Research Of Energy Coordinated Control Strategy Of Hybrid Energy Storage Of Isolated Photovoltaic DC Microgrid

Photovoltaic microgrid is composed of photovoltaic power generation unit,energy storage unit,load and control device.It is one of the most potential new energy microgrids.Solar energy is fluctuant and intermittent,resulting in unstable power generation.Therefore,efficient power tracking method,reasonable control technology of energy storage and flexible coordinated control of energy have become the focus of research in the field of photovoltaic microgrid.In this paper,the independent photovoltaic microgrid is chosen as the research object,aiming at the problems of MPPT control of photovoltaic cell,hybrid energy storage control technology and energy coordinated control of microgrid,the main research contents are as follows:First,this paper proposes a MPPT control algorithm of photovoltaic cell based on active disturbance rejection control(ADRC),traditional MPPT control algorithms are analyzed and compared and a photovoltaic cell is modeled in MATLAB/Simulink,simulation results show that the model of photovoltaic cell is correct and the control strategy is feasible.Secondly,an energy allocation control algorithm based on double fuzzy controller for hybrid energy storage system is proposed to suppress the power fluctuations,guarantee the stability of DC bus voltage and ensure the stable operation of the system.The algorithm design fuzzy controller of lithium batteries and supercapacitors,separately,based on the analysis of system structure of hybrid energy storage.The fuzzy file is generated by MATLAB and imported into the simulation model of hybrid energy storage system.The rationality of the control algorithm is verified by simulation results.On the basis of the above,the energy coordinated control strategy of hybrid energy storage photovoltaic DC microgrid is proposed.The control strategy of DC microgrid is divided into five working modes: stable operation,normal operation,hybrid energy storage exceeding limit,bus voltage over limit and extreme power feeding.According to the DC bus voltage fluctuation and battery capacity changes,analysis the switching principle between each mode.According to the principle of giving first place to energy adjustment of energy storage unit and energy exchange of other units serving as a supplement,a DC bus voltage control strategy based on system energy balancing is proposed,which brings the total energy of the system to a dynamic balance and maintain stable and efficient operation of the system.Finally,the energy coordinated control strategy of photovoltaic DC microgrid under five operation modes is modeled and simulated in MATLAB/Simulink.Simulation results prove the correctness of the proposed energy control strategy for photovoltaic microgrid.