Control strategies of doubly fed induction generators to support grid voltage

The use of wind power has been increasing very fast in the last 10 years. Many new projects for the next 10 years including offshore and onshore wind farms are been developed and planned. The fast growing of the use of wind power has brought new challenges to the Transmission System Operators (TSO) in regions where wind power has reached significant penetration levels like Denmark, United Kingdom, Spain and Germany. According to new grid code requirements wind turbines must remain connected to the grid during grid disturbances and, moreover, they must also contribute to voltage support during and after grid faults. Dynamic models of doubly fed induction generator (DFIG) were developed to investigate the behavior off different converter control and protection strategies of the back-to-back IGBT-based converters during grid fault. The results have showed that reactive power injection by DFIG-based wind farms is limited when the rotor side converter is blocked.