Direct Torque Control-Fuzzy Type 2 for Direct Current Link Voltages Balancing of the Five-Level Cascade Converters Used in a Wind Energy Conversion System

Abstract

The available power of a wind system depends mainly on the wind speed. In addition, the wind system will give a power output that varies according to the speed of its generator which is a double feed asynchronous machine in our case. In other words, there is an optimal operating point that makes the most of the power available. In this work an innovative technique of capturing maximum power based on type-2 fuzzy systems. The principle of this Maximum Power Point Tracking algorithm is to look for an optimal operating relationship at maximum power and then track the maximum power based on this relationship. As part of the variable speed conversion of wind energy, this article proposes a simplified power electronics for injecting the energy produced in the network, the conversion chain includes a variable speed double feed asynchronous generator, two (back-to-back) converters five-level Neutral Point Clamped type operating in grid side rectifier and rotor-side inverter mode. The main objective of this article is to develop a new stabilization strategy of direct control compatible with voltage inverters at five levels, more particularly Neutral Point Clamped structure. This strategy allows flow and torque control of the double feed asynchronous machine and stabilizes the input capacitor voltages of the inverter. The response of the system obtained with this algorithm makes it possible to validate the soft solution proposed and show, during variation of the wind speed, a fast and precise adaptation of the speed of the double fed induction generator.