Voltage/Pitch Control for Maximization and Regulation of Active/Reactive Powers in Wind Turbines with Uncertainties

TL;DR

This paper presents a comprehensive control strategy for wind turbines with DFIGs that maximizes and regulates active/reactive power, effectively handling uncertainties and switching between power modes without detailed aerodynamic data.

Contribution

It introduces a novel cascaded control framework combining linear and nonlinear methods to optimize power output and regulation in uncertain wind turbine models.

Findings

Effective power maximization and regulation demonstrated in simulations

Seamless switching between power modes achieved

Controller operates without detailed aerodynamic parameters

Abstract

This paper addresses the problem of controlling a variable-speed wind turbine with a Doubly Fed Induction Generator (DFIG), modeled as an electromechanically-coupled nonlinear system with rotor voltages and blade pitch angle as its inputs, active and reactive powers as its outputs, and most of the aerodynamic and mechanical parameters as its uncertainties. Using a blend of linear and nonlinear control strategies (including feedback linearization, pole placement, uncertainty estimation, and gradient-based potential function minimization) as well as time-scale separation in the dynamics, we develop a controller that is capable of maximizing the active power in the Maximum Power Tracking (MPT) mode, regulating the active power in the Power Regulation (PR) mode, seamlessly switching between the two modes, and simultaneously adjusting the reactive power to achieve a desired power factor. The controller consists of four cascaded components, uses realistic feedback signals, and operates without knowledge of the C_p-surface, air density, friction coefficient, and wind speed. Finally, we show the effectiveness of the controller via simulation with a realistic wind profile.