A theoretical derivation of the unsaturated d-axis reactances of synchronous machines from first principles

This paper presents ways of calculating d-axis natural reactances of synchronous machines from first principles. These are the d-axis unsaturated synchronous, transient and sub-transient reactances and this paper shows how the reactances of synchronous machines tend to the natural values. The results will be useful in two ways: firstly to the designers of synchronous machines and secondly to the designers of electrical systems.