Sophisticated transmissions incorporating planetary drives and frequency converter control are used in drive systems for wind generators ranging in size from small systems for village power supply in India through to 5 MW leviathans.
These ruggedly reliable and compact drive systems – incorporating technology already proved in Australasian industrial applications ranging from mining to manufacturing and materials handling - provide as high as possible an energy yield and as low as possible risk potential for the system at the same time.
With their help, the generator’s gondola (and thus the wind turbine) is constantly matched to the wind direction on the one hand, while on the other the rotor blades are brought into an ideal position.
Operation at an optimal speed is decisive for the efficiency of the energy producing drive train extending from the rotor to the generator. If it turns too slowly, insufficient energy will be produced; if it turns too quickly, there are dangers to the complete wind turbine.
Two main final control elements ensure that the speed is kept as optimal as possible:
- The first control element governs the positioning of the gondola, which has to keep the rotor directly in the wind. The wind must always hit the rotor at right angles in order to ensure optimal exploitation of the power.
- The second final control element, which is responsible for the optimal speed, relates to the position of the individual rotor blades. Aerodynamics are strongly influenced by the inclination of the blades against the wind. Incorrect inclination can result in rotor standstill in strong winds. The rotors must remain head-on to the wind.
However, system designers have to consider not only the movement torque, but also the holding torque, both of which are decisive for the design of the azimuth drive.
Several geared motors with brakes are used in order to always maintain the gondola at right angles to the wind and keep it there (no small task when you consider its weight of more than 100 tons and a rotor span of up to two football pitches).
The sensor technology employed reports wind direction changes to a control unit, which then puts several geared motors in motion in a matched way via the frequency converters, so as to track the gondola.
The tracking is usually triggered by a wind direction deviation of seven degrees. The requirements for precision and exactly matched drive behaviour are decisive in the choice of the drive system.
Drives of a few thousand Newton meters are sufficient for this task for small systems. Constructors readily find suitable geared motors from 1,000 Nm rated torque in the Bonfiglioli product range.
Bonfiglioli invests more than $A85 million a year on its product ranges and facilities, designing drives from the ground up to be a leader in their class.
The company has invested extensively in Australia and New Zealand to extend its range and capabilities across the spectrum here.
As demand expands in Australasia for clean energy alternatives, we are positioning ourselves to deliver the benefits access to truly global experience in this market.
Bofiglioli is represented by Bonfiglioli Transmission (Aust) .