局部放电条件下干式空心电抗器匝间绝缘的电老化特性研究

The Research on Electrical Aging Characteristics of Turn-to-Turn Insulation of Dry-Type Air Core Reactor under Partial Discharge

为研究干式空心电抗器匝间绝缘的电老化规律,进行了干式空心电抗器匝间绝缘模型试样的起始局部放电电压及击穿试验。采用恒定电压法及阶梯电压法进行了局部放电发生后干式空心电抗器匝间绝缘的电老化寿命试验,求得两种老化方式下的电老化反幂寿命方程。分析并试验验证了两个寿命方程存在差别的原因,并修正了局部放电发生后恒定电压下干式空心电抗器匝间绝缘模型试样的电老化反幂寿命方程。研究结果表明:发生局部放电时,干式空心电抗器匝间绝缘的电老化规律不符合反幂寿命模型,耐压寿命指数N及常数C随着试验电压的升高而增大;各种过电压下可能出现的局部放电对干式空心电抗器匝间绝缘材料的危害很大,可以通过改进制造工艺提高起始局部放电电压、选用耐局部放电能力强的绝缘材料作为匝间绝缘或者加装过电压抑制装置限制过电压幅值等方法延长干式空心电抗器匝间绝缘的使用寿命。

The electric aging rule was studied for turn-to-turn insulation of dry-type air core reactor,and partial discharge inception voltage tests and breakdown tests were performed for the model specimen of turn-to-turn insulation of dry-type air core reactor.The electrical aging life test was carried out by constant voltage method and step voltage method when partial discharges occurred in the turn-to-turn insulation of dry-type air core reactor,and the inverse power models of electrical aging life were obtained in two aging ways.The reasons for the difference of the two life equations were analyzed and verified by experiments.The inverse power life equation under constant voltage was corrected for the model of turn-to-turn insulation of dry-type air core reactor after partial discharges happened.From the results,that electric aging rule does not follow the inverse power life model when partial discharges take place in the turn-to-turn insulation of dry-type air core reactor,and the withstand voltage index N and the constant C increase with the increase of the test voltage;Partial discharge may occur under various overvoltages,which is very harmful to inter turn insulation material of dry-type air core reactor.By improving the manufacturing process to improve partial discharge inception voltage,the material with strong resistance to partial discharge used as turn insulation or installing over voltage suppression device to limit the amplitude of over voltage,these methods can prolong the service life of turn-to-turn insulation for dry-type air core reactors.