Analysis of the Characteristics of a Synchronous Generator by means of Air Gap Flux

Abstract

This paper describes the analysis of the characteristics of a synchronous generator on the basis of air gap fluxes measured by a search coil on the stator tooth top. It is especially concerned with the loss of synchronism process which governs the stability of an electric power system, but has not yet been made clear physically. That is to say, the principles of measuring air gap flux by using a search coil, methods of determining direct axis positions, derivation of no-load air gap flux density distribution, derivation of armature reaction flux, and the analysis of the loss of synchronism process are described. This is a modified paper of our previous works which is aimed at giving a total understanding of the physical behavior of a synchronous generator connected to an electric power system, over the wide range of operations from the sready-state to the step-out process. This will contribute to the efforts of both the design engineers of electrical apparatus and the power system engineers.