Grid-Forming Control of an MMC STATCOM Using Submodule Capacitors to Emulate Inertia

A grid-forming (GFM) control scheme is applied to a modular multilevel converter (MMC) which operates as a static synchronous compensator (STATCOM) in the medium voltage grid. The energy stored in the submodule capacitors is utilized as virtual inertia to provide active power infeed or absorption in case of grid disturbances. It is studied how the control scheme impacts the resilience of a predominantly renewable power grid. Simulations of a switched MMC model show the impact of the proposed solution on phase jumps and symmetric grid faults.