Research on noise and vibration reduction in pumped-storage power stations based on source and transfer path optimization

Abstract

Operation of a pumped-storage unit can induce noise and vibration in the powerhouse. In particular, abnormal responses at specific order-related frequencies may seriously affect the safe and stable operation of the power station as well as personnel comfort. In Unit 2 of a pumped-storage power station, prominent frequency components at the 9th order (45 Hz) and the 18th order (90 Hz) were observed in the noise and vibration measured at the generator floor. A comprehensive mitigation method combining source optimization and transfer path control was proposed for the two dominant frequency components. Based on the rotor–stator interaction mechanism analysis, it is confirmed that the blade passing frequency generated by the 9-blade runner and 20 guide vanes is 45 Hz, and that its second harmonic is 90 Hz. These frequencies are consistent with the dominant frequency components identified in the measurements. Taking the noise and vibration at the generator floor as target responses, an excitation source–path–response model was established based on operational transfer path analysis (OPA). The analysis identified structural vibration of the busbar floor as the dominant transfer path contributing to the 45 Hz and 90 Hz frequency components. On this basis, a local structural dynamic modification scheme for the busbar floor was proposed, and the post-modification response was predicted to evaluate the expected noise and vibration reduction after path optimization. After considering the feasibility of field implementation and the expected effect, the original 9-blade runner was replaced with a 6+6 runner with alternating long and short blades, thereby changing the excitation frequency at the source and reducing the excitation induced by rotor–stator interaction (RSI). The results show that the runner modification effectively suppresses the RSI-induced excitation amplitudes at 45 Hz and 90 Hz. At the generator floor, the vibration acceleration level at 90 Hz was reduced by 16.1 dB, and the sound pressure level was reduced by 16.2 dB(A). The proposed method provides a theoretical basis and practical reference for vibration and noise reduction in the complex vibro-acoustic environment of pumped-storage power stations.