Stability enhancement of grid side converter in PV-wind-BESS based microgrid under weak grid conditions

This article revisits the design of a feedforward controller to improve the stability of grid side converter (GSC) in a microgrid system with harmonic reinjection ability, and power transfer capability while integrating into a weak utility grid. The stability and injection/absorption of active power to the utility grid are greatly affected by grid conditions. In addition, the variable grid impedances because of the expanding utilization of renewable energy sources, long distance of transmission lines, power system faults, harmonic pollution, etc., interrupts the grid codes. In these uncertain grid circumstances, coupling between the phase-locked loop (PLL) of the D-q control scheme and the grid impedance might also lead to instability. An enhanced feedforward controller term is implemented during the proposed research to counteract this effect. The proposed controller adapts the changes in grid parameters and makes the system stable by increasing power transfer to the receiving end. Proficiency of the proposed control scheme is validated by comparing it with existing control schemes using simulation tools with different operating modes of the microgrid and weak grid conditions. It is established from the simulation results that the proposed novel feedforward controller gives substantiated results during stable operations and integration while maintaining the IEEE-1204 standards.