零序电压互感器断线对11型微机保护动作行为的影响

尽管11型微机保护在电压输入回路健全的情况下，依靠电压互感器的二次电压就能实现保护的所有功能，但是外部零序电压接入回路的缺陷仍然会造成保护动作不正确，严重危害电力系统的安全运行。为此，对11型微机保护因外部零序电压接入回路缺陷造成拒动的故障实例进行了理论分析，并通过各种故障模拟试验，阐述了11型微机保护外部零序电压接入回路在各种情况下的运行原理。理论分析和模拟试验均表明，接入外部零序电压仍然是11型微机保护在电压互感器异常的情况下正确切除故障的有效手段。

Functional characteristics of 11-digital relay imposed by disconnection of zero sequential potential transformer

Even though 11-digital relay can implement all its functions with secondary voltage of potential transformer under the complete voltage input circuit,the deficiency of the external zero-sequence voltage can result in protective malfunctions,which impact the security of the power system operation.This paper discusses one failure to operate of 11-digital relay due to deficiency of the external zero-sequence voltage in functional theory.The further simulative tests explain the functional principles of the external zero-sequence voltage in 11-digital relay under various circumstances.The theoretical analysis and simulative tests manifest that the 11-digital relay can still function correctly with external zero-sequence voltage under the failure of the potential transformer.