摘要:

In this paper, Zubov's method of construction of Lyapunov functions is applied to the transient-stability problem of a synchronous machine swinging against an infinite busbar. In the machine model, the transient saliency and the variable-field flux linkage are taken into account, but changes in prime-mover input have been neglected. Cross-sections of the stability surface for various principal planes are shown and compared with the actual stability surfaces as obtained by numerical integration. It is shown that the application of Zubov's method results in considerable improvement of stability-boundary estimates over those given by the ‘quadratic-plus-an-integral-of-the-nonlinearity’ type of Lyapunov functions which have previously been used for transient stability studies. Zubov's method generally requires machine computations. A section of the paper is, therefore, devoted to providing guidelines for digital-computer implementation of this method.

DOI:10.1049/piee.1971.0206

出版商:IEE    

年代:1971

数据来源: IET

摘要:

A method based on the matrix pseudoinverse is presented for the online identification of discrete-time systems of known order. Recursive algorithms are described which provide minimum-norm estimates of the parameter vector when insufficient data are available, and least-squares estimates with adequate data. These estimates can be updated easily with each pair of additional input-output data, as matrix inversion is not required. When the order of the system is not known, it may be determined offline using one of the two methods described. A recursive algorithm for calculating the residual error is also derived. A number of examples are given to illustrate the usefulness of the methods.

DOI:10.1049/piee.1971.0207

出版商:IEE    

年代:1971

数据来源: IET

摘要:

Under certain conditions of periodic excitation where both the input amplitude as well as the input frequency are varying, nonlinear multimodal systems can be forced exhibit a response in which jumps down occur for both an increase as well as a decrease in input frequency from a median value. This interesting phenomenon is termed ‘isolated jump resonance’. Systems of this type exhibit considerable sensitivity to changes in input frequency or amplitude at the occurrence of the jumps. Application of such systems as sensitivie detectors of frequency deviations in a periodic signal are proposed. A discussion of design considerations is given and a description is included of a system which has been constructed.

DOI:10.1049/piee.1971.0208

出版商:IEE    

年代:1971

数据来源: IET