The Basics of a Wind Energy System
Wind is a renewable resource that produces vast amounts of electricity. Its power can be captured by turbines and converted into electric energy for home or commercial use.
However, wind power has a lot of challenges to overcome before it can be used in a grid dominated by fossil fuels. Those challenges include:
Wind Speed
The wind speed at a given location is very important for a site to be suitable for a wind energy system. It determines how much power can be produced. Most modern large turbines do not generate electricity at a constant speed because that would damage the equipment so they are designed with an optimum operating wind speed above which the generator will shut down.
Wind speed is determined by using an anemometer (which can be mechanical or electronic) placed high up in the air to measure the velocity of the wind. A wind vane is also attached which measures the direction of the wind. Wind speeds above a modern utility scale turbine’s rated wind speed will cause the blades to feather or point into the wind, reducing their surface area to decrease the power output.
Between the cut-in speed and the rated wind speed, the power generated increases in a cubic relationship, such that if the wind speed doubles the energy output will increase eight times. However, this does not always occur in practice as some studies with small domestic turbines in New Zealand found that the increase is linear rather than cubic.
Wind Direction
Wind direction is a vital factor that affects power production. This is because directional wind shear can lead to a loss of power due to turbulence intensity or directional stability. This is why the wind direction is important to consider when designing a wind turbine. The analysis of appropriate operation curves is an essential step in the understanding of the behavior of a wind turbine under wake.
This article analyzes wind speed, wind direction and wind power data from a 1.8 MW wind turbine. The data is pre-filtered from cut-in to rated wind speed, and the average power curves are computed for each time bin.
Based on the correlation between wind speed and wind direction, a mixture statistical distribution model is selected. The number of components in the Wind Energy System model increases from six to nine but the value of R2 does not increase. The analysis of turbulence intensity shows that the distance from the center of the wake is closely related to the turbulence intensity in the investigated waked sectors. This relationship is non-trivial, however, owing to terrain effects.
Blades
Wind turbine blades are composed of composites with high stiffness and tensile/compressive strength. They are manufactured using resin infusion technology where fibers are placed in a closed mold and resin is injected under pressure higher than atmospheric. Then, the composite is cured with heat.
In addition to the cyclic axial and bending loads caused by gravity, wind induces lift on the surface of the blades and this generates drag forces on the trailing edge and tip of each rotor blade. These forces interact with each other in a complex manner and their magnitude fluctuates cyclically.
Modern rotor blades are twisted along their length from their root to their tips in order to maximize Solar and Battery System the angle of attack for rotation and lift. This is made possible by the fact that wind moves slower near the roots and faster at their tips. VGs can be attached to the trailing edges of these rotor blades and they can enhance their performance by delaying flow separation and aerodynamic stall.
Shaft
As wind strikes the blades and hub, it creates aerodynamic forces that rotate the rotor. This rotation is sent to the gearbox, which decreases the speed by a factor of about 25 to 1 and then to the generator, which converts mechanical energy into electrical energy. The electricity is then transferred through a transformer to the power grid for distribution.
Wind turbines require a system of sensors to help them keep track of the direction and strength of the wind. This information is used by the control systems to point the rotor into the wind. On larger turbines, this is done by a mechanism called the yaw drive. Smaller turbines use a wind vane to do the same thing.
In addition to the yaw drive, the system needs a way to ground the shaft of the generator. Shaft voltage contains high and low frequencies, which could damage components if they aren’t grounded correctly. The solution is a set of rings that surround the shaft with hundreds of thousands of conductive microfibers, which have low impedance to high-frequency electricity.
Generator
A wind turbine generates electricity using the kinetic energy of moving air to spin the blades attached to its mast or tower. The blades are connected to a generator inside the nacelle, which also houses all other working parts of the turbine. The generator converts the spinning of the blades into electrical power that is supplied to the grid.
As the world’s second most popular renewable energy source, the global installed capacity of wind turbines continues to grow. Many new innovations in materials, design and technology are making wind power more efficient, affordable and environmentally responsible.
Wind power is a non-polluting, clean and efficient energy source that produces very few greenhouse gases during its life cycle. This helps to limit climate change. However, wind power is capital intensive and has relatively high upfront costs. This can increase its price per unit of electricity compared to fossil fuel sources. The intermittency of wind can create challenges for integrating large amounts into a grid system on a daily basis. This can result in increased costs for regulation, incremental operating reserve or other power management solutions such as load shedding or storage technologies.