Bus protection and breaker failure protection of old substations can't meet the configuration requirements. A new microprocessor-based protection which contains bus protection and breaker failure protection is proposed to solve the problem. Two retrofit options are discussed: ( 1 ) cancel the original breaker protection of each interval, and start failure protection directly by contacts of line protection; ( 2 ) retain the original circuit breaker protection of each interval, and start failure protection by contacts of breaker protection. By comparing with each other in such aspects as characteristics, scope of application, etc, the second option with the minimum reformation scope is chosen. And for this option, a method to calculate the current setting is put forward, which means that failure current settings of breaker protection and failure protection have the same value. This program has been applied to a 500 kV substation of Tianjin Electric Power Corporation with good running status and no malfunction.%为解决旧变电站母线保护与失灵保护不满足配置要求的问题,提出新上一套两者合一的微机型保护装置.论述了两种可行的改造方案:(1)取消各间隔原断路器保护,由线路保护动作触点直接启动失灵;(2)保留各间隔原断路器保护,利用断路器保护的触点启动失灵.通过比较两方案的优缺点和适用范围,选择了改造涉及范围小的方案二.针对方案二,提出一种失灵电流定值的整定方法,即应将断路器保护和失灵保护的失灵电流定值整定相同.此方案已在天津市电力公司某500 kV变电站投入使用,运行情况良好,未发生误动.
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