Monthly Archives: December 2013

Performance of a hydrokinetic energy system using an axial-flux permanent magnet generator


J.M. Davila-Vilchis and R.S. Mishra – Energy, December 2013

Abstract

The high density of water has been an important factor for harnessing kinetic energy from marine current flows, tides, flowing rivers, or other artificial water channels. Thus, new technologies are being developed to generate electricity. A good example is HKES (hydrokinetic energy systems), which are devices that extract and convert energy from the motion of flowing water into electricity. Although these non-polluting machines and/or devices are still in their pilot phases, they have been growing as a sustainable source of new electric power generation. In this paper, the performance of a horizontal hydrokinetic energy system with variable-pitch blades using an axial-flux generator is evaluated. Particularly, very simple sheet blades have been used to keep system cost down. The evaluation is based on maximum power extraction and energy conversion efficiency normalized by system cost through a simpler electro-mechanical design for the hydrokinetic system. Experimental results have demonstrated that the proposed prototype possesses higher efficiency with reduced energy losses and manufacturing costs. It represents a cost-competitive alternative energy for power supply for civilian applications in remote areas or an option for expeditionary applications.

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Design and Experimental Analysis of AC Linear Generator with Halbach PM Arrays for Direct-Drive Wave Energy Conversion


Zhang, J; Yu, H.; Chen, Q.; Hu, M.; Huang, L.; and Liu, Q. – IEEE Transactions on Applied Superconductivity, November 2013

Abstract

To convert wave energy into more suitable forms efficiently, a single-phase permanent magnet (PM) AC linear generator directly coupled to wave energy conversion is presented in this paper. Magnetic field performance of Halbach PM arrays is compared with that of radially magnetized (R-magnetized) structure. Then, the change of parameters in the geometry of slot and Halbach PM arrays’ effect on the electromagnetic properties of the generator are investigated, and the optimization design guides are established for key design parameters. Finally, the simulation results are compared with test results of the prototype in wave energy conversion experimental system. Due to test and theory analysis results of prototype concordant with the Finite element analysis results, the proposed model and analysis method are correct and meet the requirements of direct-drive wave energy conversion system.

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Numerical Analysis and Scaled High Resolution Tank Testing of a Novel Wave Energy Converter


Ken Rhinefrank, Al Schacher, Joe Prudell, Joao Cruz, Chad Stillinger, David Naviaux, Ted Brekken, Annette von Jouanne, David Newborn, Solomon Yim, and Dan Cox – Journal of Offshore Mechanics and Arctic Engineering – September 2013

Abstract

This paper presents a novel point absorber wave energy converter (WEC), developed by Columbia Power Technologies (COLUMBIA POWER), in addition to the related numerical analysis and scaled wave tank testing. Three hydrodynamic modeling tools are employed to evaluate the performance of the WEC, including WAMIT, GL Garrad Hassan’s GH WaveDyn, and OrcaFlex. GH WaveDyn is a specialized numerical code being developed specifically for the wave energy industry. Performance and mooring estimates at full scale are evaluated and optimized, followed by the development of a 1:33 scale physical model. The physical tests of the 1:33 scale model WEC were conducted at the multidirectional wave basin of Oregon State University’s O.H. Hinsdale Wave Research Laboratory, in conjunction with the Northwest National Marine Renewable Energy Center (NNMREC). This paper concludes with an overview of the next steps for the modeling program and future experimental test plans.

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Nonlinear 2D analysis of the efficiency of fixed Oscillating Water Column wave energy converters


Yongyao Luo, Jean-Roch Nader, Paul Cooper, and Song-Ping Zhu – Renewable Energy, April 2014

Abstract

This paper reports on the development of a two-dimensional, fully nonlinear Computational Fluid Dynamics (CFD) model to analyse the efficiency of fixed Oscillating Water Column (OWC) Wave Energy Conversion (WEC) devices with linear power take off systems. The model was validated against previous experimental, analytical and numerical results of others. In particular, the simulation results show excellent agreement with the analytical results obtained by Sarmento and Falcão for linear waves in a 2D channel and with previous experiments by others on the interaction between nonlinear waves and a fixed barge. Continue reading

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Numerical simulation of a submerged cylindrical wave energy converter


M. Anbarsooz, M. Passandideh-Fard, and M. Moghiman – Renewable Energy, April 2014

Abstract

In this study, a numerical model based on the complete solution of the Navier–Stokes equations is proposed to predict the behavior of the submerged circular cylinder wave energy converter (WEC) subjected to highly nonlinear incident waves. The solution is obtained using a control volume approach in conjunction with the fast-fictitious-domain-method for treating the solid objects. To validate the model, the numerical results are compared with the available analytical and experimental data in various scenarios where good agreements are observed. Continue reading

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Wave and offshore wind energy on an island


M. Veigas, R. Carballo, and G. Iglesias – Energy for Sustainable Development, December 2013

Abstract

The island of Fuerteventura, a UNESCO Biosphere Reserve in the Atlantic Ocean, aims to develop renewable energy sources, in particular wave and offshore wind energy, to reduce its carbon footprint. In this context, the objectives of this work are: (i) to assess the wave and offshore wind resources around the island; and (ii) to determine the area or areas that are best suited for their exploitation, taking into account the resource assessment and other conditioning factors such as the bathymetry, distance to the coastline and ports, and offshore zoning prescribed by the authorities. Continue reading

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Design of a portable pico linear permanent magnet generator for wave energy conversion


Hamim, M.A.F.M., Ibrahim, T., and Nor, N.M. – 2013 International Conference on Information Technology and Electrical Engineering (ICITEE), October 2013

Abstract

This paper presents the design and modeling of a portable pico linear permanent magnet generator for the application of wave energy conversion system. Two types of generator technology namely the rotary and linear are identified but due to the high maintenance and low efficiency of rotary, linear generator is preferable. Three linear permanent magnet generator designs with different types of permanent magnet shape have been proposed. Preliminary results for the air gap distribution and open circuit test are demonstrated and discussed are shown to be as expected.

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Passive Control of Marine Hydrokinetic Turbine Blades


Michael R. Motley and Ramona B. Barber – Composite Structures, December 2013

Abstract

Marine hydrokinetic (MHK) turbine blades are generally constructed from fiber reinforced polymer composites and are subject to large, highly dynamic fluid forces. The bend-twist deformation coupling behavior of these materials can be hydroelastically tailored to improve system performance over the expected life of the turbine by way of rapid, passive pitch control that can increase lifetime power generation, reduce hydrodynamic instabilities, and improve load shedding and structural performance. Continue reading

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Adaptive damping power take-off control for a three-body wave energy converter


Zhe Zhang, Brekken, T., Rhinefrank, K., Schacher, A., Prudell, J., Hammagren, E., and Lenee-Bluhm, P. – 2013 IEEE Energy Conversion Conference and Exposition (ECCE), September 2013

Abstract

The performance of the power take-off (PTO) system for a wave energy converter (WEC) depends largely on its control algorithm. This paper presents an adaptive damping control algorithm which improves power capture across a range of sea states. The comparison between this control algorithm and other active control approaches such as linear damping is presented. Short term wave elevation forecasting methods and wave period determination methods are also discussed as pre-requirements for this method. This research is conducted for a novel WEC, developed by Columbia Power Technologies. All hydrodynamic models are validated with their 1:7 and 1:33 scale tests.

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Medium-voltage power converter interface for Wave Dragon wave energy conversion system


Muller, N., Kouro, S., Glaria, J., and Malinowski, M. – 2013 IEEE Energy Conversion Congress and Exposition (ECCE), September 2013

Abstract

This paper presents a medium-voltage power converter system for the Wave Dragon ocean energy conversion platform. The proposed converter configuration is an alternative to the classic back-to-back low voltage converter implemented in the original prototype. The converter configuration merges several diode rectifiers with boost converters operating with low voltage at the generators side, with a single neutral point clamped converter (NPC) operating at medium-voltage at grid side. The control schemes for generator and grid side converters are analyzed, and simulation results are presented as preliminary validation. The proposed configuration provides a simple and cost-effective interface for wave energy conversion systems with several generators, such as Wave Dragon.

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