External Inertia Emulation to Facilitate Active-Power Limitation in Grid-Forming Converters

The aim of this paper is to present a grid-forming (GFM) control strategy with a novel active-power loop (APL) structure facilitating limitation of active power while providing maximum available inertial support. This is achieved by decoupling the synchronization duties of the APL from the inertial support. The latter is provided by calculating the active-power reference through a dedicated inertia-emulation loop (IEL), which is connected in cascade with the APL. The effectiveness of the proposed method is demonstrated through laboratory experiments including frequency transients of varying size and unbalanced operating conditions.