1. China State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049 China; 2. State Grid Zhejiang Electric Power Corporation Research Institute Hangzhou 310014 China
Abstract:Post insulators within DC GIL tend to accumulate surface charge under long-term DC voltage, which easily leads to insulator flashover. Thus, it is important to study the surface charge accumulation characteristics under DC voltage in order to improve the operational reliability of DC GIL. Focusing on the post insulator in GIL, this paper researched its surface charge accumulation characteristics. An experiment platform for surface charge measurement was designed. Through the migration and diffusion equation of weakly ionized gas, the surface charge accumulation model was established by FEM. The surface charges were measured and simulated under the constant temperature condition. The dynamic processes of charge accumulation were analyzed. Meanwhile, the simulation model of ±800kV DC GIL was built, and the impacts of the surface conductivity, bulk conductivity and gas ionization rate on the electrical field distribution and surface charge accumulation of post insulator were analyzed. The conclusions deepened the understanding of the charge accumulation mechanism on gas-solid insulation interface under DC voltage, which can provide the methods and references for solid insulation structure design in DC GIL equipment.
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