f-P vs P-f based Grid-forming Control under RoCoF Event Considering Power and Energy Limits

Abstract

Grid-forming (GFM) converter is deemed as one enabler for high penetration of renewable energy resources in power system. However, as will be pointed out in this letter, the conventional power-to-frequency (P-f) GFM control will face a dilemma in keeping power limit and grid synchronization when the energy resource of the converter reaches the limit. To address this challenge, a f-P and Q-V hybrid control is proposed, which exhibits similar GFM performance, particularly under weak grid condition, but is superior in power-limiting and grid synchronization as demonstrated by comparative studies.