Grid-connected inverters for alternative energy sources with a combined voltage and current control strategy

Renewable energy sources are considered as important generation alternatives in electric power systems due to their no exhausted nature and benign environmental effects. In order to utilize the infrastructure of the actual distribution network, grid-connected inverters are needed. In this paper a new control strategy for a pulse width modulation (PWM) three-phase voltage source inverter (VSI) connected to the grid and able to support bi-directional power flow is presented. In particular, the proposed strategy is developed so as to combine the advantages of the current control and the voltage control. The effectiveness of this combined control strategy is proved by some numerical results compared with those obtained applying only the conventional current control strategy.