Reactive power compensation in three-phase four-wire distribution system using four-leg DSATATCOM based on symmetrical components

In this paper, a control algorithm based on symmetrical components is proposed to control a three-level four-leg (3L4L)DSTATCOM. The proposed control is designed in a synchronous rotating reference frame in the aim to provide high dynamic performance with complete decouple control of active power needed by the inverter and reactive power compensation required by the load. Moreover, it provides a neutral current compensation in four-wire distribution system in cases of unbalanced loads. In addition, this paper proposes a simplified algorithm of three-level three-dimensional space vector modulation (3DSVM). The proposed algorithm can reduce remarkably the complexity of 3DSVM by using two sectors only instead all the six sectors of the three-level four-leg inverter. The voltage-balancing control of DC-link capacitors is achieved based on the effective use of the redundant switching states. Simulation results are presented to verify the validity of the proposed control strategy and 3DSVM algorithm.