A new excitation regulating and harmonic eliminating equipment for fixed speed fixed pitch wind turbines

The fixed pitch fixed speed wind turbines are used in China commonly. The main problem of this type of wind turbine system is the low availability of wind energy. A solution is to change it to variable speed wind turbine system and to interconnect it to power grid through rectifying circuit and inverter unit. In this work, a new-style equipment is also designed which can regulate the excitation current and eliminate the harmonic current. It can control coordinately with the rectifier and inverter. In this proposed system, the rotating speed of the generator is variable, and the availability of both wind energy and generator is improved. And the excitation regulating equipment can also eliminate the harmonic current caused by the rectifier and inverter, which can step down the detriment to the torque of the generator and improve the performance-cost ratio of the whole system.