拉西瓦水电站机组注入式定子接地保护的研究与应用

Study and Application of Injected Stator Ground Protection in Laxiwa Hydropower Station

随着发电机组台数不断增多和单机容量的迅速增大,电力系统从安全稳定的客观要求出发,对大型发电机组的继电保护提出了更高的要求。由于拉西瓦水电站机组定子电容增大,使得常规双频零序电压式定子接地保护不能满足要求。在分析常规外加电源注入式定子接地保护及其在实际应用中的不足的基础上,提出了基于平衡原理的一套完整的微机发电机定子接地保护方案。保护方案中考虑了外加电源故障、PT断线、系统中的谐波等因素对保护的影响,能够可靠地进行发电机定子接地故障的判别。

From the point of power grid operation security and stability, the requirements on relay protection of large- scale generator are higher. As the larger stator capacitance of Laxiwa generator, the conventional two-frequency zero- sequence voltage stator ground protection can not meet the requirements. After analysing conventional injected stator ground protection with external power supply, a new injected stator ground protection with external power supply based on equilibrium principle is proposed. The influences of external power supply faults, 1~ break and system harmonic on new protection program are studied, and the result shows that the new program can detect stator grounding effectively and reliably.