Overview of Wind Turbine Engineering

Eshan ahujaeshanahuja1322@gmail.com

Dr. Navin Kumar Kohli

Wind Power

Wind Power depends on:• amount of air (volume)• speed of air (velocity)• mass of air (density) A• flowing through the area of interest (flux)Kinetic energyKE = ½ * m * v2 & Power is KE• P = ½ * m * v 2• Fluid mechanics gives mass flow rate(density * volume flux):• dm/dt = ρ* A * v

Efficiency in Wind Power

Betz Limit & Power Coefficient:• Power Coefficient, Cp, is the ratio of power extracted by the turbine to the

total contained in the wind resource Cp = PT/PW.• Turbine power output PT = ½ * ρ * A * v 3 * Cp• The Betz Limit is the maximal possible Cp = 16/27• 59% efficiency is the BEST a conventional wind turbine can do in

extracting power from the wind

Power ~ cube of velocityPower ~ air density

Power ~ rotor swept area A= πr²

Power Curve of Wind Turbine • Capacity Factor (CF):• • The fraction of the year the turbine generator is

operating at• rated (peak) power• Capacity Factor = Average Output / Peak Output

≈ 30%• • CF is based on both the characteristics of the

turbine and the• site characteristics (typically 0.3 or above for a

good site)

Wind Turbine Subsystems

Wind Turbine Subsystems•– Foundation•– Tower•– Nacelle•– Hub & Rotor•– Drivetrain•– Gearbox•– Generator•– Electronics & Controls•– Yaw•– Pitch•– Braking•– Power Electronics•– Cooling•– Diagnostics

Wind Turbine Design issues

Aerodynamics

Structures,Structural Dynamics,Vibrations, Stability,

Fatigue Life

Control systems forRPM, Pitch, Yaw

Transmission, gears, tower,

power systems, etc.

Cost

Noise,aesthetics

Parameters to be Chosen• We need to decide on

– Number of blades– Blade planform (i.e. how does chord vary with

radius)?– Blade radius– Blade twist distribution– Airfoils– RPM– Decisions about variable RPM, variable pitch

• We need to consider cost, noise, vibrations, fatigue, etc as well.

Benefits of Wind Energy

• Renewable• Emits no pollutants• No foreign dependence• Wind is free & plentiful• Cost effective• Take up less space than conventional power

plants

Conclusions

• Wind Energy is renewable & emits no pollution•Wind speed increases significantly with height•The power in the wind varies with the cube of wind speed•The Betz theory establishes a limit of 16/27=0.59 to power coefficient•The wind turbine blade is an aerofoil•The tip speed is greater than the wind speed•Lift is created as the blade slices through the wind –the tangential component of the lift is what drives the turbine•In India the rate of wind power is very competitive around Rs 4.5/kWh

thank you

eshan ahuja,Australian National University,

Australia