Modelling of the Static Response of a Wind/Hydro Turbine with Two Rotors and a 1DOF Speed Increaser

Abstract

The wind/hydro energy conversion systems that integrate speed increasers are known on the market for more than half a century, the classical solutions with one rotor being currently widely implemented worldwide. The issue of increasing their energy performance is still of great interest, many innovative solutions being presented in the literature. A relatively new variant with high performances uses counter-rotating rotors and a speed increaser, being able to supply additional energy due to the use of a secondary rotor and a planetary transmission summing the input motions or torques and, consequently, obtaining higher power compared to a classical system with one input and one output. The solution of speed increaser with two independent inputs requires a complex control to correlate the power generated at the inputs to the generator requirements. A possible solution to avoid this impediment may be the use of a 1DOF planetary speed increaser with two inputs and one output, which sums the input torques and, thus, allows an additional supply of power compared to the classical turbines by using a secondary rotor that is kinematically dependent of the main one. Therefore, the paper is focused on determining the operating point (the parameters of the steady-state regime) for the counter-rotating turbine containing a 1DOF planetary speed increaser with two inputs and one output, considering the mechanical characteristics of the rotors and generator, and the transmission functions of the speed increaser established by taking into account the friction losses. Finally, the obtained analytical model is numerically simulated on a case study.