Research On Control Strategy Of DC Microgrid Based On Active Disturbance Rejection Control

In the ’ optical-storage-fast charging ’ DC microgrid,when photovoltaic power generation and fast charging piles are connected to the DC bus,the system will have problems such as excessive bus voltage deviation,inconsistent state of charge of the energy storage system and uneven power distribution.In view of the above problems,it is necessary to design an effective converter control strategy.Active Disturbance Rejection Control(ADRC)is a control method that does not depend on the control system model to suppress system disturbances.Compared with proportional integral control,this method has better steady-state and transient effects.In this paper,the ’optical-storage-fast charging ’system is taken as the research target,and the improved scheme of ADRC is applied to the control of DC microgrid.The specific contents are as follows:The photovoltaic power generation system based on maximum power point tracking(MPPT)control has intermittent output power of photovoltaic power generation unit when the ambient temperature and irradiance change,while the traditional MPPT shows poor tracking performance in following the disturbance change.Aiming at this problem,an improved MPPT control is proposed by combining the error-based ADRC with the disturbance observation method,which realizes the effect of fast tracking the output voltage and reducing the steady-state error when the photovoltaic power generation unit intermittently generates power under different conditions.The photovoltaic power generation system model is built in the MATLAB/Simulink platform.Aiming at the step disturbance of temperature and irradiance,the error-free tracking effect of the improved control strategy on the system power and voltage is verified.By comparing with the MPPT control of fixed step perturbation observation method and variable step perturbation observation method,the superiority of the dynamic and static response of the proposed strategy is verified when tracking the maximum power point.When the fast charging unit is incorporated into the islanded DC microgrid,the system will generate a large bus voltage deviation.Only relying on the primary control of the energy storage unit,the control accuracy is still insufficient.Based on this,the secondary control based on Linear Active Disturbance Rejection Controller(LADRC)is introduced in the primary droop control,voltage regulation and battery state of charge equalization.By designing the voltage compensator and droop coefficient compensation mechanism,the problems of converter output voltage drop and battery state of charge and output power imbalance are improved.The ’optical-storage-fast charging ’ islanded DC microgrid system model and the traditional control system model based on LADRC are built in MATLAB/Simulink.By comparing the simulation results,it is verified that the proposed control method can improve the steady-state performance of the microgrid bus voltage,improve the state of charge of the hybrid energy storage system,and balance.