Representation of Saturated Salient-Pole Synchronous Machine by a Single Magnetization Curve

Abstract

The paper describes a new method of representing saturated salient-pole synchronous machine by a simple method. The essence of the model is to represent the machine, along any intermediate axis, by a single magnetisation characteristic. This approach is useful when an accurate assessment of the flux level is requireT herefore, the model expresses the magnetising or the synchronous reactance as a function of the angle between the resultant m.m.f., rather than the flux, and the d-axis. Moreover,the model is simple and can be easily defined provided that the d-and qaxis characteristics are known. Thus, the model is of value in power-systems studies. LIST OF PRINCIPAL SYMBOLS the airgap voltage corresponding to a constant airgap flux. r.m.s. value of armature current per phase. = r.m.s. value of phase current equivalent to the excitation m.m.f. = r.m.s. value of the terminal voltage per phase. = the airgap voltage corresponding to a current I r i at any intermediate axis. = the d-and the q-axis airgap voltages when the total m.m.f. operates on each axis separately. the magnetising reactance at any intermediate axis corresponding to a constant m.m.f. = the magnetising reactance at any intermediate axis corresponding to a constant airgap voltage. the d-and the q-axis magnetising reactances when the resultant m.m.f. operates on the respective axis individually. the d-and the q-axis magnetising reactances when the same resultant airgap flux operates on the respective axis individually. slopes of the airgap lines of the d-and the q-axis respectively, i.e. the d-and the q-axis unsaturated reactance coefficients. 369 Downloaded by [University of Arizona] at 10:20 03 February 2015 370 A-R.A.M.MAKKY a the angle between the airgap voltage(E ) and the excitation voltage axis. g = the angle between the resultant m.m.f. and the daxis. a power angle. = angular frequency. a phase angle between V and I.