Power Allocation Strategy Of Large Capacity Vanadium Redox Battery Energy Storage Systems And Its Application

Vanadium redox battery(VRB)has many advantages,such as free configuration of capacity and power,excellent response speed,good charge-discharge performance,long cycle time,environmental friendliness and no explosion hazard during operation.It plays an important strategic role in the application of large-capacity energy storage systems.In the operation of large-capacity energy storage systems,the power allocation among internal energy storage units has an important impact on the performance and life.In thesis,the reasonable power allocation among energy storage units in large-capacity energy storage system is studied as follows.Firstly,the structure of a large-capacity VRB energy storage systems is established,and the direction and content of the paper are clearly defined.The equivalent loss circuit model and mathematical model of 5kW/30 kWh VRB are established.Thus,the series battery model of 20kW/120 kWh VRBs is established.And the influence of the impedance inconsistency of impedance and SOC(State of Charge)inconsistency on the model is analyzed.Then,constant power charge and discharge control is performed on the 20kW/120 kWh VRBs.Secondly,the internal power allocation strategy is studied and the multi-objective power allocation model is carried out.Under the premise of meeting the demand power and the operation constraints of energy storage systems,the loss of systems operation,the loss of charging and discharging capacity of energy storage units and the SOC equilibrium between energy storage units are proposed as the evaluation indexes of power allocation.In order to eliminate the influence of different dimensions of each evaluation index,the above indicators are normalized.At the same time,various output schemes of energy storage systems are studied,and the weight coefficients of the indicators are analyzed and calculated.The Simulate Anneal Particle Swarm Optimization(SAPSO)algorithm is used as the intelligent optimization algorithm to solve the optimal power allocation of the multi-objective optimization function of large-capacity VRB energy storage systems,which composed of four 20kW/120 kWh VRB series batteries pack.The results are compared with other power allocation strategies to verify the effectiveness and feasibility of the strategy.Finally,a semi-physical simulation platform for power distribution of large-capacity VRB energy storage systems is built.WinCC OA is used as the energy management system development environment to send the demand power to the energy storage unit.The Simulink model is used as the energy storage unit to receive the demand power,and the running parameters are sent to the WinCC OA,which realizes the control and detection of the energy storage unit by the energy management system.