Analysis of Sub-Synchronous Oscillations on Hybrid Wind Farms with DFIG and PMSG

This paper has investigated the sub-synchronous oscillations (SSO) phenomenon in hybrid wind farms with DFIG and PMSG. Firstly, a mathematical model of the hybrid wind farms is established. The model includes four parts: hybrid wind turbine, DFIG rotor machine-side controller (RSC), PMSG stator grid-side controller (GSC) and series compensation line module. Based on this model, the factors affecting the SSO phenomenon in the hybrid wind farms are explored by eigenvalue analysis. It is concluded that the variation of wind speed increases the possibility of SSO generation in DFIG wind farms, but the addition of PMSG wind farms can suppress the effect of wind speed variation. In comparison to single DFIG wind farms or PMSG wind farms, hybrid wind farms are less likely to generates SSO that results from the variation of PLL parameters. In addition, too large series compensation degree can lead to a more severe dynamic response of SSO phenomenon.