Control of Seismic Excitation in Power Generation Turbomachines Utilizing Active Oil Film Bearings

Abstract A power generation turbomachine installed in seismically active areas is assessed on its capacity to receive seismic excitations of specific bandwidth and magnitude. There are several cases where seismic excitations result in an emergent trip of operation due to rotor–stator contact or high response amplitude in general. This paper demonstrates the efficiency of a novel active oil-film journal bearing to reject seismic excitations of specific characteristics, utilizing controllers such as the linear quadratic Gaussian (LQG) controller and the H-infinity (H∞) controller. The study includes a dynamic model of a realistic turbine-generator shaft-train, in which all four conventional oil-film bearings are replaced by the novel active oil-film bearings, operating on the principle of hydrodynamic lubrication considering an averaged thermal influence. The operability of the active bearings is discussed together with the response characteristics of the shaft-train during a recorded seismic excitation of the Richter scale of magnitude seven. The results demonstrate the effectiveness of the active bearings in maintaining operation and avoiding rotor–stator contact. The LQG controller appears to be more efficient when specific constraints for the active bearing operation, such as motor speed and load, apply. Desired period, with low control effort. The results create a potential for smooth periodic motions in high-speed rotating systems.