水轮发电机负序电流引起转子过电压的分析与处理方法

Analysis and Treatment of Rotor Overvoltage Caused by Negative Sequence Current in Hydro-turbine Generators

大型发电机组在非全相运行时,可能产生较大的负序电流,引起转子过电压,严重威胁发电机的安全稳定运行。针对一起大型水轮发电机组试验过程中发生的转子过电压事件进行了详细分析,并对比发电机正常运行过程中主变高压侧单相接地故障时相关波形数据,阐述了发电机负序电流与转子电压升高的相关性,主变高压侧单相接地试验表明,在转子绕组上并联一个容量较大的电阻,可钳制试验过程中转子绕组产生的过电压,可供水轮发电机组相关试验及故障分析参考。

In case of non-full-phase operation,large scale generator units may generate significant negative sequence current,resulting in rotor overvoltage faults and posing serious threats to their safe and stable operation.A rotor overvoltage accident that occurred during the testing process of a large hydro-turbine generator unit is analyzed in detail.The relevant waveform data during a single-phase grounding fault on the high voltage side of the main transformer during the normal operation of the generator unit are compared.The correlation between the negative sequence current of the generator and the rotor voltage increase is demonstrated.The single-phase grounding test on the high voltage side of the main transformer shows that the overvoltage generated by the rotor windings during the test process can be suppressed by a large capacity resistor connected parallel on the rotor windings.The results provide useful reference for relevant tests and fault analysis of similar hydro-turbine generator units.