@article {78, title = {Gain scheduled control based on high fidelity local wind turbine models}, journal = {Renewable Energy}, volume = {37}, year = {2012}, pages = {233 - 240}, abstract = {

A new design methodology of gain scheduled controllers for wind turbines is presented. The proposed methodology is intended to deal with multi-variable and high order models as those produced by high fidelity aeroelastic simulators. The methodology consists in interpolating the local controller outputs and does not require a uniform state definition either of the local controllers or of the linear models. This allows the design of each controller independently, an essential point in cases of high order models. An aeroelastic model of a typical commercial wind turbine is used to illustrate the methodology.

}, keywords = {Wind energy}, issn = {0960-1481}, doi = {http://dx.doi.org/10.1016/j.renene.2011.06.024}, url = {http://www.sciencedirect.com/science/article/pii/S0960148111003168}, author = {Bianchi, Fernando D. and S{\'a}nchez-Pe{\~n}a, Ricardo S. and Guadayol, M.} } @article {92, title = {A simple robust controller for power maximization of a variable-speed wind turbine}, journal = {International Journal of Energy Research}, volume = {34}, year = {2010}, pages = {924{\textendash}932}, abstract = {

This paper presents a high-order sliding mode control strategy that aims to optimize the power conversion efficiency of a wind energy conversion system within the partial load zone of operation. The main challenges of this control problem are related to the random variations of the wind speed, the nonlinear nature of the whole system, usual model uncertainties and external disturbances. For all these reasons, the robustness, simplicity and low computational burden of the proposed super-twisting algorithm result very attractive in this context. Simulation results that show the achievement of the desired characteristics are provided. Copyright {\^A}{\textcopyright} 2009 John Wiley \& Sons, Ltd.

}, keywords = {efficiency optimization, Robust control, Sliding mode, Wind energy}, issn = {1099-114X}, doi = {10.1002/er.1613}, url = {http://dx.doi.org/10.1002/er.1613}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando} } @conference {91, title = {Variable gains super-twisting control for wind energy conversion optimization}, booktitle = {Variable Structure Systems (VSS), 2010 11th International Workshop on}, year = {2010}, month = {June}, abstract = {

An adaptive second order sliding mode control strategy is explored in this work, to maximize the energy extracted from the wind in a wind energy conversion system (WECS). It is required to such strategy to deal with the nonlinear nature of the WECS, the randomness of the wind speed, model uncertainties and external disturbances, and also with the need to reduce mechanical loads. The special features of this adaptive technique together with the robustness, relative simplicity and other desirable inherent characteristics of the super-twisting algorithm make the proposed controller an attractive solution. The suitability of the proposed strategy is proved by extensive computer aided simulations employing a comprehensive model of the system.

}, keywords = {adaptive control, adaptive second order sliding mode control, Computational modeling, computer aided simulation, Computer Simulation, control system synthesis, Gain, Lyapunov based controller design, Lyapunov methods, nonlinear systems, optimisation, Programmable control, Robust control, Sliding mode control, Uncertainty, variable gain super twisting control, variable structure systems, Wind energy, wind energy conversion optimization, wind power, Wind speed}, doi = {10.1109/VSS.2010.5544713}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5544713}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and D{\textquoteright}ávila, A.} } @article {95, title = {Wind turbine efficiency optimization. Comparative study of controllers based on second order sliding modes}, journal = {International Journal of Hydrogen Energy}, volume = {35}, year = {2010}, pages = {5934 - 5939}, abstract = {

This paper studies the applicability of second order sliding mode control strategies to a wind energy conversion system aiming to optimise its power conversion efficiency. Four different controllers are designed and analysed, based on the {\^a}{\texteuro}{\oe}sub-optimal{\^a}{\texteuro}�, {\^a}{\texteuro}{\oe}twisting{\^a}{\texteuro}�, {\^a}{\texteuro}{\oe}super-twisting{\^a}{\texteuro}� and {\^a}{\texteuro}{\oe}with a prescribed law of variation{\^a}{\texteuro}� algorithms, which present finite-time convergence, robustness, chattering and mechanical stress reduction, and are of quite simple online operation and implementation. Representative simulation results are shown, using a complete model of the system under realistic operating conditions, where the performance of the controlled system can be appreciated for each of the controllers and some comparisons can be made.

}, keywords = {Wind energy}, issn = {0360-3199}, doi = {http://dx.doi.org/10.1016/j.ijhydene.2009.12.104}, url = {http://www.sciencedirect.com/science/article/pii/S0360319909020321}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando} } @article {98, title = {A geometric approach for the design of MIMO sliding controllers. Application to a wind-driven doubly fed induction generator}, journal = {International Journal of Robust and Nonlinear Control}, volume = {19}, year = {2009}, pages = {22{\textendash}39}, abstract = {

This paper presents a systematic methodology to design controllers for a general class of nonlinear MIMO systems affine in the control in the presence of bounded uncertainties and disturbances. The design method is developed using a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, whereas chattering reduction is achieved by utilizing the minimum discontinuous action required to ensure disturbance rejection. The proposed methodology is applied to the control of a grid-connected wind energy generation system based on a doubly fed induction generator. The control objectives considered in this paper are maximization of the wind energy conversion and reactive power regulation to minimize machine losses. Copyright {\^A}{\textcopyright} 2008 John Wiley \& Sons, Ltd.

}, keywords = {efficiency optimization, Sliding mode control, Wind energy}, issn = {1099-1239}, doi = {10.1002/rnc.1323}, url = {http://dx.doi.org/10.1002/rnc.1323}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Spurgeon, Sarah} } @article {99, title = {High-Order Sliding Control for a Wind Energy Conversion System Based on a Permanent Magnet Synchronous Generator}, journal = {Energy Conversion, IEEE Transactions on}, volume = {23}, year = {2008}, month = {Sept}, pages = {860-867}, abstract = {

This paper presents the output power control of a wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG). It is assumed that the considered wind module integrates a stand-alone hybrid generation system, jointly with a battery bank, a variable ac load, and other generation subsystems. The operation strategy of the hybrid system determines two possible operation modes for the WECS, depending on the power requirements of the load and the wind availability. The paper deals with the design of a combined high-order sliding mode (HOSM) controller for the power control of the WECS on both operational modes. The main features of the obtained controller are its chattering-free behavior, its finite-time reaching phase, its simplicity, and its robustness with respect to external disturbances and unmodeled dynamics. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {chattering-free behavior, closed loop systems, closed-loop system, external disturbances, finite-time reaching phase, High-order sliding mode (HOSM), high-order sliding mode controller, nonlinear systems, permanent magnet generators, permanent magnet synchronous generator, PMSG, Power control, power generation control, stand-alone hybrid generation system, synchronous generators, variable structure systems, WECS, Wind energy, wind energy conversion system, wind power plants}, issn = {0885-8969}, doi = {10.1109/TEC.2008.922013}, author = {Valenciaga, Fernando and Puleston, Pablo F.} } @article {63, title = {Dynamical variable structure controller for power regulation of wind energy conversion systems}, journal = {Energy Conversion, IEEE Transactions on}, volume = {19}, year = {2004}, month = {Dec}, pages = {756-763}, abstract = {

The paper addresses the problem of output power regulation of fixed-pitch variable-speed wind energy conversion systems. Operation is constrained by practical reasons to the low-speed side of the turbine power-speed curve. Unfortunately, this region is characterized by a nonminimum phase dynamics which is an obstacle to perform the regulation task. A dynamical variable structure controller is developed that accomplishes the control objective despite this limitation. The proposed control strategy presents attractive features such as robustness to parametric uncertainties of the turbine and generator as well as to electric grid disturbances.

}, keywords = {65, Aerodynamics, Control systems, dynamical variable structure controller, electric grid disturbance, Electric variables control, Induction generators, Mesh generation, nonminimum phase dynamic, parametric uncertainty, Power control, Power generation, power generation control, power regulation, power supply quality, power system dynamic stability, power system interconnection, speed curve, turbine power, variable structure systems, Wind energy, wind energy conversion system, Wind energy generation, wind power, Wind speed, wind turbines}, issn = {0885-8969}, doi = {10.1109/TEC.2004.827705}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1359955}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {70, title = {Performance analysis of a variable structure controller for power regulation of WECS operating in the stall region}, journal = {International Journal of Energy Research}, volume = {25}, year = {2001}, pages = {1345{\textendash}1357}, abstract = {

This paper deals with power regulation in variable speed wind energy conversion systems. The importance of power control in the stall region is stressed. This mode of operation is characterized by a non-minimum phase behaviour. A variable structure controller is described that provides stability by means of speed feedback and is robust to grid disturbances and model uncertainties. Performance of the controller is investigated. A compromise arises in the design of the speed feedback gain between high and low frequency wind components rejection. Furthermore, a cut-off frequency of the wind velocity measurement is obtained that minimizes the effect of turbulence on power regulation. Simulation results are presented, corroborating the features of the control strategy.

}, keywords = {energy conversion, Power control, variable structure systems, Wind energy}, issn = {1099-114X}, doi = {10.1002/er.758}, url = {http://dx.doi.org/10.1002/er.758}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {72, title = {Dynamical sliding mode power control of wind driven induction generators}, journal = {Energy Conversion, IEEE Transactions on}, volume = {15}, year = {2000}, month = {Dec}, pages = {451-457}, abstract = {

This paper concerns power regulation of variable-speed wind energy conversion systems. These systems have two regions of operation, depending on the tip speed ratio of the wind turbines. They are distinguished by a minimum phase behavior in one of these regions and a nonminimum phase one in the other. A sliding mode control strategy is proposed that assures stability in both regions of operation and imposes the ideally designed feedback control solution in spite of model uncertainties. Moreover, power regulation by the proposed sliding control in the minimum phase region is completely robust to wind disturbances and parameter uncertainties

}, keywords = {asynchronous generators, Control systems, dynamical sliding mode power control, feedback, ideally designed feedback control solution, Induction generators, machine control, minimum phase behavior, minimum phase region, model uncertainties, nonminimum phase region, parameter uncertainties, Power control, Power generation, power regulation, Power system modeling, Robustness, Sliding mode control, stability, tip speed ratio, variable speed gear, variable structure systems, variable-speed wind energy conversion systems, wind disturbances, wind driven induction generators, Wind energy, Wind energy generation, Wind power generation, wind turbines}, issn = {0885-8969}, doi = {10.1109/60.900507}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=900507}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {74, title = {Sliding mode control of wind energy systems with DOIG-power efficiency and torsional dynamics optimization}, journal = {Power Systems, IEEE Transactions on}, volume = {15}, year = {2000}, month = {May}, pages = {728-734}, abstract = {

Wind turbines with double output induction generators can operate at variable speed permitting conversion efficiency maximization over a wide range of wind velocities. However, random wind fluctuations, wind shear and tower shadow, may excite the oscillation mode of the mechanical system, producing large torque ripple. Consequently, damage to drive train components and power quality problems may occur. In this paper, a sliding mode control is developed which provides a suitable compromise between conversion efficiency and torque oscillation smoothing. The resultant sliding dynamics is completely robust to uncertainties in the electrical variables and parameters. In addition, to prevent windup problems due to saturation, a combined sliding surface that incorporates such limitations is proposed

}, keywords = {asynchronous generators, combined sliding surface, conversion efficiency maximization, double output induction generators, drive train components, electrical variables uncertainties, Fluctuations, Induction generators, large torque ripple, machine control, mechanical system, Mechanical systems, oscillation mode excitation, oscillations, Poles and towers, power efficiency, power generation control, Power quality, power quality problems, power supply quality, random wind fluctuations, resultant sliding dynamics, Sliding mode control, Torque, torque oscillation smoothing, torsion, torsional dynamics optimization, tower shadow, uncertainties robustness, variable speed, variable speed gear, variable structure systems, Wind energy, wind energy systems, wind shear, Wind speed, wind turbines}, issn = {0885-8950}, doi = {10.1109/59.867166}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=867166}, author = {De Battista, Hern{\'a}n and Puleston, Pablo F. and Mantz, Ricardo J. and Christiansen, Carlos F.} }