俄罗斯800MW机组定子接地后备保护分析

ANALYSIS OF STATOR BACKUP RESERVE PROTECTION FOR RUSSIA 800 MW GENERATOR UNITS

绥中发电厂引进俄罗斯 80 0MW发电机组 ,定子接地后备保护装置主要由基波零序电压保护和 3次谐波电压保护组成。 3次谐波组件以发电机出线端 3次谐波电压uS3 对时间的导数duS3 /dt >0为启动条件 ,以发电机定子接地故障后与故障前的 3次谐波电压比uS3 ′/uS3 >1 2 5作为测量机构动作判据 ,保护延时动作于停机。通过分析表明 ,该装置的 3次谐波组件保护发电机靠中性点侧 0～ 4 0 %的定子接地故障 ,原理简单、新颖 ,不受一次设备接线方式的限制 ,性能也较好 ,适合作为大型发电机定子接地后备保护 ,也可为只配备零序电压保护的发电机增设

The stator ground protection set of Suizhong Power Plant 800 MW generator units supplied by Russia is mainly composed of fundamental frequency zero-sequence voltage protection and third-harmonic voltage protection. The starting condition of third-harmonic component protection is based on the decision of du S3/dt>0 (u S3 is the third-harmonic voltage at the outgoing terminal of generator), and its measuring unit will act on the basis of u S3′/u S3>1.25(Here, u S3′ is the generator stator ground voltage after the fault; u S3 is the generator stator ground voltage before the fault). The protective relaying will trip after a time delay. Based on the analysis, the paper proves that: the third-harmonic component protects the stator ground faults near neutral point 0～40%. The principle is simple and novel and its performance is good. It is not limited to the connection way of primary device, so it is suitable for large generator stator ground backup protection, and it can be used as an additional function for the generator only with the zero-sequence voltage protection.