TOWER

The commonly used tower in the present proposal is tubular tower which has a door at the bottom. The door can be used to enter into the tower for operation and maintenance. The door is usually provided with locking arrangement to prevent unauthorised entry of outsiders. All the towers are provided with ladder to climb up to the top so as to do the maintenance. In these towers at certain intervals, platforms are fitted inside the tower for inspection of joints of the tower section.

BLADES

The turbines are provided with three blades. The blades are self supporting in nature made up of Fibre Reinforced Polyester. The blades are mounted on the hub.
The blades are built with aerodynamic brakes that prevent over speed of the wing.

NACELLE

The Nacelle is the one which contains all the major parts of a turbine. The nacelle is made up of thick rugged steel and mounted on a heavy slewing ring. Under normal operating conditions the nacelle would be facing the upstream wind direction.
The nacelle is fitted with a cover to protect the parts from climatic damages.

HUB

The Hub is intermediate assembly between the wing and the main shaft of the turbine. Inside the hub, a system to actuate the aerodynamic brake is fitted. The hub is covered with nose cone.

MAIN SHAFT

The shaft is to connect the gear box and the hub. Solid high carbon steel bars or cylinders are used as main shaft. The shaft is supported by two bearings.

MAIN BEARING

The main bearings are placed inside housing. The main bearings are usually roller bearings. The bearing house has the provision to fit temperature sensors and has the facility to apply lubrication.

GEAR BOX

The gearbox is used to increase the speed ratio so that the rotor speed is increased to the rated generator speed. The helical gears are used in the gearbox. Oil cooling is employed to control the heating of the gearbox. Gearboxes are mounted over dampers to minimise vibration.

BRAKE

Brake is employed in the Wind Turbines to stop the turbine mainly for maintenance check. Brakes are also applied during over speed conditions of the turbine.
The brakes are placed on the high speed shaft. There are different types of brakes used in Wind Turbines. But Hydro-spring pressure disc brakes are widely used. During the operation of the turbine the brake system is active and keeps the brakes in released condition. For this purpose, electrical power is used to pressurise the hydraulic oil or hold the spring in compressed state. Once the power falls, the brakes are applied. Hence during braking, the control system cuts off the electrical continuity to brake the system.

YAW SYSTEM

The Yaw Ring is fitted at the top of the tower over which the nacelle is seated. The nacelle is able to rotate 360 deg. around the yaw ring. The yaw ring is fabricated in such a way that it allows the nacelle to rotate freely but prevents lifting up from the tower. The yaw gear is in contact with yaw ring. The rotation of the yaw gear turns the nacelle to the desired direction. The yaw gear is coupled with an electric motor called yaw motor. Single or double yaw gear is used to operate the yaw ring. Yaw brakes are used to keep the nacelle in a steady position when it is not yawing. During yawing the nacelle is able to rotate smoothly. The yaw brake has brake liners loaded by springs, which act as brakes. While yawing the yaw gear overcomes the braking force of the yaw brake.

COUPLING

Couplings are fabricated with rubber elements over metallic shaft to reduce the strain and vibration due to error in the alignments.

GENERATOR

The generator invariably uses induction type of generator depending upon the RPM selection. For better efficiency two generators with different cu-in wind speed requirements are mounted on the same shaft. The generators are provided with monitoring sensors in each phase winding to prevent damage to the generators.

SENSOR

Different sensors are used in turbines for monitoring.

They are as listed below :

a. Anemometer - to measure the wind speed.
b. Wind Vane - to sense the wind direction
c. Tacho rotor sensor - to measure the rotor RPM.
d. Tacho gen. sensor - to measure the generator RPM
e. Yaw sensor - to measure the yawing angle of the nacelle
f. Vibration sensor - to sense the vibration of the tower
g. Twisted cable sensor - to feel the twist in the power cable of the generator.
h. Temperature sensors - to measure the temperature of main bearing, gear oil, generation winding etc.

POWER PANEL

The power panel is equipped with number of contractors, auxiliary contactors, thermo relays, soft components, phase compensation batteries and circuit braker etc. The contactors are used to connect and disconnect the generator, yaw motor, hydraulic pump motor and brake magnetic coil, etc. The auxiliary contacts used to feed information to the control system about the status of different contactors and components. Thermo relays are used as protection to the motors used in the turbines.
Soft cu-in components are either thyristers or heaters controlled by suitable module.
Phase compensation batteries are the capacitors used to reduce the reactive power consumption of the turbines.

The circuit breakers used at the incoming side of the panel is to protect the electrical systems of the turbines from damage on fault conditions and also used to shut down and attend servicing on the electrical system.

CONTROL PANEL

Micro processor based control circuits are provided in this panel. It receives input signals from the sensors and auxiliary contacts of the power panel and sends output signals to different contactors to on/off the related systems as per the programme fed into the micro processor. It has a display module, which displays instantaneous records of power produced, wind speed, grid instantaneous records of power produced, wind speed, grid voltage/current, fault status and so on. A programmable key board facility is available in the micro processor system to feed the set parameters and see different datas logged in the control processor.