SSR mitigation in wind farm connected to series compensated transmission line using STATCOM

Abstract

Series compensation is being increasingly considered for increasing transmission capacity for integration of large wind farms. This paper presents the potential of subsynchronous resonance (SSR) in large squirrel cage induction generator based wind farms connected to the series compensated transmission line. In order to suppress the unstable SSR oscillations, a STATCOM with suitable controller is proposed at the terminal of the wind farm. A detailed linear state space model is developed for the wind farm, transmission system which is a modified IEEE First SSR Benchmark system and the STATCOM. Eigenvalues are calculated for a wide range of wind farm power outputs and series compensation levels. The potential of SSR involving both induction generator effect and torsional interaction is investigated in-depth. The eigenvalues obtained from the linear state space model are validated through the electromagnetic transient simulation carried out with PSCAD/ EMTDC software. It is shown that SSR may potentially occur for large wind farms at higher level of series compensation which can be mitigated by the STATCOM with an appropriate controller.