Archimedes screws for micro hydro induction generation: Effects of the adoption of a frequency converter

In the field of the renewable energy exploitation, it is often at disposal the possibility to obtain electric power along small waterways, with values between 10 and 150 kW (micro hydro). For such cases one of the most suitable solution is the one which provides as hydromechanics turbine a cochlea, which was used in the past mainly for water pumping plants; the described solution is often indicated as Archimedes Screw Generator (ASG). Such a technical solution is more and more frequently adopted for economical reasons, and present a very large application field, with the possibility to exploit situations otherwise not convenient; an ASG provides normally an induction generator directly connected to the mains. After a short description of the mentioned systems and of their working principle, the proposal of the adoption of a frequency converter drive between the induction generator and the mains is discussed under both the technical and economical point of view.