Beyond the linear limitations by combining switching and QFT: Application to wind turbines pitch control systems

García-Sanz, Mario; Elso, Jorge

doi:10.1002/rnc.1319

Cited by 18 publications

(13 citation statements)

References 15 publications

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“…Quantitative Feedback Theory ( [26][27][28][29][30] and [38]) is a robust frequency domain control design methodology which has been successfully applied in many practical problems of different domains [10][11][12][13][14][15][16][17][18][19][20][21]. One feature that distinguishes QFT from other frequency-domain methods is its ability to deal directly with uncertainty models and robust performance criteria in a very transparent way.…”

Section: Introductionmentioning

confidence: 99%

Automatic loop-shaping of QFT robust controllers

Molins

García-Sanz

2009

Proceedings of the IEEE 2009 National Aerospace &Amp; Electronics Conference (NAECON)

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This paper introduces a methodology to design automatically QFT (Quantitative Feedback Theory) robust controllers for SISO (single input-single output) plants with model uncertainty. The method generalizes previous automatic loop-shaping techniques, avoiding restrictive assumptions about the search space. This methodology applies two strategies: a) Evolutionary Algorithms, and b) Genetic Algorithms (GA). In both cases the objective is to search the QFT robust controller that fulfils the control specifications for the whole set of plant models within the uncertainty. Each strategy has been applied to a benchmark in order to validate the techniques.

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Section: Introductionmentioning

confidence: 99%

Automatic loop-shaping of QFT robust controllers

Molins

García-Sanz

2009

Proceedings of the IEEE 2009 National Aerospace &Amp; Electronics Conference (NAECON)

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“…In [4], linear limitations of linear robust controllers overcame by combining switching and Quantitative Feedback Theory (QFT). QFT is a powerful design methodology that provides a transparent trade off between different often conflicting design specifications.…”

Section: Introductionmentioning

confidence: 99%

“…It suggests a controller with minimum cost of feedback that satisfies the set of performance specifications in spite of the plant uncertainty [5], [6]. Combining robust designs and switching, the designed controller optimizes the time response of the system by fast adaptation of the controller parameters during the transient response based on the error amplitude [4].…”

Section: Introductionmentioning

confidence: 99%

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Design of supervisory based switching QFT controllers for improved closed loop performance

Namaki-Shoushtari

Sedigh

2010

2010 18th Iranian Conference on Electrical Engineering

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In this paper, the problem of supervisory based switching Quantitative Feedback Theory (QFT) control is proposed for the control of highly uncertain plants. According to this strategy, the uncertainty region is divided into smaller regions with a nominal model. It is assumed that a QFT controller exits for robust stability and performance of the individual uncertain sets. The proposed control architecture is made up by these local controllers, which commute among themselves in accordance with the decision of a high level decision maker called the supervisor. The supervisor makes the decision by comparing the candidate local model behavior with the one of the plant and selects the controller corresponding to the best fitted model. A hysteresis switching logic is used to slow down switching for stability reasons. It is shown that this strategy leads to improved closed loop performance, and can also handle the uncertainty sets that can not be tackled by a single QFT robust controller. Simulation results are proposed to show the effectiveness of the proposed methodology.

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“…Garcia-Sanz and Elso [3] propose a methodology to design a family of robust controllers able to go beyond the classical linear limitations. Combining robust designs and stable switching, the new controllers optimize the time response of the system by fast adaptation of the controller parameters during the transient response according to certain rules based on the amplitude of the error.…”

Section: Editorialmentioning

confidence: 99%

Wind turbines: New challenges and advanced control solutions

García-Sanz

2008

Intl J Robust & Nonlinear

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After more than a decade with a quasi-exponential growing, wind energy has tripled its worldwide generation capacity in the last five years, being once again the fastest growing energy source in the world, with about 100 GW installed by 2008. Moreover, the current European and American expectations for the near future suggest a significant upward trend of about 170 GW installed by the end of 2010. The currently installed wind power capacity generates 200 TWh per year, equaling 1.3% of the global electricity consumption. The wind industry employs today 350 000 people worldwide. Simultaneously, the average power output of a wind turbine unit has increased significantly, going from 300 kW ( Wind turbines are complex systems, with large flexible structures working under very turbulent and unpredictable environmental conditions, and subject to a variable and demanding electrical grid. The efficiency and reliability of a wind turbine strongly depend on the applied control strategy. Large nonlinear characteristics and high model uncertainty due to the interaction of the aerodynamic, mechanical and electrical subsystems, stability problems, maximization of wind energy conversion matters, load reduction strategies, mechanical fatigue minimization problems, reliability issues, availability aspects, costs per kWh reduction strategies, etc. make it necessary to design powerful control systems to regulate in a coordinated way many variables such as pitch, torque, power, rotor speed, yaw orientation, temperatures, currents, voltages, power factors, etc.Furthermore, increasing level of wind energy penetration in the grid (nowadays wind power accounts for approximately 19% of electricity production in Denmark, 10% in Spain, 6% in Germany, etc.) has revealed new critical challenges and problems: response to grid voltage dips, frequency and active power control loops, voltage and reactive power regulation, restoration of grid services after power outages, wind prediction, etc. They have resulted in an urgent need for new control solutions, combining nonlinear control, adaptive techniques, robust methodologies, load sharing aspects, predictive laws, multivariable control, etc.

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Beyond the linear limitations by combining switching and QFT: Application to wind turbines pitch control systems

Cited by 18 publications

References 15 publications

Automatic loop-shaping of QFT robust controllers

Automatic loop-shaping of QFT robust controllers

Design of supervisory based switching QFT controllers for improved closed loop performance

Wind turbines: New challenges and advanced control solutions

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