Modeling and control of zero-sequence current of parallel three-phase converters using Matlab/power system blockset

This paper proposes modeling and control of zero-sequence current of parallel three-phase converters using power system blockset (PSB). Novelty of this paper lies in the application of active power filter (APF) for the cancellation of zero-sequence current produced by parallel converters using PSB. The entire system has been modeled using MATLAB/Simulink/PSB blocks. The instantaneous line reference current waveform for the APF has been generated using PSB's virtual phase locked loop (PLL) block. For the determination of reference APF current, the load current is sensed and compared with instantaneous line reference current. Carrierless hysteresis based current control is used to obtain switching signals for the IGBT's. Simulation results demonstrate the applicability of active power filter for the cancellation zero-sequence current produced by parallel converters. Comparison of source current waveforms demonstrates that the proposed method can be used even for balancing unbalanced source currents.