An Improved Analytical Model for Salient Pole Synchronous Machines Under General Eccentricity Fault

This paper develops a more precise analytical model for calculating salient pole synchronous machine (SPSM) inductances in case of general eccentricity including static, dynamic and mixed eccentricities. The developed method is based on the modifled winding function approach (MWFA) which accurately considers variable air gap function and leads to pure analytical expressions of inductances. Available analytical techniques, based on MWFA, approximate the air gap function and simplify the geometrical model of SPSM, whereas, in this study, the in∞uence of the openings between the rotor salient poles has been taken into account by using an efiective form of rotor pole shoes. Using this technique, ∞ux fringing efiect is considered. By taking into account machine geometry, type of windings connection and ∞ux fringing efiect, this method is able to model most of the important features of an eccentric SPSM. The developed analytical expressions can calculate time varying inductances of SPSMs with any eccentricity type and degree in the frame of a single program. Simulation results for static eccentricity are compared with experimental tests on a laboratory generator to verify accuracy of the proposed model.