| New energy vehicles represent the development direction of the automobile industry in the future.They are not only an important measure to relieve the pressure of energy and environment,but also the commanding heights of China's economic growth point and strategic adjustment.However,when the power battery capacity decays to less than 80% of the initial capacity,it will not meet the endurance mileage requirements and the battery needs to be replaced.Therefore,how to deal with the retired power battery has become an important issue affecting the development of new energy vehicles.At present,it is a train of thought to carry outsecond-use of retired power batteries for electric energy storage.However,different operating conditions of power batteries lead to different degradation characteristics of batteries and different remaining usable cycles during retirement,which increases the difficulty of second-use of retired power batteries.Therefore,it is of great significance to accurately estimate the number of remaining usable cycles of retired batteries and to take the degradation characteristics of retired batteries into consideration in the allocation of power storage and economic analysis.This paper studies from the battery level and the user-side energy storage level,establishes a power battery capacity decay model,proposes a configuration method for the energy storage capacity of the retired battery on the user side and an evaluation method for the value of the energy storage on the power grid side considering the decay characteristics,and analyzes the economy of the energy storage of the retired battery.The main work of this paper is as follows:Firstly,the advantages and disadvantages of all kinds of power batteries are analyzed,and the research object of this paper is determined to be retired lithium iron phosphate power batteries.The main influencing factors and results of the performance degradation of retired lithium iron phosphate power batteries are analyzed.The degradation characteristics of power batteries are studied according to the influencing mechanism of the main influencing factors.The relationship model of power battery capacity-cycle number is established.The relationship model is revised according to the characteristics of the restructured retired lithium iron phosphate power batteries.An example analysis shows that the model is quite correct for analyzing the relationship between the capacity of retired batteries and the number of times of use.Then,the cost model of retired power batterysecond-use energy storage system,which consists of recovery cost,processing and reorganization cost and energy conversion part cost of energy storage system,and the model of peak-valley arbitrage,demand electricity management and deferred investment income considering battery recession characteristics are proposed.On the basis of the cost-benefit model of retired battery energy storage,a double-layer optimal configuration model of retired battery energy storage on the user side is established,which takes into account the fading characteristics.The model provides the user with an energy storage configuration scheme and can also formulate an energy storage operation strategy according to the specific needs of the user.The example analysis shows that the model and method proposed in this paper have high accuracy,can carry out energy storage configuration according to the characteristics of typical user scenarios,and the energy storage operation strategy formulated for users can maximize the economic benefits of users.Finally,an evaluation method of the grid-side value of the retired battery energy storage on the user side considering the decay characteristic is proposed.Combined with typical cases and economic index analysis,it is found that,on the one hand,the decay characteristic of the battery has a greater impact on the retired battery energy storage on the user side,which needs to be considered in modeling analysis,and the economy of the retired battery energy storage is better than that of the new battery energy storage.On the other hand,decommissioned battery energy storage on the user side brings benefits to users,but also brings certain benefits to power grid companies.Therefore,it is highly feasible to store energy from retired batteries on the user side. |
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