Research On Control Strategy Of Optical Storage DC Microgrid Based On Adaptive Droop Control

New energy power generation has the drawbacks of strong randomness and high volatility,so the ESS is often added to DC microgrid.However,if the control strategy of the ESS is improperly used,it will not only affect the stability of the microgrid,but also affect the performance and service life of the ESS itself.Therefore,in this paper,the main research object is the batteries,and the control strategy of optical storage DC microgrid is studied.The specific research content is summarized as follows:Firstly,the working principles,the models,and the control strategies of the photovoltaic power generation system,the batteries,and the supercapacitor are introduced this paper,as well as the structure of the hybrid energy storage system consisting of the batteries and the supercapacitor.Among them,the control strategies of the photovoltaic power generation system include the backstepping MPPT control and the constant pressure droop control,while the control modes of the batteries include the improved adaptive droop control charging mode and discharging mode,the float charging mode,and the idle mode.The working principles of two types of DC voltage converters are introduced.Secondly,the working principle of the droop control is introduced,the limitations of the conventional droop control are analyzed,and the improved adaptive droop control strategy based on SOCⁿ proposed in this paper is derived.The droop coefficient during charging and discharging is designed,the batteries SOCⁿand the droop coefficient adjustment law based on the bus voltage are introduced into the droop coefficient,so that the charging and discharging power of the batteries are reasonably distributed the charge and the discharge power between the batteries according to their SOC.In addition,the supercapacitor power compensation is added to buffer the power impact of the batteries when the microgrid fluctuations.In terms of the system coordinated operation control strategy,it is composed of the upper coordinated control module and the local control units.The upper coordinated control module uses the bus voltage U_dc and the SOC of the batteries as control elements,sets voltage thresholds and SOC thresholds,divides the system into seven operating modes,and coordinate the operation between various working modes.The simulation model is built and analyzed in MATLAB/Simulink.Finally,the experimental platform of the optical storage DC microgrid system is designed to verify the effectiveness of the control strategy proposed in this paper.The experimental results show that the control strategy proposed in this paper can reasonably distribute the charge and discharge power between the batteries according to their SOC.And compared to the conventional adaptive droop control,when the external environment changes,the control strategy proposed in this paper can better maintain the stability of bus voltage,making the system have strong anti-interference ability.The added supercapacitor power compensation can buffer the power impact of microgrid fluctuations on the batteries and protect the batteries.