Figure 2 . SCIG based WECS Schematic.
2.2. Type 3 WECS
Type 3 WECS is based on the doubly fed induction generator (DFIG). In this study, each DFIG is rated at 1.5MW and in order to achieve a 9MW capacity windfarm, 6 WECSs are considered operational. Fig. 3 shows the general schematic. Field orientation schemes have been used for both the rotor side controller (RSC) and grid side controller (GSC) with both active and reactive power control achieved through the RSC using stator voltage orientation scheme. DC link voltage control, on the other hand, is achieved through the GSC using grid voltage orientation scheme. Parameters of the DFIG are obtained from [22].