| With the rapid development of new energy,DC microgrid has also attracted wide attention and research.The small medium and low voltage distribution structure of DC micro grid can not only be applied to the power supply of the island and remote rural areas,but also can be used for household roof power supply and building power supply.It can integrate distributed energy sources,improve energy efficiency and energy storage economy.New energy power generation of DC microgrid has intermittent and randomness Power fluctuations.And Power fluctuations or load fluctuations will impact on the stability of the microgrid,which will lead to the fluctuation of the bus voltage,adding energy storage device is one of the effective ways to solve this problem.in DC microgrid,and the hybrid energy storage with supercapacitor can solve the problem of instantaneous high-power fluctuation and economic operation more effectively.Photovoltaic power generation is an important part of new energy.Because of its advantages of clean,easy to install,small investment and so on,photovoltaic power generation is widely used.Therefore,the control strategy of Photovoltaic DC micro grid System with hybrid energy storage is researched,and the paper has a certain reference value to improve the application level of DC micro grid with energy storage system.This paper first introduces the structure of the DC microgrid and the photovoltaic cell model and the maximum power point tracking MPPT.A reasonable simulation model has been built successfully.On this basis,a MPPT simulation of photovoltaic cells based on perturbation and observation method has been completed.Then,this paper introduces the basic structure of hybrid energy storage and energy storage principle of two medium battery and super capacitor.The equivalent circuit models of two different energy storage media have been established.The basic model of bidirectional DC/AC converter has been studied in this paper,which supports theoretical support for microgrid interconnection.A low pass filter is used for the share of the power fluctuation of the response of the hybrid energy storage system,and a variable time constant filter limit management method is studied.A new type of variable parameter droop method is proposed in this paper,which is based on the droop control terminal in the microgrid.A new type of variable parameter droop control method is proposed in this paper,which is based on the droop control terminal in the microgrid.The parameter of the variable droop coefficient is adjusted according to the SOC change of the battery cell units of energy storage system,in the new droop control method.,When the battery parallel running,the high SOC of battery supplies more power,Finally,the SOC of each battery tends to be consistent,and the output power of each unit is equal In the traditional DC microgrid droop control,when the power fluctuates,the DC bus voltage will fall significantly.Adding voltage compensation loop and power compensation loop to the control loop can inhibit severe bus voltage dips.The MATLAB/Simulink software is used to simulate the control effect of the proposed variable parameter droop method and the compensation loop.Considering the operation mode of energy storage unit droop control,a DC microgrid coordinated control method is proposed,which optimizes the scheduling of power generation unit,energy storage unit and load in microgrid.Finally,the prototype is designed and manufactured,and the parameters of the main components and control parameters are introduced.The control part is realized by DSP28335,and the prototype is debugged to verify the correctness of the theoretical analysis. |
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