Modeling And Simulation Of Variable Speed Tidal Power Generation System Based On Full Power Converter

At present,constant speed operation mode is adopted for tidal power station units.However,due to the large water head variation of the power station,the unit operates in non optimal conditions most of the time,resulting in low operation efficiency,serious vibration and wear.With the increase of converter capacity,it is possible to adopt full power converter for Tidal Turbine generator unit.Therefore,this paper proposes a variable speed permanent magnet synchronous tidal power generation system with full power conversion.The full power converter is used to adjust the speed of generator unit according to the change of water head and load,so as to improve the operation efficiency and operating conditions.The main contents are as follows:(1)The method of using permanent magnet synchronous motor and full power converter to realize variable speed operation of tidal generator unit is proposed.The operation principle of variable speed tidal power generation system is introduced.The mathematical model of variable speed permanent magnet synchronous full power converter tidal power generation system is established,including the mathematical model of diversion system,nonlinear turbine,permanent magnet synchronous generator and full power converter.(2)According to the needs of the tidal variable-speed unit,the control strategies of the turbine,generator-side converter and grid-side converter are proposed respectively.PID control is used for the unit regulator and rotor field oriented DC for the generator-side converter Control to control the active and reactive power output of the unit,and use grid voltage directional vector control for the grid-side converter to control the active and reactive power output to the grid,thereby maintaining the stability of the DC bus voltage.(3)According to the mathematical model of variable speed permanent magnet synchronous full power conversion tidal power generation system,the system simulation model is built on the platform of Matlab/Simulink,and the changes of various related variables are simulated and analyzed when the given power increases or decreases.The simulation results show that the model can accurately reflect the dynamic characteristics of the system.The proposed control strategy can make the unit output power change with the given power value,and make the turbine operate at the optimal operating point,which verifies the correctness of the model and the feasibility of the control strategy.(4)In order to reduce the simulation time,the generator and its control system are simplified in order to reduce the simulation time.The simulation results show that the dynamic and steady processes of the simplified model and the fine model are basically consistent,but the simulation step size increases from 5×10-6s to 1×10-3s,and the simulation time is reduced from 3.0703h to 53.93s under the same hardware and software conditions The correctness of the simplified model lays a good foundation for further research.