wind powered electricity & turbine Technology

Wind turbine technology is much more than just the basic horizontal-axis three blades wind turbines, operating with their blades facing the wind at a power ranging from a few hundred kilowatts to several megawatts...

Constant and variable wind turbine speed control

Traditional wind turbines use constant speed control technology, but advanced electronics allow the adjustment of the blade pitch angle in order to achieve optimum rotational speed and higher levels of efficiency.

Constant speed rotors are designed to deflect high wind gust loads, while variable wind turbine technology controls strong and gusty winds, enabling the gust peaks to be converted to electric power.

In contrast with constant speed wind turbines, variable speed ones may attain peak efficiency at any wind speed, and not only at one specific speed, which means comparatively greater annual energy production.

GE, Suzlon and other big manufacturers are actively exploring variable speed systems.

Wind power technologies: stall and pitch control

Controlling the power output from the turbines blades is a major issue in any wind turbine, and it can be accomplished by two main technologies.

One, known as the pitch control technology, is based on the adjustment of the blades by a control system, intimately connected to the brake system.

The other technology, the stall (or passive) control technology is purely based in the aerodynamic properties of the blade, without any control system or moving parts to adjust. It’s a technology based in the twist and thickness of the blade along its length.

Wind Turbine Parts

Typical wind turbines involve a set of rotor blades (usually three), rotating around a hub. The hub is connected to a gearbox and a generator, located inside the nacelle, which houses the electrical components.

See, diagram below (source: BWEA).

The nacelle

The nacelle sits on top of the tower and contains the electrical components, namely the gearbox, the brake, the wind speed and director monitor, the yaw mechanism and the generator.

Rotor blades

The diameter of the blades is a crucial element in the turbine power: typically, the longer they are, the greater the output. But their design and the materials incorporated by them are also key elements.

Blades are often made of fiberglass reinforced with polyester or wood-epoxy. Vacuum resin infusion is a new material connected to a technology presented by manufacturers like Suzlon.

Typically blades rotate at 10-30 revolutions per minute, either at a constant speed (the more traditional solution) or at a variable speed.

Gearboxes and direct drives

Most wind turbines use gearboxes, whose function is to increase the rotational speed required by generators. Some new technologies are exploring direct drives generators in order to dispense with the expensive gears.

Brake

The brake is a disk used to stop the rotor blades in emergencies, and to ensure the safety of the turbine in case of very high damaging winds or other exceptional situations.

Controller

The controller is a set of electrical components. It controls the starting, the stopping and the turbine rotor blade speed. Typically, in the constant wind speed model, the controller starts up the turbine at wind speeds around 8 to 14 miles per hour and stops the machine at around 55 miles per hour (to avoid the damages caused by turbulent high winds).

Generator

The generator is the device responsible for the production of 60-cycle AC electricity.

The yaw mechanism of wind power generators

In more typical wind turbines, the yaw mechanism is connected to sensors (anemometers…) that monitor wind direction, turning the tower head and lining up the blades with the wind.

Wind Turbines Towers

See: Wind Turbines Towers.