Wind Turbine Variable Pitch System

 

     Angstrom Renewables Wind Turbine's electronic controller checks the power output of the turbine several times per second. When the power output becomes too high, it sends an order to the blade pitch mechanism which immediately turns the rotor blades slightly out of the wind. Conversely, the blades are turned back into the wind whenever the wind drops again. During normal operation the blades will pitch a fraction of a degree at a time - and the rotor will be turning at the same time. The pitch mechanism is operated using hydraulics. The computer will generally pitch the blades a few degrees every time the wind changes in order to keep the rotor blades at the optimum angle in order to maximise output for all wind speeds.

    Under the wind speed of 0m/s ~ 3m/s, the turbine blade remain static ,and the angle X1 formed between the blade and turbine plane is B° (X1= B°);under this angle ,the blade is most easily to be started up. As long as the wind speed reached 3m/s, the blades will begin to rotate, during the rotation, the outermost edge of the blade will be driven by the centrifugal force generated by the rotation of the blade to tilt toward the turbine plane, the aforementioned angle X1 will decrease until 0° when the blade is in parallel with the turbine plane; at this angle ,the turbine has nearly reached it’s rated output power. When the wind speed is between 11m/s ~25m/s ,the blade will keep adjusting it’s position forth and backward slightly to let the angle X1 fluctuate a little bit but maintain at around 0°roughly, so as to stabilize it’s rated power. Within the wind speed of 25m/s ~ 50m/s ,when the wind has exceeded it’s rated speed , the wind will keep drawing the blade by the centrifugal force,so the angle X1 will continue to decrease and turn into a negative angle X1= - B°(PS: B°and - B°is not the same),under this negative angle, the rotation of blade will produce a resistance on the rotation of turbine blade to slow down the rotation and protect the wind turbine from over speed operation, the maximum RPM of the turbine will be no more than 220 RPM.