On the Application of Fluid Power Transmission in Offshore Wind Turbines

Offshore wind energy is currently characterized by the high costs associated with installation and operation. Gearboxes in particular have been singled out as a key source of the high maintenance costs of offshore wind farms. For a given wind speed, the torque of the rotor increases cubically with the diameter of its swept area. As the maximum size of wind turbines continues to increase, mass reduction and reliability are of growing importance for the system’s economy. In any industry where robust machinery is required to handle large torques, hydraulic drive systems are applied. It is therefore almost the obvious solution for wind turbines. The main components of a fluid power drive train are (1) a positive displacement pump, which transforms the mechanical power of the aerodynamic rotor into a high pressure fluid flow, and (2) a hydraulic motor, which converts the hydraulic power back into mechanical power. The research presented in this thesis is centered around the questions of whether and how the application of fluid power technology is feasible as an alternative to currently applied drive train technologies for offshore wind turbines. The approach is to define several possible configurations of the fluid power transmission system. From these, a concept using seawater hydraulics for centralized electricity production within an offshore wind farm is subjected to further analysis. Through research, modelling and experiments, the feasibility of this concept, known as the Delft Offshore Turbine is analyzed. To make offshore wind a competitive source of electricity requires more than incrementally improving and scaling-up onshore turbines. The concept for power transmission as presented in this thesis is shown to be technically feasible and will significantly reduce the complexity of offshore wind energy technology. A way to further prove the functionality and demonstrate the possible use of such a drive train is by building and testing it, preferably in a real turbine, offshore.

[1]  C. Svelto,et al.  Efficiency Measurement of Water Jet Orifices by a Novel Electro-Optical Technique , 2006, 2006 IEEE Instrumentation and Measurement Technology Conference Proceedings.

[2]  D. J. Cerda Salzmann.  Ampelmann : Development of the Access System for Offshore Wind Turbines , 2010 .

[3]  S. C. Rybak,et al.  Description of the 3 MW SWT-3 wind turbine at San Gorgonio Pass, California , 1982 .

[4]  J. Jonkman,et al.  Definition of a 5-MW Reference Wind Turbine for Offshore System Development , 2009 .

[5]  Peter Albers.  Motion Control in Offshore and Dredging , 2010 .

[6]  D. J. Malcolm,et al.  WindPACT Turbine Rotor Design Study , 2006 .

[7]  Lawrence J. Martin.  Wind Energy – The Facts: A Guide to the Technology, Economics and Future of Wind Power , 2010 .

[8]  Bernd-Robert Höhn.  Future Transmissions for Wind Turbines , 2011 .

[9]  E. S. Politis,et al.  Modelling and Measuring Flow and Wind Turbine Wakes in Large Wind Farms Offshore , 2009, Renewable Energy.

[10]  K. Bergey.  The Lanchester-Betz limit (energy conversion efficiency factor for windmills) , 1979 .

[11]  Robert Piche,et al.  Fluid Transmission Line Modeling Using a Variational Method , 2000 .

[12]  T. N. Stevenson,et al.  Fluid Mechanics , 2021, Nature.

[13]  Ervin Bossanyi,et al.  Wind Energy Handbook , 2001 .

[14]  Jeremy Thake,et al.  The Micro-Hydro Pelton Turbine Manual: Design, Manufacture and Installation for Small-Scale Hydro-Power , 2001 .

[15]  Ole Gunnar Dahlhaug,et al.  Technological Advances in Hydraulic Drive Trains for Wind Turbines , 2012 .

[16]  Andrea Catania,et al.  Experimental Analysis, Modeling, and Control of Volumetric Radial-Piston Pumps , 2011 .

[17]  S.S. Venkata,et al.  Wind energy explained: Theory, Design, and application [Book Review] , 2003, IEEE Power and Energy Magazine.

[18]  M. Hand,et al.  Wind Turbine Design Cost and Scaling Model , 2006 .

[19]  Peter Tavner,et al.  Reliability of wind turbine subassemblies , 2009 .

[20]  Peter Jamieson,et al.  Light-Weight, High-Speed Rotors for Offshore , 2009 .

[21]  J G Schepers,et al.  Joint investigation of dynamic inflow effects and implementation of an engineering method , 1995 .

[22]  Noah D. Manring,et al.  The Discharge Flow Ripple of an Axial-Piston Swash-Plate Type Hydrostatic Pump , 2000 .

[23]  Erik Trostmann,et al.  Water Hydraulics Control Technology , 1995 .

[24]  Ali Volkan Akkaya,et al.  Effect of bulk modulus on performance of a hydrostatic transmission control system , 2006 .

[25]  Hubertus Murrenhoff,et al.  Hydrostatic Drive Train in Wind Energy Plants , 2011 .

[26]  Imamhusen M Patil.  POWER QUALITY ASPECTS IN A WIND POWER PLANT , 2008 .

[27]  Ervin Bossanyi,et al.  Wind Turbine Control for Load Reduction , 2003 .

[28]  Y. B. He,et al.  Modern water hydraulics--the new energy-transmission technology in fluid power , 2003 .

[29]  Tonio Sant,et al.  Performance Modelling of an Offshore Floating Wind Turbine-Driven Deep Sea Water Extraction System for Combined Power and Thermal Energy Production: A Case Study in a Central Mediterranean Context , 2013 .

[30]  John S. Cundiff,et al.  Fluid Power Circuits and Controls , 2001 .

[31]  VA TECH HYDRO.  Commissioning and Operation Experience with the World’s largest Pelton turbines Bieudron , 2001 .

[32]  Peter Tavner,et al.  Wind turbine downtime and its importance for offshore deployment. , 2011 .

[33]  N.F.B. Diepeveen,et al.  Dynamic modeling of fluid power transmissions for wind turbines , 2011 .

[34]  Hubertus Murrenhoff,et al.  Development of a hydrostatic transmission for wind turbines , 2010 .

[35]  Ata M. Hassan,et al.  Optimization of hybridized seawater desalination process , 2000 .