Effect of 3D Unidirectional and Hybrid SAGE on Electromagnetic Torque Fluctuation Characteristics in Synchronous Generator

Abstract

This paper presents a comprehensive study on the variation laws of electromagnetic torque (EMT) under static air-gap eccentricity (SAGE) conditions in synchronous generators. Different from other studies, this paper focuses on not only the impact of radial SAGE, but also the effect of axial and hybrid SAGE, on the EMT fluctuation characteristics, i.e., we actually study the 3D static rotor eccentricity. The theoretical analysis model is first set up to study the influence of SAGE on the magnetomotive force (MFD) and EMT. Then, the finite element calculation and the experimental study on the CS-5 prototype generator which is of two poles and 3000 rpm are carried out to validate the theoretical analysis. It is shown that the radial SAGE will increase the dc component of MFD and shift the whole MFD curve and the phase current upwardly, while the axial SAGE will reduce the dc component as well as the amplitudes of both the MFD and the phase current like a compressing operation. In general, no matter in unidirectional or hybrid SAGE cases, the radial SAGE will intensify the EMT ripple and increase each harmonic of EMT, while axial SAGE will play the opposite role. The research conclusion obtained in this paper is potential to be applied as a supplement criterion for the condition monitoring and control of the eccentricity faults. INDEX TERMSSynchronous generator, 3D rotor eccentricity, electromagnetic torque. ABBREVIATION SAGE Static air-gap eccentricity RSAGE Radial static air-gap eccentricity ASAGE Axial static air-gap eccentricity HSAGE Hybrid static air-gap eccentricity EMT Electromagnetic torque EMF Electromotive force MMF Magnetomotive force PPUA Permeance per unit area MFD Magnetic flux densityThe associate editor coordinating the review of this manuscript and approving it for publication was Gongbo Zhou.

Effect of static/dynamic air‐gap eccentricity on stator and rotor vibration characteristics in doubly‐fed induction generator

“…However, the frequency components of rotor UMP/ vibration are all given. According to Equation (10), since the acceleration is the second derivative of displacement, the DC component will be zero in the experimental frequency domain. The MPPUA, stator vibration, UMP and rotor vibration variation with the degree of RAGE are shown in Figures 19,20 of RHAGE as indicated in Figure 23b and Table 6.…”

Effect of Static Rotor Eccentricity on End Winding Forces and Vibration Wearing

“…The authors have also carried out some preresearches and found that the odd harmonics of the electromagnetic force will be increased, while the even harmonics will be decreased as the rotor winding interturn short circuit occurs [24]. Besides, the studies on the rotor vibration [25], the magnetic flux density [26], the phase current [27], the electromagnetic torque [28], the rotor vibration properties [29], and the shaft voltage [27,30] under static air-gap eccentricity have also been presented. However, how will the end winding force change and how the vibration response varies in the static rotor eccentricity cases have still not been studied.…”

Electromagnetic Force and Mechanical Response of Turbo-Generator End Winding under Electromechanical Faults

“…On the other hand, Iamamura et al found that when the rotor is eccentric, the magnetic field shifts with the change of the eccentric angle [10][11][12]. Moreover, radial eccentricity will increase the harmonic components and amplitude of electromagnetic torque, while the impaction of axial eccentricity is on the opposite [13,14]. Ehya et al summarized the eccentricity detection methods according to harmonic components of voltage and current, efficiency, temperature, and electromagnetic torque fluctuation [15].…”