Separated magnet yoke for permanent magnet linear generator for marine wave energy converters

In this paper the performance of a longitudinal flux permanent magnet linear generator (PMLG) for wave energy converters (WEC) is investigated. The influence of the number of slots per pole, phase q and the number of stator's winding sections are analysed. The power output and the cogging forces in the PMLG are calculated and reviewed with respect to the above design parameters. In addition, an optimised PMLG model is designed and simulated. Three-dimensional Finite Element Method (FEM) is used for solving the combined field and circuit equations of the generator.The PRIMaRE project

OMAE2011-50336 DEVELOPMENT OF A NOVEL 1:7 SCALE WAVE ENERGY CONVERTER

ABSTRACT This paper presents a novel 1:7 scale point absorber wave energy converter (WEC), developed by Columbia Power Technologies (COLUMBIA POWER). Four hydrodynamic modeling tools were employed in the scaled development and the optimization process of the WEC, including WAMIT, Garrad Hassan's GH WaveFarmer, OrcaFlex and ANSYS AQWA. The numerical analysis development is discussed, and the performance and mooring estimates at 1:7 scale and full scale are evaluated and optimized. The paper includes the development of the 1:7 scale physical model and the associated WEC field testing in Puget Sound, WA

Laboratory Observation of Waves in the Vicinity of WEC-Arrays

This paper was presented at the 9th European Wave and Tidal Energy Conference held in Southampton, UK September 4-11, 2011.The ocean deployment of multiple Wave Energy Converters (WECs) in large-scale arrays appears imminent. However, there is a significant gap in our present knowledge of the near-field scattering and potential far-field environmental effects due to WEC-arrays. This gap comes from the lack of observational data. To help fill this data gap, we have performed laboratory experiments using five, moored, point-absorber WECs. These WECs are 1:33 scale models of the commercially-designed “Manta” from Columbia Power Technologies

Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed BuoysÃÂÃÂÃÂÃÂ that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high-resolution (fine scale, very near-field) fluid/structure interaction simulations of buoy motions, as well as array-scale, phase-resolving wave scattering simulations. These modeling efforts will utilize state-of-the-art research quality models, which have not yet been brought to bear on this complex problem of large array wave/structure interaction problem

Direct Drive Wave Energy Buoy – 33rd scale experiment

Columbia Power Technologies (ColPwr) and Oregon State University (OSU) jointly conducted a series of tests in the Tsunami Wave Basin (TWB) at the O.H. Hinsdale Wave Research Laboratory (HWRL). These tests were run between November 2010 and February 2011. Models at 33rd scale representing Columbia Power’s Manta series Wave Energy Converter (WEC) were moored in configurations of one, three and five WEC arrays, with both regular waves and irregular seas generated. The primary research interest of ColPwr is the characterization of WEC response. The WEC response will be investigated with respect to power performance, range of motion and generator torque/speed statistics. The experimental results will be used to validate a numerical model. The primary research interests of OSU include an investigation into the effects of the WEC arrays on the near- and far-field wave propagation. This report focuses on the characterization of the response of a single WEC in isolation. To facilitate understanding of the commercial scale WEC, results will be presented as full scale equivalents

Direct Drive Wave Energy Buoy

The most prudent path to a full-scale design, build and deployment of a wave energy conversion (WEC) system involves establishment of validated numerical models using physical experiments in a methodical scaling program. This Project provides essential additional rounds of wave tank testing at 1:33 scale and ocean/bay testing at a 1:7 scale, necessary to validate numerical modeling that is essential to a utility-scale WEC design and associated certification

Direct Drive Wave Energy Buoy – Intermediate scale experiment

Columbia Power Technologies deployed a scaled prototype wave energy converter (WEC) in the Puget Sound in February 2011. Other than a brief period (10 days) in which the WEC was removed for repair, it was in the water from Feb. 15, 2011 until Mar. 21, 2012. The SeaRay, as this WEC is known, consists of three rigid bodies which are constrained to move in a total of eight degrees of freedom (DOF). The SeaRay is kept on station with a spread, three-point mooring system. This prototype WEC is heavily instrumented, including but not limited to torque transducers and encoders reporting generator torque applied to and relative pitch of the floats, an inertial measurement unit (IMU) reporting translational acceleration and rotational position of the spar/nacelle, a GPS sensor reporting position, load cells reporting mooring loads at the WEC connection points and a number of strain gauges embedded in the fiberglass reinforced plastic (FRP) hull. Additionally, wave and current data are collected using an Acoustic Wave And Current Profiler (AWAC), allowing performance and design data to be correlated to environmental input conditions. This data – quality controlled, processed and analyzed – is used to characterize the metocean conditions (i.e. sea states). The WEC response will be correlated to the metocean conditions. These results will primarily be used to validate numerical models. The validated numerical models will be used optimize the commercial scale WEC and inform the design process. This document details the SeaRay experiment, including the quality control, processing and subsequent analysis of the data. Furthermore, the methodology and the results of numerical model validation will be described

NUMERICAL AND EXPERIMENTAL MODELING OF DIRECT-DRIVE WAVE ENERGY EXTRACTION DEVICES

ABSTRACT The solutions to today's energy challenges need to be explored through alternative, renewable and clean energy sources to enable a diverse national energy resource plan. An extremely abundant and promising source of energy exists in the world's oceans in the forms of wave, tidal, marine current, thermal (temperature gradient) and salinity. Among these forms, significant opportunities and benefits have been identified in the area of wave energy extraction. Waves have several advantages over other forms of renewable energy such as wind and solar, in that the waves are more available (seasonal, but more constant) and more predictable, thus enabling more straightforward and reliable integration into the electric utility grid. Wave energy also offers higher energy densities, enabling devices to extract more power from a smaller volume at consequent lower costs. However, many engineering challenges need to be overcome to ensure wave energy device survivability, reliability and maintainability, in addition to efficient and high quality power take-off systems. Optimizing wave energy technologies requires a multi-disciplinary team from areas such as Electrical, Chemical, Ocean, Civil and Mechanical Engineering, to enable innovative systems-level research and development. This paper presents some recent research developments on experimental and numerical modeling on direct-drive approaches and the associated devices designed to convert the motion of the ocean waves into electrical energy using point absorber wave energy converters. This research is focused on a simplification of processes, i.e., replacing systems using intermediate hydraulics or pneumatics with direct-drive approaches to allow generators to respond directly to the movement of the ocean by employing magnetic fields for contact-less mechanical energy transmission, and power electronics for efficient electrical energy extraction. The term "direct" drive describes the direct coupling of the buoy's velocity and force to the generator without the use of hydraulic fluid or air. The wave energy buoy and spar are designed to efficiently capture ocean wave energy and transfer it to the generator. These buoys have been tested at the Oregon State University O.H. Hinsdale Wave Research Laboratory, with planned testing off the coast of Oregon. The paper will examine several direct-drive approaches, including electrical and mechanical design characteristics, describe the numerical modeling of the associated conceptual devices, prototype testing, and some ongoing research on the dynamics of buoy generator systems for design optimization. INTRODUCTION Modern ocean wave energy research began during the oil crisis of the 1970s. Much of the early work was conducted in Europe by Salter [23] and Evan