New approach to the determination of synchronous-machine parameters from tests

In the last decade or more, a number of tests on large synchronous machines and the associated analytical work have revealed certain inaccuracies in the theory of synchronous-machine performance, which has been used for the last half century. A new look is taken at the assumptions underlying the old theory and several of them are discarded in the derivation of a new theory which corrects many of the inaccuracies. The new theory results in new formulas for the calculation of machine parameters, such as transient reactance and transient time constant; it is particularly relevant in the calculation of parameters for synchronous machines with damper windings.