Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station

Abstract

Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

“…Castelli et al [202] studied the dynamic response of the Lentini earth dam in Sicily after the occurrence of the Santa Lucia earthquake and compared it with free-field 1D PLAXIS (plane strain and axial symmetry) simulation. Lian et al [203] studied the underground powerhouse of a hydropower station on the Yalong River in China using field structural vibration tests. They simplified the mechanical models and theoretically interpreted the transmission mechanism.…”

“…The testing conditions for analysis were represented by another study using an FE model, and the results showed the propagation of the longitude-river vibration and vertical vibration was less than that of lateral-river vibration. The vibration transmission caused by the hydraulic generators' rotation was equivalent to that of the vibrations caused by the fluctuation of the low-frequency tail [203].…”

“…Some case studies have been conducted on the possible seismic damage to structures, such as the Yingxiuwan underground powerhouse in China using the dynamic numerical simulation method and Brežice dam in Slovenia using a laser Doppler Vibrometer [206] and FE analysis. FE analysis has been used to examine the vibrational characteristics on the spiral case structure of the Ahai Hydropower Station, where the semi-cushion spiral structure was found to be safe [203,[207][208][209].…”

“…Various designs have been proposed to enhance the hydro-turbine efficiency, which have been tested via numerical simulations [146,163,168,177,178,[195][196][197][201][202][203]. Vibration due to powerhouse operation has been analyzed by several researchers [151,176,[201][202][203]205,206,208,209,226]; however, more comprehensive studies should be completed to connect the effect of vibration from turbines operation with design on the dam body, to assure dam safety.…”

Vibration transmission path identification in a hydropower house based on a time-delayed transfer entropy method

“…They found the vibration transmission direction in underground powerhouse was mainly perpendicular to and along the flow in the foundation rock. Lian et al (2018) concluded from the field structural vibration tests of an underground hydropower house that the transmission of lateral-river vibration was greater than those of longitude-river and vertical vibration and that the transmission ratios of vibration caused by the low and rotational frequency were basically equal. Sun and Yan (2013) proposed the time-delayed transfer entropy method to study the vibration of the hydropower house by numerical analysis of a simplified multistory structure and the prototype field experiment research.…”