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ABSTRACT: Modern automotive speed control systems are designed to provide smooth throttle movement, zero steady state speed error, good speed tracking over varying road slopes, and robustness to system variations and operating conditions. Additionally, there is a need to minimize the number of controller calibrations for different vehicle applications. All of the above objectives cannot be simultaneously met by conventional fixed gain controllers which need different calibrations for different vehicle lines. With such requirements, an adaptive controller offers benefits over a conventional controller provided its complexity does not significantly exceed that of a conventional controller.
To limit the controller complexity, the adaptive design in this study is based on sensitivity analysis and slow adaptation using gradient methods. This design method allows the use of our a priori knowledge about the plant model in order to determine a stability region for a reduced order adaptive controller, in this case a simple PI controller. The adaptive algorithm, driven by the vehicle response to road load torque disturbances, tunes a PI controller to continuously minimize a single performance based cost functional for each different vehicle over varying road terrain. This results in performance not possible with a fixed gain controller. The adaptive controller has been tested on a number of vehicles with excellent results, some of which are presented here.
04/2006: pages 1-26;
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ABSTRACT: An adaptive algorithm for adjusting the gains of a vehicle speed control system is presented. By continuously adjusting the proportional-integral control gains, speed control performance can be optimized for each vehicle and operating condition. This helps the design of a single speed control module that does not need additional calibration or sacrifices in performance for certain car lines. It also allows improved performance for changing road conditions not possible with a fixed-gain control or other types of adaptive control. The results of initial vehicle testing confirm the performance improvements and robustness of the adaptive controller
IEEE Transactions on Automatic Control 08/1993; 38(7):1011-1020. · 2.11 Impact Factor
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ABSTRACT: This paper addresses the effects of fast dynamics on direct energy methods that use a sustained fault trajectory to approximate critically cleared trajectories and the corresponding critical energies. Integral manifold concepts are used to explain why fast dynamics can destroy such an approximation. Methods to remedy this problem are given and illustrated with a 10 machine example.
IEEE Power Engineering Review 06/1989; 9(5):48-49.
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ABSTRACT: The authors address the effects of fast dynamics on direct energy
methods that use a sustained fault trajectory to approximate critically
cleared trajectories and the corresponding critical energies. Integral
manifold concepts are used to explain why fast dynamics can destroy such
an approximation. Methods to remedy this problem are given and
illustrated with a ten-machine example
IEEE Transactions on Power Systems 06/1989; · 2.68 Impact Factor
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ABSTRACT: An analysis of a single-parameter self-tuning scheme for a
high-order system is presented and applied to a typical power-system
stabilizer, as a representative of systems in which stabilization of
some modes decreases the damping of other modes. Integral manifolds and
averaging are used to find conditions for convergence to a compromise
setting of the conflicting modes
IEEE Transactions on Automatic Control 03/1989; · 2.11 Impact Factor
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ABSTRACT: Near identity coordinate transformations are used to decouple the stability problem for a class of non-linear two time scale systems into a stability problem for slow variables and a stability problem for fast variables only. This facilitates the computation of the region of attraction in the slow subspace of much lower dimension. In this paper we describe a technique to decouple the slow dynamics of the system from its fast components. This is the nonlinear counterpart of the decoupling transformation for linear systems existing in the literature. The results are applied to a three-machine power system having strong and weak connections to compute the critical clearing times.
Decision and Control, 1987. 26th IEEE Conference on; 01/1988
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ABSTRACT: This paper reviews some recent results in applying singular perturbation theory to obtain simplified power system models for stability analysis and control design. The topics include synchronous machine modeling, slow coherency and dynamic equivalencing of large power networks, and transient stability analysis using direct methods. The objective is to introduce power system engineers to singular perturbation methods as a tool for providing additional insights into power system dynamics of different time scales and for analytically deriving reduced models.
Decision and Control, 1986 25th IEEE Conference on; 01/1987
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ABSTRACT: This paper reviews some recent results in applying singular perturbations theory to obtain simplified power system models for analysis and control design. The topics include synchronous machine modeling, decomposition and aggregation of large power networks, aggregation of higher order dynamic models, and transient stability analysis using direct methods. The objective is to introduce power system engineers to singular perturbations as a tool for enhancing the understanding of time-scale dynamics and analytically deriving reduced models in power systems.
American Control Conference, 1985; 07/1985
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ABSTRACT: This paper discusses an approach to the modeling and performance for the preliminary design phase of a large (6.2 MW) horizontal axis wind turbine generator (WTG). Two control philosophies are presented, both of which are based on linearized models of the WT mechanical and electrical systems. The control designs are compared by showing the performance through detailed non-linear time simulation. The disturbances considered are wind gusts, and electrical faults near the WT terminals.
IEEE Transactions on Power Apparatus and Systems 06/1983;
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ABSTRACT: The modeling and approach to control design for a large horizontal axis wind turbine (WT) generator are presented. The control design is based on a suboptimal output regulator which allows coordinated control of WT blade pitch angle and field voltage for the purposes of regulating electrical power and terminal voltage. Results of detailed non-linear simulation tests of this controller are shown.
Decision and Control including the Symposium on Adaptive Processes, 1981 20th IEEE Conference on; 01/1982
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ABSTRACT: The slow coherency concept is introduced and an algorithm is developed for grouping machines having identical slow motions into areas. The singular perturbation method is used to separate the slow variables which are the area center of inertia variables and the fast variables which describe the intermachine oscillations within the areas. The areas obtained by this method are independent of fault locations. Three types of simulation approximations illustrated on a nonlinear 48 machine system indicate the validity of this algorithm.
IEEE Transactions on Power Apparatus and Systems 03/1981;
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ABSTRACT: The modeling and approach to control design for a large horizontal axis wind turbine (WT) generator are presented. The control design is based on a suboptimal output regulator which allows coordinated control of WT blade pitch angle and field voltage for the purposes of regulating electrical power and terminal voltage. Results of detailed non-linear simulation tests of this controller are shown.
02/1981;
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ABSTRACT: This paper reviews some recent results in applying singular perturbation theory to obtain simplified power system models for stability analysis and control design. The topics include synchronous machine modelling, slow coherency and dynamic equivalence of large power networks, and transient stability analysis using direct methods. The objective is to introduce power system engineers to singular perturbation methods as a tool for providing additional insights into power system dynamics of different time scales and for analytically deriving reduced models.
International Journal of Electrical Power & Energy Systems.
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ABSTRACT: A methodology for obtaining dynamic equivalents of a detailed power system is presented. Two types of reduced order models are developed: a model describing the local behaviour in each area and a model describing the global behaviour between areas. The centre-of-area variables developed for the global model describe equivalent aggregate machines and clarify the nature of the aggregate models. A ten-machine example illustrates the theory.
Automatica. 22(4):489-494.
