Robust Control for Islanded and Seamless Mode Switching of Wind-PV-Grid Tied Generation System

This paper deals with a robust control strategy for distributed generation system (DGS), which operates in both islanded and grid-connected modes. In islanded mode, the load side VSC (Voltage Source Converter) is controlled using the PR (Proportional Resonant) controller, thereby the CCP (Common Coupling Point) voltage quality is maintained within the IEEE-1547 standard. Moreover, the DGS is capable to synchronize to the grid without any transient current. In grid connected mode, the load side VSC switching is provided using the inner-loop SOGI based control algorithm. Generally during the mode change from standalone mode to grid connected mode and vice versa, large transients occur in the battery current due to the switching. This problem is resolved by proposed bidirectional DC-DC converter control strategy and robust inner-loop SOGI based PLL. The proposed control strategies in DGS, provide smooth mode transition from the grid connected mode to an islanded mode and vice versa, thereby the reliability of the DGS is enhanced. The proposed DGS is validated on the experimental prototype of DGS.