Transient interaction and control scheduling in multimachine power systems

Abstract

The thesis describes new methods of determining control schemes for multimachine power systems by using Linear Multivariable Control Theory. The initial stages of the work include a review of the different modelling techniques available for studying the performance of synchronous machines by analogue or digital computation. Based on this review a non linear digital program that describes any multimachine power system is produced. For control work a linearised version of this program is available. A review of the mathematical theory behind Linear Multivariable Control methods is given emphasising its link with the classical approach of Nyquist Analysis. The control theory is interfaced with the digital model of the power system to produce a series of designs by which control is achieved by either: (i) Impedance switching (ii) Fast valving (iii) Field Excitation The different control designs are compared both with each other and with control schemes suggested by other authors, forking, from a purely mathematical basis control schemes are postulated that produce improved operation to both small and large disturbances. The advantages of fast valving as a control method is outlined and suggested as the most advantageous method of overall control for both single - and multimachine power systems.