Study On Transmission System Of Tidal Current Turbine Based On Hydraulic Control

In modern times, development of society and people’s daily life could not go further without energy. With the excessive consumption of fossil fuel and environmental pollution, many countries have paid more and more attention to the exploitation and utilization of renewable and clean energy. Compared with wind energy, tidal energy is more predictable, and it has more power density, so tidal energy is very promising renewable energy in the future. Gearbox is mostly used in marine current turbine’s transmission system nowadays. Gearbox has very simple structure and proven technology. However, gearbox has only one drive ratio and couldn’t buffer the torque ripple caused by current. Hydraulic transmission system is a new kind of marine current turbine’s transmission system. It has many advantages, such as flexible drive, variable transmission and so on. This paper researches on transmission system of marine current turbine based on hydraulic transmission and control. Gearbox is replaced by hydraulic transmission in marine turbine, and the marine turbine’s variable-speed constant-frequency control is achieved by adjusting the displacements of variable pump and variable motor.The paper is divided into six chapters to research on hydraulic transmission system of marine current turbine. The main contents of each chapter can be summarized as follows:In the first chapter, the subject research background is introduced; the present situation of the development of marine current turbine and application of hydraulic system in turbines is described, and the research content and research significance are proposed.In the second chapter, the basic theory of tidal current energy generation technology is studied. Some tidal turbine foundation theories such as actuator disk theory, the Betz limit and blade element theory are introduced. Based on the introduction of the transmission system of tidal current turbine, tidal current turbine’s maximum energy capture control principle and generator’s constant speed output principle are put forward. At last, the structure and control principle of hydraulic transmission in this research are firstly introducedIn the third chapter, tidal current marine turbine with hydraulic transmission is designed, and major parameters of main components are calculated and selected.In the fourth chapter, modeling and simulation of tidal current turbine with hydraulic transmission system are researched. Based on theoretical analysis of the system, the simulation models of current speed, transmission system, and electrical components are built in Matlab/Simulink. The simulation results indicate that the hydraulic transmission and its control strategy could realize the maximum power point tracking control and the constant frequency control of the generator.In the fifth chapter, some experimental research on tidal current marine turbine with hydraulic transmission is carried out. The test branch is designed and built. The experiments include functional verification and efficiency testing of key components and the whole system.The experiments lay the research foundation for the control algorithm to achieve.In the sixth chapter, the paper’s research work and outcomes are generalized, and the directions for further working are also pointed out.