Monitoring Plat Form And System Control Of Flexible Battery Energy Storage System

In recent years,the proportion of wind power,solar energy and other new energy power generation in China's power system has gradually increased,and the corresponding battery energy storage system(BESS)has attracted wide attention.In conventional Li-on BESS,hundreds of batteries are connected in series and parallel to attain a certain level of voltage and capacity,and then connected to the converter.This requires high consistency among batteries.However,due to different conditions during the process of manufacture and utilization,the pack always suffers from batteries'inconsistency,which decreases the available energy of the battery pack.To solve this problem,flexible battery group technology is studied in this paper,which divides a large battery pack into multiple low-voltage battery packs through multilevel converters.This paper is focus on the basic principle,system control and monitoring platform of flexible group energy storage system.First the existing problem of traditional battery group and its cause are analyzed.When it comes to the concept of flexible battery group,the principle and technical features,the system constitution and different converter topology which can be used in battery flexible group system are studied.And then the H bridge cascaded inverter is chosen as the main circuit topology.Then system control of energy storage converter based on flexible battery group technology is deeply researched.First the modulation strategy and based control strategy is discussed,then the balance control strategy for flexible group energy storage system is analyzed,which contains SOC equilibrium and voltage equilibrium from the phase equilibrium and phase equilibrium point of view.Combined with the current background of returned battery echelon use in energy storage system,the SOC equilibrium control strategy based on different capacity of the battery module is put forward.This paper also set up the monitoring platform of flexible group system.The man-machine PC interface is designed in NI's LabVIEW development environment.By making full use of the existing equipment in the laboratory conditions and combined with CAN communication and TCP communication technology,24 battery modules of three phases are brought out.Each battery module control procedures use modular design,including real-time display,real-time data storage,data processing,data receiving,real-time dynamic calling core module,and the system monitoring platform running results are given.At last,simulation about modulation strategy of system,based control strategy,and system control including SOC equilibrium and voltage equilibrium and SOC equilibrium based on different capacity of battery is gived.The experimental results and waveform analysis of SOC equalization control and voltage balance control are carried out on the prototype of flexible energy storage system.