Mechanical Vibrations of Turbine-Generator Bearing Malfunctions in Hydroelectric Power Plants and Solution Methods

Abstract

The fact that the power and dimensions of hydraulic turbines manufactured today have increased significantly also brings about a serious mechanical vibration and shaft oscillation problem. It is known that a machine exposed to mechanical vibration (vi-bration event) is constantly strained by variable mechanical stresses such as pulling, pressing, bending, twisting, and shearing. The exposure of hydraulic turbines to such vibrations and oscillations significantly reduces operational safety and operating time. In this study, mechanical vibration (vibration event) and shaft oscillation failures that occurred as a result of the bearing clearance exceeding the permitted limits in a Francis type turbine belonging to a hydroelectric power plant were investigated. The shaft os-cillations that occurred after the turbine-generator bearings were re-adjusted were compared with the shaft oscillations that occurred in the event of a failure. As a result, after the dimensions of the hydraulic turbine bearings were brought to the accepted standards after the failure, mechanical vibrations and shaft oscillations returned to normal levels. Failures caused by mechanical vibration and major failures such as bearing friction that would occur as a result of excessive shaft oscillations were prevented.

Keywords

• mechanical vibration;
• shaft oscillation;
• hydroelectric

Hidroelektrik Santrallerde Türbin-Jeneratör Yatak Arızaları Sonucu Oluşan Mekanik Titreşimler ve Çözüm Yöntemleri

Abstract

Günümüzde imal edilmekte olan hidrolik türbinlerin güçlerinin ve boyutlarının çok artmış olması ciddi bir mekanik titreşim ve şaft salınımı problemini de beraberinde getirmektedir. Bilinmektedir ki mekanik titreşime (vibrasyon olayı) maruz kalan bir makine devamlı olarak çekme, basma, eğme, burma, kesme gibi değişken mekanik baskılarla sürekli olarak zorlanmaktadır. Hidrolik türbinlerin bu tür titreşim ve salınımlara maruz kalmaları işletme güvenliğini ve işletmede kalma süresini önemli derecede azaltmaktadır. Bu çalışmada, bir hidroelektrik santrale ait Francis tipi tür-binde yatak boşluğunun müsaade edilen sınırları aşması neticesinde meydana gelen, mekanik titreşimler (vibrasyon olayı) ve şaft salınımları arızası incelenmiştir. Tür-bin – Jeneratör yataklarına tekrar ayar yapıldıktan sonra oluşan şaft salınımları, arıza durumunda oluşan şaft salınımları ile kıyaslanmıştır. Sonuç olarak arıza sonrası hidrolik türbin yataklarının ölçüleri kabul edilen standartlara getirildikten sonra mekanik titreşimler ve şaft salınımları normal seviyelere gelmiştir. Mekanik ti-tre-şimden kaynaklı arızalar ve aşırı şaft salınımı sonucu oluşacak yatak sürtmesi gibi büyük arızalar engellenmiştir.

Keywords

• mekanik titreşim;
• şaft salınımı;
• hidroelektrik

References

1. M. K. Padhy and R. P. Saini, “A review on silt erosion in hydro turbines,” Renewable and Sustainable Energy Reviews, vol. 12, no. 7, pp. 1974–1987, 2009.
2. V. S. Singh and S. K. Singal, “Operation of hydro power plants-a review,” Renewable and Sustainable Energy Reviews, vol. 69, pp. 610–619, 2017.
3. U. Dorji and R. Ghomashchi, “Hydro turbine failure mechanisms: An overview,” Engineering Failure Analysis, vol. 44, pp. 136–147, 2014.
4. A. Barbour and W. T. Thomson, “Finite element study of rotor slot designs with respect to current monitoring for detecting static airgap eccentricity in squirrel-cage induction motors,” in IAS’97. Conference Record of the 1997 IEEE Industry Applications Conference Thir-ty-Second IAS Annual Meeting, vol. 1, Oct. 1997, pp. 112–119.
5. S. Nandi, H. A. Toliyat, and X. Li, “Condition monitoring and fault diagnosis of electrical motors-a review,” IEEE Transactions on Energy Conversion, vol. 20, pp. 719–729, 2005.
6. D. Basak, A. Tiwari, and S. P. Das, “Fault diagnosis and condition monitoring of electrical machines-a review,” in Proc. IEEE International Conference on Industrial Technology (ICIT 2006), Mumbai, India, 2006, pp. 3061–3066.
7. R. K. Mohanta, T. R. Chelliah, S. Allamsetty, A. Akula, and R. Ghosh, “Sources of vibration and their treatment in hydro power stations,” Engineering Science and Technology, an In-ternational Journal, vol. 20, pp. 637–648, 2017.
8. J. R. Stack, T. G. Habetler, and R. G. Harley, “Effects of machine speed on the development and detection of rolling element bearing faults,” IEEE Power Electronics Letters, vol. 1, pp. 19–21, 2003.

9. S. Wei and L. Zhang, “Vibration analysis of hydropower house based on fluid-structure cou-pling numerical method,” Water Science and Engineering, vol. 3, no. 1, pp. 75–84, 2010.
10. C. H. Zhang and Y. L. Zhang, “Nonlinear dynamic analysis of the Three Gorge Project powerhouse excited by pressure fluctuation,” Journal of Zhejiang University–Science A, vol. 10, no. 9, pp. 1231–1240, 2009.
11. F. Feng and F. Chu, “Dynamic analysis of a hydraulic turbine unit,” Mechanics of Structures and Machines, vol. 29, pp. 505–531, 2001.
12. Y. Zhang, X. Zheng, J. Li, and X. Du, “Experimental study on the vibrational performance and its physical origins of a prototype reversible pump turbine in the pumped hydro energy storage power station,” Renewable Energy, vol. 130, pp. 667–676, 2019.
13. Y. Wu, S. Li, S. Liu, H. S. Dou, and Z. Qian, Vibration of Hydraulic Machinery. Springer Netherlands, 2013.
14. P. J. Tavner, “Review of condition monitoring of rotating electrical machines,” IET Electric Power Applications, vol. 2, pp. 215–247, 2008.
15. S. H. Yang, C. Kim, and Y. B. Lee, “Experimental study on the characteristics of pad flut-tering in a tilting pad journal bearing,” Tribology International, vol. 39, pp. 686–694, 2006.
16. A. Chasalevris and F. Dohnal, “A journal bearing with variable geometry for the suppression of vibrations in rotating shafts: Simulation, design, construction and experiment,” Mechanical Systems and Signal Processing, vol. 52, pp. 506–528, 2015.