A Half-bridge Inverter Based Active Power Quality Compensator for Electrified Railways

Abstract

-This paper proposes a half-bridge inverter based Active Power Quality Compensator (APQC) for electrified railways. The proposed APQC is composed of three-leg structured power switching devices with two DC capacitors. The first-leg is connected to -phase feeder, and second-leg is to -phase feeder. These two legs perform a half-bridge inverter based APQC, compensating the reactive, unbalanced active and harmonic currents on two feeders. The third-leg is used to balance two DC capacitor voltages. The basic principle of the proposed half-bridge inverter based APQC is discussed in detail. The validity and excellent practicability of the proposed APQC is confirmed using PSIM software. Simulation results demonstrate that the balanced source currents with the unity power factor are obtained on the primary side of the Scott transformer in the traction substation systems, balancing two dc capacitor voltages.Keywords electrified railways, active power quality compensator, half-bridge inverter, voltage balancer, constant dc capacitor voltage control.