Modeling and Simulation of Grid Connected Wind Energy Conversion System Based on a Doubly Fed Induction Generator (DFIG)

Abstract

This paper deals with the analysis, modeling, and control of a grid connected doubly-fed induction generator (DFIG) driven by the wind turbine. Recent advancements in size and technology of wind turbines require sophisticated control systems to effectively optimize energy conversion and enhance grid integration. This article investigates the power flow analysis of grid connected Wind Energy Conversion System (WECS) in a highly fluctuating wind environment. The WECS is equipped with a DFIG and a back-to-back converter in the rotor circuit. A control technique is presented for extracting the maximum power from the wind turbine. The grid side converter maintains the DC link voltage and the task of the rotor side converter is to track the maximum power point for the wind turbine. The description for the proposed system is presented with the detailed dynamic modeling equations. Simulation results for different operating conditions are presented. speed. Because the power converter only process the slip rotor power, which is typically 25% of the rated output power, the DFIG offers the advantages of speed control for a reduction in cost and power losses (2)-(3). This paper presents a DFIG wind turbine system that is modeled in Matlab/Simulink and PLECS. A full electrical model is implemented that includes the power converter for the rotor side and a dq model of the induction machine. The aerodynamics of the wind turbine and the mechanical dynamics of the induction machine are included to extend the use of the model for variable wind speed conditions. For longer simulations that include these slower mechanical and wind dynamics, an averaged PWM converter model is presented. The averaged electrical model offers improved simulation speed at the expense of neglecting converter switching detail. The main feature of the implemented model is the possibility to investigate topics related to the diagnosis and Low Voltage Ride Trough (LVRT) capability of WECS. Simulation results for different operating conditions are presented in this paper, whereas the LVRT characteristics will be analyzed in a next paper.