Analysis and characterization of the shunt reactor switching over-voltages interrupted by SF6 circuit breakers with chopping current

Shunt reactor interruption by circuit breakers may produce current chopping and cause severe overvoltages. The four-legged reactor interrupting transients are elucidated with equivalent circuit analysis, and the mechanism of beat frequency oscillation is also characterized, further, a 3-D portfolio of the beat frequency, specifically regarding shunt reactor interrupting with a short line distance is given to describe the variation trend versus the shunt reactor´s parameters. Based on the available parameters from an installed 750kV transmission line in China, simulations of the four-legged reactor interruption process are carried out with adoption of an appropriate arc model for SF6 circuit breakers, and the scenario of the switching overvoltages is presented for the shunt reactor interrupting. The research results present useful reference for future construction and operation of the EHV and UHV transmission lines.