Simulation of Arc Breaking in a 252kV Circuit Breaker Under Harmonic Current

With the development of electric power technology, large-scale renewable energy sources have been connected to power grid through the interface of power electronics, which brings new energy to the electric power system, but also brings the influence of harmonics. In order to figure out how harmonics in current influence the arc-breaking performance of high-voltage breakers in power systems, based on the structure of a 252kV SF 6 gas circuit breaker, a magnetohydrodynamic model is established and the simulation of arc breaking under different harmonic frequencies is carried out. The study of this paper shows that the harmonics in the current can cause the change rate of arc current di/dt to significantly increase, especially when current crosses zero, which affects the dissipation of arc energy. Meanwhile, the arc conductivities at the time of 200ns and 500ns before the current crosses zero G200, G 500 are also higher because of the harmonics, which increases the probability of arc reignition. In the process of arc burning, the harmonics also cause the rise of temperature in arc extinguishing room. Therefore, the existence of harmonics can influence the breaking process of circuit breakers, not helpful to successful breaking.