大型水轮发电机定子单相接地故障的暂态仿真

TRANSIENT SIMULATION FOR THE STATOR GROUND FAULT OF LARGE-SIZED HYDRO-GENERATOR

根据水轮发电机定子和转子的绕组结构 ,在利用多回路理论计算定子和转子绕组电感参数的基础上 ,考虑定子绕组对地电容的分布性 ,建立了新的水轮发电机定子绕组单相接地故障暂态仿真模型 ,将定子绕组单相接地问题的研究统一在一个模型之中。文中以三峡发电机的一种设计方案为例 ,分析了定子绕组对地分布电容对模型的影响 ,讨论了单相接地过程中机端与中性点处零序电压及接地故障电流随故障位置和接地电阻的变化关系。该模型适合发电机定子绕组单相接地故障的全过程仿真 。

Considering the actual structure of stator and rotor windings, this paper presents a new transient simulation model for the stator ground faults of hydro-generator based on the calculation of the inductance parameters of windings by using the multi-loop theory. Taking a design for Three Gorges generators as an example, the paper analyzes the effects of distributed stator ground capacitance on the model. The relationship between zero-sequence voltage at the generator terminal and its neutral and the ground fault position and ground resistance are discussed, the characteristics of ground fault current as a function of ground fault position and ground resistance are also presented. The model can simulate the whole process of stator ground fault well. The simulation results will provide guidelines for the relay protection checking and new protection scheme development.