发电机单元件横差保护误动分析及对策

单元件横差保护是一种简单灵敏的反应匝间短路等发电机定子绕组内部故障的主保护。分析了发电机单元件横差保护的基本原理,阐述了二滩水电厂大型水轮发电机单元件横差保护的具体配置。描述了一起由于发电机失磁引起的单元件横差保护误动事件,结合保护动作时和后期试验时的故障录波数据,对保护的动作行为进行了详细分析。根据分析结果给出了合理的改进措施:在不改变保护配置的情况下对整定值进行修改;结合发电机保护装置改造对保护原理进行改进。现场试验和机组运行实践证明了改进措施的可行性和有效性。

Misoperation Analysis and Countermeasures for Unit-transverse Differential Protections of Generators

The unit-transverse differential protection(UTDP) is a simple and sensitive main protection responding to inter-turn short circuit and other internal faults of generator stator winding.The operation principle of UTDP is analyzed,and the specific configurations of UTDP of generator at Ertan Hydropower Plant are presented.A misoperation case of UTDP caused by field loss fault of a generator is described.According to recorded data of the protection misoperation and the following test,the protection operation action is analyzed in details.Reasonable improvement measure based on the analysis results is given,such as modifying the setting without change of present protection configuration and reforming the protection principle combined with the technical innovation of generator protection device.Field test and generator operation proves the feasibility and validity of the improvement measure.