@article {178, title = {Multiple-input-multiple-output high-order sliding mode control for a permanent magnet synchronous generator wind-based system with grid support capabilities}, journal = {IET Renewable Power Generation}, volume = {9}, year = {2015}, pages = {925-934}, abstract = {This study presents a control design for a grid connected wind energy conversion system based on a gearless PMSG. The generation system structure comprises a three blade turbine, a 2 MW multi-pole PMSG and a full-scale back-to-back frequency converter linked to the utility grid. The proposed control scheme allows following dynamical specifications taking into account operational requirements and ancillary services imposed by the recent grid connection codes, that is, reactive power regulation and fault ride-through (FRT) capabilities. The control actions to be applied during normal grid operation are designed through second-order sliding mode techniques using a two-stage cascade structure. The multi-variable controller designed attains to regulate the active and reactive powers delivered to the grid, minimising the resistive losses into the generator and maintaining important internal variables into the desired range. This controller presents attractive advantages such as robustness against unmodelled dynamics and external perturbations, finite time convergence to the sliding surfaces and chattering mitigation. To endorse the controlled system with FRT capabilities, a switching control scheme based on voltage grid measurements is also proposed. The performance of the whole control approach is analysed through representative simulations which include parameter variations, external perturbations and three-phase voltage dips.}, keywords = {active power regulation, blade turbine, blades, chattering mitigation, control system synthesis, external perturbation, fault ride-through capability, frequency convertors, FRT capability, full-scale back-to-back frequency converter, gearless permanent magnet synchronous generator, grid connected wind energy conversion system, grid support capability, machine control, MIMO systems, multiple-input-multiple-output high-order sliding mode control design, multipole PMSG, multivariable control systems, multivariable controller design, permanent magnet generators, permanent magnet synchronous generator wind-based system, power convertors, power generation control, power generation faults, power grids, power system measurement, reactive power control, reactive power regulation, resistive loss minimization, second-order sliding mode technique, switching control scheme, synchronous generators, variable structure systems, voltage control, voltage measurement, wind power plants, wind turbines}, issn = {1752-1416}, doi = {10.1049/iet-rpg.2014.0417}, author = {Valenciaga, Fernando and Fern{\'a}ndez, Roberto. D.} } @article {88, title = {Lyapunov-Designed Super-Twisting Sliding Mode Control for Wind Energy Conversion Optimization}, journal = {Industrial Electronics, IEEE Transactions on}, volume = {60}, year = {2013}, month = {Feb}, pages = {538-545}, abstract = {

This work explores an adaptive second-order sliding mode control strategy to maximize the energy production of a wind energy conversion system (WECS) simultaneously reducing the mechanical stress on the shaft. Such strategy successfully deals with the random nature of wind speed, the intrinsic nonlinear behavior of the WECS, and the presence of model uncertainties and external perturbations acting on the system. The synthesized adaptive controller is designed from a modified version of the super-twisting (ST) algorithm with variable gains. The suitability of the proposed strategy is proved by extensive computer-aided simulations employing a comprehensive model of the system emulating realistic conditions of operation, i.e., considering variations in the parameters and including external disturbances. Additionally, a second controller based on the traditional ST algorithm is also designed and simulated. Results are presented and discussed in order to establish a comparison framework.

}, keywords = {adaptive control, adaptive second-order control strategy, Algorithm design and analysis, CAD, Computational modeling, control system synthesis, Control systems, direct energy conversion, extensive computer-aided simulations, external disturbances, external perturbations, Generators, intrinsic nonlinear behavior, Lyapunov methods, Lyapunov-designed super-twisting sliding mode control, mechanical stress reduction, model uncertainties, Sliding mode control, ST algorithm, suitability strategy, super-twisting (ST), system emulating realistic conditions, Torque, variable gains, variable structure systems, WECS, wind energy conversion optimization, wind power, Wind power generation, Wind speed, wind turbines}, issn = {0278-0046}, doi = {10.1109/TIE.2012.2188256}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6153362}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and Fridman, Leonid M.} } @article {115, title = {2-sliding active and reactive power control of a wind energy conversion system}, journal = {Control Theory Applications, IET}, volume = {4}, year = {2010}, month = {November}, pages = {2479-2490}, abstract = {

This study presents the control of a variable-speed wind energy conversion system based on a brushless doubly fed reluctance machine. The control objectives are the tracking of the maximum power conversion point and the regulation of the reactive power injected by the generation system into the grid. The control design is approached using multi-input second-order sliding techniques which are specially appropriate to deal with non-linear system models in the presence of disturbances and model inaccuracies. The controller synthesised through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behaviour. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {2-sliding active power control, 2-sliding reactive power control, brushless doubly fed reluctance machine, brushless machines, chattering-free behaviour, closed loop systems, closed-loop system, control design, control system synthesis, controller synthesis, generation system, grid, maximum power conversion point tracking, multiinput second-order sliding technique, Nonlinear control systems, nonlinear system model, Power conversion, power generation control, reactive power control, reactive power regulation, reluctance machines, representative computer simulation, variable structure systems, variable-speed wind energy conversion system, wind power}, issn = {1751-8644}, doi = {10.1049/iet-cta.2009.0437}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5645800}, author = {Valenciaga, Fernando and Evangelista, Carolina A.} } @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.} } @conference {104, title = {A Geometric Approach for the Design of MIMO Sliding Controllers. Application to a Wind Driven Double Output Induction Generator}, booktitle = {Variable Structure Systems, 2006. VSS{\textquoteright}06. International Workshop on}, year = {2006}, month = {June}, 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 proposed design method is developed through a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, while chattering reduction is attained by utilising 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 double output induction generator

}, keywords = {asynchronous generators, chattering reduction, control system synthesis, Control systems, controller design, Convergence, Design methodology, finite time convergence, geometric approach, grid connected wind energy generation system, Induction generators, MIMO, MIMO sliding mode controllers, MIMO systems, Nonlinear control systems, nonlinear MIMO systems, power generation control, Robust control, Sliding mode control, Uncertainty, variable structure systems, wind driven double output induction generator, Wind energy generation, wind power}, doi = {10.1109/VSS.2006.1644503}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1644503}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Spurgeon, Sarah} }