Effect of Static Eccentricity and Stator Inter-Turn Short Circuit Composite Fault on Rotor Vibration Characteristics of Generator

Abstract

This paper investigates the radial rotor vibration characteristics under static air-gap eccentricity and stator inter-turn short circuit composite faults. The air-gap magnetic flux density is firstly deduced to obtain the unbalanced magnetic pull (UMP) on rotor. Then the rotor vibration characters, as well as the developing trend between the faulty parameters and the vibration amplitudes, are analyzed. Finally, the experiments are taken on a SDF-9 type simulating generator. It is shown that the radial deformation possibility, the 2nd, 4th, and 6th harmonic vibrations will be caused by the composite faults. Besides, the development of the inter-turn short circuit, the increment of the static eccentricity, and the rise of the exciting current will all get the deformation trend and the vibration amplitudes increased.

Analysis on the Amplitude and Frequency Characteristics of the Rotor Unbalanced Magnetic Pull of a Multi-Pole Synchronous Generator with Inter-Turn Short Circuit of Field Windings

“…Therefore, ϕ s,−2/3,2/3 and ϕ s,−4/3,4/3 in Equation (16) are always constants in the field current change process. As the 2/3-th and 4/3-th harmonic current in the stator branch are produced by the 2/3-th and 4/3-th MMF generated by the DC component of the rotor field current, both of F s,−2/3,2/3 and F s,−4/3,4/3 are proportional to F r,2/3 and F r,4/3 .…”

“…Then, F s,−2/3,2/3 , F s,−4/3,4/3 , F r,2/3 , F r,4/3 and F r,1 in the above equation are proportional to the DC component of the field current after failure, so the value of F sr,2 should be proportional to the square of the field current DC component, namely F sr,2 ∝ I 2 f . However, only four items which have a great impact on UMP amplitude are analyzed in Equation (16). Other items with relatively less impact cannot influence the relationship between the rotor UMP and field current, but not all the amplitudes of the items are proportional to the square of field current DC component.…”

“…There are some scholars who have explored and studied the characteristics of rotor UMP and vibration in faults. Reference [16] investigated the radial rotor vibration characteristics under static air-gap eccentricity and stator inter-turn short circuit composite faults. The vibration response characteristics based on the UMP model for the generator rotor are calculated and analyzed in [17].…”

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

“…Achievements obtained for SAGE mainly focus on the three-phase current or voltage change [3][4][5][6], the circulating current inside parallel branches (CCPB) and its corresponding diagnosis method [7][8][9], the unbalanced magnetic pull (UMP) calculation via FEM [10,11], the winding inductance variation based on improved winding function theory [12], and so forth.…”

“…However, the stator vibration properties are found to be much more distinguishable. The stator will vibrate at f, 2f, 3f, and 4f under RISC [20,21] and 2f, 4f, and 6f under SISC [23,24], respectively, while under the mass unbalance fault the stator vibration will change very little. Therefore, comparably, the stator vibration has a more sensitive effect to identify the failure types, though most scholars have paid their primary attention to the rotor vibrations but not the stator vibration characteristics [18,[20][21][22]24].…”