

Influence of DC Bias in Sending-end Gird with Multi-HVDC and its Countermeasures

针对宁夏地区已投运和即将投运的直流输电工程产生的直流偏磁风险,进行了宁夏电网直流偏磁研究。通过综合分析宁夏地区2020年电网结构及土壤结构,建立了直流偏磁仿真模型。根据银川东-山东、灵州-绍兴、上海庙-临沂3个直流输电工程不同运行状况,对宁夏电网220 kV以上厂站进行直流偏磁仿真分析。仿真结果表明,在直流输电工程单极大地情况下,有多个变电站/电厂的主变压器存在直流偏磁风险,尤其在2个工程单极大地运行情况下直流偏磁更为严重。结合灵绍特高压直流工程调试,对采用该模型当年电网结构的仿真结果进行实测验证,采用电容型隔直装置对部分变电站进行了直流偏磁治理工作,取得了良好的效果。

According to DC bias existed in HVDC projects in service and will be in service in Ningxia,the paper makes a study on the DC bias in Ningxia power grid.Firstly,a simulation model of the DC bias is established by analyzing the power grid and soil structure in Ningxia in 2020.Then the simulation analysis of 220 kV above stations in Ningxia power grid is done based on the different operation conditions of Yinchuandong-Shandong,Lingzhou-Shaoxing and Shanghaimiao-Linyi HVDC projects.The results show that there is the DC bias hazard problem in the main transformers for several stations when HVDC works in monopole to ground operation,especially when 2 HVDC projects are in monopole to ground operation.When Lingzhou-Shaoxing HVDC project is in commissioning,the DC bias test is conducted,and applying blocking capacitor to restrain the DC bias in several stations is implemented with good results.