高压直流输电极隔离方法的优化及相关问题分析

直流输电中单纯的优先分断直流高压极母线线路端隔离开关,或者优先分断中性母线开关方法,均不能适应所有的电网故障情况,甚至可能造成无谓的双极停运。针对这个问题,提出了如下的优化的极隔离方法：对需要快速分断中性母线开关隔离故障区域的故障,应用优先快速分断中性母线开关方法;对其他类型故障,则优先分断高压极母线线路端隔离开关。此外,分析了极隔离优先分断中性母线开关可能带来的问题：一是中性母线开关失灵,对此讨论了中性母线开关保护动作后的三种处理策略;二是中性母线电压过高,分析显示,59EL保护原理及其动作处理策略的设计可以避免双极停运。

The Optimization of HVDC PoleIsolating Methods and Analysis on the Related Problems

There are two kinds of pole isolating method in HVDC transmission: to break the HV pole bus switch at the line side in priority, or to break the neutral bus switch (NBS) in priority. It is impossible to simply adopt one of them dealing with all kinds of power network's fault, sometimes even leading to unnecessary bipolar out of operation. Aiming at the issue, this paper proposes an optimized pole isolating method as follows: For the faults to be treated in a way to quickly isolate the fault area with the neutral bus switch, the method of breaking the neutral bus switch (NBS) in priority is adopted, while for the other faults the method of breaking the HV pole bus switch at the line side in priority is adopted. In addition, this paper analyzes two problems that may occur in breaking NBS: the neutral bus switch failure and the neutral bus overvoltage too much higher. For the former, three kinds of fault clearing actions (FCA) of the NBS protection are discussed; and for the latter, the analysis indicates that bipolar out of operation can be avoided with 59EL protection principle and FCA design.