Research On Hybrid Energy Storage And Power Coordinated Control In Microgrid

Microgrid is widely used as one of the effective solutions for absorbing new energy.However,there are uncertainties such as fluctuation,intermittent and randomness and light microsources,which leads to problems such as stable operation,scheduling and power quality.In microgrid,how to eliminate the power fluctuations by means of hybrid energy storage devices and practical energy storage control strategies and methods.Therefore,in order to ensure the safe and stable operation of microgrid and rapid power adjustment,this thesis focuses on the mixed energy storage of lead-acid batteries and super capacitors and their coordinated power control,which has theoretical significance and application value.In order to realize the effective use of energy storage devices in microgrid,the super capacitors and lead-acid batteries are taken as the research objects.Based on the physical structure,function and working principle of the energy storage devices,the steady state and dynamic models of the battery and the super capacitors.The first-order and second-order RC models compare and analyze the charging and discharging characteristics of the two,and give the difference between the terminal voltage and the rate at different time scales during charging and discharging.Aiming at the power coordination control of the hybrid energy storage microgrid,a control strategy called time-sharing energy storage power charging and discharging control is proposed.The control strategy first sets the upper and lower limits of the charge and discharge threshold voltage,and divides the charge and discharge into priority areas and working areas according to the different thresholds.Then,the hysteresis control is used for the area conversion during the charge and discharge process,and the droop control is used to stabilize the work area Eliminate voltage fluctuations in microgrid and achieve power smoothing.A system simulation model is built in MATLAB/Simulink,and the simulation results show that the control strategy proposed in this thesis can effectively control the bus voltage under different time periods and realize the power coordination of the hybrid energy storage.In order to further verify that the hybrid energy storage system can play the role of power balance,the hybrid energy storage is used as the PQ control node under the control strategy proposed.A unified method is used to calculate the power flow calculation in microgrid.The calculation results show that the proposed hybrid energy storage improved control strategy can effectively suppress power fluctuations,effectively and quickly adjust the output of active and reactive power in the system,and ensure the stability of the DC bus voltage.