Inverter control strategy for DG systems based on the Conservative power theory

Considering that typical distributed generators are equipped with a switching power interface and most of them have a DC-AC converter, this paper deals with a multi task control strategy for distributed generation (DG) inverters. Such strategy simultaneously allows the DG systems to inject the available energy, as well as to work as a voltage drop compensator or an active power filter, mitigating load current disturbances and improving power quality. The main difference of the proposed methodology with respect to others in the literature is that the proposed control loops are based on the Conservative Power Theory decompositions. This provides decoupled power and current references for the inverter control, offering a very flexible, selective and powerful strategy for the DG control system. The paper also discusses the choice of the waveform reference for injecting/absorbing active power into/from the grid, and both sinusoidal and resistive current injection have been compared. Finally, simulation and experimental results are reported in order to validate the proposed functionalities of the DG control strategies.