Wind Turbine
How do wind turbines work?
A brief guide to how electricity is generated from our country India most abundant renewable sources: wind.solar Hydro
One of the most popular questions people ask us is how is our renewable electricity generated. The simple answer is through wind, sun and rain/ hydro – but this doesn’t really paint the whole picture.
How do we turn energy from the sun, wind and water into clean electricity to power our homes? Here’s (almost) everything that you need to know about generating electricity from the wind.
How wind turbines generate electricity,
How do wind turbines work?
Wind turbine blades rotate when hit by the wind. And this doesn’t have to be a strong wind, either: the blades of most turbines will start turning at a wind speed of 3-5 meters per second, which is a gentle breeze.
It’s this spinning motion that turns a shaft in the nacelle – which is the box-like structure at the top of a wind turbine. A generator built into the nacelle then converts the kinetic energy of the turning shaft into electrical energy. This then passes through a transformer, which steps up the voltage so it can be transported on the National Grid/ Off grid system for domastice houses or used by a local site.
From micro-turbines for an individual house we can go fo off grid system or hybrid system from 1 KW to 100 KW subject to wind speeds .
Right up to enormous, off-shore wind farms, all wind turbines use the same mechanics to generate electricity.
A wind turbine of one KW
How much electricity can generate .Per hr it’s generate 800 watts to 900 watts .
Most onshore wind turbines have a capacity of 2-3 megawatts (MW), which can produce over 6 million kilowatt hours (kwh) of electricity every year. That’s enough to meet the electricity demand of around 1,500 average households.
Up to a certain level, the faster the wind blows, the more electricity is generated. In fact, when the wind speed doubles, up to eight times more electricity is generated. But if the wind is too strong, turbines will shut themselves down to prevent being damaged.
All this means that the ability of a wind turbine to generate the maximum amount of power it can depends on the wind. Wind farms are carefully planned to make sure they’re in locations with a reliable amount of wind all year round. This tends to be on the summit of a hilltop with lots of open space around, and in coastal locations. It’s why there are quite a lot of wind farms in places such as Gujarat,India & Cornwall and Scotland.
Wind turbines in the UK are producing electricity 70-80% of the time, making them a reliable source of power throughout the year. Tamil Nadu,Andhra Pradesh, Telengana, Gujrat, particularly well-suited to wind power.
Almost most part of India have 3 to.4 ms above wind speeds above 30 to 40 ft we all may go for micro wind turbines vertical or horizontal wind turbines or hybrid system wind and solar micro hydros
Delabole UK wind farm
The wind blows all year round – making wind power a reliable renewable power source. It also tends to be windiest in winter, meaning wind turbines can produce are producing more power at the time of the year when we’re also using the most electricity. Both of these points make the UK well positioned to make the most of both offshore and onshore wind power and reduce its reliance on fossil fuels.
Another added bonus is the low carbon footprint that is created in building wind farms – it’s one of the smallest among new renewable generators.
Ready for Rooftops Horizontal and Verticals.
HAWT (Horizontal Axis Wind Turbines)
HAWTs are the most common wind machine designs in use today. HAWTs utilize aerodynamic blades (i.e. airfoils) fitted to a rotor, which can be positioned either upwind or downwind. HAWTs are typically either two- or three-bladed and operate at high blade tip speeds. Machines with upwind rotors require a yaw, or tail vane, to help them orient into the wind while downwind rotors have blades that are coned allowing the turbine to orient on its own. One drawback identified with downwind rotors, however, is that they have been known to ‘walk’ around when trying to line up with winds during low speed conditions, diminishing low wind speed energy production (Gipe, 2009).
Modern HAWTs use the aerodynamic lift force to turn each rotor blade, in a manner similar to the way an airplane flies. The lift force generally works as follows. When exposed to winds, air flows around both the upper and lower portions of a blade. As a result of the blade’s curvature, however, air passes over the top of the blade more quickly (owing to a longer fetch length) than the lower portion, producing a low-pressure area on the topside. The pressure difference created between the top and bottom sides of the blade produces a force in the direction of the top of the blade (Mathew, 2006).
VAWT(Vertical-axis wind turbines)
Vertical-axis wind turbines (VAWTs) have an axis of rotation that is vertical, and so, unlike the horizontal wind turbines, they can capture winds from any direction without the need to reposition the rotor when the wind direction changes (without a special yaw mechanism). Vertical-axis wind turbines were also used in some applications as they have the advantage that they do not depend on the direction of the wind. It is possible to extract power relatively easier. But there are some disadvantages such as no self-starting system, smaller power coefficient than obtained in the horizontal-axis wind turbines, strong discontinuation of rotations due to periodic changes in the lift force, and the regulation of power that is not yet satisfactory.
The horizontal-axis wind turbines are generally used. Horizontal-axis wind turbines are, by far, the most common design. There are a large number of designs commercially available ranging from 50 W to 4.5 MW. The number of blades ranges from one to many in the familiar agriculture windmill. The best compromise for electricity generation, where high rotational speed allows the use of a smaller and cheaper electric generator, is two or three blades. The mechanical and aerodynamic balance is better for three-bladed rotor. In small wind turbines, three blades are common. Multiblade wind turbines are used for water pumping on farms.
Based on the pitch control mechanisms, the wind turbines can also be classified as follows:
- Fixed-pitch wind turbines
- Variable-pitch wind turbines
Different manufacturers offer fixed-pitch and variable-pitch blades. Variable pitch is desirable on large machines because the aerodynamic loads on the blades can be reduced and when used in fixed-speed operation they can extract more energy. But necessary mechanisms require maintenance, and for small machines, installed in remote areas, fixed pitch seems more desirable and economical. In some machines, power output regulation involves yawing blades so that they no longer point into the wind. One such system designed in Western Australia has a tail that progressively tilts the blades in a vertical plane so that they present a small surface to the wind at high speeds.
Wind power plants, or wind farms, produce electricity
Wind farms are clusters of wind turbines that produce large amounts of electricity. A wind farm usually has many turbines scattered over a large area. One of the United States’ largest wind farms is the Horse Hollow Wind Energy Center in Texas, which at the end of 2021, had 422 wind turbines spread over about 47,000 acres. The project has a combined electricity-generating capacity of about 735 megawatts (or 735,000 kilowatts).
The Hybrid Solution: In the hybrid solution, we divide the lifetime of the network into multiple long time intervals. Every user needs to update his keying materials to maintain his access privilege for the next time interval, similar to the passive deprivation. During each time interval, we adopt the idea of proactive deprivation. In other words, when a user’s access privilege needs to be revoked, the trusted server will broadcast a revocation message. Every sensor node needs to maintain an interval revocation list (IRL), which includes the IDs of the users revoked in the current time interval (not the entire lifetime). Intuitively, the hybrid solution is more practical in terms of storage overhead and deprivation delay. The details of this scheme are given as follows:
Initialization: In our hybrid privilege deprivation, each constraint Cu assigned to user u includes a time interval index, indicating that Cu is only valid for the corresponding time interval. This means that a user has to update its constraint from time to time to maintain his access capability. The duration of a time interval is thus made large enough to reduce the overhead and allow a user to update its privilege before the time expires.
Privilege Update: Each user u must update its access privilege for each time interval Ti to access the sensor data during this time interval. This can be done by contacting the parent of user u, i.e., the user who delegated its privilege to u or the trusted server. Because user devices usually have longer communication range, this will not be a big problem in practice. When the trusted server or the parent of a user u receives an updating request, it will check whether user u‘s access privilege needs to be deprived. If not, it generates a new constraint Cu, which contains the index Ti, re-computes the hash keys using this new index, and sends this new constraint and the updated hash keys to u. An additional benefit of this update is that we can adjust the access privilege of a user dynamically. Note that when a user’s privilege is updated, it is not necessary to update the constraints for its descendants because their actual privileges are indirectly determined by u‘s updated privilege Cu. In other words, their access privileges are implicitly updated as well.
Proactive Revocation: In addition to periodically renew user privileges, it is also critical to revoke a user’s privilege as soon as possible in certain scenarios. In proactive revocation, the trusted server needs to broadcast a revocation message once a user is detected to be compromised or become malicious. Each sensor node maintains an interval revocation list L, which includes the IDs of all users revoked in the current interval. If a user’s ID is included in this list L, his access request will be immediately rejected.
Note that in proactive revocation, each sensor node has to maintain a revocation list. When there are many users revoked in a given time interval, the storage overhead at sensor nodes can be a big problem. A Bloom filter [17] can be used to reduce such storage overhead. However, it is well known that a Bloom filter introduces false positives but no false negatives [17]. In other words, although we can build a Bloom filter to match the IDs of all revoked users and revoke their access to the sensor data, this Bloom filter will also match the IDs of some non-revoked, benign users and revoke their access too. To address this problem, we propose a Bloom filter pair approach. Specifically, we construct two Bloom filters. The first filter, called the sensor-side Bloom filter, identifies all revoked user IDs, while the second filter, called the server-side Bloom filter, removes all false positives generated by the first Bloom filter.
Sensor-Side Bloom Filter A: Each sensor node maintains an array A of M bits, all set to 0 initially. Whenever a sensor node receives an authenticated broadcast message indicating that the access privilege of a user u is revoked, it computes m positions {h(i||u) mod M}i∈{1,…,m} and sets the corresponding bits in A to 1, where m is a system parameter for Bloom filters and h is a non-cryptographic hash function, which is much more efficient than the one-way hash function H we used before. When a sensor node receives an access request from user u, it will first compute all these m positions in the same manner and check the corresponding bits in the array. If the bits are not all set to 1, the user has not been revoked and the access request will be further checked in the same way as before; otherwise, this user could be a malicious user, and this sensor node will need to further check the server-side Bloom filter to make the decision.
