700MW水电机组定子铁芯压紧螺杆接地故障分析

Grounding fault analysis on compression screw of stator core of 700MW hydro-generators

对穿芯结构的铁芯压紧螺杆短路情况展开了分析,根据分析结果,提出了螺杆短路适宜的处理方案。在分析中,选取最恶劣的接地故障情况对短路电流及其引起的温升进行计算,从而得到了螺杆温升与螺杆长度的对应关系。计算结果表明:短路会导致螺杆的温度升高,且该温升会随着短路点之间距离的增加而增加,当首位两端发生短路故障时,短路电流和损耗会达到最大,螺杆的温度达到374. 5°。在实际运行中,一旦发生该类故障,可通过对空载和负载条件下螺杆的电压进行对比分析,判断出发生接地故障的螺杆,并对其进行清扫,从而消除故障。

This paper analyzes the short circuit fault of the core compression screw of piercing structure,and put forward the treatment plan according to the analysis result.Aiming at the most unfavorable grounding fault condition,the short-circuit current and the temperature rise are calculated and the corresponding relationship between screw temperature rise and screw length is obtained.Result shows the short circuit will cause the screw temperature rise and the temperature rise increases with the distance between the short-circuit points.If the short-circuit fault occurs at the two ends,the short-circuit current and loss will reach the maximum with the temperature of the screw up to 374.5℃.In the case of occurrence of the fault,the fault grounding screw can be judged by comparing the screw voltage under light load and load cases,and the fault can be eliminated through cleaning the screw.