Analogue Computer Study of some Fundamental Control Relations Involving Alternators and Diesel Engines

The purpose of this investigation is to study the effect that the amortisseur winding has on the stability of an alternator when it is driven by an engine. The simulation of the system was done with the use of an analogue computer. The effect of each amorlisseur winding was studied separately and together. This type of information is not available and the control engineer needs these results when analysing certain complex systems. In order to arrive at system equations, the alternator is treated as a many-winding transformer, and the equations are obtained from the transformer equipment circuit. A transformation due to Blondel was applied to these system equations which in effect causes the demodulation of the frequency of the alternator. Then, on the analogue computer, only variations of amplitude and not the individual frequency had to be simulated. This study revealed that the amorlisseur windings could be treated as feedback compensation to the prime mover, and this paper presents the development of a transfer function that represents the effect of the amorlisseur windings. An analogue computer diagram is developed to represent the diesel engine. This particular alternator analogue diagram is different from those tried for other simulations ; the analogue computer is stable and yields accurate results when wired in the manner described in this report. A root locus analysis shows conditions where the amorlisseur windings can help stabilize a system. For the particular alternator parameters used in this study the amorlisseur winding is most effective if the system tends to have oscillations in the neighbourhood of two or three hertz.