A novel robust control and fault ride through for wind turbines with doubly fed induction generator operating in weak grids

Doubly-Fed Induction Generator based wind turbines are highly susceptible to a disturbance such as faults and grid unbalance voltages. They are disconnected from the grid during disturbance conditions, leading to poor utilization of wind turbine. Future grid codes will require each turbine to have Low Voltage Ride Through (LVRT) capability to keep turbine operating during the low grid voltage condition. Thus, maintaining the turbine operating during various disturbances and low grid voltages is a real challenge. In this research a control strategy for grid side converter and rotor converter in the rotor circuit is implemented to maintain the turbine connected to the grid during various disturbances, low grid voltages and variations in the system parameters and wind. A robust controller based on H infinity technique and mu - analysis is designed to minimize the effects of disturbances and variations, and to provide reactive power support to the grid. The control scheme is tested on a low-power laboratory prototype.