Simulation Analysis of AC Filter Circuit Breaker Switching

An AC filter serves dual purpose of filtering harmonics and compensating reactive power for the power systems, which makes it a crucial component within a converter station of a high-voltage DC (HVDC) system. Frequent switching of the AC filters, during the operation of the DC system, results in high amplitude inrush current and overvoltages, both of which pose risks to a reliable operation of the circuit breakers (CBs). The objective of this paper is to conduct an electromagnetic transient simulation analysis on a relationship between switching inrush current and switching phase of AC filter CB. Thereby it would provide an insight for the CB's state evaluation and for controlled switching strategy. In this paper, a switching overcurrent and overvoltage of AC filter is given at first. Secondly, a transient simulation of HP3 AC filter switching based on MATLAB and a comparative analysis with field operation is made. Simulation results reveal that HP3 filter of Yinmin converter substation is not a capacitive load and it is an inductive load. When it is switched from voltage phase-angle 0° to 90°, the inrush current of its circuit breaker #5612 decreases with the increase of phase angle. During the voltage phase-angle from 90° to 180°, the #5612 circuit breaker inrush current increases with the increase of phase-angle.