The composite insulation system in a wind turbine generator (WTG) is subjected to either the AC or the repetitive pulse voltage, which may lead to degradation in the insulation. In this paper, the effects of voltage amplitude, waveform, repetition rate and composite insulating material constitution on the electrical tree morphology and development are studied. The results indicate that higher AC voltage produces sparser branches, shorter initiation time, and higher growth rates in the impregnating varnish and along interfaces. Electrical trees are initiated and grow easier under repetitive pulse voltage than AC voltage. Increasing repetition rate of pulse voltage promotes the initiation and propagation of electrical trees. It has been found that the peak of the pulse overshoot on the rising edge plays an important role in the initiation and propagation of electrical tree, while the average of pulse voltage dominates the breakdown time of the composite insulation system.

中文翻译：

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风力发电机复合绝缘中交流和重复脉冲电压下的电树特性

风力涡轮发电机 (WTG) 中的复合绝缘系统会受到交流电压或重复脉冲电压的影响，这可能会导致绝缘性能下降。本文研究了电压幅值、波形、重复频率和复合绝缘材料构成对电树形态和发展的影响。结果表明，较高的交流电压会在浸渍漆中和沿界面产生更稀疏的分支、更短的引发时间和更高的生长速率。电树在重复脉冲电压下比交流电压更容易启动和生长。增加脉冲电压的重复率促进了电树的萌生和传播。