Computer-aided analysis and design of control systems using model approximation techniques

Abstract

One of the objectives of this paper is to describe some of the available techniques and tools which are believed to be particularly useful in practical problems of model approximation. The issues and methods described are grouped under the following headings: (i) order-reduction algorithms, (ii) dominant pole selection, (iii) quality indices, (iv) open- and closed-loop optimization procedures, and (v) model validation. Another objective is to show that model approximation techniques can also be used in quite an effective way in the analysis and synthesis of control systems. It is shown, by way of examples, how the techniques and tools described in the first part of the paper may be used not only to compute reliable simplified models but also to obtain qualitative and quantitative information regarding the original system. In addition, an example is provided which illustrates how some of the tools and methods can be easily used in the design of reduced-order controllers. Examples taken from the models of a power system and a thermal power station are provided to illustrate the main points of the paper.