一起主变高后备保护越级动作的分析及改造方案研究

Analysis and Modification of the Skip Operation Caused by High Backup Protection of Main Transformer

根据主变后备保护动作逻辑,当出线开关失灵不能隔离故障时,主变低后备保护应动作,跳开主变低压侧开关,避免事故进一步扩大。针对一起10 kV出线故障后主变高后备保护越级跳闸事件的原因进行分析与探讨。首先,根据该站的保护设置情况对此次故障的过程进行分析;其次,在此基础上进一步探讨事故越级跳闸的原因;最后,针对此次事故原因,在分析常规方法利弊的基础上提出一种不需改变现有接线方式和保护定值的方法。

According to the backup protection logic of the main transformer, when the outlet switch fails to isolate the faults, low backup protection of the main transformer will act, and the low-voltage side switch of the main transformer will be tripping off to avoid the further expansion of the accident. In this paper, the reasons for a 10 kV outlet fault touching off skip operation of high backup protection of the main transformer are analyzed. Firstly, according to the station's protection settings, the process of the fault is analyzed. Secondly, on the basis of this analysis, the reasons of the skip trip are further discussed. Finally, in view of the cause of the accident, a method that does not need to change the existing wiring mode and the protection setting values is proposed after analyzing the advantages and disadvantages of the conventional methods.