# Wind turbine lab report

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Energy Resources
AET-1003

Wind Turbine Interface

Presented By: Ricardo Cuello
Date Performed: Nov.05.2009

Mathieu Brown
Lee Mcgough
Group 12 – AET1003

November 12, 2009

Abstract

The goal of this lab was to demonstrate the basic operating principles of a wind turbine. In this case, a 3 Phase VAWT (Vertical Axis Wind Turbine) was usedconnected through the computer with a circuit board. The aim of the lab was to investigate the differences between the star and delta configuration. The Star configuration produced higher voltages than the Delta. The efficiency of this turbine was well below the theoretical value estimated using Betz law. Efficiencies were in the 0.05 to 0.38 percent ranges. Higher voltages were reached when acapacitor was used; a 10% more compared with the no capacitor configuration.

Introduction

The development of renewable energy resources from both industrial and residential points of view highlights the importance of the environment’s protection. This is a global trend due to the finite amount of the classical energy resources. Wind energy does not pollute and it is readily available. Theenergy of the wind is extracted with a wind turbine. A wind turbine is a device that converts the kinetic energy of wind into mechanical energy. Then, this mechanical energy is converted to electrical energy using a generator. Most generators are permanent magnet generators. One of the main issues is the efficiency of that conversion.

The kinetic energy (E) carried by the wind with speed (v)is modeled by the following formula:
E= 12×m×v2 ( Formula 1 )

The derivative with respect the air mass flow over time is:
E=P= 12×ρ×A×v3 ( Formula 2 )

Where ρ is the density of air and A is the area.
But this kinetic energy cannot be captured 100% by a wind turbine. One of the wind capabilities is to flow around any obstacle. This flow causes the turbine to rotate and slows down thewind. Applying the first law of thermodynamics, the energy lost by the wind (kinetic) is transferred to mechanical energy in the turbine. However, if we capture 100% of the wind’s kinetic energy, then it will stop it. A balance must be found between stopping the air and forcing it to flow through the blades. This limitation is governed by Betz law. Betz law states that, independently of theturbine’s design, only 59.3% of the kinetic energy can be converted to mechanical energy(1).

(1) Betz Law [online] http://en.wikipedia.org/wiki/Betz%27_law

Figure 1. Energy transfer principle of a wind turbine. (2)
Now using formula 2, a theoretical maximum power that can be obtained from a wind turbine is:
E=P= 12×ρ×A×v3× 0.593 ( Formula 3 )

Wind turbines are classified depending of itsrotation axis. They can be horizontal or vertical. Currently, HAWT (Horizontal-Axis Wind Turbines) are more common than VAWT (Vertical Axis Wind Turbine). Every type of turbine has its own applications.

HAWT(3) | VAWT(3) |