Efficient control scheme of wind turbines with doubly fed induction generators for low-voltage ride-through capability enhancement

As the penetration of wind power in electrical power systems increases, it is required that wind turbines remain connected to the grid and actively contribute to the system stability during and after grid faults. This study proposes an efficient control strategy to improve the low-voltage ride-through (LVRT) capability in doubly fed induction generators (DFIGs). The proposed scheme consists of passive and active LVRT compensators. The passive compensator is based on a new crowbar arrangement located in series with stator windings. It considerably reduces the rotor inrush current at the instants of occurring and clearing the fault. The active LVRT compensator is realised through rotor voltage control and reduces the oscillations of electrical torque, rotor instantaneous power and DFIG transient response during the voltage dip. The proposed LVRT control not only reduces the peak rotor fault current, but also minimises the rotor instantaneous power oscillations, and consequently limits the dc-link voltage fluctuations. At the end, results of theoretical analyses are verified by time-domain simulations.