电力系统发生震荡时，不会误动的保护有（   ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69377' and id < 4491409 and id<>'4491409' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69377' and id > 4491409 and id<>'4491409' order by id asc limit 5