Electrical-thermal Field Distributions and Optimal Design of Bridge-along HVDC Cable Joints Based on Nonlinear Conductive Insulation

doi:10.11985/2022.02.026

Abstract

Abstract:

Aiming at the uniform distribution of electric-thermal coupling field in the HVDC cable joints laying along bridges, the electric field of HVDC cable joints is optimized and designed based on nonlinear conductive insulation in this paper. The influence of the non-linear conductivity characteristics of polymer insulating materials on the distribution of the insulation electric field of DC cable joints under the multi-filed of electrical, thermal and mechanical stress is studied, and the optimization design for the reinforced insulation of HVDC cable joints is analyzed. The results show that the nonlinear conductivity of the silicone rubber is greatly enhanced by doping silicon carbide(SiC) nanofillers, the electric field strength coefficient of the silicone rubber insulation are improved, and the threshold electric field strength of conductivity entering the nonlinear region is reduced. When the ambient temperature in the bridge beam box reaches 40 ºC, the maximum field in the cable joint is up to 40 kV/mm, located at the root of stress cone. The distortion of electric field of stress cone in the UHVDC cable joint are obviously suppressed by the modified silicone rubber reinforced insulation material. The modified silicone rubber, used as the reinforced insulating material for UHVDC cable joints, can make up for the insufficient that the field distortion in the joint cannot be suppressed effectively by adjusting the structural size of cable joints. The research can play an import role in the electric field modification and design of bridge-along HVDC cable joints.

Key words: Bridge-along cables, HVDC cable joints, polymer insulation, nonlinear conductivity, electrical and thermal field

CLC Number:

TM215

LI Hanping, CONG Yun, LI Xiaobing, ZHANG Zhenpeng, LIU Yong. Electrical-thermal Field Distributions and Optimal Design of Bridge-along HVDC Cable Joints Based on Nonlinear Conductive Insulation[J]. Journal of Electrical Engineering, 2022, 17(2): 226-234.

Figures/Tables 16

References 16

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材料	密度/ (kg/m³)	电导率/ (S/m)	相对介电常数	导热系数/ [W/(m·K)]	恒压比热容/ [J/(kg·K)]
线芯	8 940	5.998×10⁷	1	400	385
XLPE 绝缘	920	σ_X (E, T)	2.3	0.28	2 600
半导电层	1 100	2×10^-3	30	0.4	2 180
增强绝缘	2 500	σ (E, T, γ)	3.25	0.27	1 700
PE护套	2 530	5×10^-13	2.4	0.28	950