Simulation Study Of Partial Discharge In HVDC Cables

With the rapid development of China's economy,the power network has also entered a stage of rapid development,and high-voltage direct current transmission has become an important part of the power system.The insulation performance of HVDC transmission lines is directly related to the safe and reliable operation of the power system.The insulation of HVDC cables is non-self-healing insulation,and there may be local defects in the insulation that may cause partial discharge behavior.Partial discharge is one of the effective means to evaluate the insulation performance of power equipment.It is necessary to study the characteristic law of partial discharge under the condition of high voltage direct current.Firstly,this paper reviews the current domestic and foreign research status of cable partial discharge under DC voltage,introduces possible insulation problems in DC cables,and analyzes four theoretical models of cable partial discharge simulation,which provides a theoretical basis for the simulation work of this article.Secondly,the thesis based on the conductance model of partial discharge simulation,the equivalent simulation model of high-voltage DC cable insulation was established using COMSOL software,and the solid insulation single air gap partial discharge was simulated,and the influence of superimposed harmonic DC voltage on the discharge characteristics was considered.The influence of the content of superimposed harmonics and the order of harmonics on the partial discharge of the insulation air gap is studied,and the relationship between insulation temperature and discharge characteristics is explored.The simulation results show that the increase of the content of harmonics and the order of harmonics will cause the repetition rate of partial discharge increases.In addition,the change of insulation temperature will affect the repetition rate and average discharge capacity of the air gap discharge.Finally,in order to verify the effectiveness of the simulation method,the published test data considering the influence of direct current ripples,insulation temperature and air gap pressure on partial discharge are collected,and the simulation model of partial discharge is established by referring to the test conditions,and the simulation parameters are adjusted reasonably.,Which can make the simulation results show a good correspondence with the published test results.This paper investigates the influence of direct current ripples,insulation temperature and air gap pressure on the characteristics of air gap partial discharge through simulation.The research results are helpful to improve the understanding of the partial discharge phenomenon of high voltage DC cable insulation and promote the research of DC cable partial discharge detection.And application.