大型电机定子线棒防晕层电场的有限元研究

Finite Element Study of Electric Fields on Stator Bar Anti-corona Layer for Large Generator

大型电机定子线棒防晕层的电场计算,对优化防晕设计、提高线棒耐压水平意义重大。本文在分析传统方法基础上,提出了非线性防晕层电场计算的新型有限元方法,该方法不含空气域,大幅减小了建模尺寸,并提高求解效率和准确率。对不同额定电压下的防晕层表面电位、场强及损耗密度进行了计算,结果表明:随着电压升高,防晕层的表面电位、场强和损耗密度峰值分布均出现向防晕末端移动现象;转角内侧的损耗密度明显大于外侧,最大值一般出现在中低阻交界面的内侧棱角处。通过电老化试验和阻容链算法的验证,该有限元方法能够满足工程防晕设计精度,并可对三维电场进行定位分析,为存在表面电阻率的有限元电场计算提供了求解思路。

Electric fields calculation on stator bar anti-corona layer for large generator is important to the optimization design of anti-corona structure and increasing the level of the high voltage potential test of stator bar. In this paper, based on traditional methods, a new finite element method （FEM） for electric fields calculation of nonlinear anti-corona layer was bring forward, which does not contain the air domain, it greatly reduced the model size and improved the calculation efficiency and accuracy. The field strength and loss density of the anti-corona layer under different rated voltage were calculated, the results showed that as voltage increasing, the peak of the potential, field strength and loss density distributions moving to anti-corona end. The loss density inside corner was significantly greater than that the outside, the maximum value generally appears to the inside edges where is the interface between low resistance region and medium resistance region. Tested by electrical aging and RC-chain algorithm, this method could meet the anti-corona design accuracy of engineering, and location analysis for three-dimensional electric field, more over provide a solving idea for the finite element electric field computing which with surface resistivity.