THE APPLICATION OF THE FAST FOURIER TRANSFORM FOR THE COMPtJrATION· OF SYNCHRONOUS MACIUNE DYNAMIC BEHAVIOUR
Khalil, Hamdy Saleh
The. present trend towards using 'larger synchronous machines has given more importance to the study of their dynamic behaviour. In order to utilize such large machines fully, the tendency is to operate them nearer to their stability limits. A more reliable anaiysis of their stability problems as well as their dynamic behaviour is necessary in order to achieve safe and reliable operation. As a consequence, synchronous machine modelling has been given more attention in recent years. With more accurate and detailed modelling, the mathematical representation of power systems becomes more complicated and it is necessary to explore new numerical techniques that will give accurate analysis requiring less computation time. This thesis presents a new technique known as the fast Fourier transform. This technique is based on inverting the frequency responses of the transfer functions of the synchronous machine and its regulators to the time domain to obtain their transient solutions. The inversion is carried out using a FORTRAN program constructed on the basis of the Cooley and Tukey version of the fast Fourier transform. The fast Fourier transform and the Runge-Kutta method are both applied to some typical problems of synchronous machines. A comparison between both techniques has shown that the application of the fast Fourier transform in the field of power system analysis could be of great advantage. It has been found that this technique requires less computation time than that of the Runge-Kutta method to give results of comparabie accuracy.