A coupled finite-element state-space approach for synchronous generators. I. model development

Abstract

Presented here is the development of a time stepping coupled finite-element state-space (CFE-SS) modeling environment, totally within the natural time domain ABC flux-linkage frame of reference, to predict the steady-state machine parameters and performance characteristics, including laminated iron core losses, of salient-pole synchronous machines. The time stepping CFE-SS model allows one to rigorously account for the full synergistic impact of space harmonics and time harmonics on the machine parameters and performance characteristics.Manuscript

CFE-SS approach for salient-pole synchronous generators under unbalances

“…Notice that this 2-pole machine has an armature with a 60 ± e phase-belt layout. The modeling of the damper cage was detailed in [1,2]. Accordingly, only the developed damper cage representation [1,2] is given in Fig.…”

“…Also, in the absense of solid iron in the rotors of such machines the need for a curl-curl diffusion-based solution would appear to these authors to be unnecessary. This is particularly the case here since the paths of induced diffusion-type currents are so well defined and confined to the damper cage bars, where a coupled circuit lumped parameter approach as described in [1,2] was found to be quite an effective and sufficient analysis tool.…”

“…This is in addition to the synergism which inherently takes place between these space harmonics and what they generate in the form of time harmonics in the resulting flux linkage, voltage and current waveforms of the armature, field and damper windings of a given synchronous machine. From such performance parameters and magnetic field solutions, this CFE-SS model [1,2] also produces the damper bar ohmic losses as well as iron core losses including the effect of space harmonic contents in the flux density waveforms throughout the magnetic circuit.…”

“…This CFE-SS modeling environment of [1,2] enables one to compute the periodic, yet nonsinusoidal, steady-state time-domain profiles of the machine parameters (inductances), damper cage bar currents, other machine winding current/voltage waveforms and torque profiles, as well as other magnetic field related quantities. This approach includes the full impact of space harmonics due to magnetic saturation as well as magnetic circuit and winding layout configurations of a given machine.…”

“…A time-stepping coupled finite element-state space (CFE-SS) modeling environment, formulated in terms of natural machine winding flux linkages, voltages and currents, was detailed in [1,2] for simulation of open-circuit, short-circuit, and balanced impedance load performance of high speed salient-pole synchronous machines. This CFE-SS modeling environment of [1,2] enables one to compute the periodic, yet nonsinusoidal, steady-state time-domain profiles of the machine parameters (inductances), damper cage bar currents, other machine winding current/voltage waveforms and torque profiles, as well as other magnetic field related quantities.…”