SYNCHRONOUS MACHINE MODELS USING FEEDBACK CONTROL

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Riassunto

A new form of simulation of synchronous generators has been investigated and a "combined" model is presented. It consists of a small round-rotor machine with two rotar windings, both controlled through external feedback circuits. An analogue computer is combined with the machine in arder to produce the appropriate driving signal far the feedback amplifier. The investigation covered by the present thesis consisted of a theoretical study associated with experimental work. Heaviside's operational method has been used in solving the fundamental equations, and in addition graphical methods (block diagrams and flow-graphs) have been employed as aids in formulating and visualising feedback problems. It has been found that all the important parameters of a synchronous machine can be controlled by external feedback circuits and therefore any large machine can be represented - no matter what its parameters or combination of parameters - by simple adjustment of the feedback controls, with an accuracy limited only by the components of the sustem.
Experiments have been carried out using a laboratory universal BKB machine (with a rated power of 2k VA), which had to be suitably modified.
FORTRAN IV programming has been used in conjunction with an IBM 7090 computer for predicting the short circuit armature currents and the direct - and quadrature-axis operational impedances: the experiments, compared with computed results, showed reasonable agreement.