影响GIS支柱绝缘子闪络电压的沿面电场特征参数

Characteristic Parameters of Electric Field Along the Surface Affecting the Flashover Voltage of GIS Pillar Insulators

优化绝缘子沿面电场分布能够有效提高绝缘子的闪络电压,但决定绝缘子闪络电压的电场分布特征尚不明确。为进一步研究影响绝缘子闪络电压的沿面电场分布特征,通过调节绝缘子沿面形状、内嵌电极、外屏蔽电极的几何参数得到具有不同沿面电场分布的48种等高环氧支柱绝缘子;采用有限元分析法计算得到试样的静电场分布,通过后处理得到沿面电场及其切、法向分量的最大值、平均值、梯度、平方积分、电势分布等特征参数;实验测量了试样在0.2 MPa SF6中、标准雷电电压下的闪络电压。通过研究闪络电压与电场分布特征之间的相关性,发现绝缘子闪络电压不仅与沿面电场分布有关,与电场的切、法向分量的分布也显著相关。采用不同筛选策略,得到了与闪络电压相关但又互相独立的特征参数:沿面电场最大值及对应位置电场的法向分量、沿面电场切向分量的场不均匀度及其梯度的最大值、沿面电场切向分量大于其最大值90%区域的积分,并定性分析了这些特征参数对闪络起始和发展过程的影响机制。

Optimization of the electric field distribution along the insulator surface can effectively improve the flashover voltage of insulators,but the characteristics of the electric field distribution which determine the flashover voltage of insulators are still unclear.In order to further study the characteristics of the electric field distribution along the flashover voltage of insulators,48 kinds of epoxy pillar insulators with different electric field distributions along the surface were obtained by adjusting the geometrical parameters of the insulator’s surface shape,embedded electrode and external shielding electrode.The static electric field distribution of the samples was calculated by finite element method.The maximum,average,gradient,square integral and potential distribution of the electric field along the surface and its tangential,normal components were obtained by post-processing.The flashover voltages of the samples immersed in 0.2 MPa SF6 were measured experimentally under a standard lightning voltage.By studying the correlation between flashover voltage and electric field distribution,it is found that the flashover voltage of insulators is not only related to the distribution of electric field along the surface,but also significantly related to the distribution of tangent and normal components of electric field.After screening,the characteristic parameters which are related to the flashover voltage and are independent of each other are obtained as follows:the maximum value of the electric field along the surface and its normal component,the field inhomogeneity and maximum gradient of the tangential component of the electric field along the surface,the integral of the area where the tangential component of the electric field along the surface is greater than 90%of its maximum value.Moreover,the influence mechanism of these characteristic parameters on the flashover initiation and development process is also qualitatively analyzed.