Simulation And Optimization Of A Hybrid Energy Storage Stand Along Photovoltaic Power System

For remote areas without electricity,stand-alone PV systems are a viable solution,and energy storage is an important component of stand-alone renewable energy systems.The independent PV power generation technology is used more storage battery power,and battery technology have limitations,short service life,need frequent replacement,greatly increased the whole cycle running cost independent PV power generation system,pumped storage has the characteristics of large capacity storage for a long time,both in technology and economy is renewable energy system feasible energy storage system.Because of a single energy storage technology can’t meet the needs of load all,pumped storage battery and integration is a kind of better technology,improve the flexibility of renewable energy system,response time,significantly reduce the cost of energy storage system at the same time,so for the hybrid energy storage of independent PV power generation system is of great significance to the research.Firstly,the main components of the hybrid energy storage independent PV power generation system(PV array,battery,pumped storage)are modeled.The output characteristics of PV array under different working conditions are studied.The parameter changes of terminal voltage,state of charge and discharge depth of the battery model under different charge-discharge conditions were studied.The pumped-storage model consists of a pump,a hydro generator set and a reservoir,and the system pipe loss is added into them to form a dynamic equivalent pumped-storage model.Secondly,taking a village(100 households)in Kunming,Yunnan Province as an example,this paper carried out the optimization design of the hybrid energy storage(pumped storage energy + battery)independent PV power generation system,and applied the perfect PV water lifting to pumped storage energy for the first time.Under the premise of daily load of 539.975 k Wh in winter,381.975 k Wh in spring and autumn,387.775 k Wh in summer and 4 days of system self-sufficiency,according to the principle of energy storage capacity allocation,pumped storage energy accounts for 75% of the total energy storage demand,and battery accounts for 25%.The pumped storage system consists of three 125 k W pumps,one 125 k W turbine and a6,000 m 3 storage tank.The battery group is composed of 270 2V1000 Ah single battery in series.Finally,the total installed capacity of PV is 556.8KW.In this paper,the optimal capacity allocation scheme of the hybrid energy storage independent PV power generation system,as well as the principle and process of system design and selection are presented,which also have a certain generalization for the system application design in other areas.Thirdly,a charge and discharge energy management control strategy is proposed for the hybrid energy storage independent photovoltaic power generation system,which determines the charge and discharge of the system through the positive and negative values of the net power of the system.And through the Matlab/Simulink software to a year of four kinds of typical day(the vernal equinox,summer solstice,autumnal equinox,winter solstice),simulation analysis by using load power shortage rate(LOSP),storage,the overall performance(SOP)and energy utilization efficiency(EUR)as evaluation index,it is concluded that the control strategy of load power shortage rate is zero,better overall performance and energy utilization system storage,verify the feasibility of the hybrid energy storage system.Finally,this paper establishes the economic analysis model of the independent photovoltaic power generation system,and compares the economic analysis of the four energy storage schemes.The analysis shows that the hybrid energy storage scheme is more competitive than the single battery energy storage scheme.In the mixed energy storage scheme,the cost per kilowatt hour of mode 3(lead-acid battery+ pumped storage)is 1.091 yuan /k Wh,and that of mode 4(lithium battery + pumped storage)is 1.121 yuan /k Wh.From the practical engineering point of view,should be mode four,battery replacement fewer times;If funds are insufficient at the initial stage of construction,mode 3 is chosen.The optimal design scheme,selection principle and method and charge and discharge energy management strategy of the hybrid energy storage independent PV power generation system proposed in this paper have a better promotion and application prospect for all-weather power supply in remote areas without electricity.It is only applicable to construction sites with water sources,especially those with a certain height difference and construction sites with storage tanks.