the classical swing equation model of a synchronous generator is augmented to include the effects of variable damping, nonlinear frequency dependence of the input torque, and lossy transmission lines. In each case osc...
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the classical swing equation model of a synchronous generator is augmented to include the effects of variable damping, nonlinear frequency dependence of the input torque, and lossy transmission lines. In each case oscillations are shown to occur for certain parameter values. these oscillations are due to a Hopf bifurcation.
In this paper, linguistic models are used to summarize information in a corporate data base. this approach provides a tool for analyzing generalizations made by managers which involve subjective data. In particular, f...
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In this paper, linguistic models are used to summarize information in a corporate data base. this approach provides a tool for analyzing generalizations made by managers which involve subjective data. In particular, fuzzy sets and the concept of quantification of a proposition are used to help generate these linguistic summaries. the ideas of truth and specificity are introduced to provide a quantitative measure of the model performance.
this paper presents a unified treatment of aggregability, lumpability, coherency and similar properties allowing model simplification. Each of the N groups of states is represented by one aggregate variable and an agg...
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this paper presents a unified treatment of aggregability, lumpability, coherency and similar properties allowing model simplification. Each of the N groups of states is represented by one aggregate variable and an aggregate model is formed. Interpretation is given when groups are coherent, but not aggregable and vice-versa. In a class of systems aggregability and coherency hold simultaneously.
the problem of management of production for an automated manufacturing system is described. the system consists of machines which can perform a variety of operations on a family of parts. the machines are unreliable, ...
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the problem of management of production for an automated manufacturing system is described. the system consists of machines which can perform a variety of operations on a family of parts. the machines are unreliable, and the chief difficulty the control system faces is to meet production requirements while the machines fail and become repaired at random times. A three-level hierarchical control algorithm is proposed which involves stochastic optimal control, network optimization, and scheduling. An example is presented.
the applicability of the recently developed frequency-domain, matrix-norm robustness margins for physical systems is explored in this paper using a power-system example. the power system is modeled using the damping- ...
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the applicability of the recently developed frequency-domain, matrix-norm robustness margins for physical systems is explored in this paper using a power-system example. the power system is modeled using the damping- and synchronizingtorque framework. the robustness margins evaluated at several junctions of the power-system model are shown to be useful measures of the system's tolerance for unmodeled shaft torsional dynamics and variations in the effectiveness of power-system controllers (e.g. multi-terminal high-voltage DC modulators). In addition, the robustness margins are shown to be useful for comparing the robustness of alternate controller designs. this paper ends with general guidelines for applying the matrixnorm robustness margins to physical systems.
We propose a systematic approach for estimating the Liapunov practical stability domain, along with some other fast techniques for transient stability analysis of power systems. the direct criterion thus derived is in...
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We propose a systematic approach for estimating the Liapunov practical stability domain, along with some other fast techniques for transient stability analysis of power systems. the direct criterion thus derived is investigated and illustrated through a good number of simulations performed on several test systems and practical power networks. It is shown to be reliable, straightforward and computationally very fast. Besides being appropriate for conventional studies, the acceleration approach offers also another interesting possibility: the derivation of a transient stability index for on-line stability assessment and contingency evaluation.
A lattice implementation of the extended least-squares algorithm was recently developed. the convergence of that algorithm depends on a positive real condition, a fact which limits its usefulness in some applications....
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A lattice implementation of the extended least-squares algorithm was recently developed. the convergence of that algorithm depends on a positive real condition, a fact which limits its usefulness in some applications. In this note the lattice equivalent of the recursive maximum likelihood algorithm is derived. this technique does not require the positive real condition and is suitable for modeling and prediction of general ARMA time-series.
Load management, which involves tailoring electric energy use to match electric energy supply, has been frequently suggested as an alternative for increasing the efficiency of the electric energy system. However, trad...
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Load management, which involves tailoring electric energy use to match electric energy supply, has been frequently suggested as an alternative for increasing the efficiency of the electric energy system. However, traditional utility analysis tools are frequently inadequate for assessing the costs and benefits of alternative load management options. One such problem is the consideration of active utility load control in the unit commitment/ economic dispatch problem. A model has been developed to determine how a power system with an active load control system should be operated to make the best use of its available resources. the model uses a dynamic programming successive approximation technique called gradient dynamic programming developed during the project to solve this control problem for realistically sized systems. the development of the model and its computer implementation are presented. the use of the model is demonstrated on several case studies of current interest. the case study results indicate that the production cost savings that can be achieved through the use of direct load control are highly dependent on utility characteristics, load characteristics, storage capacity, and penetration.
In this paper an innovative approach to the optimization of feedback control systems is presented. the proposed method uses 'banded' prediction for computing the state trajectories, and converges to the optimu...
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In this paper an innovative approach to the optimization of feedback control systems is presented. the proposed method uses 'banded' prediction for computing the state trajectories, and converges to the optimum parameter vector by minimizing a family of I object functions in succession. this family is constructed, and ordered, in such a manner that the extremum of Ji is in the region of rapid convergence of Ji+1. Because of banded prediction, each of these functions retains a nearly quadratic behavior with respect to the vector of design parameters. these multiple object functions are minimized by the well known modified Newton method, hence the name, Multiple Object Function Newton Method (MOFNM). the success of the method is demonstrated by application to an example.
this paper is concerned withthe long-standing problem of optimal unit commitment in an electric power system. We follow the traditional formulation of this problem which gives rise to a large-scale, dynamic, mixed-in...
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this paper is concerned withthe long-standing problem of optimal unit commitment in an electric power system. We follow the traditional formulation of this problem which gives rise to a large-scale, dynamic, mixed-integer programming problem. We describe a solution methodology based on duality, Lagrangian relaxation, and nondifferentiable optimizationthat has two unique features. First, computational requirements typically grow only linearly withthe number of generating units. Second, the duality gap decreases in relative terms as the number of units increases, and as a result our algorithm tends to actually perform better for problems of large size. this allows for the first time consistently reliable solution of large practical problems involving several hundreds of units within realistic time constraints. Aside from the unit commitment problem, this methodology is applicable to a broad class of large-scale dynamic scheduling and resource allocation problems involving integer variables.
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