SSR Alleviation by STATCOM in Induction-Generator-Based Wind Farm Connected to Series Compensated Line

In this paper, a static synchronous compensator (STATCOM) with a voltage controller is proposed to mitigate the potential of sub synchronous resonance (SSR) in a series compensated induction-generator (IG)-based wind farm. Detailed eigenvalue analysis is performed to demonstrate that IG effect SSR is successfully alleviated by STATCOM. The results are validated through electromagnetic transient simulation with PSCAD/EMTDC. The impacts of symmetrical fault at different locations and collector cables are investigated, and the effectiveness of the proposed STATCOM controller is illustrated. It is shown that a three-phase fault close to the wind farm may cause severe oscillations in the point of common coupling (PCC) voltage, electromagnetic torque, and shaft torque of the wind turbine generator. To examine this situation, an equivalent circuit analysis is presented, which predicts the band of resonant speeds within which the wind turbine becomes unstable. The study is extended to other commercially available IGs, which also show the potential for SSR even at realistic levels of series compensation levels, and the capability of the proposed STATCOM controller to obviate its occurrence.