New techniques for the determination of synchronous machine parameters

The ever-increasing complexity of power systems is leading to more severe problems of system stability, and considerations of this are requiring a more detailed modelling of the system generators than has hitherto been undertaken. The induced eddy currents in the iron body of the machine, and the considerable active resistance of this iron, have previously been regarded as fully accounted for by a single damper circuit on each axis of the machine. However, recent work has shown that this is not an adequate representation, and that calculations on this basis may exhibit considerable discrepancies with practical measurements of the transient performance of the machine. Measurements of the generator parameters has been based on a single damper representation, and it is now necessary to reexamine carefully the assumptions underlying these tests and to determine if they can be used to provide an improved machine model. The main aim of this thesis is to investigate the possibility of using step-response tests to obtain the parameters of a machine model with two damper windings on each axis. From an investigation of this form of equivalent circuit, expressions in the form of transfer functions are developed for the operational inductance of the machine, and these are correlated with measured results to provide the necessary numerical data. Some of the results required can also be obtained from well-established test procedures, and these are therefore used to provide further confirmation of the accuracy of the new machine representation.