This paper presents a theoretical study of wind farm based on doubly fed induction generator (DFIG), connected to the power grid through a five-level level neutral point clamped inverter (5-LNPCI). A dc filter model is proposed, proportional integral controllers are used for maintaining the dc voltages of each capacitor constant. Thus the imbalance capacitor voltage improved and the overvoltage on the semiconductors of the five-level inverter avoided. The proposed topology allows to: extract power over wide range of speed variation, control of active and reactive powers injected into the power grid, improve the quality of voltage waveform, reduce the harmonics content, improve the power injected into the grid and avoid the bulky connecting transformer. The system’s mathematic model is implemented and simulated on software MATLAB/Simulink.

Keywords: Doubly fed induction generator (DFIG), Wind energy conversion systems (WECS), Five-level inverter, Power quality, Total harmonics distortion (THD)