The protection & safety systems of small wind turbine
After 30 years development, there are many different protection and safety systems for small wind turbine from 1kw to 50kw. This article introduced most of the popular protection systems in the world including the mechanical protection and electronic protection. The small wind turbine manufacturers usually choose some of them in their design, no one can cover all of below protections in the system.
1． Yaw Control: PLC Control will control the yaw motor to deviate wind turbine from the wind direction at an angle of 30 degrees, 60 degrees or 90 degrees when it detects the faults of over wind speed, over voltage or generator over temperature.
2． Electronic Brake: Dump load box adopts the PWM technology as the electronic control and keeps the rotor speed under the stable range to protect the operation of wind turbine. When the wind speed is over the rated wind speed or the generator's output power exceeds 125% of the rated power, the dump load box will be initiated to consume the extra electricity to keep the rotor speed under a stable situation. Meanwhile, it can keep the electrical appliance secure to some degree.
3． Mechanical Brake: As the secondary protection system, mechanical brake was driven by high quality German hydraulic station. It could stop the wind turbine rotor in over speed, over voltage, over temperature or grid failure.
4． Tail-bend protection: When the wind speed exceeds 25m/s, the rotor of the turbine will yaw a certain degree from the wind direction automatically. And the rotating speed of the rotor will drop off. As it has such a reliable mechanical protecting system, the system has no other electrical or magnetic safety device.
5． Pitch control: when the generator is over than rated power, it can adjust the pitch of the blades to make the power define the rated power' range. And it owns the high wind energy index in certain point.
6． Tilt angle of rotor shaft: The main function of it is to prevent the blades and tower crashing.
7． Over wind speed protection: When the wind speed exceeds a certain level of wind speed, it will carry out the protective function. For example, if the protective wind speed of the turbine is 20m/s, it will start to protect the turbine when the wind speed is over this level.
8． Over temperature protection: When the temperature exceeds a certain temperature, it will carry out the protective function.
9． Over voltage protection: When the voltage exceeds the rated voltage, it will carry out the protective function to keep the turbine in secure situation.