Energy Management Research And Engineering Application Design Of Mobile Energy Storage System For Low Temperature

As the goal of carbon peak in 2030 and carbon neutrality in 2060 are proposed,increasing the proportion of renewable energy power generation has become an inevitable choice for the state grid to reduce carbon emissions.However,high proportion of renewable energy power generation will seriously threaten the stability of the grid.Mobile energy storage systems(MESS)can meet the energy storage demand of multiple nodes of the grid in different time periods,and are considered to be an effective means to absorb renewable energy and improve the stability of the grid.However,traditional MESS are based on lithium iron phosphate battery(LIPB)which have low cost and low charge and discharge efficiency at low temperatures.The lithium titanate battery(LTB)with excellent low temperature performance is not suitable for MESS due to its high cost and low energy density.Hence,this paper proposes a dual-batterybased mobile energy storage system for low temperature(MESSLT).Under the premise of controlling the cost and weight within a reasonable range,it achieves high-efficiency charging and discharging at low temperatures.The following research work has been specifically carried out:1)Modeling of the electrothermal coupled MESSLT considering the effect of charging and discharging time on the heat required for the battery: First,this paper studies the energy flow between the two batteries and other devices in MESSLT.Then,by fitting the measured data,this paper obtained the relationship between the chemical energy consumption and the output power of the LIPB and the LTB.Based on this,this paper considered the battery power constraints and capacity constraints,and obtained the MESSLT electric model.Finally,this paper derives the models of ohmic heat,polarization heat,reaction heat,and side reaction heat emitted by cells,and obtains a linear model of the heat and temperature of the battery.Based on the heat balance equation,the battery heating model and heating device heating are coordinated.The thermal model of MESSLT is obtained.All of above laid a theoretical and model foundation for the follow-up content.2)Non-convex optimization of energy management of MESSLT: First,this paper analyzes the reasons for the high-order nonlinearity caused by the electrical and thermal coupling.Then,this paper proposes the feasible operation area of LIPB and that of LTB to convert this nonconvex problem into a convex problem.Next,this paper designs a test system and five cases,and the effectiveness of the dual-battery framework is verified through the comparison of simulation results.Finally,this paper conducts a sensitivity analysis of the proportion of lithium titanate batteries and the thermal resistance of MESSLT,which provides a reference for the parameter selection of the prototype of MESSLT.3)Application design of MESSLT: First,this paper introduces the basic data of MESSLT prototype,and studies the organizational structure of the equipment in the MESSLT.Then,to solve the problem of power supply for the control circuit at low temperature,this paper designs a control circuit for MESSLT that can take power from the four power supply ports.Next,according to the working scene of MESSLT,this paper designs five working modes of MESSLT.Finally,based on the working mode and control interface,the control algorithm for the prototype of MESSLT is designed.