1、Single unit capacity and power generation of wind turbines
When the “big windmill” rotates once, it can generate at least about 1.5 kilowatt-hours of electricity, and the maximum can reach several hundred kilowatt-hours. Therefore, how much electricity a wind turbine can generate depends on its single unit capacity.
What does single machine capacity mean? To put it simply, it means how many kilowatt-hours of electricity the fan can generate in one hour. For example, if the capacity of a single unit is 1,500 kilowatts, it means that it can generate 1,500 kilowatt-hours of electricity in one hour. 1,500 kilowatts is the minimum specification for onshore wind turbines. We will use this smallest windmill as an example to calculate.
2、Wind turbine blade speed and power generation efficiency
①Power generation and uses of wind turbines
When the wind speed is 3 meters per second, the fan blades can rotate. It takes about 4 seconds to rotate once, so it can rotate 900 times in one hour. The power generation per rotation is: 1500÷900≈1.67 degrees. However, this is only a theoretical value, and the actual value is smaller, about 1.5 degrees. What can you do with 1.5 kilowatt hours of electricity? It can charge your phone dozens of times, or let your TV play for two or three hours.
②Differences in unit capacity of onshore and offshore wind turbines
Generally speaking, the unit capacity of onshore wind turbines is relatively low, mostly 1,500 kilowatts, 2,000 kilowatts, and 2,500 kilowatts.The unit capacity of offshore wind turbines is relatively high, mostly 3,000 kilowatts and above. Theoretically, the larger the capacity of a single machine, the more electricity it generates, and of course the higher the cost.
When we look at the big windmill on the train, we always feel that it rotates slowly and leisurely, and worry about whether it can generate electricity. However, in fact, the amount of electricity generated has nothing to do with whether the blades rotate fast. If the blades rotate too fast, problems will occur.
③Wind turbine blade speed and power generation efficiency
When the blades rotate at a constant speed, the gearbox in the engine room can drive the rotor of the generator to rotate together. This gearbox has the structure of a planetary gear. The planetary gear is a large wheel that drives several small wheels to rotate. When the large wheel rotates once, the small wheels can rotate several times.
④Wind turbine blade rotation speed and safety
So despite the fact that the windmill blades rotate slowly on the surface, in fact, as long as the gearbox is adjusted, the small generator inside can spin and emit smoke.
And if the blades rotate at excessive speed, not only the small rotor inside may rotate and break… In more serious cases, the entire generator will be destroyed, such as this:
When the wind speed exceeds the limit, the blades’ eccentricity increases, disrupting the turbine’s balance and leading to blade disintegration or breakage. Therefore, when the wind is too strong, the wind turbine needs to stop working.
⑤So how can we increase the power generation of wind turbines? Can it be made into 4 leaves?
Yes, but not necessary. The cost of making four blades will increase significantly, but the revenue will not keep up, which is not cost-effective.
4、The relationship between the number of blades and power generation efficiency
Generally speaking, whether it is an electric fan in our home or a windmill, 3 blades will be more efficient than 4 blades.Because three leaves can form asymmetrical mechanical power, when one leaf does not have dynamic potential energy, the other two leaves with dynamic potential energy can easily drive this one to rotate, which can save a lot of energy.
In fact, if you want to increase power generation, a better way is to make the blades larger.
5、Ways to increase power generation from wind turbines
The power generated in wind power generation depends on the length and size of the blades. Larger blades have a larger force-bearing area, leading to greater mechanical energy conversion and higher power generation.
Blade lengths of 2MW wind turbines range from 48 to 59 meters, while 5MW turbines can exceed 60 meters, towering above nearby structures. The slow rotation of windmills is due to their large blades and higher single machine capacity. From a distance, they may seem fine, but up close, the immense pressure they withstand is evident.
