Wind turbine WTH continual variation of transmission ratio-design and testing methodology -

Abstract

Wind speed variation presents the main problem for electricity production in wind power industry. Although wind is all around us, it is impossible to control its stochastic nature. As a result, existing wind turbines produce electricity with variable frequency, which demands synchronization with electric net. Synchronization process implies frequency conversion, which generates significant power losses in the system. Present researches mainly focus on reduction of power losses and efficiency increase of WT's through speed control and maintain of electric generator speed at the same level. In this work as a backbone of wind power plants innovation, authors present a new design of WT gear train with variable transmission ratio according to wind speed variation, providing direct synchronization to electric net - a hybrid gearbox that consists of mechanical, electro-electronic and software system. Mechanical system contains one specific planetary gearbox, with total transmission ratio i=1/25 and one planetary gear set for continual variation of overall transmission ratio. Electro-electronic system consists of motor-generator for transmission ratio variation and of electronic components for closed loop speed control. Software system provides control system variation and variation of components characteristics based on process identification and predictive control model decision. Concepts of software and control systems are presented and discussed in this work. For each of these systems, testing methodology is developed, with proposal of new closed power loop test rig design. The new design of testing rig provides testing of load capacity of complete WT drivetrain and verification of the system operation quality.