The generator in large commercial size horizontal axis wind turbines is mounted in a nacelle that is located at the top of a tower behind the turbine’s rotor. A gearbox for increasing speed may also be placed in between the rotor hub and the generator in order to reduce the cost and weight of the generator.
The rotors on commercial size generators carry field windings that allow the production of a rotating magnetic field inside the stator. If a wind generator is quite small, it may use permanent magnets, but because of its size, these are too costly for us in large machines. In addition, they do not permit the generator’s voltage to be regulated conveniently.
Electrical generators usually have a built-in system for producing AC power. Some of the older style wind generators tend to rotate at a constant speed in order to match the frequency of power lines. Because of this, less costly induction generators were permitted. Unlike the older wind turbines, new models most often turn at the speed that allows it to generate electricity most efficiently, most often usually multiple technologies that allow the production of variable frequency current, which in turn is converted to DC and then converted back to AC current allowing it to match the voltage and frequency of the line. The equipment is costly and causes power loss, but the turbine has the ability to capture a larger amount of the wind energy than with turbines that produce only AC power. There may be times when a central inverter will be used to connect the DC energy to the grid. This is especially useful when turbines are placed offshore and allows the DC energy to pass from the turbine to the inverter before connection to the grid.
Because of its resin matrix, carbon fiber is one of the best construction materials for building wind turbine blades. It’s the strongest and stiffest material available, but because it is very expensive, its use is limited to some blade manufacturers who use it only in parts of the rotor blades that are highly loaded, namely those where stiffness is critical. In modern blades, the composition is that of lightweight glass-reinforced plastic using an epoxy or polyester resin matrix.
Wind turbines can be made from different materials, but some are more effective than others. However, the key to its operation is not in the material that is used, but how the turbine generates power in order for it to create the electricity. In short, what happens in this process is the wind turns the blades on the rotor, which then turns the low-speed shaft at a speed of 30 to 60 rotations per minute. Once that operation is in motion, gears connect the low-speed shaft to the high-speed shaft, thus increasing the rotations per minute to something in the area of 1200 to 1500. The key to producing electricity is to get the rotations per minute as high as possible. The more rotations the blades make means more electricity is produced. The generator of a wind turbine is a simple one that converts the kinetic energy of the gears into usable electric energy that you can use to run machinery or provide electricity to your home or business more efficiently and cheaper than what you pay your local power company to provide the same power.
Your wind turbine will also include the yaw drive and motor whose purpose is to keep the blades facing in the right direction. If the blades are not facing into the wind, it is impossible for the turbine to capture its power in order to convert that wind power into electricity. Other equipment includes an anemometer is necessary in order to collect data on wind speed, a wind vane to monitor wind direction, and a controller so that if the wind speeds are too high or too low, the turbine can be turned off. Wind speeds should typically be 8 to 16 mph minimum and 65 mph maximum.