In the recent past, wind energy has proved to be an essential facet in the implementation of environmentally sustainable low carbon globe. As such, the demand for wind energy has been tremendously rising in areas such as human consumption and even industrial production. The fact that this energy source is cheap and cost-effective has also been a contributing factor to the rise in demand. However, it is critical to state that the mass-roll-out of wind turbines is still at the infancy stage in many countries. Numerous governments have been slow to react to this economies of scale contributor despite the drive towards sustainable energy production. With this in mind, chances are high that many neighborhoods or even your home is yet to be powered by a wind turbine. On that note, this piece seeks to demystify how wind turbine generators work.
It is evident that the utilization of wind energy dates back to 5000 B.C. The earliest windmills would arrive around 2000 B.C in ancient Persia CNET reports and were used to grind grain. Later on, this energy source would be used to pump water, and drive vehicles in ancient China and the middle east. However, the first documented windmill is recorded in a book pneumatics whose author was Hero of Alexandria between the first century B.C and the first century of A.D. Consequently, the windmills would be used in the conversion of kinetic energy into mechanical energy. Over time, the modern utility-scale turbines we know of today were developed.
It was not until the late 19th century when wind energy was used in the generation of electricity. This energy source did not gain momentum, however, as steam turbines were dominant in the production of electricity. Wind energy would gain interest from various stakeholders in the mid-1970s after the oil crises. Moreover, this period had intensified concerns regarding the conservation of resources. Wind energy was therefore used to generate electricity for charging batteries in residential-scale power systems, utility networks, island power frameworks, and remote power systems. While the wind turbines are ideally small (less than 100 kW), they could be compounded in a large wind turbine farm leading to approximately 5MW.
Later on in the 1990s, numerous wind projects took off and a shift from onshore to offshore development was witnessed particularly in Europe. Offshore wind turbines seemed appealing as they have unique characteristics such as higher wind speeds, lower wind shear, larger developmental sites and even lower intrinsic turbulence intensity. During the last 3 decades, the wind turbine industry has significantly transformed globally. Global wind markets have grown and as of 2009, the world capacity was able to reach 160 GW. Moreover, wind energy penetration rose from 1% in 2008 to 8% in 2035. Currently, modern wind turbines are quiet, reliable and commercially competitive. Wind turbine technologies are now mature making wind power the most feasible source of renewable energy.
By definition, a wind turbine is a tool that transforms kinetic energy from the wind into electrical energy. Modern turbines possess different characteristics. For instance, turbines can be classified with respect to their rotor axis orientation, rotor position, rotor speed, the number of blades, rigidity, power control or even the yaw control. However, the most common type of wind turbine topology in today’s market is the horizontal-axis wind turbine. The crucial parts of this kind of turbine include:
These are basically the sails of the entire turbines. In essence, the rotor blades typically act as wind barriers. As the wind forces these blades to spin, some of the wind’s energy ends up being transferred to the rotor. Turbine experts indicate that blades can reach speeds of 160 miles per hour hence oblige an ideal construction process.
The shaft is connected to the center of the rotor. Therefore, the shaft spins with the spin of the rotor. This way, the rotor transfers its mechanical-rotational energy to the shaft. Consequently, this enters the electrical turbine generator on the end.
The generator is a simple yet critical tool in a turbine. A generator makes use of electromagnetic induction to create electrical voltage. Voltage is the electrical pressure that moves electrical current from region to another. This translates to the generating voltage creating the current. A basic generator is comprised of a conductor and multiple magnets. While the conductor is a coiled wire, the shaft gets connected to the assembly of permanent magnets that surround the coil's wire. The principles of electromagnetic induction cite that when a conductor is surrounded by multiple magnets and one of the facets rotates relative to the other, the voltage gets induced. As such, the rotor ends up sinning the shaft which consequently spins the collection of magnets. A voltage gets generated in the coil of the wire. In turn, the voltage propagates alternating current (AC Power) through the stipulated power lines for the purposes of distribution.
The next section expounds more on the wind turbine generators as it is evident that they play a significant role in the production of electrical current.
A major limiting factor in wind turbines tends to lie in the type of generator technology. However, a consensus has not yet been reached with regards to the industry and academics on the ideal wind turbine generator technology. Turbines basically fall into the fixed speed turbine and variable wind turbines. The former is the most common as most manufacturers have the induction generator connected directly to the grid. However, it has major flaws in that it does not control the grid voltage optimally. On the other hand, the variable speed turbines give a high level of stability and also reduce noise at low speeds. The twist arises from the fact that to operate a variable speed turbine, an electronic converter has to be present and this prompts the need for a turbine generator. Luckily, all the generators discussed in this piece have the capability to run at both variable and fixed speeds. Some types of these generators include;
The DC wind generator framework consists of a turbine, a DC generator, a transformer, an insulated gate bipolar transistor (IGBT) inverter, a controller and finally a power grid. Shunt-wound DC generators have the field current increasing constantly with the operational speed. Consequently, the balance that exists between the turbine drive torque ends up dictating the actual speed. As such, electricity gets extracted through brushes hat connect the commentator. The commentator converts the alternating current (AC) generated into DC input.
Note* that except in low power demand applicability, DC generators are uncommon in turbines. The reason behind this is that they oblige regular maintenance which at times can be costly due to the brushes and commutators.
These types of generators can prompt regular or DC excitations from electromagnets or permanent magnets. For this reason, these generators end up being dubbed either ‘electrically excited synchronous generators (EESGs) or ‘permanent magnet synchronous generators (PMSGs)’. The working mechanism for the generators is in such a way that when the turbine propels the rotor, 3-phase power is created in the windings that are connected to the main grid. For fixed-speed synchronous generators, rotor speeds ought to ought to be similar to the synchronous speed otherwise synchronism gets lost. The synchronous generators are a proven technology as they have been studied hence are widely accepted. While they are preferred in wind turbine applications due to their low mass and high power density, they are costly yet prone to failure than their induction counterparts. They are therefore ideal in small wind turbine generators.
While traditional systems use synchronous generators, modern wind energy systems utilize induction tools uniquely in turbine applications. As such, the induction generators get classified as fixed-speed induction generators (FSIGs) that possess squirrel-cage rotors and double-fed induction generators (DFIGs) that have wound rotors. These generators have the ability to absorb speed fluctuations of the rotor. A distinction, however, is that FSIGs possess restrictions in the narrow range of discreet speeds context, noise, and even the size. Therefore, approximately 85% of the installed wind turbines globally use DFIGs that have less mechanical stress, high energy yield, no power fluctuations, and the reactive power can be easily controlled.
Wind Turbine Generators-Finally, the switched reluctance generators possess rigid rotors and a stator. During the rotation of the rotor, the reluctance of the magnetic circuit integrating both the stator and rotor changes. Conversely, electric current gets induced on the winding of the stator. Uniquely, this kind of generator is made through the assembly of laminated steel sheets. Therefore, there are no permanent magnets or even electrical field windings. They are the best as they can work in harsh climates.
Thanks to the advancements in internet technology, you are able to find numerous ways of building your own small wind turbine. However, the universal principle of electricity production remains the same. Some of the components that required to build a residential home turbine or generator include tools, a motor, the body, blades, tail, tower, diode, batteries, and the central hub. A point worth remembering at this stage is that you end up dictating the amount of electricity you want to produce. For the sake of the basic understanding, the following process focuses on the production of the bare minimum green energy.
You are going to start with essential tools such as soldering irons and wire strippers. For the generator, you will oblige recyclable tools such as plastic soda bottles (2-liter bottles) the bottle caps, light yet thin metal strips, glue, and epoxy. Traditional tools like wrenches, drill, and a saw will also be crucial. With these, you can proceed to craft a plan.
This is the area that will be collecting the wind for your turbine. In this, your bottles should be sawn off under their necks. This should be an easy step as you can even utilize a kitchen knife.
In the quest to extend the wind-catchment area, have the epoxy join your bottle tops. Here, it is recommended that you fix them till you end up with 4 coupling parts.
The product in this stage will not be used as a fan. However, it inclines to a fan mechanically. As such, you are required to carve an X shape out of the metal strips you have. This shape should at least be 1 foot in length and 1 inch in width. After this, secure the couplets you created to the ‘fan’ through the epoxy. Allow the epoxy to harden before proceeding to the next step.
As long as you designed and built the couplets in the right manner, this step is simple. All is required is to fix the bottle tope to the couplets by using some screws.
After assembling the fan, the next thing on your DIY list should be the generator. Luckily, the diodes and battery you collected fulfill the need of a generator. Therefore, stick together the generator and the fan through the epoxy. Any edges can be secured with glue.
Finally, you need an ideal place to erect your DIY turbine. This solely is dependent on the type of motor you designed and built. Unlike large commercial turbines, this stand should be small. The best choice would be to go for a rectangular piece of wood. The next thing is to attach both your generator and fan to this stand. Ensure that the apparatus is rigidly secured so as to prevent toppling over by strong winds.
By following these steps, you end up with a fully functional turbine. This is a sustainable, clean yet aesthetic energy source.
It is clear that wind energy continues to attract lots of attention from varying stakeholders globally. A specific area that is experiencing tremendous growth is the offshore wind turbine market. This piece focused on the utilization of wind energy which led to debunking the different small wind turbine parts such as the shaft and generators. Moreover, the various types of generators were exclusively covered and finally, a DIY wind turbine guide was accorded. This information therefore is crucial for those interested in a residential or alternatively small wind turbine.