Assimilating a higher fidelity representation of wave energy converters in a spectral model
Date
2016-10-03
Authors
Luczko, Ewelina
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Abstract
To accommodate future power demands, wave energy converters will be deployed in arrays, but largely unanswered questions of the annual energy production and environmental impact of such installations present regulatory dilemmas. In recent years, Sandia National Laboratories (SNL) has developed a modified version of the Simulating Waves Nearshore (SWAN) wave model to simulate WEC energy extraction in a propagating wave field. This thesis presents a novel WEC meta-model that calculates the power intercepted by a WEC from the incident wave field. Two representations were developed with which a user could model a WEC’s impact on the incident waves in a spectral wave model. These alterations are based on power a WEC captures from the sea and power dissipated by hydrodynamic losses calculated in an external six degree of freedom (DOF) time domain WEC simulation.
The two WEC meta-models were compared in terms of significant wave height reduction in the WEC’s lee and annual power production. The first WEC representation removes a constant percentage of power from each frequency bin while the second representation employs frequency dependent energy extraction. The representations were then applied in modelling a 54 MW WEC array off of Amphitrite Bank on the West Coast of Vancouver Island. Over the course of a year, the power captured by a farm when represented with a constant percentage extraction is reduced by 2.9% while a frequency dependent percentage extraction reduced the farm’s total captured power by 2.3% when compared to the reference case. Similarly small changes were observed in significant wave height reductions. The significant wave height in the lee of a farm was reduced by less than 2% for both representations at the shoreline, approximately six kilometres behind the farm.
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Keywords
wave energy, spectral model, resource assessment, wave arrays