±400kV高压直流电缆绝缘厚度设计与验证

Thickness Design and Verification for ±400 kV HVDC Cable Insulation

本研究以±400 kV高压直流模型电缆为研究对象,开展了直流耐压试验和冲击耐压试验,获取模型电缆在最高运行温度下的直流击穿电压和冲击击穿电压,求解其在直流击穿电压和冲击击穿电压下的电场分布;基于平均场强法和最大场强法分别设计±400 kV高压直流电缆绝缘厚度,并计算了直流电压和冲击电压下绝缘层电场分布;通过对比±400 kV高压直流电缆和模型电缆的电场分布,最终得出了±400 kV直流电缆绝缘厚度。结果表明:采用平均场强法进行高压直流电缆绝缘厚度设计时,绝缘厚度取决于冲击电压;而采用最大场强法进行绝缘厚度设计时,绝缘厚度取决于直流电压。

A±400 kV HVDC model cable was conducted DC withstand voltage test and impulse withstand voltage test,and the DC breakdown voltage and impulse breakdown voltage of the model cable under the highest operating temperature were obtained.The electric field distribution under DC breakdown voltage and impulse breakdown voltage were calculated.On the basis of average field intensity method and maximum field intensity method,the insulation thickness of±400 kV HVDC cable was designed,and the electric field distribution of insulation layer was calculated under DC voltage and impulse voltage.At last,the insulation thickness of±400 kV DC cable was obtained by comparing the electric field distribution of±400 kV HVDC cable and model cable.The results show that when the insulation thickness of HVDC cables is designed by the average field strength method,the insulation thickness depends on the impulse voltage.When the insulation thickness is designed by the maximum field strength method,the insulation thickness depends on the DC voltage.By comparing the electric field distribution of±400 kV DC cable and the electric field strength of the model cable when breakdown,it is obtained that the insulation thickness of 400 kV DC cable is 26 mm.