This paper proposes a backstepping technique for designing discrete-time adaptive excitation controller enhance the transient stability of power systems under large sudden faults. This approach can be applied directly...
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This paper proposes a backstepping technique for designing discrete-time adaptive excitation controller enhance the transient stability of power systems under large sudden faults. This approach can be applied directly on nonlinear model of power system and it allows for abrupt changes in the power system parameters caused by three phase short circuit faults. It is shown that the proposed excitation controller can enhance transient stability when the power system suffers large sudden faults. The robustness of the power system under the proposed excitation controller is established in the presence of time-varying parametric uncertainties, unmodeled dynamics and external disturbances. Both theoretical analysis and simulation results are presented to show the effectiveness of the proposed controller.
This paper utilizes robust modeling and control techniques to solve the problem of synthesizing a controller that ensures closed loop stability as well as maintaining the desired performance of large space structures ...
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This paper utilizes robust modeling and control techniques to solve the problem of synthesizing a controller that ensures closed loop stability as well as maintaining the desired performance of large space structures under various predicted failure conditions. The approach is divided into two parts. First, we develop a family of MIMO models that includes various predicted failure states in the structures. Then a controller that guarantees robust stability and performance of the entire closed loop family is designed by using the μ-synthesis technique. The key ingredients of this approach are 1) use of the interval transfer function to model the structures with predicted damage and 2) utilization of the properties of interval transfer functions to simplify the μ-synthesis procedure. Steps to validate the proposed approach are carried out by simulation.
In this paper, first, the structure of the trial production of the mechanical system of the noncontact hold and transfer controlsystem consisting of a magnetic robot hand and a mobile robot with two independent drive...
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In this paper, first, the structure of the trial production of the mechanical system of the noncontact hold and transfer controlsystem consisting of a magnetic robot hand and a mobile robot with two independent drive wheels is expressed. Then, the state equation of the magnetic robot hand attached to the mobile robot is derived, and the robust noncontact hold controlsystem with the magnetic levitation control is designed by use of the mixed sensitivity method based on the H∞ control theory. On the other hand, the disturbance observer for the mobile robot is designed using the equation of motion of the mobile robot, and the trajectory tracking controlsystem of the mobile robot is constructed by use of the PD control and the disturbance observer. Furthermore, the experimental results concerning the noncontact hold and transfer control of a steel sphere are demonstrated, and the usefulness of the present noncontact hold and transfer controlsystem with the magnetic robot hand attached to the mobile robot is confirmed.
In this paper an adaptive controller known as the self-tuning regulator (STR) is employed for actively controlling an actuator for vibration isolation. Numerical simulations of the developed STR for active vibration i...
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In this paper an adaptive controller known as the self-tuning regulator (STR) is employed for actively controlling an actuator for vibration isolation. Numerical simulations of the developed STR for active vibration isolation of a simple mass-spring-damper system of two-degree-of-freedom subject to external disturbances are carried out. Experimental studies of vibration isolation by using magnetostrictive actuator with Terfenol-D rod are also presented. Both studies demonstrate the validity and effectiveness of the STR for active vibration isolation when the system is disturbed by a pure harmonic, two-modes harmonic, random, or even band-limited white noise excitation. In addition, the results are shown to be superior in terms of faster convergence and more vibration attenuation to those obtained by using previously developed adaptive plant disturbance canceler.
Bifurcation control deals with the modification of the bifurcation characteristics of a parameterized nonlinear system by a judiciously designed control input. In this paper, we investigate the problem of active contr...
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Bifurcation control deals with the modification of the bifurcation characteristics of a parameterized nonlinear system by a judiciously designed control input. In this paper, we investigate the problem of active control of Rayleigh-Benard convection (RBC) via a bifurcation control approach. Active control of Rayleigh-Benard convection is a problem of importance to both theoretical research and industrial applications. Several forms of bifurcation control laws are designed based on the mathematical analysis of the governing partial differential equations for RBC. Simulations as well as experimental studies have been carried out to validate the controldesigns. A composite bifurcation control law combining a linear control law and a cubic control law is found to be most effective and flexible for this problem.
Traditional approaches to unit testing involve establishing test vectors from the source code and establishing expected results that can be used to determine if a particular case has been addressed. This approach is t...
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Traditional approaches to unit testing involve establishing test vectors from the source code and establishing expected results that can be used to determine if a particular case has been addressed. This approach is time consuming and expensive. The availability of computeraidedcontrolsystemdesign (cacsd) tools for software modeling has permitted expected values to be automatically established from an executable specification. Further automation and implementation independence can be achieved by generating test vectors directly from the executable specification. A model driven automatic unit testing tool architecture and specification has been established. This paper discusses the architecture and requirements of such a tool. Topics include control coverage, data flow coverage, domain coverage, path sensitizing and test management.
Grade change on a paper machine is a transition from one set of operating conditions to another. During the transition, without proper coordination and control, the entire process could have radical fluctuations and p...
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Grade change on a paper machine is a transition from one set of operating conditions to another. During the transition, without proper coordination and control, the entire process could have radical fluctuations and produce significant amounts of off-spec paper or even cause sheet break. The production loss and the efforts to recycle off-spec waste are very costly. To address the issue, this paper formulates the dynamic models of paper-making processes and presents an effective control of grade change transitions. The method has been applied to several hundreds of paper machines. A real application example is included here to demonstrate the actual performance of the described approach.
Metalorganic chemical vapor deposition (MOCVD) is a promising technology for the growth of epitaxial semiconductors. It has traditionally lacked real-time growth monitoring and control, which limits the precise reprod...
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Metalorganic chemical vapor deposition (MOCVD) is a promising technology for the growth of epitaxial semiconductors. It has traditionally lacked real-time growth monitoring and control, which limits the precise reproducibility needed for high performance devices. Two complementary control approaches are investigated experimentally. The first is a feedforward disturbance rejection strategy using ultrasonic concentration measurements to reject source gas bubbler disturbances. The second is a feedback system using an ultraviolet (UV) absorption sensor for real-time monitoring of reaction chamber gas concentrations. Post-growth X-ray analysis of InP/GaInAs superlattice test devices is used to evaluate controlsystem performance.
This paper proposes a simultaneous tuning approach for power system damping controllers which seems better able than current SISO-based methods to cope with the foreseeable increase in system complexity and adverse in...
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This paper proposes a simultaneous tuning approach for power system damping controllers which seems better able than current SISO-based methods to cope with the foreseeable increase in system complexity and adverse interactions. To tackle the most difficult situations, the retained control architecture comprises several degrees-of-freedom in terms of dynamic feedback loops, each consisting of a high-order differential filter. The tuning of these flexible controllers is then performed by minimizing a selective modal performance index in the parameter space. Adding stability and robustness constraints greatly improves the engineering significance of the resulting design. Three examples adapted from the literature are used for illustration: a robust power system stabilizer (PSS) for a single-machine infinite-bus system with multiple operating points, a thyristor-controlled series capacitor (TCSC) controller for a large power system, and a coordinated design of multiple PSSs for a two-area/four-machine test system.
Switching power converters are nonlinear and time variant systems. The classical controller design for a switching power converter based on the linear model derived by one of conventional modelling methods. However th...
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Switching power converters are nonlinear and time variant systems. The classical controller design for a switching power converter based on the linear model derived by one of conventional modelling methods. However the parameter and load variations and input unregulated voltage are not taken into consideration simultaneously in a controller design. In this paper, we use `input-output feedback linearization' technique for nonlinear control issue, and `Kharitonov, H∞ and μ-synthesis' techniques for robust control issue to design of nonlinear and linear robust controllers to access both satisfactory stability and satisfactory performance, even in case of uncertainties and disturbances, for typical fifth-order DC-DC Switching power converter. The stability and performance of the converter and the effectiveness of the proposed controllers are demonstrated by some simulated results. Making use of simulation results, varies comparisons between these controllers and a variety of other controllers are then made, exhibiting the high efficiency of these methods compared to conventional methods.
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