A Comparative Performance Analysis of Counter-Rotating Dual-Rotor Wind Turbines with Speed-Adding Increasers

Radu Saulescu,Olimpiu Munteanu,Mircea Neagoe,Codruta Jaliu

doi:10.3390/en14092594

Abstract

Increasing the efficiency of wind power conversion into electricity poses major challenges to researchers and developers of wind turbines, who are striving for new solutions that can ensure better use of local wind potential in terms of both feasibility and affordability. The paper proposes a novel concept of wind systems with counter-rotating wind rotors that can integrate either conventional or counter-rotating electric generators, by means of the same differential planetary speed increaser, aiming at providing a comparative analysis of the energy performance of counter-rotating wind turbines with counter-rotating vs. conventional electric generators. To this end, a generalized analytical model for angular speeds and torques has been developed, which can be customized for both system configurations. Three numerical simulation scenarios have been contrasted: (a) a scenario with identical wind rotors in both systems, (b) a scenario with the secondary wind rotors being identical in the two applications, but different from the primary rotors, and (c) a scenario with different secondary rotors in the two wind turbines. The results have shown that the wind systems with counter-rotating generator are more efficient and have a higher amplification ratio, compared to systems with conventional generators. In addition, the analyzed wind system with a counter-rotating generator displays better energy performance with low values for output power and ratio of input speeds, whereas the wind turbine with a conventional generator proves to be more efficient in the high-value range of the above-mentioned parameters.

Highlights

Wind energy has become increasingly popular among renewable energy sources worldwide, representing a valuable alternative to fossil fuels and other polluting sources of energy production
This paper aims to bridge the gap and proposes a novel concept of a counter-rotating wind system that can integrate one of the two types of electric generator and uses the same 2-DOF planetary speed increaser
The paper presented a comparative study of the energy performance of wind turbines with two counter-rotating rotors (R1 and R2) and differential speed increaser, in the functional configurations with counter-rotating vs. conventional generator

Summary

Introduction

Wind energy has become increasingly popular among renewable energy sources worldwide, representing a valuable alternative to fossil fuels and other polluting sources of energy production. Most of the wind turbines that are currently in operation both onshore and offshore have a conventional structure, consisting of a single wind rotor, a speed increaser and a conventional generator. As the use of wind energy is gathering pace, there is a constant need for either improving the existing wind turbines or developing innovative higher performance models. A better use of wind potential and a more efficient energy conversion, leading to a boost in electricity production, are major milestones that researchers, designers and developers in the field are constantly striving to reach. Several innovative wind turbine solutions have been developed with improvements regarding the wind rotor, the speed increaser or the electric generator. A number of studies have been conducted on various issues, such as:

Objectives

Methods

Findings

Conclusion