小型水电站铁磁谐振案例分析及控制措施

Case Analysis and Control Measures of Ferromagnetic Resonance in Small Hydropower Stations

结合某小型水电站发电机保护改造完成,进行同期并网试验时,发生3U0定子接地保护动作,跳出口断路器及停机这一案例对铁磁谐振发生的原因进行分析表明,在设备选型改造、回路设计时应采用技术性能和工艺质量更好的电压互感器,其铁芯在系统扰动时不容易发生饱和从而避免发生铁磁谐振;对存在铁磁谐振现象的电站,应根据实际情况选取变更运行方式、采用“4PT接线法”、装设消谐电阻等方式也可以有效消除谐振现象。

During the synchronous grid connection test of a small hydropower station after the renovation of the generator protection,3U0 stator grounding protection action occurred,resulting in the tripping of the outlet circuit breaker and the unit shutdown.Analysis of the causes of the ferromagnetic resonance fault shows that voltage transformers with better technical performance and manufacturing quality should be used in the equipment selection and renovation and the circuit design.The iron cores are less prone to saturation in case of disturbance,thus avoiding the ferromagnetic resonance.For hydropower stations with the ferromagnetic resonance phenomena,engineering measures can be adopted to effectively eliminate the resonance,including changing the operation mode,adopting the 4PT wiring method,and installing the resonance elimination resistors.