PWP法柔性直流电缆空间电荷特性研究

Research on Space Charge Characteristics of HVDC Flexible Cable by PWP Method

为探究柔性直流电缆的空间电荷特性,采用压力波(PWP)法模型电缆空间电荷测试系统,研究了30 k V柔性直流电缆在电场为-10、-15和-20 k V/mm,导体温度为30、50和70℃,以及在电场13.9 k V/mm下热循环过程中的空间电荷分布。结果表明:在试验外加电场下,当电缆导体温度为30℃时,电缆绝缘层中几乎没有空间电荷积聚;当导体温度升高到50℃和70℃时,绝缘层两侧出现异极性空间电荷积聚,空间电荷密度随着导体温度和电场的升高而增大,且绝缘层外侧的空间电荷积累量大于绝缘层内侧;在电场为13.9 k V/mm的热循环过程中,柔直电缆绝缘层在加热阶段积聚的空间电荷在降温阶段不易消散。

To investigate the space charge characteristics of flexible direct current cable, the space charge distribution of 30 kV HVDC flexible cable was studied using pulsed wave propagation （PWP） model cable space charge measurement system under the electric field of-10 kV/mm, -15 kV/mm, and-20 kV/ mm and the conductor temperature of 30℃, 50℃, and 70℃, as well as under thermal cycle process with the electric field of 13.9 kV/mm. The results show that under the applied electric field, there is little space charge accumulation in the cable insulating layer when the conductor temperature is 30 ~C. When the conductor temperature increases to 50 ~C and 70 ~C, there is hetero space charge accumulation on both sides of insulating layer; the space charge density increases with the increase of conductor tem- perature and electric field, and the space charge accumulation outside the insulating layer is larger than that inside the insulating layer. Under the thermal cycle process with the electric field of 13.9 kV/mm, the space charge accumulated in the insulating layer of HVDC flexible cable during the heating stage is not easy to dissipate in the cooling stage.