Electric Field Analysis of ±1100 kV Resin Impregnated Paper UHVDC Wall Bushing under Different Voltage Forms

Abstract

The ±1100 kV resin impregnated paper (RIP) wall bushing is a key power equipment in the ±1100 kV UHVDC power transmission project in China. The electric field distribution of RIP UHVDC wall bushing under complex operating conditions in DC system is quite necessary to be investigated. Finite element method (FEM) is employed in this paper to calculate the electric field distribution of a ±1100 kV wall bushing under DC, AC and DC polarity reversal voltage cases. Electric field distribution around grading ring, inner shield and hollow insulator surface are analyzed. The results show that under DC case, the maximum field strength at grading ring and inner shield are 1.80 kV/mm and 11.14 kV/mm respectively. Under AC case, the maximum field strength (peak value) at grading ring and inner shield are 1.79 kV/mm and 5.94 kV/mm respectively. The numerical results show that the electric field values are below the breakdown or flashover threshold values and meet the field strength requirements. Under DC polarity reversal case, the location of maximum field strength shifts during the polarity reversal process. The electric field analysis can provide numerical references for the design, optimization and operation of UHVDC wall bushing.