Modeling and control of DFIG via back-to-back multilevel converters using fuzzy logic controller

Abstract

This paper deals with the power generation in variable speed wind turbine systems. In this context, the wind energy conversion system (WECS) is equipped with a doubly-fed induction generator (DFIG) and two back-to-back five-level Neutral-Point-Clamped (NPC) converters in the rotor circuit. The modeling and the control of the five-level converter is presented. For controlling the DC-link voltage of the five-level rectifier, the proposed control algorithm consists of controlling the average value of the DC-link voltage. A vector control of the rotor side converter (RSC) provides an independent control of the generated active and reactive power and optimal speed tracking for maximum energy capture from the wind. An intelligent fuzzy inference system was proposed as alternative of the conventional proportional-integral (PI) controller in the maximum power point tracking (MPPT) control system; three fuzzy controllers are used in the RSC for the speed, stator active and reactive power control. The proposed control system has been applied to a WTS (wind turbine system) driving a 1.5MW DFIG, and tested in MATLAB/ SimPowerSystem environment.