500kV金属氧化物避雷器不同污秽状态下内部电场及电压分布仿真分析

Simulation Analysis of Field and Voltage Distribution of 500 kV Metal Oxide Arrester Under Different Pollution Conditions

建立500 kV金属氧化物避雷器(Metal Oxidation Arrester,MOA)的三维模型,对不同污秽状态下的MOA进行静电场仿真计算,探究内部电场及电压分布的变化规律。计算结果表明,均匀干污秽状态下的MOA与清洁状态下的MOA差异很小,不会影响设备正常运行;均匀湿污秽状态下的MOA不同位置电阻片所承担的电压差异非常大,会加速电阻片劣化,缩短MOA运行寿命;整体不均匀污秽状态下的MOA内部电场强度大幅度增加,易出现局部放电,进而加速电阻片和瓷套劣化;局部不均匀污秽状态下的MOA内部电场强度非常大,特别是在均压环泵和最上部法兰电压为597 kV的极端情况下,氮气绝缘层的绝缘强度已远远不够,会发生绝缘击穿,损坏设备。

To establish a three⁃dimensional model of 500 kV metal oxide arrester(MOA),perform electrostatic field simulation calculation for MOA in different filthy states,and explore the changed rule of internal electric field and voltage distribution.The calculation results show that there is little difference between the MOA in uniform dry and dirty state and the MOA in clean state,which will not affect the normal operation of the equipment.In the condition of uniform wet pollution,the voltage difference of the resistance pieces at different positions of MOA is very large,which will accelerate the deterioration of the resistance pieces and shorten the operating life of MOA.The internal electric field intensity of MOA in the overall non⁃uniform pollution state increases greatly,and partial discharge is easy to occur.The internal electric field intensity of MOA in the state of local uneven pollution is very large.In extreme cases,the insulation strength of the nitrogen insulation layer is far from enough,resulting in the insulation breakdown and the damage of the device.