交流500kV交联聚乙烯海缆绝缘材料的步进工频击穿特性及寿命模型

Step Breakdown Characteristics and Life Model of AC 500 kV Crosslinked Polyethylene Submarine Cable Insulating Material

世界首条500 kV交联聚乙烯(XLPE)海缆已于2018年底在舟山敷设完成。为了研究500 kV XLPE海缆绝缘材料的绝缘与老化特性,对交流500 kV XLPE海缆绝缘材料进行不同温度下的短时工频击穿试验和步进应力工频击穿试验,并运用反幂模型对该材料在电-热应力下的寿命进行计算。结果表明:该500 k V XLPE海缆绝缘材料的短时工频击穿强度在25~85℃内呈现先上升后下降的趋势,工频击穿强度显著下降的阈值温度在70℃左右;相同温度下,步进应力下的工频击穿强度随加压时间步长上升而下降;相同加压时间步长下,步进应力下的工频击穿强度和耐压时间均随温度升高先增大后减小;寿命指数n和常数C随温度的升高也呈现先上升后下降的趋势。最后提出了基于反幂模型的该交流500 kV XLPE海缆材料的寿命计算公式,可为该材料类型海缆的寿命计算以及采用该材料进行电缆结构设计提供参考。

The world’s first 500 k V crosslinked polyethylene(XLPE) submarine cable was laid in Zhoushan at the end of 2018. In order to study the insulating and ageing characteristics of 500 k V XLPE submarine cable insulating material, the AC 500 kV XLPE submarine cable insulating materials were conducted short time power frequency breakdown tests and step stress power frequency breakdown tests at different temperatures, and the life of the material under electro-thermal stress was calculated using inverse power model. The results show that the short time power frequency breakdown strength of the 500 kV XLPE submarine cable insulating material increases firstly and then decreases at 25~85 ℃,and the threshold temperature at which the power frequency breakdown strength decreases significantly is about 70 ℃. At the same temperature, the power frequency breakdown strength decreases with the increase of pressure time step, and at the same pressure time step, both the power frequency breakdown strength and voltage withstanding time increase firstly and then decrease with the increase of temperature.With the increase of temperature, the life index n and the constant C also increase firstly and then decrease. Finally, the life calculation formula of the AC 500 k V XLPE submarine cable material based on the inverse power model is proposed, which can provide reference for the life calculation of this type of material cable and the structure design of cable using this material.