Research On Coordinated Control Strategy For The Operation Of DC Microgrid Based On The Generation Of Wind-Solar-Storage

Due to the intermittent and randomness of the output power of wind power,photovoltaic and other distributed micro-power sources,direct access to the large power grid will affect the power quality.The network does not need to consider the frequency and phase of the bus voltage,and the control structure is simple,so it has been widely concerned by a large number of scholars at home and abroad.The paper firstly analyzes the mathematical models of wind turbines,permanent magnet synchronous generators,photovoltaic cells,batteries,grid-side inverters,DC loads and AC power grids in the wind-solar-storage DC microgrid.The wind energy utilization coefficient when the pitch angle changes and the output characteristics of the wind turbine under constant pitch and variable wind speed are simulated.Topological structure and mathematical model of DC converter and battery bidirectional DC/DC converter.Secondly,the control strategies of photovoltaic,wind power,battery and grid-side inverter in the wind-solar-storage-DC microgrid are studied.First,the variable-step disturbance observation method of photovoltaic power generation system is given.This method is compared with the traditional disturbance.The observation method has better applicability,and then the photovoltaic constant voltage control strategy is given,and its rationality is verified by simulation,and then the speed control and pitch angle control strategies of the wind power sy stem are given,and they are verified by simulation.Then,the charging and discharging strategy of the battery is given,that is,two-stage charging and constant voltage discharging,and simulation is carried out to verify their rationality.Then,the control strategy of the grid-side inverter is given,namely Grid voltage oriented vector control based on d-axis.Finally,the overall modeling and simulation of the wind-solar-storage-DC microgrid is carried out,a coordinated control strategy based on bus voltage recovery is designed,and its energy management modes are divided into five types,namely gridconnected operation mode and grid short-term failure mode.,grid-side inverter currentlimiting mode,islanded distributed generation power reduction mode and islanded load-shedding mode,and then five energy management modes are simulated and verified.