Wind Power Generation Basics

It is very fascinating to watch the wind turbine generator system used for wind power generation convert the energy in a breeze or a storm into electrical energy. In principle, a wind energy turbine's rotating blades help convert the kinetic energy in wind into rotational movement of a shaft. The rotating shaft coupled to the shaft of an alternator turns it and thereby generates electricity. The electricity is then transmitted through wires down the wind generator tower to a utility grid.

Each wind blade's profile is an engineered aerofoil. It captures the wind's energy. Most modern wind turbine generators use a set of three blades. With this configuration, the best compromise is attained between the balance that is made possible with multiple blades and the highest efficiency that is possible with a single blade. The rotor comprises the blades and the hub they are attached to.

The rotor is known as the system's collector. It intercepts the winds that flow past the blades. Upwind turbines constitute most of the machines available in the market today. Their blades are on the tower's windward side. Some downwind turbines are also available in the market. However, neither of these turbines has a distinct performance advantage over each other.

In the majority of small-scale wind turbine generator designs, the rotor is directly coupled to a permanent magnet alternator's shaft, which generates fluctuating, 3-phase AC. Fluctuating, 3-phase electricity is generated due to continuous variation in the voltage and frequency with the wind speed.

The voltage and frequency so produced are not non-fluctuating values in contrast with the 60 Hz 120 VAC electricity available at usual household outlets. The fluctuating output is converted to DC to either feed a grid-synchronous inverter or to charge batteries. In the majority of such wind turbine generator designs (limited within 15 KW peak capacity), the rotor is often connected directly to the alternator.

This helps eliminate additional upkeep of gears. However, in 20 kW and larger capacity wind turbine generator designs as also in some lower capacity wind turbine generator systems, the alternator speed is increased through use of a gearbox. The gearbox steps up the slower turning rotor speed to the higher alternator shaft speed.

For the blades to rotate to face the wind, a yaw bearing is required. This allows the wind turbine to track the direction-shifting winds. The tail of the blades directs the rotor to rotate into the wind. The rotor rpm and the generator output is limited through use of a speed governor to protect the turbine from high winds. The machine can be stopped when necessary through use of a shutdown mechanism. This may be essential in the face of an extreme storm, when energy utilization is not needed or when the system is under maintenance.

Generally, a wind turbine generator system used for wind power generation includes at least a wind turbine generator, a wind turbine generator tower, a brake, and a backup generator.