直流高压下GIS支柱绝缘子表面电荷积聚特性

Charge Accumulation on Post Insulator Surface Under HVDC in GIS

支柱绝缘子表面的电荷积聚问题是影响直流气体绝缘设备安全运行的重要因素。为了获取直流高压下GIS支柱绝缘子表面电荷的积聚特性,采用静电探头法对直流电压作用一段时间后的两种不同形状绝缘子进行了表面电位的测量,并基于测得的表面电位利用Comsol仿真软件进行了表面电荷的反演计算,得到了绝缘子在不同加压时间、幅值、极性的直流高压下的表面电荷分布特性,结合现存的3种表面电荷积聚机理对实验结果进行了初步的探讨和分析。研究表明:加压时间、幅值的增长会促进绝缘子表面电荷的积聚,电压极性的改变会影响绝缘子表面电荷的分布,绝缘子表面的法向场强分量是绝缘子表面电荷积聚的根本原因,自由电荷通过气体侧传导的方式是绝缘子表面电荷积聚的主要途径,表面传导对电荷积聚也能起到一定的作用。

The accumulation of surface charges along the supporting insulators is one of the key factors which greatly threaten the insulation level of the DC gas insulated equipment. In order to get the charge accumulation characteristics on insulator surface under HVDC, the surface potentials of two types of insulators are measured using an electrostatic probe after applying DC voltage to the insulators. The distribution of surface charge can be gotten by complicating inverse cal- culations based on surface potential measurement using the Comsol simulation software. The surface charge distributions under different time duration of the applied voltage, voltage amplitudes and polarities are calculated. Based on the results, three kinds of accumulation models were evaluated. The experimental results show that the charge density increases with the increase of the amplitude and time duration of the applied voltage, and surface charge distribution is closely related with the polarity of the applied voltage, normal-field strength on the surface of insulator is the essential factor for the deposition of surface charges, charge transport in the gas space is the dominant mechanism for charge accumulation, and surface conduction has little effect on the charge accumulation.