Frame and Stator Core Vibration Analysis of a Medium Power Generator through Finite Element Method

This research employs a numerical method to extract dynamic characteristics of the frame and stator core of a medium power turbo-generator and investigates their behavior under rotor unbalance and 4-nodal electromagnetic forces. Harmonic analysis is conducted to evaluate the forced vibration response, and modal analysis is utilized to determine the natural frequencies and mode shapes of the frame and stator core assembly.The laminated stacked core is simplified and modeled as an equivalent cylindrical core. The Foundation is excluded from modeling due to its high mass relative to the generator, and the generator interface with the concrete below is considered as a fixed boundary condition.Results reveal that modifications applied to springs, ribs, and core clamping components cause the main natural frequencies of the stator core and frame, as well as local mode shapes of the pedestal region, to be located away from excitation frequencies. The harmonic analysis demonstrates that the dynamic response ratio of frame-to-core (it means core-to-frame vibration transmission) is less than 1, and the bearing is acceptable according to ISO 20816-2. This research contributes to understanding of generator dynamics and provides valuable insights for improving design, optimizing structural performance, and enhancing the reliability of generators.