Universal operation of a distributed power generation system based on the power converter control

The penetration of Distributed Power Generation Systems (DPGS) is contributing to a low-voltage active distribution grid characterized by the possibility to operate some portions in island mode operation. Power converters, interfacing the DPGS energy source with the rest of the power system, can experience stability problems due to the plant variability moving form grid-connected to stand-alone operation. The paper treats an adaptive droop control for a three-phase DPGS whose gains and power references are modified moving from grid-connected to stand-alone operation. The overall control structure is based on cascade loops and it is designed with the aim to limit at the least the required changes in case of operation modes variation. Experimental validation confirms the feasibility of the proposed control system and the related tuning procedure.