09172013 wind turbines

7/27/2019 09172013 Wind Turbines

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WIND TURBINESPresented By:

Aditya Chaudhary

7/27/2019 09172013 Wind Turbines


Introduction

• A Modern Wind Turbine is an energy-converting machine

to convert the kinetic energy of wind mechanical energy

and in turn into electrical energy.

• Wind turbines can be classified according to the• Turbine Generator Configuration

• Airflow Path Relative to the Turbine Rotor

• Turbine Capacity

• The Generator-Driving Pattern

• The Power supply mode• The Location of Turbine Installation

• The Modern Wind Turbine is Horizontal-axis Upwind Wind

Turbines operating inland or in near-shore with generation

capacity in megawatts.

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Main Parts of HAWT

1. Foundation

2. Connection to the electricgrid

3. Tower

4. Access Ladder

5. Wind Orientation Control

6. Nacelle

7. Generator

8. Anemometer

9. Brake10. Gearbox

11. Rotor Blade

12. Blade pitch control

13. Rotor hub

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Towers

• Monopole (Nearly alllarge turbines)• Tubular Steel or

Concrete

• Lattice (many Mediumturbines)• 20 ft. sections

• Guyed• Lattice or monopole

• 3 guys minimum

• Tilt-up• 4 guys

• Tilt-up monopole

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Nacelle

Rotor

• Blades are connected to a hub, which is connected to a shaft

• Rotational speed will depend on blade geometry, number of blades,

and wind speed (40 to 400 revolutions per minute typical speed

range)

• Gear box needed to increase speed to 1200-1800 RPM for generator

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Active vs. Passive Yaw

• Active Yaw (all medium &large turbines produced

today, & some small turbines

from Europe)

• Anemometer on nacelle tellscontroller which way to point

rotor into the wind

• Yaw drive turns gears to point

rotor into wind

• Passive Yaw (Most smallturbines)

• Wind forces alone direct rotor

• Tail vanes

• Downwind turbines

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Propeller Anemometer

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Pitch Control vs. Stall Control• Pitch Control

– Blades rotate out of thewind when wind speedbecomes too great

• Stall Control

– Blades are at a fixed pitchthat starts to stall whenwind speed is too great

– Pitch can be adjusted for particular location’s windregime

• Active Stall Control – Many larger turbines todayhave active pitch controlthat turns the bladestowards stall when windspeeds are too great

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Lift & Drag Forces

• The Lift Force isperpendicular to thedirection of motion. Wewant to make this force

BIG.

• The Drag Force is parallelto the direction of motion.We want to make thisforce small.

α = low

α = medium

<10 degrees

α = High

Stall!!

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Number of Blades – One

• Rotor must move morerapidly to capture sameamount of wind – Gearbox ratio reduced – Added weight of

counterbalance negates some

benefits of lighter design – Higher speed means more

noise, visual, and wildlifeimpacts

• Blades easier to installbecause entire rotor can be

assembled on ground• Captures 10% less energythan two blade design

• Ultimately provide no costsavings

7/27/2019 09172013 Wind Turbines


Number of Blades - Two

• Advantages &disadvantages similar to one blade

• Need teetering hub andor shock absorbersbecause of gyroscopicimbalances

• Capture 5% lessenergy than threeblade designs

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Number of Blades - Three

• Balance of gyroscopic

forces

• Slower rotation

– increases gearbox &

transmission costs

– More aesthetic, less noise,

fewer bird strikes

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Brakes

• Electrical Braking• Braking of a small wind turbine can also be done by dumping energy

from the generator into a resistor bank, converting the kinetic energy of the turbine rotation into heat. This method is useful if the kinetic load onthe generator is suddenly reduced or is too small to keep the turbine

speed within its allowed limit.• Mechanical braking

• A mechanical drum brake or disk brake is used to stop turbine inemergency situation such as extreme gust events or over speed. Thisbrake is also used to hold the turbine at rest for maintenance as asecondary mean, primarily mean being the rotor lock system. Such

brakes are usually applied only after blade furling and electromagneticbraking have reduced the turbine speed generally 1 or 2 rotor RPM, asthe mechanical brakes can create a fire inside the nacelle if used tostop the turbine from full speed. Also the load on turbine increases if brake is applied on rated RPM. These kind of mechanical brake aredriven by hydraulic systems and connected to main control box.

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Gearbox

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Hubs

The hub holds the rotor together and transmitsmotion to nacelle

Three important aspects

• How blades are attached

• Nearly all havecantilevered hubs(supported only at hub)

• Struts & Stays haven’tproved worthwhile

• Fixed or Variable Pitch?

• Flexible or Rigid Attachment

• Most are rigid

• Some two bladed designsuse teetering hubs

7/27/2019 09172013 Wind Turbines


Thank You

09172013 wind turbines

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