Stress Characteristic Analysis of Pump-Turbine Head Cover Bolts during Load Rejection Based on Measurement and Simulation

Xingxing Huang, Liu Chen, Zhengwei Wang, Haibo Li, Shunyi Chen, Kun Hu, Chengjun Li and Lan Qiu
Additional contact information
Xingxing Huang: S.C.I. Energy, Future Energy Research Institute, Seidengasse 17, 8706 Zurich, Switzerland
Liu Chen: China Institute of Water Resources and Hydropower Research, No. 20, Chegongzhuang West Road, Beijing 100048, China
Zhengwei Wang: State Key Laboratory of Hydroscience and Engineering, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
Haibo Li: Huadong Yixing Pumped Storage Co., Ltd., No. 3 Qinhu Road, Yixing City 214256, China
Shunyi Chen: Powerchina Huadong Engineering Corporation Limited, No. 201 Gaoxiao Road, Hangzhou 311122, China
Kun Hu: Huadong Yixing Pumped Storage Co., Ltd., No. 3 Qinhu Road, Yixing City 214256, China
Chengjun Li: Powerchina Huadong Engineering Corporation Limited, No. 201 Gaoxiao Road, Hangzhou 311122, China
Lan Qiu: Huadong Yixing Pumped Storage Co., Ltd., No. 3 Qinhu Road, Yixing City 214256, China

Energies, 2022, vol. 15, issue 24, 1-16

Abstract: It is not uncommon for pump-turbine units in pumped storage power plants to experience load rejections due to the sudden disconnection of the generator from the power grid. Load rejection can suddenly increase the rotating speed of the pump-turbine and cause strong pressure fluctuations in the flow passage of the pump-turbine unit. During load rejection, the strong pressure fluctuations caused by the water hammer effect can cause strong structural vibrations, high stresses and even damage to the turbine runner, head cover, stay ring, bottom ring, head cover bolts and bottom ring bolts. In order to study, in detail, the flow-induced stress characteristics of the prototype pump-turbine unit, and the pressure variations during load rejection in a high-head pumped storage power plant were measured first. Then the measured data were used to set up computational fluid dynamics (CFD) simulations in the entire flow passage of the prototype pump-turbine and to calibrate the simulation results. The calculated pressure distributions in the flow passage during load rejection were exported and mapped on the finite element model of the stationary structures of the pump-turbine unit so that the flow-induced stresses on the head cover, stay ring, bottom ring, head cover bolts and bottom ring bolts can be calculated. The results of the analysis show that the maximum stresses in the head cover bolts and bottom ring bolts are located on the rounded corner of the bolt near the stay ring and that the stresses in the bolts vary with time during load rejection. The maximum stresses of the head cover bolts are higher than the maximum stresses of the bottom ring bolts, and the maximum stresses of the bolts are above two-thirds of the yield strength of the bolt material. It is recommended to use larger nominal diameter bolts to avoid damage to the connecting bolts of the pump-turbine unit.

Keywords: prototype pump-turbine; load rejection; head cover bolts; flow-induced stress analysis; measurement and simulation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
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