Design and Analysis of Fuzzy Logic Controller of Vector Controlled Doubly Fed Induction Generator in Wind Energy Conversion System for Maximum Power Transfer Capability

Abstract

In recent times, the environmental pollution has added up a major concern in individual’s lifestyle and a possible energy crisis has led them to create modern innovations for generating energy. Renewable energy assets have gained critical consideration of the industry and scholars, since it is ecologically friendly. Wind energy has gotten to be one of the foremost important and promising sources of renewable energy due to its cost effectiveness and availability. It has been recognized that, doubly fed induction generator (DFIG) based variable speed wind turbine technology is the foremost successful with less cost and high-power generation. Hence, this study has chosen a 2MW DFIG based wind turbine framework for complete study of modeling, analysis and control research. It consists of stator and rotor windings, where the stator part is directly connected to the electrical network, and the rotor is connected to the grid through AC/DC/AC voltage source converters. The AC/DC/AC voltage source converter includes both machine side converter and grid side converter with a common Dc-link capacitor. The main purpose of the generator side converter is to adjust the speed of the generator rotor and independently control the active and reactive power of the stator. The grid-side converter regulates the DC-link bus voltage to a constant value and maintains the reactive power exchange between the electrical grid and wind turbine generator with the unity power factor to produce the maximum active power output. In this thesis work, an artificial fuzzy logic control strategy is designed and developed for a vector controlled DFIG to regulate rotor speed. When compared with proportional integral control method, the proposed control strategy, which is applied to the speed loop reduces the settling time by 40% and eliminate the maximum overshoot to zero. Maximum power point tracking control strategy is designed by using an indirect speed control procedure in order to drive the aerodynamic torque to follow the maximum power curve proportional to wind speed change. Since, power electronic voltage source converters are connected with the rotor part of the generator, the grid faces voltage and current harmonic problems at the point of common coupling. In order to mitigate such harmonic disturbances, an LCL filter is introduced and three-phase multi-level voltage source converter is modeled and designed by applying space vector pulse width modulation (SVPWM) technique. The overall analysis, modeling and simulation have been developed by using MATLAB/Simulink software.