Research On Design And Control Strategy Of Electrical System For Grid-connected Tidal Current Turbine

With the fossil energy depleting and environmental pollution deteriorating,the development and utilization of renewable clean energy is attracting more and more countries' attention.With the advantages of strong regularity and predictability,high power density and stable energy,tidal current energy generation technology is becoming a research hotspot both at home and abroad.The thesis took 120kW horizontal-axis Tidal Current Turbine(TCT)as the research object and studied the electrical system,grid-connected operation control strategy and maximum power point tracking of the TCT.The corresponding hardware circuits were designed,and the MATLAB/Simulink simulation model of power system was built.Comparing the simulation results with the actual operation data,the thesis verified the rationality of TCT electrical systems and control strategy.The contents of each chapter are as follows:The first chapter summarized the background of the thesis,and introduced the development of TCT and the electrical systems of TCT both abroad and at home.The second chapter proposed the overall topological structure of 120kW grid-connected Tidal Current Turbine power generation system.The structure of AC-DC-AC grid-connected electrical system was established.The components of the TCT power generation system were analyzed and studied to determine the relevant topological structure.The third chapter studied the correct and effective grid-connected control strategy and grid voltage lock technique of TCT power generation system.The working principle of the inverter was analyzed and the mathematic model of grid-connected inverter in different coordinate systems was established.The chapter adopted the voltage and current double-loop control strategy based on grid voltage orientation.The SVPWM technology was used to modulate the inverter,and the phase-locked loop technique was also studied.The fourth chapter studied the maximum power point tracking of tidal current energy,then proposed a maximum power point tracking method based on grid side power control.The fifth chapter designed hardware circuits and determined the parameters of the main components according to the performance requirements of TCT grid-connected system.In this chapter,the power system simulation model was built by MATLAB/Simulink software.Comparing the simulation results with the actual operation data,e the thesis verified the rationality of TCT electrical systems and control strategy.The sixth chapter summarized the work of this thesis,and put forward the further research direction.