1. Field of the Invention
The present invention relates to the field of wind turbines that use environmental air current and winds to generate electrical energy with an electrical generator.
2. Background of the Art
The wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is called a windmill or wind pump. Developed for over a millennium, today's wind turbines are manufactured in a range of vertical and horizontal axis types. The smallest turbines are used for applications such as battery charging or auxiliary power on sailing boats; while large grid-connected arrays of turbines are becoming an increasingly large source of commercial electric power. Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common horizontal axes.
Horizontal axis—These are defined as components of a horizontal axis wind turbine (gearbox, rotor shaft and brake assembly) after being lifted into position. Horizontal is nominally in reference to perpendicularity to gravity and/or parallelism with the horizon. Those positions are approximate, and with devices that may also shift with respect to the horizon to adjust for wind speed, that approximation may be significant.
Horizontal-axis wind turbines (HAWT) have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a servo motor. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator.
Since a tower produces turbulence it, the turbine is usually positioned upwind of its supporting tower. Turbine blades are made stiff to prevent the blades from being pushed into the tower by high winds. Additionally, the blades are placed a considerable distance in front of the tower and are sometimes tilted forward into the wind a small amount.
Downwind machines have been built, despite the problem of turbulence (mast wake), because they don't need an additional mechanism for keeping them in line with the wind, and because in high winds the blades can be allowed to bend which reduces their swept area and thus their wind resistance. Since cyclical (that is repetitive) turbulence may lead to fatigue failures, most HAWTs are of upwind design.
Turbines used in wind farms for commercial production of electric power are usually three-bladed and pointed into the wind by computer-controlled motors. These have high tip speeds of over 320 kilometers per hour (200 mph), high efficiency, and low torque ripple, which contribute to good reliability. The blades are usually colored light gray to blend in with the clouds and range in length from 20 to 40 meters (66 to 130 ft) or more. The tubular steel towers range from 60 to 90 meters (200 to 300 ft) tall. The blades rotate at 10-22 revolutions per minute. At 22 rotations per minute the tip speed exceeds 300 feet per second (91 m/s). A gear box is commonly used for stepping up the speed of the generator, although designs may also use direct drive of an annular generator. Some models operate at constant speed, but more energy can be collected by variable-speed turbines which use a solid-state power converter to interface to the transmission system. All turbines are equipped with protective features to avoid damage at high wind speeds, by feathering the blades into the wind which ceases their rotation, supplemented by brakes.
Wind turbines are designed to exploit the wind energy that exists at a location. Aerodynamic modeling is used to determine the optimum tower height, control systems, number of blades and blade shape. Wind turbines convert wind energy to electricity for distribution and typically are not combined with any storage capability. Conventional horizontal axis turbines can be divided into three components.                The rotor component, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low speed rotational energy.        The generator component, which is approximately 34% of the wind turbine cost, includes the electrical generator, the control electronics, and most likely a gearbox (e.g., planetary gearbox, adjustable-speed drive or continuously variable transmission) component for converting the low speed incoming rotation to high speed rotation suitable for generating electricity.        The structural support component, which is approximately 15% of the wind turbine cost, includes the tower and rotor yaw mechanism.        
A 1.5 MW wind turbine of a type frequently seen in the United States has a tower 80 meters high. The rotor assembly (blades and hub) weighs 48,000 pounds (22,000 kg). The nacelle, which contains the generator component, weighs 115,000 pounds (52,000 kg). The concrete base for the tower is constructed using 58,000 pounds (26,000 kg) of reinforcing steel and contains 250 cubic yards (190 cubic meters) of concrete. The base is 50 feet (15 m) in diameter and 8 feet (2.4 m) thick near the center.
Above 10 m/s, where power regulation caused blade coning, the early data recorded was erratic and use of these figures would distort further data processing. A cut off point was set at 3500 seconds and the readings taken before this point were not used for the detailed calculations. As the wind speed during the day did not fall below 6 m/s, and regulation cut in at 10 m/s, the final results were based on a narrow band of rotor speeds between 3.1 and 4.4 rev/s
The universal standard to assess the performance of a wind turbine is a plot of the Power Coefficient versus the Tip Speed Ratio performance curve. This curve tells you how efficiently a turbine converts the energy in the wind to electricity. Various methods were used to plot this curve. The results are show in Figure.