Robust Grid-Forming Control With Active Susceptance

Abstract

This letter proposes a grid-forming control scheme that is robust against a wide range of short-circuit ratio (SCR) of the ac grid. The approach modifies the traditional power synchronization control by adding an active susceptance loop, which enhances system damping for high stability robustness and enables to use a standard voltage-oriented vector current control. The latter can avoid major software changes on a classical grid-following control structure. Both small-signal dynamics analysis and experimental results confirm the effectiveness of the approach from ultraweak (SCR = 1, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> ratio = 7) to stiff (SCR = 38.5) grids.