Study on working condition of 750 kV AC filter breaker in ± 1100 kV UHVDC system

In this article, the Changji-Guquan ± 1100 kV ultra-high voltage direct current (UHVDC) system has been established by PSCAD software, especially for the arc of the circuit breakers. The AC filter groups and the control strategy have been analysed based on the reactive power demand of this system, AC system voltage amplitude, and harmonic limit. This article mainly studies inrush currents and overvoltage, especially recovery voltage caused by switching circuit breaker of AC filter in the different working conditions. Simulation results show that the currents through circuit breakers are capacitive and contain a variety of harmonics. There will be a high inrush current when a circuit breaker of AC filter is closing, which can be suppressed by phase selection switch device and appropriate closing resistance. A higher DC transmission power and a less short circuit both make the recovery voltage of circuit breakers higher when the AC filters are removed. The maximum transient recovery voltage of circuit breakers of AC filters can be suppressed by adding the parallel opening resistors. In a certain range, higher resistance of opening resistor makes a better suppression effect on recovery voltage