China’s 10-year progress in DC gas-insulated equipment:From basic research to industry perspective

The construction of the future energy structure of China under the 2050 carbon-neutral vision requires compact direct current(DC)gas-insulation equipment as important nodes and solutions to support electric power transmission and distribution of long-distance and large-capacity.This paper reviews China's 10-year progress in DC gas-insulated equipment.Important progresses in basic research and industry perspective are presented,with related scientific issues and technical bottlenecks being discussed.The progress in DC gas-insulated equipment worldwide(Europe,Japan,America)is also reported briefly.

Shape optimisation of basin insulator for DC gas insulated switchgear/gas insulated transmission lines based on artificial bee colony algorithm

The surface charge accumulation on the basin insulator is a particular problem in high-voltage direct current(HVDC)gas insulated switchgears(GIS)and gas insulated trans-mission lines(GIL),which restricts the development and application of extra/ultra high-voltage(EHV/UHV)technology.The surface charge distribution and anti-flashover performance are closely related to the insulator shape.To obtain the optimal basin insulator,a shape optimisation model based on artificial bee colony algorithm was established,and the minimisation objective functions based on capacitive(initial)electric field distribution and resistive(steady-state)electric field distribution were respectively constructed.The optimisation results of the two objective functions were calculated,and the electric field and charge distribution on the surface of the insulator before and after optimisation were evaluated and compared using the simulation model.The results indicated that the optimisation based on the capacitive electric field can significantly inhibit the surface charge accumulation,and the optimised insulator can significantly reduce the surface normal electric field and make the distribution of the tangential electric field more uniform,and the maximum tangential electric field can be reduced by 10%;the optimisation based on resistive electric field can achieve similar results,but requires more computational resources.Based on the results,the‘anti-charge’basin insulator structure suitable for the DC field was given.

Dynamics of surface charge and electric field distributions on basin-type insulator in GIS/GIL due to voltage polarity reversal

In this study,a simulation model of surface charge accumulation has been established.The model considers three accumulation ways,i.e.electrical conduction within the gas,through insulator volume and along the insulator surface.The generation,diffusion,drift and recombination of charge carriers are also taken into account.Based on it,the influence of polarity reversal,reversal time on surface charge and electric field distribution on a basin-type insulator are studied.The polarity of the surface charges and the direction of the electric field change after the voltage polarity reversal.When the preload voltage is equal to reversal voltage,the surface charge and the electric field distributions at steady state before and after voltage polarity reversal are all the same with opposite sign,and not affected by the reversal time.However,the time to reach the steady state varies with different reversal time.The steady-state surface charge and electric field increased with the rise of reversal voltage.The transient normal and tangential electric field would not exceed the value of the steady state,which means voltage polarity reversal has no additional influence on insulation performance.This research can provide guidance to the design and manufacture of DC GIS/GIL.