Simulation of the Transient and Subtransient Reactances of a Large Hydrogenerator by Finite Elements

This paper describes a method for the computation of the transient and subtransient reactances of synchronous machines by finite elements. It employs the concept that boundary conditions may be used to isolate different regions of the problem domain. By using this approach, the regions of the problem domain which contain induced currents in the transient and subtransient regimes, are isolated. Great simplification of the problem is gained as a result of this practice. The method is implemented on a large water-wheel generator with first order nonlinear triangular elements. Extreme load levels as well as armature flux angles have been examined. The computational results in all the cases studied show a good accordance with the manufacturer´s shop-floor tests.