Direct torque control and direct power control with multilevel converters for variable speed wind turbines

This paper presents WECS (wind energy conversion system) installed with BTB (back-to-back) medium voltage diode clamped five-level converter and SCIG (Squirrel-Cage-Induction-Generator) for a large capacity wind turbine (5MW). The DTC (direct torque control) has been used for the machine side diode clamped five-level converter. The use of DTC with the MLC (multilevel converter) gives a better performance of SCIG (flux, torque, current and speed) to improve the energy efficiency of a variable speed WECS. Utility-grid side diode clamped five-level converter uses the DPC (direct power control) technique. This technique is used to improve the performance of the delivered power flowing from the dc-link to the electric utility-grid (decrease ripples of the DC-link voltage, decrease THD (total-harmonic-distortion) and improve the power factor of the injected power to the utility-grid). The proposed system simulation is done using Matlab/SimulinkSimscape Power Systems to compare this system and the classical two-level converter.