Research On Optimal Scheduling Of Microgrid Second-Life Battery Energy Storage System Considering Risks

With the popularization of new energy vehicles,the number of decommissioned power batteries in vehicles has increased sharply year by year.If not handled properly,it will cause serious waste of resources and environmental pollution.The cascade utilization of second life batteries can not only greatly relieve the pressure on the environment from the recycling of second life batteries,but also maximize the full life cycle value of batteries,which is in line with the national dual carbon strategy promotion needs.It is of great economic and environmental significance to improve the cascade utilization system of second life power batteries.Unlike new batteries,second life batteries have poor consistency and a high probability of failure and shutdown,which is currently difficult to apply on a large scale.Based on the above background,this paper uses the second life batteries in the energy storage system in a cascade,and coordinates with the new battery energy storage and distributed energy.Considering the uncertain factors such as the failure and outage of second life batteries,fluctuations of new energy sources and load changes,a two-stage optimal scheduling model for microgrid considering risks is proposed to ensure the safe and stable operation of microgrid while meeting certain risk constraints.The main research contents are as follows:Firstly,a reliability model of decommissioned battery energy storage system based on improved topology is established.Based on the two-parameter Weibull distribution function,the calculation method of the failure probability of the second life battery module is given,and the inconsistency of the capacity and state of charge of the second life battery module is analyzed;According to the improved topology,a second life battery energy storage system is established,and a method for calculating the failure and outage probability of the second life battery energy storage system based on the improved topology is proposed,and the multiple operating states and their occurrence probability of the second life battery energy storage system are obtained,which are used as the outage scenario of the second life battery energy storage system.Secondly,a optimization scheduling method for microgrid is proposed,which takes into account the cost of second life battery failure and life loss.Calculate the decommissioning battery loss cost according to the battery life decay model,and include it in the total dispatch cost as the operating cost of the second life battery energy storage system;Based on the PV and load forecast values,and taking the minimum total dispatch cost of the microgrid as the objective function,a dispatching model of the microgrid considering the failure of second life batteries is established.The calculation example results show that the proposed method can effectively reduce the total cost of microgrid dispatching,but the failure of the second life battery energy storage system will cause the microgrid to have a certain risk of loss of load.On this basis,a two-stage optimal scheduling strategy for microgrid decommissioned battery energy storage system considering risks is proposed.In the day-ahead stage,based on photovoltaic and load forecast information,formulate the optimal scheduling plan for second life batteries and thermal power units;In the intra-day phase,new batteries are put in to solve the power fluctuation problem of the microgrid,and the output of the new batteries is adjusted according to the updated photovoltaic power generation information,load demand changes and the actual operating status of the second life batteries.Taking the minimum total cost of microgrid day-ahead and intra-day two-stage scheduling as the objective function,and taking the conditional value-at-risk constraints and risk aversion coefficients into the function,a two-stage optimal scheduling model based on conditional value-at-risk is established.The calculation example results show that the constructed model can effectively alleviate the risk of load loss caused by uncertain factors.In addition,by analyzing the impact of different risk aversion coefficients on scheduling schemes,operators can choose different schemes according to the degree of risk preference to balance operating costs and risks.