**Author details**

But it is possible to apply another technical solution. Batteries can be used to power the electrical circuits of the rotor if placed on a rotating part (**Figure 32**). In this case, the exiting alternator can be excluded. The battery pack will additionally

In practice it is impossible to use windmills without energy storage devices. It is

Nowadays the storage batteries are the acceptable energy storage devices taking in consideration the reliability and cost. The double-fed alternator allows combining two concepts (creating the standard energy and storage energy) at one device. In sketch, it is possible to see that the rotor has enough place for allocation the batteries

• The supplying the electric energy to electronic control system. This solution allows extending the limits of the windmill working operation. Indeed, for short time, it is possible to use windmill with fixed rotor when we have no

Nowadays the development of windmill industry is holding back by one serious

problem. It is very difficult to transform with high efficiency the nonstandard energy to the standard energy. The using of the induction alternators or the synchronous alternators cannot solve this problem with good results. As a rule in this case we have low efficiency, complex design and high total cost. The problem is becoming more difficult when you make attempt to build the row of windmills from small power to big power (10 kW–1 MW). The concept of the DFIA proves to be very effective for solving windmills problems. It is possible to transform the nonstandard energy in to the standard energy with high efficiency. Windmills may operate as stand-alone or grid tied. It is possible to build the row of windmills with the same design. But the main reason of the application the DFIA is the low total cost of windmill and electronic control system. The new design of this concept is

necessary for us to have a stable energy supply but wind has unstable action.

These batteries can solve two problems. They are:

function as a storage device [4].

*DFIA design with built-in rechargeable batteries.*

• The electric energy storage.

(**Figure 32**).

**Figure 32.**

*Aerodynamics*

wind.

**9. Conclusion**

**26**

Sergey Gandzha\* and Anton Kotov South Ural State University, Chelyabinsk, Russia

\*Address all correspondence to: gandja\_sa@mail.ru

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
