Multifunction current controller for inverter-based distributed generation using combined pi-sliding mode controller via Sigma-Delta Modulation

The fast changes in the reactive power consumption can cause considerable variations at the load-side and can influence on the operation of other power consumers which and point of common coupling (PCC) voltage. In this paper, a current control strategy based on sigma delta modulation (SigmaDeltaM) is presented for the interfacing DG inverter. The inverter is called sigma-delta based current controlled voltage source inverter (SigmaDelta_CC_VSI). It controls active and reactive powers independently with fast voltage regulation. It is shown that the SigmaDeltaM generates sliding mode regime. As a result, it is possible to combine the proportional-integral (PI) with sliding mode controllers. It is shown that the proposed SigmaDelta_CC_VSI reduces the harmonics amplitude variations of the unfiltered voltage. Therefore, it reduces the electromagnetic interference (EMI) problems.