换流站接地网替代直流接地极运行的方案研究

Application Analysis on Converter Station Grounding Grid as DC Grounding Electrode

直流输电无接地极运行有助于尽早实现双极送电,换流站接地网替代直流接地极是目前最有效的措施。换流站接地网替代直流接地极情况下可能存在人身和二次设备安全问题、变压器直流偏磁危害、接地网发热和腐蚀问题。论文对这些问题进行逐一分析,最后综合各影响因素提出了直流输电控制策略的要求,即单极故障联跳双极、不平衡电流控制和双极同步解闭锁。研究工作为直流输电新型的无接地极运行方式提供了有效参考,相关控制策略在南方电网普侨特高压直流输电工程中得到了良好的应用。

HVDC without grounding electrode is helpful to achieve bipolar transmission as soon as possible, replacing DC grounding electrode with converter station grounding grid is the most effective measure so far. However, there may be personal and secondary equipment safety problem, transformer DC biasing, heating problem and corrosion problem of the grounding grid. This paper analyses these problems one by one, and puts forward the requirements of DC transmission control strategy, namely,unipolar failure coupling bipolar, unbalanced current control, bipolar synchronization lock and unlock. This paper provides effective reference for HVDC without grounding electrode operation mode, the related control strategies are applied in the Puqiao UHVDC transmission engineering of Chinese southern power grid.