The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Eduard Muljadi - One of the best experts on this subject based on the ideXlab platform.
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active Torque control for gearbox load reduction in a variable speed wind turbine
IEEE Transactions on Industry Applications, 2012Co-Authors: Goran Mandic, Eduard Muljadi, Adel Nasiri, F OyagueAbstract:With the advent of power electronics, the size, weight, and cost of power converters have been drastically reduced while efficiency is improved. The use of variable-speed wind power Generators has seen considerable growth. The use of gearboxes in the wind turbines allows for smaller size, lower weight, and higher speed Generators. However, gearboxes have shown to be one of the least reliable components of the wind turbines. In this paper, we propose a method that can extend the life and reliability of wind turbine gearboxes by reducing the mechanical stress on gearbox components. Reduction of mechanical stress is achieved by the Generator Torque control that minimizes resonant torsional vibrations within a drivetrain caused by variations in wind velocity. A detailed model for the drivetrain of a 750-kW wind turbine, including a gearbox is presented. Experimental results are used to calculate the parameters of the gearbox. A controller is designed to adjust the Generator Torque at the end of the drivetrain to remove the unwanted and damaging Torque variations from the drivetrain. Simulation results verify the effectiveness of the proposed method.
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Mechanical stress reduction in variable speed wind turbine drivetrains
2011 IEEE Energy Conversion Congress and Exposition, 2011Co-Authors: Goran Mandic, Adel Nasiri, F Oyague, Ehsan Ghotbi, Eduard MuljadiAbstract:The use of variable-speed wind power generation has seen considerable growth. The use of gearboxes in wind turbines allows for smaller size, lower weight, and higher speed Generators. In this paper, we attempt to describe methods to extend the life and reliability of wind turbine drivetrains by reducing the mechanical stress. We will represent a two-mass model for the drivetrain of a 750-kW wind turbine. This model is verified by using simulation and experimental results. A controller is designed to adjust the Generator Torque at the end of the drivetrain to remove the unwanted and damaging Torque variations from the drivetrain. The ultimate goal of this study is to present a detailed model of the drivetrain, including the gearbox and ways to mitigate the stress on the gearbox.
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a conservative control strategy for variable speed stall regulated wind turbines
19th American Society of Mechanical Engineers (ASME) Wind Energy Symposium Reno NV (US) 01 10 2000--01 13 2000, 2000Co-Authors: Eduard Muljadi, K Pierce, P MiglioreAbstract:Simulation models of a variable-speed, fixed-pitch wind turbine were investigated to evaluate the feasibility of constraining rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded Generator Torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded Generator Torque and the resulting rotor speed were controlled to cause the wind turbine to operate near maximum efficiency. Using the developed models, simulations were conducted of operation in turbulent winds. Results indicated that rotor speed and power output were well regulated. Preliminary investigations of system dynamics showed that, compared to fixed-speed operation, variable-speed operation caused cyclic loading amplitude to be reduced for the turbine blades and low-speed shaft and slightly increased for the tower loads. This result suggests a favorable impact on fatigue life from implementation of the proposed control strategy.
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control strategy for variable speed stall regulated wind turbines
American Control Conference, 1998Co-Authors: Eduard Muljadi, K Pierce, P MiglioreAbstract:A variable-speed, constant-pitch wind turbine was investigated to evaluate the feasibility of constraining its rotor speed and power output without the benefit of active aerodynamic control devices. A strategy was postulated to control rotational speed by specifying the demanded Generator Torque. By controlling rotor speed in relation to wind speed, the aerodynamic power extracted by the blades from the wind was manipulated. Specifically, the blades were caused to stall in high winds. In low and moderate winds, the demanded Generator Torque and the resulting rotor speed were controlled to cause the wind turbine to operate near maximum efficiency. A computational model was developed, and simulations were conducted of operation in high turbulent winds. Results indicated that rotor speed and power output were well regulated.
David T Westwick - One of the best experts on this subject based on the ideXlab platform.
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multiple model predictive control for wind turbines with doubly fed induction Generators
IEEE Transactions on Sustainable Energy, 2011Co-Authors: Mostafa Soliman, O P Malik, David T WestwickAbstract:A multivariable control strategy based on model predictive control techniques for the control of variable-speed variable-pitch wind turbines is proposed. The proposed control strategy is described for the whole operating region of the wind turbine, i.e., both partial and full load regimes. Pitch angle and Generator Torque are controlled simultaneously to maximize energy capture, mitigate drive train transient loads, and smooth the power generated while reducing the pitch actuator activity. This has the effect of improving the efficiency and the power quality of the electrical power generated, and increasing the life expectancy of the installation. Furthermore, safe and acceptable operation of the system is guaranteed by incorporating most of the constraints on the physical variables of the wind energy conversion system (WECS) in the controller design. In order to cope with nonlinearities in the WECS and continuous variations in the operating point, a multiple model predictive controller is suggested which provides acceptable performance throughout the whole operating region.
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multiple model multiple input multiple output predictive control for variable speed variable pitch wind energy conversion systems
Iet Renewable Power Generation, 2011Co-Authors: Mostafa Soliman, O P Malik, David T WestwickAbstract:A multivariable control strategy based on model predictive control techniques for the control of variable-speed variable pitch wind energy conversion systems (WECSs) in the above-rated wind speed zone is proposed. Pitch angle and Generator Torque are controlled simultaneously to provide optimal regulation of the generated power and the Generator speed while minimising torsional Torque fluctuations in the drive train and pitch actuator activity. This has the effect of improving the power quality of the electrical power generated by the WECS and increasing the life time of the mechanical parts of the system. Furthermore, safe and acceptable operation of the system is guaranteed by incorporating most of the constraints on the physical variables of the WECS in the controller design. In order to cope with the non-linearity in the WECS and the continuous variation in the operating point, a multiple model predictive controller is suggested to provide near optimal performance within the whole operating region.
Houria Siguerdidjane - One of the best experts on this subject based on the ideXlab platform.
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nonlinear control with wind estimation of a dfig variable speed wind turbine for power capture optimization
Energy Conversion and Management, 2009Co-Authors: Boubekeur Boukhezzar, Houria SiguerdidjaneAbstract:A cascaded nonlinear controller is designed for a variable speed wind turbine equipped with a Doubly Fed Induction Generator (DFIG). The main objective of the controller is wind energy capture optimization while avoiding strong transients in the turbine components and specially in the drive train. The inner loop controller ensures an efficient tracking of both Generator Torque and stator flux, while the outer loop controller achieves a close tracking of the optimal blade rotor speed to optimize wind energy capture. It is combined to a wind speed estimator that provides an estimation of the wind speed and the aerodynamic Torque involved in the controller. The global controller is firstly tested with a simplified mathematical model of the aeroturbine and DFIG for a high-turbulence wind speed profile. Secondly, the aeroturbine controller is validated upon a flexible wind turbine simulator. These new control strategies are compared to other existing controllers based on tests upon an aeroelastic wind turbine simulator. The obtained results show better performance in comparison with the existing controllers.
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nonlinear control of variable speed wind turbines for Generator Torque limiting and power optimization
Journal of Solar Energy Engineering-transactions of The Asme, 2006Co-Authors: Boubekeur Boukhezzar, Houria Siguerdidjane, M HandAbstract:To maximize wind power extraction, a variable-speed wind turbine (VSWT) should operate as close as possible to its optimal power coefficient. The Generator Torque is used as a control input to improve wind energy capture by forcing the wind turbine (WT) to stay close to the maximum energy point. In general, current control techniques do not take into account the dynamical and stochastic aspect of both turbine and wind, leading to significant power losses. In addition, they are not robust with respect to disturbances. In order to address these weaknesses, a nonlinear approach, without wind speed measurement for VSWT control, is proposed. Nonlinear static and dynamic state feedback controllers with wind speed estimator are then derived. The controllers were tested with a WT simple mathematical model and are validated with an aeroelastic wind turbine simulator in the presence of disturbances and measurement noise. The results have shown better performance in comparison with existing controllers.
Silviu Epure - One of the best experts on this subject based on the ideXlab platform.
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real time replication of a stand alone wind energy conversion system error analysis
International Journal of Electrical Power & Energy Systems, 2014Co-Authors: Ciprian Vlad, Antoneta Iuliana Bratcu, Iulian Munteanu, Silviu EpureAbstract:This paper provides adequate information about the problem of real-time replicating in laboratory conditions. The dynamic behavior of stand-alone low-power wind energy conversion systems (WECS) in response to the wind speed variations and also to the electrical load variations is replicated. The investigated system consists of a variable-speed wind turbine based on a permanent-magnet synchronous Generator (PMSG), a diode bridge rectifier, a DC-DC step-down converter and a wide range DC load. Because of reduced noise level and better steady-state accuracy, a speed-driven hardware-in-the-loop physical WECS simulator has been used to accomplish this task. Its significant drawback - that is, a reduced bandwidth - has been significantly alleviated by using an enhanced software simulator structure which uses a feed-forward compensation of the inherent physical disturbance produced by the Generator Torque variations. Both time-domain experimental results and a thorough frequency-domain error analysis show good replication performance in the frequency range of variation of both wind speed and electrical load.
Mostafa Soliman - One of the best experts on this subject based on the ideXlab platform.
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multiple model predictive control for wind turbines with doubly fed induction Generators
IEEE Transactions on Sustainable Energy, 2011Co-Authors: Mostafa Soliman, O P Malik, David T WestwickAbstract:A multivariable control strategy based on model predictive control techniques for the control of variable-speed variable-pitch wind turbines is proposed. The proposed control strategy is described for the whole operating region of the wind turbine, i.e., both partial and full load regimes. Pitch angle and Generator Torque are controlled simultaneously to maximize energy capture, mitigate drive train transient loads, and smooth the power generated while reducing the pitch actuator activity. This has the effect of improving the efficiency and the power quality of the electrical power generated, and increasing the life expectancy of the installation. Furthermore, safe and acceptable operation of the system is guaranteed by incorporating most of the constraints on the physical variables of the wind energy conversion system (WECS) in the controller design. In order to cope with nonlinearities in the WECS and continuous variations in the operating point, a multiple model predictive controller is suggested which provides acceptable performance throughout the whole operating region.
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multiple model multiple input multiple output predictive control for variable speed variable pitch wind energy conversion systems
Iet Renewable Power Generation, 2011Co-Authors: Mostafa Soliman, O P Malik, David T WestwickAbstract:A multivariable control strategy based on model predictive control techniques for the control of variable-speed variable pitch wind energy conversion systems (WECSs) in the above-rated wind speed zone is proposed. Pitch angle and Generator Torque are controlled simultaneously to provide optimal regulation of the generated power and the Generator speed while minimising torsional Torque fluctuations in the drive train and pitch actuator activity. This has the effect of improving the power quality of the electrical power generated by the WECS and increasing the life time of the mechanical parts of the system. Furthermore, safe and acceptable operation of the system is guaranteed by incorporating most of the constraints on the physical variables of the WECS in the controller design. In order to cope with the non-linearity in the WECS and the continuous variation in the operating point, a multiple model predictive controller is suggested to provide near optimal performance within the whole operating region.