Reignition overvoltages caused by 40.5 kV vacuum circuit breaker switching-off shunt reactors and suppression methods

Abstract

During the process of switching-off shunt reactors with vacuum circuit breakers (VCBs), reignition overvoltages (ROVs) may occur due to current chopping and arc reignition, which may damage the insulation of main power equipment and endanger the stability and safety of the power grid. In order to analyze the transient characteristics and potential hazards, in this research an accurate three-phase arc reignition model of the VCB, is developed in PSCAD/EMTDC with considering the arc characteristics of the two contacts of VCBs. Then the system simulation model of a 220 kV substation is further established. Then two factors are considered to analyze their effects on ROVs, including the opening angle and the dielectric insulation recovery velocity of VCBs. Subsequently, two types of coordinated protection schemes are proposed, including a surge arrester (SA) and a RC snubber, and a SA and a ferrite magnetic ring (FMR). Then their suppression performance is compared with that of the SA, RC snubber and FMR installed alone, and the mitigation performance of different installation positions is also investigated. Finally, the effectiveness of the proposed coordinated protection schemes for ROVs is validated. The research results of this paper can provide theoretical support for practical applications of switching-off shunt reactors and the overvoltage suppression.

Keywords

• shunt reactor
• phase-to-ground reignition overvoltages
• phase-to-phase reignition overvoltages
• suppression methods
• 40.5 kv vacuum circuit breaker
• ferrite magnetic ring