现行保护机制对10kV无内熔丝电容器组早期故障预警策略的影响

Effect of Current Protection Mechanism on Early Fault Warning Strategy of 10 kV Capacitor Bank Without Inner Fuses

针对近年来国内电容器组在线监测装置罕有成功预警案例的现象,通过分析10 kV无内熔丝电容器组的外熔断器和继电保护协同机制,指出尽管理论条件下,通过监测电容器内部单个元件击穿时的电气量突变情况能够实现预警功能,但在工程实践中,由于保护的实际整定值远低于理论值,单台电容器内部击穿1个元件通常即可触发继电保护动作,各类基于突变量的预警方法将丧失时间裕度,需适当调高保护定值、允许电容器组短期带病运行,方能发挥其预警功效。

In view of the rare successful early warning cases of online monitoring devices for domestic capacitor banks in recent years,it is pointed out by analyzing the cooperative mechanism of external fuse and relay protection of 10 kV capacitor bank without inner fusesthat the early warning function can be achieved by monitoring the sudden change of electrical quantity at breakdown of single element of capacitor at theoretical condition,yet in engineering practice,since the actual setting value of protection is much lower than the theoretical value,the breakdown of a single element in capacitor can usually trigger the relay protection.Various kinds of early warning methods based on mutation will lose time margin.It is necessary to adjust the protection setting value appropriately and allow the capacitor bank to run with illness for a short termin order to play warning effect of online monitoring devices.