Generalised grid-forming VSC control for grid connection and island network

This study proposes a generalised grid-forming VSC control for grid connection and island network for distributed generations. The proposed control scheme is based on grid-forming direct voltage control to establish the AC voltage and frequency for island network, while it works as a controlled AC voltage source to regulate the active and reactive power flowing to the local load and AC grid during grid-connected operation. Strategy for fault current limiting is also proposed to overcome the overcurrent problem brought by the grid-forming direct voltage control. Simulation results during three-phase AC fault and transition from grid-connected operation to islanding operation are presented to confirm the feasibility and effectiveness of the proposed control strategy.