Theoretical analysis and numerical FEM calculations, together with segmental experiment studies, are used to study the impact of the static air-gap eccentricity forms on the rotor unbalanced magnetic pull (UMP) of turbogenerator. The universal expression of the magnetic flux density under different forms of SAGE is firstly deduced, based on which the detailed UMP formulas for the normal condition and three SAGE cases are obtained, respectively. Then the exciting characteristics of the UMP for each SAGE form to generate vibrations are analyzed. Finally, numerical FEM calculations and segmental experiments are carried out to investigate the effect of SAGE forms on the rotor UMP, taking the SDF-9 type non-salient-pole fault simulating generator as the object. It is shown that, no matter what kind of SAGE occurs, amplitude increments at each even harmonic component of the UMP and the rotor vibration, especially the 2nd harmonic component, will be brought in. Meanwhile, the UMP keeps directing to the very position where the minimum radial air-gap is. Among the different SAGE forms, the rotor offset has the most sensitive effect on the rotor UMP and vibration, while the stator ellipse deformation has the weakest impact.
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.
The purpose of this paper is to investigate the effect of the axial air-gap eccentricity (AAGE) on the electromagnetic characters such as the axial unbalanced magnetic pull (UMP) and the electromagnetic torque (EMT). Firstly, the theoretical model of AAGE is set up, and the formulas of the axial UMP and EMT are deduced. Then the simulation study of a SDF-9 nonsalient pole synchronous generator is taken with Ansoft Maxwell to calculate the detailed axial UMPs and EMTs under normal condition and five AAGE conditions, respectively, with 2 mm to 10 mm rotor displacements. It is shown that an apparent axial UMP will be produced due to AAGE, while EMT and the phase current will be decreased. In addition, the magnetic flux density (MFD) on the stator end and the rotor end, which are more far from the center position of the stator core in the axial direction, will be decreased, while the MFD on the other ends will be generally kept stable. As AAGE develops, the axial UMP will be increased, while EMT and the phase current will be decreased. The proposed work offers a reference for the fault diagnosis and monitoring on AAGE.
This paper used theoretical analysis and numerical calculation to analyze winding electromagnetic force (EF). QFSN-600-2YHG type turbo-generator is the research object. This paper investigated EF on exciting windings of turbo-generator before and after rotor interturn short circuit (RISC) fault. The impact of RISC on the air-gap magnetic flux density (MFD) was firstly studied. The EF formulas were deduced based on the air-gap MFD. Then the detailed EF values were obtained by numerical calculation. The winding EFs are of centrosymmetry under normal condition. RISC mainly affects the EF of the very coil where the short circuit takes place. As RISC develops, the EF will decrease. This study is probable to be beneficial to insulation monitoring.
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