Enhanced dual-converter resonance control coordinated with gate- controlled series capacitor for sub-synchronous resonance mitigation in series-compensated DFIG-based wind energy systems

Fixed series capacitors are effective in increasing transmission line capacity in grid-connected Doubly Fed Induction Generator (DFIG)-based wind farms. Sub-Synchronous Resonance (SSR) phenomena occur when the series capacitors are in operation. The Gate-Controlled Series Capacitor (GCSC) model is used to eliminate the SSR effect. However, while the GCSC can control low series capacitance conditions, it is insufficient in high series capacitance conditions. To address this problem, this study aims to enhance a resonance control model for the Rotor-Side Converter (RSC) and Grid-Side Converter (GSC) circuits to reduce the SSR effect and improve the system's efficiency under different operating conditions in the DFIG. By enhancing the resonance control models for the GCSC and converter circuits, comparisons are made on some parameters in the DFIG at different wind speeds and different fixed series compensation ratios. In these comparisons, evaluations were made using the traditional model, the GCSC model, and the enhanced resonance control model in multiple applications in the RSC and RSC-GSC circuits. In addition, eigenvalue analyses were examined in detail in the comparisons. The results showed that the resonance control models enhanced for the GCSC and RSC-GSC circuits stabilized the system in a short time, and the resulting oscillations were quickly damped.