Three-phase modeling of 40.5-kV vacuum circuit breaker switching off shunt reactors and overvoltage suppression measure analysis

Abstract

Shunt reactors are commonly used in substations to compensate the capacitive reactive power of electric power systems. When a vacuum circuit breaker (VCB) switches off shunt reactors, an overvoltage with high amplitude and high frequency (HF) is generated because of the current chopping and multireignition of the VCB. The objective of this paper is to build the 40.5 kV statistical VCB model, simulate the overvoltage caused by switching off shunt reactors in a 35 kV substation, and analyze the impact of five types of overvoltage suppression measures under identical VCB conditions and substations. The statistical VCB model is established in MATLAB/Simulink and verified by the field tests. Three basic factors are considered in this model: chopping current value, dielectric dynamic insulation strength and HF current quenching capability of the VCB. The simulation results show that the suppression effects in descending order are the phase-controlled VCB, adding surge arresters, adding RC snubbers, double-break VCB and increasing the cable length.