United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

Abstract

-The purpose of this paper is to investigate the united Electromagnetic characteristics for the effective monitoring on the static air-gap eccentricity (SAGE) of turbo-generator. Different from other studies, this paper not only studies on the unbalanced magnetic pull (UMP) and the vibration characteristics of the stator and the rotor, but also investigates the harmonic features of the magnetic flux density and the circulating current inside the parallel branches (CCPB). The theoretical calculation, together with the finite-element-method (FEM) simulation and the experiment verification, is taken for a SDF-9 type non-salient generator. It is shown that, when SAGE occurs, apparent doublefrequency UMP and vibrations will be produced both on the stator and the rotor, while the CCPB will have an obvious increment at the 1 st harmonic component. In addition, the amplitude of the magnetic flux density will be of cosine distribution in the circumferential position of the air-gap, while in normal condition it is a constant. Moreover, the pass-band amplitude, together with the 1 st harmonic of the magnetic flux density, will be enlarged as well. These united electromagnetic characteristics can be used as the diagnosis and monitoring criterion for SAGE.

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].…”

Hybrid Fault Diagnosis Method Based on Mechanical-Electrical Intersectional Characteristics for Generators

“…The generator is the key equipment for a power plant and needs timely and accurate monitoring and maintaining. Typically, after a long-term operation, generators may endure many electrical faults such as the rotor interturn short circuit (RISC) [1] and the stator interturn short circuit [2,3], as well as mechanical faults such as rotor eccentricity [4].…”