A Self-Regulating Virtual Synchronous Generator Control of Doubly Fed Induction Generator-Wind Farms
Preeti Verma, K. Seethalekshmi, Bharti Dwivedi
Abstract
The inverter-driven renewable energy sources (RESs), such as wind energy conversion systems (WECS), pose major threats toward system stability due to lack of inertia. Hence, virtual inertia concepts have gained popularity, for control and improvisation of the dynamic behavior of RESs, by simulating the kinetic inertia of the synchronous generator. This article focuses on developing an improved self-regulating virtual synchronous generator (VSG) control for grid-tied doubly fed induction generator (DFIG)-wind farms (WFs). The proposed scheme provides frequency support to the system while ensuring the low-voltage ride through (LVRT) capability at transient conditions, as per grid code requirements (GCRs). This has been achieved by introducing an additional control at grid side converter (GSC). This auxiliary control consists of a combined approach of VSG control and a current limiting approach. The VSG loop that alters the inertia of the system improves the frequency of the system and the current limiting loop provides the required inductance to limit fault current. This overall loop uses a self-regulating approach, and the developed concept helps to suppress the transients in stator current. The study obtained on a multimachine system and also for a weak grid system confirms the effectiveness and viability of the modified converter control structure.