A novel comprehensive compensator for electrified railway system

Based on the topology consisting of several branch of thyristor switched filters (TSF) and a small rating active power filter (APF), a novel comprehensive compensator is proposed, which compensates for harmonics and reactive power in electrified railways. A cascaded multilevel inverter constructs the main circuit of the APF in the novel compensator. A new method detecting specified order harmonic and a combining control strategy are proposed for the first time. Particular attention has been paid to designing a suitable control law for a TSF bank and its implementation in a real circuit. A digital control system based on double DSPs was designed. Finally, methods of estimating VA rating and designing coupling transformer are provided. Experimental results obtained from a 1 MVA prototype exhibit excellent performance of the new comprehensive compensator.