Analysis and Mitigation on Switching Transients of Medium-Voltage Low-Harmonic Filter Banks

This paper presents the switching transients of medium-voltage low-harmonic filter banks, which have alower back-to-back inrush current and higher transient recovery voltage (TRV) compared with capacitor banks. The switching transients of the filter banks are described by the analytical approach and field measurements for 150 MVA back-to-back filter banks are provided to support the switching phenomena described in this paper. As a mitigation measure of the high transient recovery voltage, a double-breaker type switchgear is analyzed in terms of the operating sequence and the time of the upper and lower breakers. From the analyses, an operation scheme for the double-breaker switchgear is proposed to avoid insulation failure of the breaker during the interruption by mitigating the transient recovery voltage across each breaker.