Grid-mode controller design for a dual-mode inverter interface for a distributed generation source

Power electronics applications to electric power processing are playing an increasingly indispensable role in the power quality and power reliability enhancement, especially in view of the growing importance of distributed (especially renewable) energy sources´ contribution to electric power generation. Grid-interactive distributed generation systems have huge potential to significantly enhance the power supply reliability, especially when effective control of their power electronics interface units enables their efficient operation both when in grid-tie mode and autonomously (i.e. dual-mode operation capability). In this paper, the grid-tie mode operation of a dual-mode power electronic (inverter) interface unit for a distributed generation source is considered. Firstly, requirements underlying the control strategy design for the dual-mode inverter are outlined, highlighting the commonly employed strategies together with their main characteristics. Then the controller design procedure for the grid-tie mode operation is presented, which forms part of the larger-scope dual-mode control strategy design, but not covered in its entirety in this paper. The designed grid-mode controller has been implemented in the Matlab/Simulink software development environment, considering a 15-kVA three-phase power inverter connected to the power utility´s distribution network. The results obtained from the computer simulations attest to the designed control system´s effectiveness in enabling the distributed generation system to supply high-quality, low-distortion current to the grid.