Stator Vibration Characteristic Identification of Turbogenerator among Single and Composite Faults Composed of Static Air-Gap Eccentricity and Rotor Interturn Short Circuit

Abstract

This paper investigates the radial stator vibration characteristics of turbogenerator under the static air-gap eccentricity (SAGE) fault, the rotor interturn short circuit (RISC) fault, and the composite faults (CFs) composed of SAGE and RISC, respectively. Firstly, the impact of the faulty types on the magnetic flux density (MFD) is analyzed, based on which the detailed expressions of the magnetic pull per unit area (MPPUA) on the stator under different performing conditions are deduced. Then, numerical FEM simulations based on Ansoft and an experimental study are carried out, taking the SDF-9 type fault simulating generator as the study object. It is shown that SAGE will increase the stator vibration at 2f (f is the electrical frequency) which already exists even in normal condition, while RISC and CF will bring in stator vibrations at f, 2f, 3f, and 4f at the same time. The vibration amplitudes under CF are larger than those under RISC. As SAGE increases, the vibration amplitudes of each harmonic component under CF will all be increased, while the development of RISC will decrease the 2nd harmonic vibration but meanwhile increase the 4th harmonic vibration. The achievements of this paper are beneficial for fault identification and condition monitoring of the turbogenerator.

A Hybrid Method to Diagnose 3D Rotor Eccentricity Faults in Synchronous Generators Based on ALIF_PE and KFCM

“…e typical faults of generator include rotor short circuit, stator short circuit, and air-gap eccentricity. Among them, eccentricity fault will lead to the change of air-gap magnetic field which would worsen the performances of generator and even damage the machine as a result of vibration, rotor bending, winding wear, and friction between stator and rotor [3]. erefore, eccentricity fault detection is one of the important contents of generator fault diagnosis.…”

Impact of Single and Combined Faults Composed of Rotor Eccentricity and Stator Interturn Short Circuit on Electromagnetic Torque Ripples in Synchronous Generator

“…For SAGE, scholars have investigated both the mechanical and the electrical faulty properties. For instance, He et al investigated the unbalanced magnetic pull (UMP) [8], the vibration characteristics of the rotor [9], and the circulating current inside the parallel branches [10]. Besides the mechanical characteristics, it is also found that the stator phase current is an effective tool to identify the broken magnet and SAGE in permanent magnet synchronous motors [11], while at the same time, the shaft voltage measurements have been found as a better means for the optimal measurement modality that leads to a minimal identification error of SAGE in synchronous machines [12].…”

Analysis on Electromagnetic Force Properties of End Windings in Turbo-Generators

“…However, the above two methods need accurate stator current information, and it is therefore limited for application in some complex running cases, for example, the winding inter-turn short circuit or rotor eccentricity. Yu-Ling He analyzed the stator and rotor vibration characteristics in eccentricity and inter-turn shortcircuit composite faults by magneto-motive force (MMF) superposition principle and air gap magnetic conductivity method [3,4]. Yucai Wu analyzed the virtual work during the rotor inter-turn short circuit [5].…”