A look-up table based approach for fault ride-through capability enhancement of a grid connected DFIG wind turbine

In wind power systems consisting of grid connected doubly fed induction generators (DFIGs), transient faults usually occur for a couple of milliseconds (typically between 100-700 ms) due to many reasons and cause voltage sags in different spots of wind power systems. During fault and after fault clearance, the parameters of DFIG such as produced active power, rotor speed, and rotor current profiles, experience disturbances for several seconds. The mean rate of wind speed and the kind of transient fault are two important factors which directly affect the duration and severity of disturbances. This paper described a new, simple approach for improving fault ride-through (FRT) capability of a grid connected DFIG wind turbine via using the look-up table (LUT) based procedure. The proposed method was based on the correction of the reference current value of the rotor current control in the rotor side converter (RSC) to smooth the reference current profile, which was destructed due to the occurrence of transient faults. Moreover, a speed damping loop was utilized by applying the other LUT for extracting the values of rotor reference speed to add the oscillations of the rotor speed to the improved reference current (Ird2∗) profile for compensation. Different simulations were carried out on the test system to validate the proposed method considering different mean wind speeds with various kinds of transient faults. The obtained results indicated that applying this approach could significantly improved DFIG performance in the case studies of symmetrical and asymmetrical transient faults, also oscillations on the produced active power, rotor speed and rotor current magnitude were significantly mitigated.