A novel constant switching frequency strategy for a three-leg DSTATCOM

A novel current control strategy for a three-phase three-leg distribution static compensator is propounded in this paper. Improvement is achieved in terms of constancy and reduction in switching frequencies of all the switches of the voltage source inverter. The switching commands for one of the three inverter legs are given directly from a square pulse of a user-defined frequency. The other two legs are operated in hysteresis current tracking mode. The proposed controller unlike the other controllers allows the user to directly set the switching frequency of all the inverter switches and is devoid of any transformation, modulation, look-up table or complexity to achieve the objectives. The proposed scheme is validated through extensive simulation results in a three-phase three-wire distribution system with non-linear unbalanced load.