VERTICAL AXIS WIND TURBINE PARTS

Today our post is about vertical axis wind turbine parts. Vertical axis wind turbine are one whose axis of rotation is vertical with respect to ground. There are many  parts of vertical axis wind turbine but we have discus few of them

Vertical Axis Wind Turbine Parts

Follow are the vertical axis wind turbine parts

• Guide wire
• Hub
• Rotor 
• Blades
• Shaft 
• Brake
• Gear
• Generator
• Base

Guide Wire of vertical axis wind turbine

Vertical axis wind turbine normally needs guide wire to keep the rotor shaft in a fixed position and maximized possible mechanical vibration

Hub of vertical axis wind turbine

The hub is the center of the rotor to which the rotor blades are attached. Cast iron or cast steel is most often used. In VAWT there are two hibs upper and lower because blades are attached at two points. 

Rotor of vertical axis wind turbine

The rotor is the heart of a wind turbine and consists of multiple rotor blades attached to a hub. It is the turbine component responsible for collecting the energy present in the wind and transforming this energy into mechanical motion. 

As the overall diameter of the rotor design increases, the amount of energy that the rotor can extract from the wind increases as well. Therefore, turbines are often designed around a certain diameter rotor and the predicted energy that can be drawn from the wind.

Rotor Blades of vertical axis wind turbine

Rotor blades are a crucial and basic part of a wind turbine. They are mainly made of aluminum, fibber glass or carbon fibber because they provide batter strength to weight ratio. 

The design of the individual blades also affects the overall design of the rotor. 

Rotor blades take the energy out of the wind; they “capture” the wind and convert its kinetic energy into the rotation of the hub. there are two types of blades use in VAWT 

• Drage force type blades ( savonius wind turbine)
• Lift force type blades (Darrieus and giromill wind turbine)

Shaft of vertical axis wind turbine

The shaft is the part that gets turned by the turbine blades. It in turn is connected to the generator within the main housing

Electrical Braking of vertical axis wind turbine

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 on the generator is suddenly reduced or is too small to keep the turbine speed within its allowed limit.

Cyclically braking causes the blades to slow down, which increases the stalling effect, reducing the efficiency of the blades. This way, the turbine's rotation can be kept at a safe speed in faster winds while maintaining (nominal) power output. 

This method is usually not applied on large grid-connected wind turbines.

Mechanical Braking of vertical axis wind turbine

A mechanical brake is normally placed on the high speed shaft between the gearbox and the generator, but there are some turbine in which the brake is mounted on the low speed shaft between the turbine and gear box

A mechanical drum brake or disk brake is use to stop turbine in emergency situation such as extreme gust events or over speed. This brake is also used to hold the turbine at rest for maintenance as a secondary mean, primarily mean being the rotor lock system. 

Such brakes are usually applied only after blade furling and electromagnetic braking have reduced the turbine speed generally 1 or 2 rotor RPM, as the mechanical brakes can create a fire inside the nacelle if used to stop the turbine from full speed. 

Also the load on turbine increases if brake is applied on rated RPM. These kind of mechanical brake are driven by hydraulic systems and connected to main control box.

Gear Box of vertical axis wind turbine

The main function of the gear box is to take low rotational speed from shaft and increase it to increase the rotational speed of the generator. Among the types of gear stages are the planetary, helical, parallel shaft, spur and worm types. Two or more gear types may be combined in multiple stages. they are made up of aluminum alloys, stainless steel and cost iron 

Generator of vertical axis wind turbine

The conversion of rotational mechanical energy to electrical energy is performed by generator. Different types of generator have been used in wind energy system over the years. 

For large, commercial size horizontal-axis wind turbines, the generator is mounted in a nacelle at the top of a tower, behind the hub of the turbine rotor. 

Typically wind turbines generate electricity through asynchronous machines that are directly connected with the electricity grid. 

Usually the rotational speed of the wind turbine is slower than the equivalent rotation speed of the electrical network - typical rotation speeds for wind generators are 5-20 rpm while a directly connected machine will have an electrical speed between 750-3600 rpm. 

Therefore, a gearbox is inserted between the rotor hub and the generator. This also reduces the generator cost and weight

Base of vertical axis wind turbine

Base of VAWT is usually the roof of building on which it is installed. 

WIND TURBINE

Wind turbine is a mechanical device which converts the kinetic energy of the moving wind to the electricity energy. People are using mechanical devices to convert wind energy in mechanical energy from pre historic times. Wind turbines are great source of getting green and renewable energy. They can be installed at any place fulfilling two qualities huge free space and moving wind

Types of wind turbine

There are many ways in which you an classify wind turbine but following are the two most widely used and known types of wind turbine 
1. Vertical axis wind turbine
2. Horizontal axis wind turbine
Vertical axis wind turbine have axis of rotation of their blades vertical to ground on which they are installed and horizontal axis wind turbine have axis of rotation parallel to ground.

Parts of wind turbine

Each wind turbine needed different parts on the basis of its type and working condition but following is the list of parts that are present in most of the common turbine

1. Hub
2. Rotors blades
3. Shaft (low speed)
4. Shaft (high speed)
5. Pitch mechanism
6. Electrical Brake
7. Mechanical Brakes
8. Gear box
9. Generator
10. Converter
11. Wind sensor
12. Yaw drive
13. Yaw motor
14. Tower
15. Nacelle
16. Guide wire ( only in vertical axis wind turbine)

Working of wind turbine

Working of wind turbine is quite simple, everyone know that moving wind have kinetic energy and this energy is converted into the rotation motion of blades of a wind turbine when wind strike on the turbine blade. Blades are attached to shaft so as the blades move shaft also start to move. This shaft is attached to a gear box which increase or decrease its speed according to the turbine design. After the gear box shaft is attached to a generator whose rotation causes the production of electricity.

Advantages of wind turbine

1. Produce the electricity in clean and natural friendly manner
2. Wind energy is available almost every where
3. It is renewable source of energy
4. Produce electricity at low prices
5. Remote areas that are not connected to the electricity power grid can use wind turbines to         produce their own supply.
6. Reduce the dependence on fossil fuel

Disadvantages of wind turbine

1. Created noise pollution
2. Bad visual impact
3. Cover huge area
4. High initial cost 
5. High maintenance cost
6. Not a constant source of energy

Working of Vertical Axis Wind Turbine, Their Parts, Pros and Cons

Vertical axis wind turbine is one whose axis of rotation of blades is perpendicular to the ground. Blades of these wind turbines are attached at two points, upper point is called upper hub and lower point is called lower hub. Shaft at which blades are attached is called low speed shaft. Generator and gearbox are placed on the ground and Guy wires are needed to give spot to wind turbine 

Vertical axis wind turbine are classified into two main types

1. Lift type

2. Drag type

Lift types is one which use the lift forces produce by the moving air to produce the rotation of turbine blades and drag type wind turbine is one which use the drag force of wind to produce the rotation motion of blades

Parts of vertical axis wind turbine

Following are vertical axis wind turbine parts

1. Upper hub

2. Blades

3. Low speed shaft

4. Lower hub

5. Gear box

6. Guy wires

7. Generator

8. High speed shaft

Working of vertical axis wind turbine

Like horizontal axis wind turbine kinetic energy of the wind is converted into the rotation motion of the blades and blades are attached to shaft and the shaft is attached to the generator through the gear box. So the rotation of blades result into the rotation of generator which produce the electricity

pros of vertical axis wind turbine

• They can produce electricity in any wind direction
• Strong supporting tower in not needed because generator, gearbox and other components are placed on the ground
• Low production cost as compared to horizontal axis wind turbine
• As there is no need of pointing turbine in wind direction to be efficient so yaw drive and pitch mechanism is not needed
• Easy installation as compared to other wind turbine
• Easy to transport from one place to other
• Low maintenance cost
• They can be install in urban area
• Low risk for human and birds because blades moves at relatively low speed
• They are particularly suitable for areas with extreme weather conditions, like in the mountains where they can supply electricity to mountain huts.

cons of vertical axis wind turbine

• As only one blade of wind turbine work at a time so efficiency is very low
• They need a initial push to start, this action use few of its own produce electricity
• When compared to horizontal axis wind turbine they are very less efficient with respect to  them. this is because they have an additional drag when their blades rotates.
• They have relative high vibration because the air flow near the ground creates turbulent flow
• Because of vibration bearing wear increase which result in the increase of maintenance cost
• They create noise pollution
• Guide wires which hold up the machine, need some are to install 

Horizontal Axis Wind Turbine

Horizontal axis wind turbine is one in which the axis of rotation of blade is parallel to the ground. These wind turbines have been considered as a stander for wind turbine that is their efficiency, working, manufacturing cost, advantages and disadvantages all are taken as a stander for any other types of wind turbine.

Due their design they need to be installed at some height from the ground so that their blades might not hit the ground during rotation and that’s why all their components are placed in a box called nacelle which is placed on top of a huge tower.

Number of blades on a Horizontal axis wind turbine is not fixed one can use any number of blades on a wind turbine but due to high efficiency three blade wind turbine is most common and it is also considered as a slandered design but there are also one, two and four blades wind turbine available in the market

Parts of Horizontal axis wind turbine

Following are the basic parts of a Horizontal axis wind turbine

• Blades 

• Rotor

• Pitch

• Brakes

• Low speed shaft

• Gear box

• Generator

• Wind vain

• Nacelle

• High speed shaft

• Yaw drive

• Yaw motor

• Tower

Horizontal axis wind turbine parts

Working of horizontal axis wind turbine

Working mechanism of the horizontal axis wind turbine is really simple. 

Wind moving at high speed have kinetic energy in it and when wind strike with the blades of wind turbine its kinetic energy is converted in to the rotational energy of the blades. 

As blades are attach to shaft and shaft is attach to generator so the rotating blades finally result into the production of electricity by the generator

Advantages of horizontal axis wind turbine

Following are the top five advantages of a Horizontal axis wind turbine

• Relatively high efficiency than vertical axis wind turbine

• Pitch mechanism can save it from storms

• Self-starting ability

• Angle of attack of blades can be change to get maximum energy from slow wind speed

• All blades work at a time so maximum energy is taken from the wind

Disadvantages of horizontal axis wind turbine

Following are 9 disadvantages of Horizontal axis wind turbine

• High initial cost

• High maintenance cost

• Noise problem

• Very bad visual impact

• Need huge ground to install

• Dangerous for bird’s population

• Cannot be installed near human population

• Because of long structure of blades and tower they are difficult to transport

• Create navigation problem when they are installed off shore

WIND TURBINE TYPES

Taking about classification of wind turbine, they can be classified in verity of ways, some classified them only on their axis of rotation, some classified them upon their capacity and some classified them on place they are installed. I have classified them in verity of ways shown below

• Types Of Wind Turbine
• Vertical and Horizontal axis wind turbines
• Upwind and Downwind turbines
• Constant and Variable speed wind turbines  
• Capacity of wind turbines
• Direct-Drive and Gear-Drive wind turbines
• ON-Grid and Off-Grid wind turbines
• ON-Shore and Off-Shore wind turbines

Vertical and Horizontal axis wind turbines

Horizontal-axis wind turbine are one in which the rotating axis of blades is parallel to the wind stream. The vertical-axis wind turbines is one in which the blades rotate with respect to their vertical axes that are perpendicular to the ground

Upwind and Downwind turbines

Upwind turbines are one in which the wind rotors face the wind. Downwind turbine are one in    which wind blows first through the nacelle and tower and then the rotor blades.

Constant and Variable speed wind turbines

Constant speed wind turbine produce electricity on special constant speed. This happen with the help of gear system. Variable speed wind turbine  achieve maximum energy conversion efficiency over a vied range of wind speed.Can adjust its rotational speed according to wind speed

Capacity of wind turbines

  There are five capacity ranges in which wind turbines are classified

•    micro wind turbines:-  Turbine with the rated power less than several kilowatts can be categorised as micro  wind turbine

•     small wind turbines:-  The turbines with the output power less than 100 kW


•     medium wind turbines:- The turbines with the  power ratings  from 100 kW to 1 MW    
                                         
•     large wind turbines:-  Wind turbines up to 10 MW may be classified as large wind turbines


•     ultra-large wind turbines:-  Ultra-large wind turbines are referred to wind turbines with the capacity more than 10 MW.

Direct-Drive and Gear-Drive wind turbines

To increase the generator rotor rotating speed to gain a higher power output, a regular geared drive wind turbine typically uses a multi-stage gearbox to take the rotational speed from the low-speed shaft of the blade rotor and transform it into a fast rotation on the high-speed shaft of the generator rotor. In direct drive wind turbine the multi-stage gearbox  is eliminating from a generator system and the generator shaft is directly connected to the blade rotor

ON-Grid and Off-Grid wind turbines
Living “off grid” means you are not connected to a utility company power line, the electrical grid. You must produce your own electrical power to meet your needs, In on-grid system electricity produce by turbine is given to grid station which further distribute it to houses

ON-Shore and Off-Shore wind turbine

The wind turbine which are installed on dry land are called on-shore wind turbines and the turbines installed on water bodies are called off-shore wind turbine. 

horizontal axis wind turbine (HAWT) types

American style wind mills

They typically have many blades and are used by farmers to generate electricity on a small scale. They have low efficiency since the blades operate at a tip speed ratio (TSR) (the ratio between the speed of wind and the speed of the tips of the blades of the turbine) that is equal or less that 1

Conventional wind turbine wind

The common, modern wind turbines produce electricity and are used in many countries for the clean energy they provide. They usually have three blades, because it provides the best balance of high rotation speed and load balancing, but sometimes they only have two blades and sometimes just even one. They have high tip speed ratios, high efficiency and low torque ripple, which subtracts the minimum torque from the maximum during one revolution. As the number of blades decreases, the vibration modes increase in peak intensity, which can cause loud noise and wear and tear of the machine.

Modern three bladed horizontal wind turbine

Unconventional wind turbine

Ducted rotor:-

The ducted rotor is a turbine inside a duct. The technology is still under research. It can operate in a wide range of wind, and the generator can operate at high ratio rate. It doesn’t use gearbox, which makes it lighter, but the duct is however heavy, adding more weight to the tower.

Counter rotating wind turbine:-

The counter rotating wind turbine can increase the ratio speed of the electrical generator. The two turbines can either be on the same side of the tower or on the opposite side. When placed on the same side of the tower, the blades on the turbine in the front have to be slightly angled forward in order to not hit the turbine behind. When placed on the opposite side of the tower, the one in the back should be smaller than the one at the front so that they both turn at low wind speeds. At intermediate wind speeds, the front turbine stalls (where the air foil experiences an interruption of airflow resulting in loss of lift and a tendency to drop.) while the rear one keeps on turning. At high wind speeds both turbines stall. The counter rotating wind turbine allows the generator to function at a wider wind speed range than a single turbine generator.

Yet due to gearing losses, additional complexity, waste of some electricity and waste of mechanical power, this type of turbines was not sold at large practically over the last 5 years.

Wind mills

They are four bladed buildings which mainly are used to grind grain or pump water.

Difference between horizontal and vertical axis wind turbine

Axis of rotation

It is the main and biggest difference they have. As the name say horizontal axis wind turbine have axis of rotation parallel to the ground and vertical axis wind turbine have axis of rotation perpendicular to ground

Number of blades working at a time

If we take 3 blades wind turbine then in horizontal axis wind turbine all three blades work at a time while in vertical axis wind turbine one blade work at a time.

Working wind direction

Vertical axis wind turbine work in all wind directions while horizontal axis wind turbine only works in a specific wind direction, when wind direction change horizontal axis wind turbine have to move itself in the direction

Efficiency at a given wind speed

Because all blades of horizontal axis wind turbine work ata time so its efficiency is much more than the vertical axis wind turbine.

Area needed for installation

Because of the axis of rotation area need for the horizontal axis wind turbine is much more than needed for vertical axis wind turbine.  Height is also a concern for horizontal axis wind turbine but not for vertical axis wind turbine

Location of installation

Because of area needed and protection precision  horizontal axis wind turbine cannot installed near population whereas vertical axis wind turbine is designed for installation in urban areas