海洋核动力平台发电机定子绕组单相接地故障风险分析与实时定位

Risk analysis and real-time locating of single-phase grounding fault of generator stator winding for offshore nuclear power plant

海洋核动力平台发电机不同运行工况下直连线路对地电容的变化将影响接地故障电流,基于发电机3次谐波电压特征,提出一种无需外加设备的直连线路对地电容实时求解方法。利用故障分量原理在计及基波和3次谐波情况下求解接地故障电流,并依据实时故障风险自适应决定保护出口方式。为缩短故障检修排查时间,构建故障绕组电势与故障相电势满足的几何关系式及其与零序电压满足的幅值相位方程,通过解析计算准确定位故障点与中性点间线圈占完整分支的匝数比,实现接地故障定位。PSCAD/EMTDC仿真分析表明,所提方法具有较高的准确性。

The grounding fault current is affected by the change of grounding capacitance of the directly connected lines under different generator operating conditions of the offshore nuclear power plant.Based on the characteristics of the third-order harmonic voltage of the generator,a real-time calculating method of grounding capacitance without external equipment is proposed.The grounding fault current is solved considering the fundamental and third-order harmonic waves through the principle of fault component.Thus the protection outlet mode is adaptively determined according to the real-time fault risk.To shorten the maintenance time,the geometric relationship satisfied by the fault windings’ electromotive force and the fault phase electromotive force,and the amplitude-phase equations satisfied by the fault windings’ electromotive force and the zero-sequence voltage are constructed.The turns ratio of the coil between the fault point and the neutral point in the whole branch can be accurately determined by analytical calculation,and the fault locating is realized.Simulation analysis of PSCAD/EMTDC shows that the proposed method has high accuracy.