Energy is an issue currently facing mankind. Traditional energy slowly decrease, already cannot meet people's needs, more serious, such as thermal power generation, oil and gas, environmental damage is very large, therefore, the development of new clean energy has become an inevitable trend. Among them, the wind power is a clean energy future, more and more people's attention. Communication slip ring for wind power generation, as the pitch system power supply, transmission control signal and communication functions important part, which is mounted on the hub rotates coaxially with the speed gearbox low speed shaft. After the fan speed, communications slip ring as a carrier of the transmission signal may fail, so that the system cannot normally receive pitch over speed signal speed information, cockpit issued timely action cannot respond to, such overdrive fans cannot get timely containment. Therefore, there is a big security risk fans, how the fan speed, reliable protection of the pitch system, it becomes quite important.

The general solution is in communication through the slip ring tail install encoders, encoder and communication slip ring bearing synchronous rotation, detecting the number of revolutions of the fan, the encoder measured fan revolution number signal delivered to the master system, the master system to the number of revolutions of signal processing, computing, to give the fan speed per unit of time - that is, the fan speed signal; the fan speed signal and the main control system programmed maximum speed value comparison, if higher than the set value , then the fan speed, the main control system control unit sends a signal, through the slip ring to the pitch, the pitch excitation system actuators quickly the OARS, to protect the fan. In this way, under normal circumstances can solve the security problem in the fan speed status. However, because the speed of the process through more components, long communication process, the speed signal to go through multiple conversions can finally pitch into the system, with a certain delay, but also multiple conversions to generate attenuation and signal transmission error. Moreover, the domestic wind power technology is not yet mature, communications slide slip ring communication function is not reliable, it will be affected by interference and external conditions inside the equipment, etc., so that the signal transmission is not accurate, even in the case of overs peed, communication slip ring failure, resulting in signal cannot be transferred. Thus, there is still a big fan of security problems, so to develop a new fan system for domestic wind power development has important significance.