Title

Active Drive Train Control to Improve Energy Capture of Wind Turbines

Publication Date

4-2007

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Major Advisor

John Gardner

Abstract

Continuously variable transmissions have been increasingly used in the automotive industry to eliminate shift shock and improve vehicle efficiency. This thesis evaluates the effectiveness of a differential continuously variable transmission (DCVT) used in a different application: wind turbine generators. The Controls Advanced Research Turbine (CART) was modeled utilizing Matlab, Simulink, and SymDyn. First the CART was modeled using its normal fixed ratio transmission. It was then modeled to incorporate a two stage planetary gear train differential, in which the speed of second stage ring gear was controlled to achieve two operating goals: constant generator speed and constant tip speed ratio. The results were then analyzed to determine the DCVT's effects on power production, and also on the torques and speeds associated with that power, in an attempt to optimize the wind turbine generator system. It was discovered that when the system was controlled to achieve a constant generator speed and constant tip speed ratio there was an increase in power production. Though when the system was controlled to maintain a constant tip speed ratio the amount of power used to control it was approximately twice that of the constant generator speed model, while producing larger torques then either of the other systems. Due the negative aspects associated with the constant tip speed ratio system, and the fact the average power produced of the two controlled systems were approximately equally to each other, the constant generator speed appears to be the more promising of the two.

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