Research On Constant Speed Control Of Hydraulic Storage Type Wind Turbine

The development of the wind power industry plays an important role in adjusting the energy structure of various countries,saving energy use,protecting the global ecological environment,and promoting the economic development.Traditional wind turbines require variable gearboxes and inverters with variable frequency capabilities to achieve 50±0.5Hz grid condition for wind turbines,however the large,expensive and inconvenient maintenance of gearbox and converter equipment restrict the development of wind turbines.The hydraulic transmission type wind turbine adopts the hydraulic transmission system instead of the gear box to transfer the energy of the wind wheel to the ground,eliminating the need for gear box and the generator being moved to the ground,not only reducing the weight of the top cabin,but also the hydraulic transmission can be precisely adjusted.So synchronous generators can be to access the Internet directly,eliminating the need for expensive converter equipment.Therefore,research on hydraulic energy-storage wind turbines is of great significance to the development of the new-generation wind power technology.This paper takes the constant speed control of the storage and power generation system of the hydraulic energy-storage type wind turbine as the research object,and adopts a combination of theoretical analysis,simulation research and experimental research,based on the open hydraulic system of the accumulator-variable motor.Studying the typical working conditions of hydraulic energy-storage type wind power turbine--the constant speed control of the system of the accumulator group as the power source driving variable motor to drive the synchronous generator.The main research contents are as follows:Firstly,analyze the characteristics and reliability of constant speed control technology for various hydraulic wind turbines,and summarize experience.Next,in order to analyze the cause of influencing variable motor speed,mathematical modeling and force analysis were performed on the variable mechanism and synchronous generator of the accumulator,variable motor,variable motor,respectively,and the accumulator-variables were established according to the mathematical models of each part.According to the mathematical model of each part,the mathematical model and transfer function of the accumulator-variable motor speed system are established,and the control method of speed control based on volume speed control and the combined speed control method based on volumetric speed control and throttle speed regulation are proposed according to the requirements of the accumulator as the variable pressure power source and the synchronous generator for the output control of the variable motor constant speed.Finally,the proposed method was verified in AMESim simulation software.The response speed of the variable motor variable mechanism,the initial charging pressure of the accumulator,the maximum charging pressure of the accumulator,the step load,and the controller parameters were analyzed on the variable motor speed.In order to verify the correctness of the theoretical analysis and simulation analysis,an experiment was conducted on the prototype of a 600 k W hydraulic energy-storage type wind turbine jointly researched and developed by the Lanshi Institute and Lanzhou University of Technology.In this study,preliminary experiments on the constant speed control method presented in this paper were carried out to verify the effect of step load on the speed of the variable motor.Experiments show that the speed control method based on the volume control is effective and get the rule about how step load influence the speed of the variable motor.