Mario Rotea - Academia.edu (original) (raw)
Papers by Mario Rotea
IFAC Proceedings Volumes, Sep 1, 1991
... Their method took 59 iterations with 47 evaluations of their cost function to determine that ... more ... Their method took 59 iterations with 47 evaluations of their cost function to determine that Specifica tion 1 is feasible ... in order to solve the synthesis problem of finding a controller such that an "upper bound" for the generalized 2 cost of one closed loop transfer matrix and the ...
Scaling the inputs and outputs of a digital controller is necessary to guarantee that these signa... more Scaling the inputs and outputs of a digital controller is necessary to guarantee that these signals do not exceed the dynamic range of the analog-to-digital and digital-to-analog converters. This paper gives two optimization problems that can be used to efficiently compute fullscaling matrices. An example that demonstrates the advantages of full scaling over the more conventional diagonal scaling is given.
ABSTRACT Cascade compensators are often used to direct the available control energy to a particul... more ABSTRACT Cascade compensators are often used to direct the available control energy to a particular subset of plant modes whose dynamics is to be modified. In certain applications the cascade compensators can be taken to be simple frequency selective filters such as low-pass or band-pass filters. There are applications in which such simple solutions do not work. This paper describes a method to obtain cascade compensators when frequency selective filters do not suffice. The computations required to implement the results are rather simple and involve the calculation of the generalized singular value decomposition of a matrix pair constructed with frequency response data. When combined with robust methods for controller design, the results in this paper yield a simple and effective method for designing controllers that modify the dynamics associated with a specified subset of plant poles
Renewable Energy, Sep 1, 2018
This paper reports the findings from the 2016 Wind Energy Research Workshop held in Lowell, MA. T... more This paper reports the findings from the 2016 Wind Energy Research Workshop held in Lowell, MA. The workshop examined the state-of-the-art in wind energy research within the following three core topic areas: (A) Wind Turbine Design and Manufacturing including: blades, towers/foundations and nacelle, (B) Wind Farm Development including: offshore installations/siting, flow characterization and loads/waves/wind characterization, and (C) Wind Farm Operations including: controls, power production, wind farms, sensing, diagnostics, testing, structural health monitoring, reliability, energy storage, the grid and power transmission. Research challenges and future directions were discussed and are reported for each sub-topic area.
Journal of physics, May 1, 2022
Decades of wind turbine research, development and installation have demonstrated reductions in le... more Decades of wind turbine research, development and installation have demonstrated reductions in levelized cost of energy (LCOE) resulting from turbines with larger rotor diameters and increased hub heights. Further reductions in LCOE by up-scaling turbine size can be challenged by practical limitations due to a mass increase trend. On-blade, active flow control devices have the potential to disrupt this trend by allowing longer blades with less mass through an active load control system. Typically, these load control systems are developed for specific wind turbines, making it difficult to study load reduction trends with turbine size to gain further insights into the benefits and risks of this control technology. This paper quantifies the variation in load reduction, complexity, and robustness of load control systems with flow control actuators for three turbines of increasing size. It is shown that, under limited control authority, load reduction can increase with turbine size provided more elaborate control algorithms are used to preserve the bandwidth and robustness of the control system.
Wind energy science, Jun 21, 2022
This paper describes the design and characterization of a scaled wind turbine model, conceived to... more This paper describes the design and characterization of a scaled wind turbine model, conceived to support wake and wind farm control experiments in a boundary layer wind tunnel. The turbine has a rotor diameter of 0.6 m and was designed to match the circulation distribution of a target conceptual full-scale turbine at its design tip speed ratio. In order to enable the testing of plant-level control strategies, the model is equipped with pitch, torque and yaw actuation and is sensorized with integrated load cells, rotor azimuth and blade pitch encoders. After describing the design of the turbine, its steady-state performance and wake characteristics are assessed by conducting experiments in two different wind tunnels, in laminar and turbulent conditions, collecting wake data with different measurement techniques. A large-eddy simulator coupled to an actuator-line model is used to develop a digital replica of the turbine and of the wind tunnel. For increased accuracy, the polars of the low-Reynolds-number airfoil used in the numerical model are tuned directly from measurements obtained from the rotor in operation in the wind tunnel. Results indicate that the scaled turbine performs as expected: measurements are repeatable and consistent, and the wake appears to have a realistic behavior in line with expectations and with a similar but slightly larger scaled model turbine. Furthermore, the predictions of the numerical model are well in line with experimental observations.
2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, Sep 1, 2011
IFAC Proceedings Volumes, Jul 1, 1993
This paper considers the problem of constructing a controller which quadratically stabilizes an u... more This paper considers the problem of constructing a controller which quadratically stabilizes an uncertain system and minimizes a guaranteed cost bound on a quadratic cost function. The solution is obtained via a parameter-dependent linear matrix inequality problem.
Ima Journal of Mathematical Control and Information, Jun 1, 1996
ABSTRACT A problem of practical importance is to find a linear controller that shapes the closed ... more ABSTRACT A problem of practical importance is to find a linear controller that shapes the closed loop frequency responses in some desirable fashion. When the magnitude of the target shapes are specified, this problem may be cast as that of finding a controller such that several H ∞ norms satisfy prespecified bounds. In this paper we show that under suitable assumptions on the plant under control, an exact solution to this multiobjective problem H∞ problem can be obtained. The method we propose requires the solution to: (1) a finite dimensional convex program, and (2) a standard single objective H∞ problem for a suitably constructed auxiliary plant. We illustrate the results using a numerical example. The example shows that the conventional approach of lumping the individual objectives into a single H∞ objective may be unduly conservative when compared with an exact solution to the multiobjective H∞ problem
This paper describes the design and characterization of a scaled wind turbine model, conceived to... more This paper describes the design and characterization of a scaled wind turbine model, conceived to support wake and wind farm control experiments in a boundary layer wind tunnel. The turbine has a rotor diameter of 0.6 meters, and was designed to match the circulation distribution of a target conceptual full-scale turbine at its design tip speed ratio. In order to enable the testing of plant-level control strategies, the model is equipped with closed-loop pitch, torque and yaw control, and is sensorized with integrated load cells, as well as with rotor azimuth and blade pitch encoders. After describing the design of the turbine, its performance and wake characteristics are assessed by conducting experiments in two different wind tunnels, in laminar and turbulent conditions, collecting wake data with different measurement techniques. A large-eddy simulator coupled to an actuator-line model is used to develop a digital replica of the turbine and of the wind tunnel. For increased accuracy, the polars of the low-Reynolds airfoil used in the numerical model are tuned directly from measurements obtained from the rotor in operation in the wind tunnel. Results indicate that the scaled turbine performs as expected, measurements are repeatable and consistent, and the wake appears to have a realistic behavior in line with expectations and with a similar slightly larger scaled model turbine. Furthermore, the predictions of the numerical model are well in line with experimental observations. 1 Introduction Over the last decade, wind tunnel tests conducted with miniature wind turbine models have gained an increase attention from the research community (Bottasso and Campagnolo, 2020). The main focus of recent studies conducted with scaled turbines has been on wakes, including the characterization of the effects of the turbine operating conditions, of inflow profiles, and of thermal stability, and the testing of plant control strategies, as reported by-among many others-Chamorro and Porté-Agel
IFAC Proceedings Volumes, Jul 1, 1993
A control problem that combines 1i2 and 1ioo design objectives for discrete time systems is consi... more A control problem that combines 1i2 and 1ioo design objectives for discrete time systems is considered. Under a minimal set of assumptions, we give formulas for solving the problem of minimizing an upper bound for the generalized 1i2 norm of a closed loop transfer matrix subject to an 1ioo constraint on another closed loop transfer matrix; both, full information and output feedback cases are solved. The formulas are given in terms of a finite dimensional convex program over a constraint set defined by linear matrix inequalities.
IFAC Proceedings Volumes, Jul 1, 1993
Using a fixed quadratic Lyapunov function approach (quadratic stabilization) we investigate the p... more Using a fixed quadratic Lyapunov function approach (quadratic stabilization) we investigate the possibility of reducing the robust stabilization problem of a given uncertain system to a similar problem f~r an uncertain subsystem with fewer• number of states; this subsystem is the so-called regular subsystem associated with the original system. It is shown that when some of the control input. channels o~ the give~ unccrtain system are "free of uncertainty" this reduction is possible. We show that a given uncertam systcm IS quadratically stabilizable via linear state-feedback if and only if the same holds for its regular subsystem. When the regular subsystem is quadratically stabilizable via linear state-feedback, a simple formula for a controller that quadratically stabilizes the original system is given .
Journal of physics, Sep 1, 2016
ABSTRACT The Dynamic Data Driven Applications Systems (DDDAS) concept entails capabilities where ... more ABSTRACT The Dynamic Data Driven Applications Systems (DDDAS) concept entails capabilities where application simulations can dynamically accept and respond to field-data and measurements, and/or can control such measurements. This synergistic and symbiotic feedback control-loop between simulations and measurements goes beyond the traditional control systems approaches, and advances applications and measurement approaches, beneficially impacting science and engineering fields, as well as manufacturing, commerce, transportation, hazard prediction/management, medicine, etc. DDDAS environments extend the current computational grids. The multi-agency DDDAS Program Solicitation (www.cise.nsf.gov/dddas) fosters systematically the relevant research areas. NSF, NOAA and NIH, the NSF/OISE and SBIR Offices, and the EU-IST and e-Sciences Programs are cooperating sponsors. This session will consist of a panel of experts, including awardees of DDDAS projects and representatives from funding agencies, and will provide a forum to engage the broader community in open discussion for expanding the opportunities and impact of DDDAS.
This paper describes a multi-objective ESC strategy that determines Pareto-optimal control parame... more This paper describes a multi-objective ESC strategy that determines Pareto-optimal control parameters to jointly optimize wind turbine loads and power capture. The method uses two optimization objectives calculated in real time: (a) the logarithm of the average power and (b) the logarithm of the standard deviation of a measurable blade load, tower load or the combination of these loads. These two objectives are weighted in real-time to obtain a solution that is Pareto optimal with respect to the power average and the standard deviation of chosen load metric. The method is evaluated using NREL FAST simulations of the 5-MW reference turbine. The results are then evaluated using energy capture over the duration of the simulation and damage equivalent loads (DEL) calculated with MLife.
International Journal of Robust and Nonlinear Control, Jul 15, 1998
This paper considers the problem of constructing a controller which quadratically stabilizes an u... more This paper considers the problem of constructing a controller which quadratically stabilizes an uncertain system and minimizes a guaranteed cost bound on a quadratic cost function. The solution is obtained via a parameter-dependent linear matrix inequality problem.
IFAC Proceedings Volumes, Sep 1, 1991
... Their method took 59 iterations with 47 evaluations of their cost function to determine that ... more ... Their method took 59 iterations with 47 evaluations of their cost function to determine that Specifica tion 1 is feasible ... in order to solve the synthesis problem of finding a controller such that an "upper bound" for the generalized 2 cost of one closed loop transfer matrix and the ...
Scaling the inputs and outputs of a digital controller is necessary to guarantee that these signa... more Scaling the inputs and outputs of a digital controller is necessary to guarantee that these signals do not exceed the dynamic range of the analog-to-digital and digital-to-analog converters. This paper gives two optimization problems that can be used to efficiently compute fullscaling matrices. An example that demonstrates the advantages of full scaling over the more conventional diagonal scaling is given.
ABSTRACT Cascade compensators are often used to direct the available control energy to a particul... more ABSTRACT Cascade compensators are often used to direct the available control energy to a particular subset of plant modes whose dynamics is to be modified. In certain applications the cascade compensators can be taken to be simple frequency selective filters such as low-pass or band-pass filters. There are applications in which such simple solutions do not work. This paper describes a method to obtain cascade compensators when frequency selective filters do not suffice. The computations required to implement the results are rather simple and involve the calculation of the generalized singular value decomposition of a matrix pair constructed with frequency response data. When combined with robust methods for controller design, the results in this paper yield a simple and effective method for designing controllers that modify the dynamics associated with a specified subset of plant poles
Renewable Energy, Sep 1, 2018
This paper reports the findings from the 2016 Wind Energy Research Workshop held in Lowell, MA. T... more This paper reports the findings from the 2016 Wind Energy Research Workshop held in Lowell, MA. The workshop examined the state-of-the-art in wind energy research within the following three core topic areas: (A) Wind Turbine Design and Manufacturing including: blades, towers/foundations and nacelle, (B) Wind Farm Development including: offshore installations/siting, flow characterization and loads/waves/wind characterization, and (C) Wind Farm Operations including: controls, power production, wind farms, sensing, diagnostics, testing, structural health monitoring, reliability, energy storage, the grid and power transmission. Research challenges and future directions were discussed and are reported for each sub-topic area.
Journal of physics, May 1, 2022
Decades of wind turbine research, development and installation have demonstrated reductions in le... more Decades of wind turbine research, development and installation have demonstrated reductions in levelized cost of energy (LCOE) resulting from turbines with larger rotor diameters and increased hub heights. Further reductions in LCOE by up-scaling turbine size can be challenged by practical limitations due to a mass increase trend. On-blade, active flow control devices have the potential to disrupt this trend by allowing longer blades with less mass through an active load control system. Typically, these load control systems are developed for specific wind turbines, making it difficult to study load reduction trends with turbine size to gain further insights into the benefits and risks of this control technology. This paper quantifies the variation in load reduction, complexity, and robustness of load control systems with flow control actuators for three turbines of increasing size. It is shown that, under limited control authority, load reduction can increase with turbine size provided more elaborate control algorithms are used to preserve the bandwidth and robustness of the control system.
Wind energy science, Jun 21, 2022
This paper describes the design and characterization of a scaled wind turbine model, conceived to... more This paper describes the design and characterization of a scaled wind turbine model, conceived to support wake and wind farm control experiments in a boundary layer wind tunnel. The turbine has a rotor diameter of 0.6 m and was designed to match the circulation distribution of a target conceptual full-scale turbine at its design tip speed ratio. In order to enable the testing of plant-level control strategies, the model is equipped with pitch, torque and yaw actuation and is sensorized with integrated load cells, rotor azimuth and blade pitch encoders. After describing the design of the turbine, its steady-state performance and wake characteristics are assessed by conducting experiments in two different wind tunnels, in laminar and turbulent conditions, collecting wake data with different measurement techniques. A large-eddy simulator coupled to an actuator-line model is used to develop a digital replica of the turbine and of the wind tunnel. For increased accuracy, the polars of the low-Reynolds-number airfoil used in the numerical model are tuned directly from measurements obtained from the rotor in operation in the wind tunnel. Results indicate that the scaled turbine performs as expected: measurements are repeatable and consistent, and the wake appears to have a realistic behavior in line with expectations and with a similar but slightly larger scaled model turbine. Furthermore, the predictions of the numerical model are well in line with experimental observations.
2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, Sep 1, 2011
IFAC Proceedings Volumes, Jul 1, 1993
This paper considers the problem of constructing a controller which quadratically stabilizes an u... more This paper considers the problem of constructing a controller which quadratically stabilizes an uncertain system and minimizes a guaranteed cost bound on a quadratic cost function. The solution is obtained via a parameter-dependent linear matrix inequality problem.
Ima Journal of Mathematical Control and Information, Jun 1, 1996
ABSTRACT A problem of practical importance is to find a linear controller that shapes the closed ... more ABSTRACT A problem of practical importance is to find a linear controller that shapes the closed loop frequency responses in some desirable fashion. When the magnitude of the target shapes are specified, this problem may be cast as that of finding a controller such that several H ∞ norms satisfy prespecified bounds. In this paper we show that under suitable assumptions on the plant under control, an exact solution to this multiobjective problem H∞ problem can be obtained. The method we propose requires the solution to: (1) a finite dimensional convex program, and (2) a standard single objective H∞ problem for a suitably constructed auxiliary plant. We illustrate the results using a numerical example. The example shows that the conventional approach of lumping the individual objectives into a single H∞ objective may be unduly conservative when compared with an exact solution to the multiobjective H∞ problem
This paper describes the design and characterization of a scaled wind turbine model, conceived to... more This paper describes the design and characterization of a scaled wind turbine model, conceived to support wake and wind farm control experiments in a boundary layer wind tunnel. The turbine has a rotor diameter of 0.6 meters, and was designed to match the circulation distribution of a target conceptual full-scale turbine at its design tip speed ratio. In order to enable the testing of plant-level control strategies, the model is equipped with closed-loop pitch, torque and yaw control, and is sensorized with integrated load cells, as well as with rotor azimuth and blade pitch encoders. After describing the design of the turbine, its performance and wake characteristics are assessed by conducting experiments in two different wind tunnels, in laminar and turbulent conditions, collecting wake data with different measurement techniques. A large-eddy simulator coupled to an actuator-line model is used to develop a digital replica of the turbine and of the wind tunnel. For increased accuracy, the polars of the low-Reynolds airfoil used in the numerical model are tuned directly from measurements obtained from the rotor in operation in the wind tunnel. Results indicate that the scaled turbine performs as expected, measurements are repeatable and consistent, and the wake appears to have a realistic behavior in line with expectations and with a similar slightly larger scaled model turbine. Furthermore, the predictions of the numerical model are well in line with experimental observations. 1 Introduction Over the last decade, wind tunnel tests conducted with miniature wind turbine models have gained an increase attention from the research community (Bottasso and Campagnolo, 2020). The main focus of recent studies conducted with scaled turbines has been on wakes, including the characterization of the effects of the turbine operating conditions, of inflow profiles, and of thermal stability, and the testing of plant control strategies, as reported by-among many others-Chamorro and Porté-Agel
IFAC Proceedings Volumes, Jul 1, 1993
A control problem that combines 1i2 and 1ioo design objectives for discrete time systems is consi... more A control problem that combines 1i2 and 1ioo design objectives for discrete time systems is considered. Under a minimal set of assumptions, we give formulas for solving the problem of minimizing an upper bound for the generalized 1i2 norm of a closed loop transfer matrix subject to an 1ioo constraint on another closed loop transfer matrix; both, full information and output feedback cases are solved. The formulas are given in terms of a finite dimensional convex program over a constraint set defined by linear matrix inequalities.
IFAC Proceedings Volumes, Jul 1, 1993
Using a fixed quadratic Lyapunov function approach (quadratic stabilization) we investigate the p... more Using a fixed quadratic Lyapunov function approach (quadratic stabilization) we investigate the possibility of reducing the robust stabilization problem of a given uncertain system to a similar problem f~r an uncertain subsystem with fewer• number of states; this subsystem is the so-called regular subsystem associated with the original system. It is shown that when some of the control input. channels o~ the give~ unccrtain system are "free of uncertainty" this reduction is possible. We show that a given uncertam systcm IS quadratically stabilizable via linear state-feedback if and only if the same holds for its regular subsystem. When the regular subsystem is quadratically stabilizable via linear state-feedback, a simple formula for a controller that quadratically stabilizes the original system is given .
Journal of physics, Sep 1, 2016
ABSTRACT The Dynamic Data Driven Applications Systems (DDDAS) concept entails capabilities where ... more ABSTRACT The Dynamic Data Driven Applications Systems (DDDAS) concept entails capabilities where application simulations can dynamically accept and respond to field-data and measurements, and/or can control such measurements. This synergistic and symbiotic feedback control-loop between simulations and measurements goes beyond the traditional control systems approaches, and advances applications and measurement approaches, beneficially impacting science and engineering fields, as well as manufacturing, commerce, transportation, hazard prediction/management, medicine, etc. DDDAS environments extend the current computational grids. The multi-agency DDDAS Program Solicitation (www.cise.nsf.gov/dddas) fosters systematically the relevant research areas. NSF, NOAA and NIH, the NSF/OISE and SBIR Offices, and the EU-IST and e-Sciences Programs are cooperating sponsors. This session will consist of a panel of experts, including awardees of DDDAS projects and representatives from funding agencies, and will provide a forum to engage the broader community in open discussion for expanding the opportunities and impact of DDDAS.
This paper describes a multi-objective ESC strategy that determines Pareto-optimal control parame... more This paper describes a multi-objective ESC strategy that determines Pareto-optimal control parameters to jointly optimize wind turbine loads and power capture. The method uses two optimization objectives calculated in real time: (a) the logarithm of the average power and (b) the logarithm of the standard deviation of a measurable blade load, tower load or the combination of these loads. These two objectives are weighted in real-time to obtain a solution that is Pareto optimal with respect to the power average and the standard deviation of chosen load metric. The method is evaluated using NREL FAST simulations of the 5-MW reference turbine. The results are then evaluated using energy capture over the duration of the simulation and damage equivalent loads (DEL) calculated with MLife.
International Journal of Robust and Nonlinear Control, Jul 15, 1998
This paper considers the problem of constructing a controller which quadratically stabilizes an u... more This paper considers the problem of constructing a controller which quadratically stabilizes an uncertain system and minimizes a guaranteed cost bound on a quadratic cost function. The solution is obtained via a parameter-dependent linear matrix inequality problem.