Matching a Permanent Magnet Synchronous Generator to a Fixed Pitch Vertical Axis Turbine for Marine Current Energy Conversion

Abstract

This is an author-produced version of a paper published in IEEE Journal of Oceanic Engineering. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the published paper: Yuen K., Thomas K., Grabbe M., Deglaire P., Bouquerel M., Österberg D., Leijon M. "Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion" IEEE Journal of Oceanic Engineering, 2009, 34(1) Access to the published version may require subscription. I. INTRODUCTIONF REE flow marine currents, i.e. unregulated water courses, tides and other ocean currents, are an energy resource yet to be utilized on a commercial scale. Without dams, this nonfossil source can give an environmentally benign contribution to the world electricity production. The European tidal potential alone has been estimated to be 39-58 TWh annually [1]- [3]. A number of projects involved with extracting energy from this resource exist, and most concepts are similar to wind energy converters in that they include a turbine and a generator, e.g. [4]- [7].Wind power is similar to marine current energy as it is concerned with harnessing the kinetic energy in a flowing fluid, and there are many relevant comparisons concerning underlying physics, practical engineering experience, etc. However, there are also a number of significant differences, e.g. resource characteristics. As most parts of the system will be submerged in water and thus not easily accessible, it is good to try to minimize needs for maintenance and repair by avoiding mechanically complex systems with many moving parts. In [8], it is concluded that up to 20 percent of the downtime for a wind power plant is due to gearbox failures, and that the majority of these failures are due to wear. Therefore, avoiding gearboxes, yawing and blade pitching is likely to be beneficial Manuscript

Global renewable energy and its potential in Malaysia: A review of Hydrokinetic turbine technology

“…Hydrokinetic turbines have a close similarity to wind turbines in terms of physical principles of operation, electrical hardware and variable speed capability for optimal energy extraction [48], however, the density of water is 800 times greater than the density of air, thus, a 12 miles per hour (mph) marine current generates the equivalent amount of force that is contained in a constant 110 mph wind [63], therefore, water turbines are more efficient than wind turbines even at low current speed. In addition, wind turbine technology requires a huge land area to operate, whereas hydrokinetic turbines can operate under water [64,20].…”

“…Among different renewable energy options, hydropower is the prime choice to contribute to the world's energy generation because it is continuously available, high density, powerful, predictable and independent of random weather conditions, as opposed to solar and wind options, and has less impact on environmental and human activity [15][16][17][18][19][20][21].…”

Technological Cost-Reduction Pathways for Axial-Flow Turbines in the Marine Hydrokinetic Environment.

“…However, gearboxes may be prone to failure and have high OPEX. 36,43 Directdrive PTOs reduce complexity by directly attaching the rotor shaft to the generator but require high torque, low speed generators. 8,34,36 These generators require improved controls and are more expensive due to the size, efficiency and cost of permanent magnets used.…”

Generator requirements and functionality for ocean energy converters

“…Tidal turbines [30,31] Horizontal axis tidal turbines are the marine equivalent of wind turbines, with energy being extracted through the lift forces of the moving water on the turbine blades. The significantly higher density of sea water relative to air results in significantly smaller diameter turbine blades than equivalent power rated wind turbines.…”