Maximum power control of grid-connected DFIG-based wind systems

This paper presents maximum power control of doubly-fed induction generator (DFIG) based grid-connected wind energy system. The control system used a combination of MPPT method with pitch control to extract maximum power from the wind turbine. PWM hysteresis controller is used to control the back to back converter which output is connected to the utility grid through a multivariable filter. The overall wind system is theoretically analyzed and modeled in Matlab/Simulink/ SimPowerSystems environment. The grid-connected wind system's performances are evaluated.

I. INTRODUCTION

During the last decades, wind energy knew a strong growth because of its advantages for the environment, technological breakthroughs and subsidies programs from governments [1]. This increase of installed wind power will have growing impact on utility networks because of the important range of the variation of wind speeds. To maximize the output wind power, the speed of the turbine must be adjusted accordingly to wind speed [2]. This is reason why, medium and high power wind systems connected to utility networks, operate generally in variable speed mode. Doubly Fed Induction Generator (DFIG) is one of the most popular wind generators. DFIG wind system provides many advantages: •

The back to back converter used in the rotor's circuit is smaller (around one third of the generator's rated power)

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There are less losses in semiconductors

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The control system can be operated to compensate reactive power and currents harmonic at the point of common coupling (PCC) [2]–[7].