介绍了大型汽轮发电机100%定子接地动作保护基本原理和适用范围，阐述了双频式100%定子接地保护动作区域和保护判据。针对电厂#2机运行中出现的100%定子接地保护信号告警问题，结合发电机100%定子接地保护原理和故障处理原则，分析了可能引起三次谐波电压比值远远超过整定值的故障原因，并根据现场继电保护设备动作特性和测量数据，做出准确判断。经现地检查及故障处理后，#2机中性点接地变压器二次引线锈蚀松动故障得到成功处理。% Introduction was made to the basic principle and the range of applicability of huge turbine-generator’s 100% stator ground fault protection action. This paper expounded on action region and protection criterion of dual-frequency 100% stator ground fault protection. Aim-ing at the issue of signals reporting an emergency of 100% stator ground fault protection during the number two turbine-generator operation in electric power plant, and combining with the action principle and fault handling of 100% stator ground fault protection, this paper analyzed the fault cause which possibly resulted in the triple frequency harmonic voltage ratio well over setting values, and made an accurate judg-ment, eliminating the fault location according to the operating characteristics and measurement data of on-site relay protection equipment. After on-site inspection and fault handling, the second lead corrosion looseness fault of the number two turbine-generator neutral grounding transformer is processed successfully.
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