A variety of unique wind turbines have been introduced since the production of wind turbines, such as the dual-feed asynchronous wind generator. This is a kind of wound rotor induction generator, at the same time is also the core component of variable speed constant frequency wind generating set, its composition and average wind turbines, also including the motor body and cooling system of two parts.
But if you look closely, the stator windings of the double feed asynchronous wind generator are connected directly to the grid, while the rotor winding is connected to the grid through the frequency converter. So that the frequency of the generator rotor winding of the power, voltage, amplitude and phase can be in accordance with the requirements by the converter running automatic adjustment, implementation under different rotational speed constant frequency electric, meet the requirements of electricity load and interconnection.
Because doubly-fed asynchronous ac excitation is adopted in wind turbines, and with the generator and power system constitutes the flexible connection, so you can according to the power grid voltage, current and the speed of the generator to adjust the excitation current, thus accurate regulating the generator output voltage, make its can meet the requirements.
The converter of the double feed asynchronous wind generator consists of two parts, the rotor side converter and the power grid side converter, but they are independently controlled by each other. Power electronic converter is the rotor side converter by controlling the rotor current component of active power and reactive power control, and the grid side converter control dc bus voltage and make sure the converter running in unity power factor.
Compared with the normal type of step wind generator, the double-fed asynchronous wind generator can control the reactive power, and the independent control rotor excitation current decouples the active power and reactive power control. Furthermore, the device does not need to excite the grid from the grid, and excitation from the rotor circuit; And generate reactive power.