Influence of interfacial air gap defects and moisture on electric field distribution in intermediate joint of±320 kV DC cables
To investigate the impact of interface air gap and moisture defects on the multilayer composite dielectric insulation interface of±320 kV DC cable intermediate joints on their electric field distribution mechanism,a simulation model of±320 kV DC cable intermediate joint was built,and the electric field distribution of the cable joint with air gap and moisture defects on the multilayer composite dielectric interface region was calculated using the finite element method.The effect of these defects on the electric field distribution of the cable joint were analyzed at no load and load conditions,and their differences under AC/DC electric fields were discussed.The results show that there is significant electric field distortion at the composite dielectric interface of the DC cable joint due to air gap and moisture defects under the action of DC electric field.The multiple of electric field distortion of air gap defects is 9.6 times at no load and 1.7 times at load condition.The electric field strength in the water film defects decrease over 99.9%at both operating conditions.Interestingly,the electric field distortion induced by air gap defects in cable joints at no load is larger than that at load condition,and the temperature differentials across the joint play a role in field homogenization.However,the temperature differentials across the joint induced by moisture at load promote the accumulation of space charge in the joint,which leading to the multiple of electric field distortion at moisture defect bigger than than at no load.Notably,the multiple of electric field distortion resulting from defects in DC cable intermediate joint is bigger than that of AC cables.
cable intermediate jointDCinterfacial defectselectric field distribution
万方数据
维普
