Uniform Field and Circuit Coupled Finite Element Method for short-circuit transient eddy analysis on aeronautic AC power synchronous generator

Abstract

Traditional methods of AC synchronous generator short-circuit fault analysis such as symmetrical component method, coordinate transformation method can not consider eddy current, while multi-loop method can only use air-gap magnetic conductivity concept to calculate inductances, which roughly considers the saturation of ferromagnetic materials. Finite Element Method (FEM) can solve the above problems, but it has disadvantage of considering single coil type in one model. Therefore Uniform Field and Circuit Coupled FEM (UFCCFEM) is proposed in this article. It adds additional variable loop-current into external circuit equations to form systematic coupled equations, which can fully consider solid coil eddy current influence and stranded coil current linear distribution influence. This method has less simulation time than pure eddy FEM model and more accurate short-circuit current transient characteristic than pure transient FEM. Perform this method on a certain aeronautic AC power synchronous generator, eddy current and electric potential transient waveforms are obtained and compare with experimental values to verify the correctness of the method. Spatial flux linkage transient distribution plot also show that UFCCFEM can conveniently consider transient armature reactance towards magnetic field. This method has been successfully applied on synchronous generator short-circuit fault analysis of constant speed and frequency aeronautic AC power.