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Date of Award

2016

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science in Engineering (M.S.Eng.)

Department

Engineering

First Advisor

Scott Larwood

First Committee Member

Brian Weick

Abstract

Modelling studies have shown that 1.5 and 3.0 MW wind turbines with blade sweep have an increased annual energy production (AEP) of approximately 5% when compared to straight-blade wind turbines. The objective of the research was to further increase below-rated, variable speed, power capture when using swept-blades. When operating in the variable speed region, the turbine’s torque is proportional to the square of the generator speed, and k is the proportionality constant (T = kΩ 2 ). Initial studies indicated that the value of k needed to be lowered from the original value to increase AEP. This proved to be slightly beneficial for the 3.0 MW turbine but not for the 1.5 MW turbine. The optimal tip speed ratio was too high for both turbines and limited the ability to increase AEP. Original swept-blade chords were designed to fit a linear pattern for manufacturing purposes, but it is believed this is no longer a necessary constraint. The blades were redesigned to have a non-linear chord distribution, which is based on the Betz optimal design method, and the resultant increase in solidity proved to be the solution for slowing down the blades’ rotational speed. The change in chord design proved to be beneficial for both 1.5 and 3.0 MW wind turbines and had immediate, measurable increases to AEP. An effort to further increase AEP was then conducted by using an alternative torque-speed controller, which used a different equation to relate speed and torque. This method only resulted in an increase of AEP for the 1.5 MW turbine. In conclusion, the highest recorded AEP increases from straight-blade values were 6.9% and 8.9% for the 1.5 and 3.0 MW turbines, respectively. The 1.5 MW turbine benefited from the custom controller and redesigned chords, whereas the 3.0 MW turbine only benefited from redesigned chords.

Pages

34

ISBN

9781339784465

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