Theoretical study and experimental verification of vibration control of offshore wind turbines by a ball vibration absorber

AbstractIn this paper, a ball vibration absorber (BVA) is introduced for vibration control of offshore wind turbines. The dynamic responses of offshore wind turbines equipped with a BVA are presented. Both theoretical and experimental investigations are carried out. An analytical model for the wind turbine tower system with installed BVA is developed based on Lagrange's equation. The BVA-structure integrated equations are derived and solved in both time domain and frequency domain. A series of shaking table tests on a 1/13-scale wind turbine model with and without a BVA were carried out to evaluate the effects of BVA on the vibration mitigation of the wind turbine tower system under earthquakes and equivalent wind-wave loads. Numerical simulations of the system are performed and compared with the experimental results. Good agreement between the numerical and experimental results is observed. The results indicate that BVA could effectively improve the performance of the offshore wind turbine.Keywords:: offshore wind turbineball vibration absorberanalytical modelvibration controlshaking table test AcknowledgementsFinancial supports from the National Natural Science Foundation of China (Grant Nos 90715033 and 11172210), National Hi-Tech Development Plan (863 Plan) (Grant No. 2008AA05Z413) and the State Key Laboratory of Disaster Reduction in Civil Engineering (Grant Nos SLDRCE08-A-01 and SLDRCE10-B-02) are greatly appreciated. The authors are grateful to Mr D. Wang for his help in generating the shaking table input and to Mr X.Y. Bai, Mr K. Huang, Mr Y.K. Liu, Ms Y. Feng and Mr W. F. Liu for their help in the experiments.