Wind turbines require gear boxes to transfer the power from the turbine’s shaft to a generator or load.Learn more about Wind Turbines components in this article
Table Of Content
As was discussed on the page devoted to a wind turbine’s components, the power that is generated by the spinning of the rotor of the wind turbine is sent to the generator through the power train. This involves the power being transmitted via the main shaft, the gearbox, and the high-speed shaft.
But why do you need to use a gearbox? Wouldn’t it be simpler if we simply used the electricity coming from the main shaft to directly drive the generator?
As we can see on the page about changing generator rotational speed, if we used an ordinary generator and directly connected it to a 50 Hz AC (alternating current) three-phase grid with two, four, or six poles, we would need an extremely high-speed turbine with between 1000 and 3000 revolutions per minute (rpm). Given that the rotor has a diameter of 43 meters, this would suggest that the tip speed of the rotor is far higher than twice the speed of sound; thus, we should just forget about it.
Constructing a slow-moving alternating current (AC) generator with a large number of poles is still another alternative. If you were to connect the generator directly to the grid, however, you would need a generator with 200 poles, or 300 magnets total, in order to achieve the 30 revolutions per minute that is considered appropriate.
Another issue is that the mass of the generator’s rotor must be approximately proportionate to the amount of torque (moment, or turning force) that it is required to manage. Therefore, a directly operated generator will be very cumbersome (and expensive) in any circumstance.
Less Torque, More Speed
The employment of a gearbox is the pragmatic option, as it is used in the opposite direction in a lot of different industrial apparatus and is also used in conjunction with automobile engines. A gearbox is used to transform the power that is produced by a wind turbine rotor, which rotates slowly and generates a high torque, into power that rotates quickly and generates a lower torque, which is then used for the generator.
It is not possible for the gearbox of a wind turbine to “shift gears.” In most cases, there is just one gear ratio that exists between the rotation of the rotor and the rotation of the generator. Generally speaking, the gear ratio for a machine that has 600 or 750 kW is anywhere from 1 to 50.
The wind turbine gearbox seen below has a capacity of 1.5 megawatts (MW). Because it contains flanges for two generators on the high-speed side, this particular gearbox is a little more peculiar than the average one (to the right). The hydraulically actuated emergency disc brakes are the orange devices that are located directly below the generator attachments on the right side of the vehicle. You can make out in the background the bottom portion of the nacelle that belongs to a 1.5 MW turbine.
Conclusion
It has been demonstrated that there is a tool for calculating the dependability of gearbox bearings and gear systems. This evaluation technique has been used here in order to assess the state of the maintenance. Any gearbox may be analyzed, even with the information that is now available. When the system’s fundamental dependability is poor, improving the maintenance’s influence on its reliability might be helpful for the design. It is important to do an analysis to determine whether preventative maintenance procedures, such as increasing the oil’s viscosity or cleaning it more thoroughly, should be put into practice. In particular, when it comes to oil bath lubrication, having clean oil might be really necessary.
FAQ
Why is it necessary for a wind turbine to have a gearbox?
In order to enhance the rotating speed of a wind turbine’s main shaft from a low speed to a high speed so that it can link with an electrical generator, a gearbox is often used in these machines. The fluctuating wind loads that wind turbine gearboxes experience are stochastically unpredictable, which results in severe cyclic stress on the gears of the gearbox.
In wind turbines, what kinds of gears are utilized?
The majority of gearboxes in wind turbines with a rated power range of 1.5 MW employ a one- or two-stage planetary gearing system, which is also known as an epicyclic gearing system at times. In this configuration, there are a number of outside gears, which are the planets, that rotate around a single central gear, which is the sun.
How are gears used in windmills?
A gearbox is used to transform the power that is produced by a wind turbine rotor, which rotates slowly and generates a high torque, into power that rotates quickly and generates a lower torque, which is then used for the generator. It is not possible for the gearbox of a wind turbine to “shift gears.”
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