Medium voltage series connected 12-pulse compensated current source controlled rectifier with a novel front end transformer configuration

The series connected twelve-pulse current source converter can operate under controlled p-q operation with symmetrical or asymmetrical firing of the two series connected 6-pulse converters. The input power factor and input current total harmonic distortion, THD, are dependent on the power locus which the converter operation follows. In this paper, a new p-q locus is introduced where the maximum reactive power absorbed by the converter is halved and provides minimum input current THD. To improve the input current THD and input power factor, an active power filter is used. In order to reduce the cost and size of the compensated system, different configurations for the front end phase shifting transformer(s) and active power filter(s), APF(s), are investigated and compared.