Comparative Analysis of Decoupling Control Methodologies and H∞ Multivariable Robust Control for Variable-Speed, Variable-Pitch Wind Turbines: Application to a Lab-Scale Wind Turbine

Abstract

This work is focused on the improvement of variable-speed variable-pitch wind turbine performance by means of its control structure. This kind of systems can be considered as multivariable nonlinear processes subjected to undesired interactions between variables and presenting different dynamics at different operational zones. This interaction level and the dynamics uncertainties complicate the control system design. The aim of this work is developing multivariable controllers that cope with such problems. The study shows the applicability of different decoupling methodologies and provides a comparison with a H ∞ controller, which is an appropriate strategy to cope with uncertainties. The methodologies have been tested in simulation and verified experimentally in a lab-scale wind turbine. It is demonstrated that the wind turbine presents more interaction at the transition zone. Then, this operational point is used as the nominal one for the controller designs. At this point, decoupling controllers obtain perfect decoupling while the H ∞ control presents important interaction in the generated power loop. On the other hand, they are slightly surpassed by the robust design at other points, where perfect decoupling is not achieved. However, decoupling controllers are easier to design and implement, and specifically dynamic simplified decoupling achieve the best global response. Then, it is concluded that the proposed methodologies can be considered for implantation in industrial wind turbines to improve their performance.

Improvement of Small Wind Turbine Control in the Transition Region

“…The wind speed profile generated in the experimental tests is modeled as a stationary stochastic process. The reader is referred to [5,25] and the references therein for more detailed information about the employed wind speed model. The generated wind speed is based on the four components described by the following equation:…”

“…On the other hand, there is the high speed region or full load (power regulation The main aim of this work is to provide a reliable controller with good performance properties in the different operating points of a wind turbine. In a previous work [5], the authors compared different multivariable control methodologies to improve the energy capture, power quality, and wind transient alleviation for variable-speed variable-pitch (VS-VP) wind turbines. These techniques showed a proper closed-loop response, specifically at the transition region, which presents more interaction.…”

“…The dependence of the wind turbine dynamic response with the operating point has motivated the research of different control techniques, from standard PID controllers to more complex strategies, such as neural network-based controls [9], model predictive controls [10,11], robust H∞ controls [12], optimal linear quadratic Gaussian (LQG) controls [13], linear parameter varying (LPV) The main aim of this work is to provide a reliable controller with good performance properties in the different operating points of a wind turbine. In a previous work [5], the authors compared different multivariable control methodologies to improve the energy capture, power quality, and wind transient alleviation for variable-speed variable-pitch (VS-VP) wind turbines. These techniques showed a proper closed-loop response, specifically at the transition region, which presents more interaction.…”

Adaptive State Feedback—Theory and Application for Wind Turbine Control

“…The inclusion of aerodynamics and an aeroelastic interaction with a highly flexible blade makes the system more complex, which introduces uncertainties during modeling. A wide spectrum of controller architecture, such as traditional Proportional-Integral-Derivative (PID) [4], multivariable [5,6], robust [7,8], model predictive [9,10] architecture, and so forth, have been used to achieve different performance goals. However, an adaptive control architecture is very attractive because of its capability to incorporate the uncertainty involved in the system.…”

Distributed Coordinated Control of Offshore Doubly Fed Wind Turbine Groups Based on the Hamiltonian Energy Method

“…Furthermore, wind-power control technology has gained increasing research interest [1][2][3][4]. Recently, the research focus has shifted from simple-machine control to cluster control, and the coordinated control of multi-machine systems has become an attractive topic [5,6].…”