55 / 2018-08-20 17:17:07

Experimental study and numerical simulation of space charge in XLPE coaxial cable under temperature gradient

XLPE coaxial cable, cylindrical geometry, temperature gradient, space charge, bipolar charge transportation model

Space charge will accumulate in the insulation of XLPE coaxial cable under DC voltage, which will affect the aging and breakdown performance of cable insulation. Based on the cylindrical geometry of coaxial cable, bipolar charge transportation model by blocked extraction of injected carriers is built up in cylindrical coordinates to simulate the space charge distribution in XLPE coaxial cable in this paper. Considering the effect of temperature gradient on carriers transportation and accumulation in the insulation of cable, the space charge distribution characteristics of 10 kV and 160 kV XLPE coaxial cables with temperature gradient of 0℃、10℃、20℃ and electric field strength of 10 kV/mm and 15 kV/mm are measured respectively. At the same time the space charge distribution in 10kV and 160kV XLPE coaxial cables is simulated based on the bipolar charge transportation model. The research shows that the simulation results are highly consistent with the experimental results. Temperature gradient seriously distorts the electric field distribution in the insulation of coaxial cable, the higher the temperature gradient is, the more serious the electric field distortion is and the maximum electric field strength is biased towards the low temperature side. With the increase of electric field strength, the amount of heterocharge accumulated near the electrodes on both sides of coaxial cable increases. And the accumulation of heterocharge decreases to a certain extent with the increase of insulation thickness, so proper insulation thickness should be adopted in the actual design of cables, and deep trap materials should be doped without substantially reducing the insulation performance.