In above rated conditions, wind turbines are often subjected to undesirable high struc- tural loa... more In above rated conditions, wind turbines are often subjected to undesirable high struc- tural loading. We investigate two feedback control techniques in combination with a feed- forward control method for reducing blade ap bending loads in above rated wind con- ditions. The feedback controls studied include both disturbance accommodating/tracking and integral augmented/repetitive types that incorporate models of persistent disturbances at
W ind is recognized worldwide as a cost-effective, environmentally friendly solution to energy sh... more W ind is recognized worldwide as a cost-effective, environmentally friendly solution to energy shortages, and wind energy is currently t he fa stest-g row i ng energ y source in the world. Wind power investment worldwide is expected to expand threefold in the next decade, from about $18 billion in 2006 to $60 billion in 2016 . While the cost of wind energy is already very competitive with energy from coal and natural gas, there are still many unsolved challenges in expanding wind power. From bearings under constant friction to blades that must be able to handle gusts, lightning, and constantly changing wind conditions, today's wind turbines need increasingly sophisticated component designs, sensors, and control systems. Further, better wind forecasting methods are needed to improve site selection, optimize operations, and mitigate load fluctuations on the power grid. Although the United States receives only about 1% of its electrical energy from wind [2], the corresponding figure in Denmark is more than 15% . The integration of more than 20% penetration of wind energy into the grid will require modifications of the grid design and operation, with the possible addition of new transmission lines and energy storage systems.
Proceedings of the 2011 American Control Conference, 2011
In below-rated wind conditions, a wind turbine operates to maximize the amount of available power... more In below-rated wind conditions, a wind turbine operates to maximize the amount of available power harvested from the wind and is said to be operating in region 2. In above-rated wind conditions, where regulation is the main objective to prevent over power and speed faults and to mitigate loads, the turbine is said to be in region 3. There is no standard method for operation at the boundary of the two regions and transitions between them can be problematic. In this study, we use iterative learning control to determine the control actuation necessary to accurately track idealized candidate trajectories during the transition between regions 2 and 3. The amount of control actuation required to track a transition trajectory and the ability to do so with minimal collateral loading determines which trajectory is most amenable for a given turbine. Trajectories are also graded by the average power produced during transition since they take the turbine off of the optimal power point.
AbstractWe review the objectives and techniques used in the control of horizontal axis wind turb... more AbstractWe review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence ...
Light detection and ranging systems are able to measure conditions at a distance in front of wind... more Light detection and ranging systems are able to measure conditions at a distance in front of wind turbines and are therefore suited to providing preview information of wind disturbances before they impact the turbine blades. In this study, preview-based disturbance feedforward control is investigated for load mitigation. Performance is evaluated assuming highly idealized wind
measurements that rotate with the blades and more realistic stationary measurements. The results obtained using idealized, "best case" measurements show that excellent performance gains are possible with reasonable pitch rates. However, the results using more realistic wind measurements show that without further optimization of the controller and/or better processing of measurements, errors in determining the shear local to each blade can remove any advantage obtained by using preview-based feedforward techniques.
In above rated conditions, wind turbines are often subjected to undesirable high struc- tural loa... more In above rated conditions, wind turbines are often subjected to undesirable high struc- tural loading. We investigate two feedback control techniques in combination with a feed- forward control method for reducing blade ap bending loads in above rated wind con- ditions. The feedback controls studied include both disturbance accommodating/tracking and integral augmented/repetitive types that incorporate models of persistent disturbances at
W ind is recognized worldwide as a cost-effective, environmentally friendly solution to energy sh... more W ind is recognized worldwide as a cost-effective, environmentally friendly solution to energy shortages, and wind energy is currently t he fa stest-g row i ng energ y source in the world. Wind power investment worldwide is expected to expand threefold in the next decade, from about $18 billion in 2006 to $60 billion in 2016 . While the cost of wind energy is already very competitive with energy from coal and natural gas, there are still many unsolved challenges in expanding wind power. From bearings under constant friction to blades that must be able to handle gusts, lightning, and constantly changing wind conditions, today's wind turbines need increasingly sophisticated component designs, sensors, and control systems. Further, better wind forecasting methods are needed to improve site selection, optimize operations, and mitigate load fluctuations on the power grid. Although the United States receives only about 1% of its electrical energy from wind [2], the corresponding figure in Denmark is more than 15% . The integration of more than 20% penetration of wind energy into the grid will require modifications of the grid design and operation, with the possible addition of new transmission lines and energy storage systems.
Proceedings of the 2011 American Control Conference, 2011
In below-rated wind conditions, a wind turbine operates to maximize the amount of available power... more In below-rated wind conditions, a wind turbine operates to maximize the amount of available power harvested from the wind and is said to be operating in region 2. In above-rated wind conditions, where regulation is the main objective to prevent over power and speed faults and to mitigate loads, the turbine is said to be in region 3. There is no standard method for operation at the boundary of the two regions and transitions between them can be problematic. In this study, we use iterative learning control to determine the control actuation necessary to accurately track idealized candidate trajectories during the transition between regions 2 and 3. The amount of control actuation required to track a transition trajectory and the ability to do so with minimal collateral loading determines which trajectory is most amenable for a given turbine. Trajectories are also graded by the average power produced during transition since they take the turbine off of the optimal power point.
AbstractWe review the objectives and techniques used in the control of horizontal axis wind turb... more AbstractWe review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence ...
Light detection and ranging systems are able to measure conditions at a distance in front of wind... more Light detection and ranging systems are able to measure conditions at a distance in front of wind turbines and are therefore suited to providing preview information of wind disturbances before they impact the turbine blades. In this study, preview-based disturbance feedforward control is investigated for load mitigation. Performance is evaluated assuming highly idealized wind
measurements that rotate with the blades and more realistic stationary measurements. The results obtained using idealized, "best case" measurements show that excellent performance gains are possible with reasonable pitch rates. However, the results using more realistic wind measurements show that without further optimization of the controller and/or better processing of measurements, errors in determining the shear local to each blade can remove any advantage obtained by using preview-based feedforward techniques.
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Papers by Jason Laks
Papers/Reports by Jason Laks
measurements that rotate with the blades and more realistic stationary measurements. The results obtained using idealized, "best case" measurements show that excellent performance gains are possible with reasonable pitch rates. However, the results using more realistic wind measurements show that without further optimization of the controller and/or better processing of measurements, errors in determining the shear local to each blade can remove any advantage obtained by using preview-based feedforward techniques.
measurements that rotate with the blades and more realistic stationary measurements. The results obtained using idealized, "best case" measurements show that excellent performance gains are possible with reasonable pitch rates. However, the results using more realistic wind measurements show that without further optimization of the controller and/or better processing of measurements, errors in determining the shear local to each blade can remove any advantage obtained by using preview-based feedforward techniques.