SSR suppression via STATCOM in series compensated wind farm integrations

The growing need to the clean and renewable energy has led to the fast development of wind power systems all over the world. Large wind farms are going to be connected to electrical networks which have been series compensated to guarantee the safe and stable transmission of bulk power. However a series compensated power system may encounter with a very important problem known as subsynchronous resonance (SSR). Flexible ac transmission systems (FACTS) controllers are widely applied to mitigate subsynchronous oscillations. The main objective of this work is to study the capability of the static synchronous compensator (STATCOM) for mitigation of SSR caused by an induction-generator (IG) effect as well as torsional interactions (TI) in a wind farm. In order to conduct the studies, the IEEE first benchmark model on SSR is adapted with the combination of self-excited induction generator (SEIG) based wind turbine. An STATCOM with a simple voltage control is first employed at the generation terminal. It is shown that the STATCOM can damp the SSR even without a specific control. In the following the same STATCOM is shown to effectively damp SSR when equipped with an auxiliary SSR damping (SSRD) controller. Extensive transient simulations have been carried out using EMTDC/PSCAD to demonstrate the capability of STATCOM in damping SSR.