| Wind Power is one of the rapidly emerging energy sources in the world these days. It is a clean source of energy, as it doesn't emit any greenhouse gases. However the growth of wind power has its own hurdles. Grid connection of wind turbines isn't as easy as any other turbine connections to the grid. There are certain requirements being proposed by power authorities. Few such requirements are as follows: reactive power compensation, low voltage ride through and voltage unbalance compensation. In this thesis a new scheme is proposed to connect wind turbines to the power grid. With this scheme it is possible for wind turbines to remain synchronized to the grid even during fault. This scheme also takes care of grid voltage unbalances and reactive power compensation.; The proposed scheme makes use of series converters to achieve the desired objectives. One single-phase converter is connected in series of each phase. DC link voltage balancing is achieved by all three converters during normal operation. In the event of a fault or voltage unbalance, one of the converters injects voltage in one of the phases to limit the fault current or to compensate for the voltage unbalance. Reactive power compensation and speed control are done by stator flux oriented vector control of Doubly Fed Induction Generator. |
