电力主设备继电保护存在的问题及对策

Problems of protections for main equipment and countermeasures

理论分析及运行实践表明,电力主设备使用的某些保护,在其构成原理、交流接入回路以及构成逻辑方面存在一些问题,影响了电力主设备的安全经济运行。着重阐述了变压器纵差保护、变压器分侧差动保护、发电机复合电压闭锁过流保护、零序电压式定子接地保护以及频率异常保护存在的问题,并针对这些问题提出了以下对策:变压器纵差保护应采用同步识别及动作状态记忆来保证差动速断的动作可靠性;变压器分侧差动保护应采用涌流闭锁环节;复合电压闭锁过流保护的过电流元件应设置高低2个定值;零序电压式定子接地保护应同时反应机端及中性点两路零序电压;发电机上不宜设置频率异常保护。

Theoretical analysis and operational practices show that,there are defects in the principle,AC input circuits or logic of some protections for main equipment,which endanger its safe and economical operation.The problems existing in the transformer differential protection,transformer split-side differential protection,compound voltage blocking overcurrent protection,stator grounding protection and frequency protection are discussed and the countermeasures are suggested：sync identification and operating state memory should be applied to ensure the instantaneous trip of transformer differential protection;inrush current blocking should be adopted in transformer split-side differential protection;two overcurrent thresholds should be set in compound voltage blocking overcurrent protection;zero sequence voltage of both terminal and neutral point should be reflected in stator grounding protection;and frequency protection is not suitable for generator.