Efficient finite-element computation of synchronous machine transfer functions

An efficient two-dimensional finite-element (FE) model is developed for the calculation of synchronous machine transfer functions. The numerical model uses two equivalent sinusoidally distributed stator windings substituting the actual three-phase machine by an equivalent two-phase one, leading to simplified FE simulations. Just two complex solutions per frequency are needed to obtain the three transfer functions that completely describe the two-port nature of the d axis network. A new FE-based method is proposed to accurately establish the rotor base quantities, allowing the calculated transfer functions to be in per-unit. Results are validated by comparing the performance of a two-axis equivalent circuit, derived from the FE transfer functions, with a reference transient FE program.