直流滤波器高压电容器不平衡保护分析

Analysis of the Imbalance Protection of DC Filter's High Voltage Capacitors

RCS-976D数字式直流滤波器保护装置,是高压直流滤波器保护的一种常规配置。解读了RCS-976D保护装置技术规范中有关直流滤波器高压电容器不平衡保护的原理,介绍了暂态和稳态不平衡保护动作的特征和实现逻辑框图,结合上海南桥换流站在主变空充(空载充电)试验时,发生直流滤波器BD23的第一套和第二套保护装置的不平衡Ⅲ段同时动作,导致直流滤波器开关跳闸的案例,进行深度排查隐患分析。分析认为:主变充电时如果不平衡电流过大,会引发保护装置动作。针对这一事件,提出了主变充电时的相应技术措施和防范建议。

The RCS-976D digital DC Filter protection device is a conventional configuration for the high voltage DC filter relay protection. This article illustrates the principle of the imbalance protection of the high voltage capacitors in the frame of the technical specification of the RCS-976D protection system, and introduces the features and the logic framework of the transient and steady imbalance protection. The deep investigation and analysis is carried out combining with the case that the DC filter tripped off resulting from the simultaneous operation of the third zone of the imbalance protection equipment of the first and the second set of the DC Filter BD23 when the experiment of the no-load transformer was being charged in Nanqiao converter substation. The analysis shows that if the transformer is being charged, the unbalanced current will be too large to trigger the action of the protection equipment. According to this issue, the relevant technical measures and precautious advice are given in this article.