Research On Heterogeneous Energy Storage System Of Decommissioned Power Battery In Photovoltaic Microgrid

Due to the extensive use of traditional fossil energy,environmental pressure is imminent,and distributed photovoltaic power generation(distributed photovoltaic generation,DPVG),which can replace fossil energy,also has many limitations and deficiencies.The instability and volatility of photovoltaic generation,as well as the uncertainty of load variation,are obstacles to the stable operation of DPVG system.The injection of the energy storage system into the DPVG system is helpful to solve this problem.The power fluctuation can be suppressed and the robustness of the power grid will be enhanced so as to improve the proportion of renewable energy access.With the strengthening of the awareness of environmental protection and the rapid development of the domestic market,the number of new energy vehicles is bound to increase in the next few years.At that time,how to deal with decommissioned power batteries will have to be considered.Based on this,the application of echelon energy storage unit of decommissioned power battery in DPVG system can effectively improve the stability of DPVG,promote wind and wind power dissipation,and provide a theoretical basis for solving the problem of difficult recovery of retired batteries.The parameters of decommissioned battery are generally characterized as the residual capacity,that is,the internal resistance(R)of the(SOC),state of healthy(SOH),among which SOC is the important basis for layered energy management and energy storage isomerization.In view of the imprecise SOC estimation of decommissioned power batteries,Kalman filter combined with real-time identification of parameters is used to estimate the SOC of decommissioned power batteries quickly.After the decommissioned battery cells are in series and used for a long time,the SOC of each monomer is different,which will reduce the use of the battery pack greatly,so it is necessary to balance the circuit.By using the equalization circuit proposed in this paper,the equalization control of the battery pack is carried out to keep the SOC of a large number of battery packs consistent.Cascaded H-bridge can construct large-capacity and high-voltage grade energy storage system,and can realize large-scale energy storage power station construction.The cascaded H-bridge converter and the energy storage unit are considered as agent modules,and the group system consistency algorithm is used to realize the consistency of output and state of the energy storage system.Based on the research of energy conversion mechanism and energy management of heterogeneous energy storage,an integrated energy management system is constructed,which accepts cascade energy storage and is compatible with heterogeneous energy storage.In this paper,the coupling mechanism of multi-time scale and decoupling control method are studied deeply,and the coordinated control scheme of heterogeneous energy storage energy management system is established.The applicability of decommissioned battery in photovoltaic microgrid is verified by simulation.