Hu Qi, Li Qingmin, Liu Zhipeng, Xue Naifan, Ren Hanwen, Haddad Manu
State key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China.
Advanced HV Engineering Research Centre, Cardiff University, Cardiff CF24 3AA, UK.
Polymers (Basel). 2022 Mar 28;14(7):1374. doi: 10.3390/polym14071374.
Metal contaminants can distort the surface electric field of the tri-post epoxy insulator and cause serious surface charge accumulation, significantly reducing the insulation performance of the insulator under the superimposed DC and lightning impulse voltage. In this paper, an experimental platform for charge accumulation and surface flashover of tri-post epoxy insulators under the superimposed DC and lightning impulse voltage was built, by surface point measurement and charge inversion calculation, the surface charge distribution characteristics of tri-post insulators with attached particles was experimentally explored and the influence law of attached metal particles on the charge accumulation was discussed. The results show that metal particles can cause a surge in the surface charge density of the tri-post epoxy insulator, forming bipolar charge spots whose polarity is opposite to that of the adjacent electrodes. The adsorbed metal dust can cause the polarity reversal of adjacent surface charges, forming a large-area unipolar charge spot. Moreover, the flashover voltage of a tri-post insulator under DC superimposed lightning impulse voltage with a clean surface and attached metal particle was measured, and the synergistic induction mechanism of charge spot accumulation and metal particle discharge on the flashover along the face of the tri-post insulator is thereby revealed. Compared with the clean insulators, the surface flashover voltages of tri-post epoxy insulators with metal contaminants adhered decrease under the superimposed voltages of different polarities, but the decline amplitude is greater under the heteropolar composite voltage. When adhered to the middle of the insulator leg, the distribution range of bipolar charge spots is the widest, and the surface flashover voltage decreases sharply, which can drop by 32% compared with the absence of particles. In addition, when the metal dust adsorbed by the tri-post epoxy insulator has a wide distribution range, the impact of metal dust on the flashover voltage is greater than that of the attached metal particles, and its hazard cannot be ignored. The research results can provide a reference for the insulation test method and optimal design of the DC tri-post epoxy insulator.
金属污染物会扭曲三柱式环氧绝缘子的表面电场，导致严重的表面电荷积聚，显著降低绝缘子在叠加直流和雷电冲击电压下的绝缘性能。本文搭建了三柱式环氧绝缘子在叠加直流和雷电冲击电压下的电荷积聚及表面闪络实验平台，通过表面点测量和电荷反演计算，实验探究了附着颗粒的三柱式绝缘子的表面电荷分布特性，并讨论了附着金属颗粒对电荷积聚的影响规律。结果表明，金属颗粒会导致三柱式环氧绝缘子表面电荷密度激增，形成极性与相邻电极相反的双极性电荷斑。吸附的金属粉尘会导致相邻表面电荷极性反转，形成大面积的单极性电荷斑。此外，测量了清洁表面和附着金属颗粒的三柱式绝缘子在直流叠加雷电冲击电压下的闪络电压，从而揭示了电荷斑积聚和金属颗粒放电对三柱式绝缘子沿面闪络的协同诱导机制。与清洁绝缘子相比，附着金属污染物的三柱式环氧绝缘子在不同极性叠加电压下的表面闪络电压均降低，但在异极性复合电压下下降幅度更大。当附着在绝缘子支柱中部时，双极性电荷斑的分布范围最宽，表面闪络电压急剧下降，与无颗粒时相比可下降32%。此外，当三柱式环氧绝缘子吸附的金属粉尘分布范围较宽时，金属粉尘对闪络电压的影响大于附着金属颗粒，其危害不可忽视。研究结果可为直流三柱式环氧绝缘子的绝缘试验方法及优化设计提供参考。
