500KV母线防护1.25.ppt

每段母线有两套母差保护； 分别作用于不同的跳闸线圈Y1，Y2 直流电源亦不同 失灵保护与其中一套母差保护共出口 对于母线保护最关键的是当保护区外故障时不误动，因为，母线故障的几率较小，多数是区外元件故障，此时即使在TA严重饱和下也不应误动。但是一旦母线故障涉及面大，必须准确判断故障并跳闸。 其实，500KV母线与220母线保护相比要简单一些 500母线一般3/2接线，220接线一般双母线 1、500母线无倒闸操作，无需运行方式识别 2、无充电保护 3、无互联状态 4、 Bus interconnection unit 母线集中连接元件 Bus CT disconnection unit 母线CT分散元件 Transformer unit Bay 1-4 电流互感器元件1-4间隔 Breaker failure relay Bay 1-9, BC 断路器失灵保护单元 Bay 1-9 间隔1-9（最大可达9串） Trip unit 跳闸元件 Bus coupler CT’s 母线CT 耦合器？ Terminal rack 端子排 综合变比 n = k / nTA k为辅助变流器的变比 nTA为电流互感器的变比 综合变比 n = k / nTA k为辅助变流器的变比 nTA为电流互感器的变比 TAm因流过1~（m-1）条支路的短路电流而饱和，TAm和 Tm的二次电流均为0 RD11很大---高阻抗 RD11较大---中阻抗 分析表明 系统故障后约5ms后，TA饱和 如有源支路的TA饱和，则情况如外部故障 保护将拒动。 但是，该保护在5ms内可以动作完成 启动元件KSR、差动元件KDR 都可以在1~3ms内动作， 制动回路和差动回路的时间常数小 故继电器可以在5ms内可靠动作。 Before and during operation of dR Before operation of SR The current that runs in the curcuit enables the differential relay to measure correctly. During this sequence the TMZ has a resistance of 70 kohms. From measuring point of view TMZ has no function. The current in the differential circuit measured by dR passes mainly resistance Rd11. After operation of dR During and after operation of SR At this sequence the electrical parameters are concentrated to its function as to activate SR and not to affect the data measured by other relays in the same CT-circuit. As the REB 103 detects a fault before the saturation of any current transformer, the dynamic sequence afterwords is of very little interest for the bus differential relay. What is important, however, is the influence the differential relay at the time of saturation has on other relays connected to the same current transformer circuit. With the present design this influence is extremely limited. From this it could be seen that the differential relay switches from a burden of 3 kohms down to 12 ohms when the saturation reactor TMZ has entered into saturation. 继电器的斜