Windmill control system and its working principles.

1. WINDMILL CONTROL SYSTEM

2. What is Wind Turbine?
• Wind turbines use wind to make electricity.
The wind turns the blades, which in turn spins
a generator to create electricity.
• The principle behind wind turbines is very
simple: the energy in the wind turns the blades
around a rotor. The rotor is connected to the
shaft, which spins a generator to create
electricity.

3. Major Parts of Wind Turbine
A simple wind turbine consists of three main parts, the
blades, shaft and generator
1) Blades: The blade acts as barriers to the wind. When
the wind forces the blade to move, some of the wind
energy is transferred to the rotor.
2) Shaft: When the rotor spins, the shaft also spins, and
transfers the mechanical energy into rotational energy.
3)Generator: A generator uses the difference in
electrical charge to produce a change in voltage. Voltage
is actually electrical pressure, the force that moves an
electrical current. The voltage drives the electrical
current (alternating current power) through power lines
for distribution.

4. Major Parts of Wind Turbine

5. How Wind Turbine Works?
• When the wind flows across the blade, the air
pressure on one side of the blade decreases.
• The difference in air pressure across the two sides of
the blade creates both lift and drag.
• The force of the lift is stronger than the drag and this
causes the rotor to spin.
• The rotor is connected to the generator, either directly
(if it's a direct drive turbine) or through a shaft and a
series of gears (a gearbox) that speed up the rotation
and allow for a physically smaller generator.
• This translation of aerodynamic force to rotation of a
generator creates electricity.

6. Device in Wind Turbine
1. Nacelle
2.Rotor Blades-27 m
3.Hub –Rotor Hub to Shaft
4.Low Speed Shaft -Receive 19 to 20 RPM
4.Gearbox – Gives 1500 RPM
5.High Speed Shaft With Its Mechanical Brake
6.Electrical Generator
7.Yaw Mechanism – to turn the nacelle with the rotor
against the wind.
8.Electronic Controller
9.Hydraulics System

7. Device in Wind Turbine
10.Cooling Unit –Cooling oil and Fan
11.Tower -50 to 80m-Tubular and lattice Towers
12.Anemometer and Wind Vane-
• The electronic signals from the anemometer are used by the
wind turbine's electronic controller to start the wind turbine
when the wind speed reaches approximately 5 metres per
second (10 knots).
• The computers stops the wind turbine automatically if the
wind speed exceeds 25 metres per second (50 knots) in
order to protect the turbine and its surroundings.
• The wind vane signals are used by the wind turbine's
electronic controller to turn the wind turbine against the
wind, using the yaw mechanism

8. Control Systems in Wind Turbine
• To enable automatic operation.
• Keep the turbine aligned with the wind.
• To Engage and disengage the generator.
• To govern the rotor speed.
• To protect the turbine from over speed.
• To sense malfunctions and warn operators.

9. Control Systems in Wind Turbine
Types:
• Passive Control-own sensing and actuation
• Active Control-use mechanical, electrical,
pneumatic or other combination
Active control used transducer.
Too much control add extra hardness to the
machine to run.

10. RPM Control
• Start the rotor turning based on wind velocity.
• Set the pitch angle to a run position.
• Control RPM to prevent the rotor from
overpowering the generator.
• Protect the rotor and system from high wind-
velocity damage.

11. Electronic Controls
Sensor-
RPM,Vibration,Power,
Blade pitch angle
Computer Pitch Actuators
Rotor

12. Electronic Controls
• Primary Control System failed Backup over
speed control system works based on tip
brakes or spoilers to stall the blade pitch angle.

13. Additional RPM Control Techniques
• A tail vane to rotate the rotor edgewise to the
wind direction.
• Blade tip plates that extended to cause
braking .
• In VAWT(Vertical Axis Wind Turbine) an
axis control system.
• Mechanical methods and Micro switch
connected with the generator is unreliable.
• Rotor shaft coupling failure causes high
current in slip rings

15. Electrical Cut-in
• In DC generators have a very low power
output at low RPM.
• In AC generator design condition is more
difficult to meet, first of all synchronous
frequency is meet for rotor shaft and generator.
• In case when the power to the computer is
gone and blade pitch servo actuators is also
gone this is very dangerous situation.

16. Power Collection System
• MCCB-Detect over load of generators
• Molded Case Circuit Breaker (MCCB) is a
circuit breaker and trip device assembled in a
mould case. Also it can automatically cut off
electric power in case of overload and short
circuit. It is meant for higher rated current and
is commonly used in Industrial applications.
Its usual range is 250A-800A.
• Individual turbines has its own transformer

17. Earthing of Wind Farms

18. Earthing of Wind Farms
• Minimize Shock hazards to
personnel.
• Establish low impedance
path.
• Improve protection from
lightning.
• Prevent large potential
difference.

19. Lightning Protection
• Wind turbines are made up of conducting
materials if we prefer carbon fiber is used to
reinforce blades, additional precautions
needed.
• Lightning Flashes –
1. Downward inception, negative and positive
polarity.
2. Upward inception, negative and positive
polarity.

20. Lightning Protection
• Downward inception, negative and positive
polarity are the most common.
• Downward flashes a high amplitude burst of
current lasting for a few microseconds
followed by current of few hundred amperes.
• Peak current of lightning is 200 KA, charge
transfer are 400C and specific energy 20
MJ/ohm

21. Effects of Various aspects of lightning
on a wind turbine

23. Wind power integration into grid
• Short term measures-grid management procedure
and addition of some tie lines.
• Long term measures-existing grid network
operating at high voltage for long distance
transmission.
• The large percentage of wind power affects the
stability of grid network.
Variability:
• Short term variability-scheduling of generation
units.
• Long term variablility-sesonal meteorological
patterns

24. Impact of variability can be overcome
• Frequency regulation by automatic generation.
• Load follow up unit commitment schedule can
take place in a period of few minutes to a
couple of hours.
• Unit commitment based on load profile
prediction.

25. Cluster of Wind Turbines
• Combining ancillary power plants-gas
turbine or oil fired power plant with wind
farm.
• Using hydro storage reserves.
• Interconnection with other grids will
improve
• The reliability of intermittancy
management.