Modeling and comparative analysis of different grid-forming converter control concepts for very low inertia systems

Abstract: As renewable power from DC sources are constantly increasing their power generation share compared to the high inertia generators that provide robustness to the grid, the overall stability of the grid decreases. Grid forming converter could be the solution to this problem. This thesis includes a pre-study of grid forming control methods, implementation of the most promising and relevant methods in a generic PSCAD modeling environment for comparative analysis and for establishing pros and cons. Lastly, studying the system impact of each grid forming control method through small-signal stability and fault analysis. Four methods of grid forming were implemented and evaluated during the course of the thesis, which were: Droop control, Virtual Synchronous Generator control, Power Synchronization control and Synchronous Power control. All methods fulfilled the criteria for successful implementation with good results. For further developments, we would recommend Synchronous Power control and Virtual Synchronous Generator control for their development potential and operational width.