A Maximum Power Tracking Technique for Grid-Connected DFIG-Based Wind Turbines

Abstract

In this paper, a maximum power tracking technique is presented for doubly fed induction generator (DFIG)-based wind turbines. The presented technique is a novel version of the conventional method, i.e. the electrical torque is proportional to the square of the rotor speed, in which the proportional-coefficient is adaptively adjusted in real-time through three control laws. The first control law calculates the desired electrical torque using feedback linearization, assuming that the power capture coefficient and the desired rotor speed are instantaneously identified. The second control law estimates realtime values of the power capture coefficient from a Lyapunovbased analysis, and the third control law provides the desired rotor speed. These control laws cause the turbine to adaptively adjust the rotor speed towards a desired speed in which the operating point moves in the direction of increasing the power capture coefficient. The proposed maximum power tracking method differs distinctly from the perturb-and-observe scheme by eliminating a need for adding a dither or perturbation signal, and robustly tracks the trajectory of maximum power points even in the event of a sudden wind speed change that can cause the perturb-and-observe technique to fail. In this paper, the NREL 5 MW reference wind turbine model is used to demonstrate the validity and robustness of the proposed method.

Development and Control of Generator-Converter Topology for Direct-Drive Wind Turbines

“…The controller is equipped with one of the existing MPPT techniques, e.g. P * = K opt ω R 3 , [36,37]. Figure 8 shows the block diagram of the controller for the boost CSI.…”

Candid inquest on modeling methods of doubly fed induction generator, and corroboration through simulation study

“…The electromagnetic torque expression, In the general dq model, by transforming the three phase variables of stator and rotor into the rotating reference frame, the mutual inductance corresponds to stator and rotor become independent of rotor speed and position [23][24]. The voltages, currents and flux linkage expressions are similar but the electromagnetic torque is given as the function of flux linkage and currents with half of the pole pair.…”

Indirect boost matrix converter and low‐voltage generator for direct drive wind turbines

“…The measured power on the dc‐side is compared to the desired active power signal, , and the error is forced to zero through a proportional integral (PI) controller, while generating the desired q ‐axis voltage, , for the converter input. The desired active power, , signal is generated from the generator rotor speed, using the an existing MPPT technique, where , [17, 18]. The generated and the measured are used to compute the reference signals for generating the switching signals for the VSC using sine pulse width modulation (PWM) switching technique.…”