Print Email Facebook Twitter Small Scale Fluid Power Transmission for the Delft Offshore Turbine Title Small Scale Fluid Power Transmission for the Delft Offshore Turbine Author Kempenaar, A.S. Contributor Van Bussel, G.J.W. (mentor) Diepeveen, N.F.B. (mentor) Albers, P.S. (mentor) Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Programme Offshore Engineering - Sustainable Energy Technology Date 2012-03-12 Abstract The Delft Offshore Turbine (DOT) project is a research project within the Delft University Wind Energy Research Institute (DUWIND). The main objective of the DOT research project is to make offshore wind energy a competitive energy source. One of the research lines in the DOT project is considering the centralization of electricity generation within a wind farm. The complete process of wind energy extraction up to the connection with the electrical grid must be taken into account in order to develop an optimal technology to generate electricity from offshore wind energy. The DOT project thus approaches the design of a wind farm by regarding the entire farm as one system instead of a collection of systems. For this purpose a renewed wind farm concept was developed within the DOT project. A unique aspect of the DOT concept are the fluid power transmission systems used to transfer the energy of single turbines to a central platform for electricity generation. The main objective of this thesis is to prove the functionality of the DOT transmission concept. To prove the functionality of this concept a small scale demonstration set-up of the DOT transmission was designed, constructed and tested. Prior to the start of the design process the design objectives and requirements were identified. The transmission is designed for a specific 10kW rotor. The rotor speed needs to be controlled close to its optimal tip speed ratio in order to maximize the energy extraction from the wind. This is achieved by using a passive control strategy together with accurately sized components in the transmission. A dynamic model of the transmission was developed to increase the physical understanding of the transmission and to assist in the design process. The demonstration set-up was constructed in the water laboratory at the faculty of Civil Engineering and Geosciences of the TU Delft. In the demonstration set-up the rotor is simulated by an electric motor with a controllable speed. The dynamic model was validated successfully with experiments in steady state and dynamic conditions. The functionality of the transmission was analyzed by simulations with the validated transmission model and a simplified rotor model. The following conclusions are drawn from the experiment and simulation results: For constant wind speed conditions above 4.7m/s the passive control method controls the rotor speed at an almost constant tip speed ratio. With the available 5.96mm nozzle diameter the rotor operates at 90% of the maximum power coefficient CP,max. To operate the rotor at its optimal tip speed ratio (100% of CP,max) the nozzle diameter is the only parameter that needs to be adjusted. Simulations with turbulent wind speeds show that the tip speed ratio variation is much larger in these conditions than in steady state conditions. In these conditions the rotor operates between 75% and 90% of the maximum power coefficient. The relatively slow response to fluctuations in the transmission cause the larger variations in tip speed ratio in turbulent wind speed conditions. The total efficiency of the transmission is between 43% and 48% at wind speeds above 4.7m/s. The estimated required wind speed to start the transmission is between 4 and 6m/s. The complete system of rotor and transmission is strongly damped. Therefore no problems are expected when the system is excited at one of its natural frequencies. The experiment and simulation results prove the functionality of the developed transmission. In the near future experiments with the transmission and a 10 kW rotor are planned at a test facility of the Energy research centre of The Netherlands (ECN). Based on the results of this thesis project no problems are expected during these experiments with rotor. The simplicity of the passive control strategy is a great advantage of this control method. An in-depth research of the suitability of this method for large single turbines or wind farms is recommended. Based on the analysis in this thesis, the main concern for large scale application is the slow response of the transmission to fluctuations in the wind speed. The response time will increase due to the reduced stiffness caused by longer pipelines with larger diameters. Subject wind energyDOToffshore turbineWindenergy To reference this document use: http://resolver.tudelft.nl/uuid:b8b0375d-f377-4231-ad97-752f50856824 Part of collection Student theses Document type master thesis Rights (c) 2012 Kempenaar, A.S. Files PDF Anton_Kempenaar_r.pdf 10.25 MB Close viewer /islandora/object/uuid:b8b0375d-f377-4231-ad97-752f50856824/datastream/OBJ/view