Modeling and control of unbalanced and distorted grid voltage of grid-connected DFIG wind turbine

This paper presents a mathematical modeling and current control of DFIG wind turbine system in the presence of unbalanced and harmonic distortions in the grid voltage. A proportional resonant (PR) current controller is modeled and implemented to reduce the impacts caused by the presence of double-frequency, fifth and seventh harmonic components in the generator torque, active and reactive power and the grid active power to which the wind generation system is connected. To reduce the impacts of the presence of the harmonics and unbalanced voltage in the stator and grid active and reactive powers, the dq-axis current components of these harmonics are controlled separately in the rotor and grid side converters. The use of PR controllers represents the addition of a specific function that eliminates the negative sequence and harmonic components from the rotor current components which reduce the oscillations of the generator torque and grid active power. The performance of the proposed control algorithm is validated through experiments and evaluated during the grid disturbances.