Mitigation of subsynchronous oscillations in a series compensated wind farm with Thyristor Controlled Series Capacitor (TCSC)

Abstract

Wind power penetration is rapidly growing all over the world as the alternative, renewable and environment friendly resource of energy production. With this rapid growth of wind power, the power systems of future will likely see the integration of large wind farms with electrical networks that are series compensated for ensuring stable transmission of bulk power. This may potentially lead to subsynchronous resonance (SSR) issues. Although SSR is a well-understood phenomenon that can be mitigated with FACTS devices, scant information is available on the SSR problem in a series compensated wind farm. This paper reports the occurrence and mitigation of SSR caused by induction generator (IG) effect as well as torsional interactions (TI), in a series compensated wind farm. SSR suppression is achieved as an added advantage of a thyristor controlled series capacitor (TCSC) actually installed to increase the power transfer capability of the transmission line. In this study, a wind farm employing self-excited induction generator (SEIG) is connected to the grid through a series compensated line. A thyristor controlled series capacitor (TCSC) is shown to damp subsynchronous oscillations when provided with closed loop current control. Extensive simulations have been carried out using EMTDC/PSCAD to validate the performance of TCSC in damping SSR.