Research On Autonomous Control Of DC Microgrid Systems With Energy Storage Unit

As the less power conversion link, the higher efficiency of systems, and theadvantages of control simply, many researchers have focused on DC microgrid currently.Energy storage system as one of the core unit of DC microgrid is crucial to the reliabilityof power supply, power quality, the utilization efficiency of renewable energy generation.The DC microgrid system with battery energy storage is researched on, and a generalmethod of autonomous control method based on the DC bus voltage which ensures thesystem economic operation is proposed. The method is suitable for control strategy designof DC microgrid without communication links. The control strategy designed using thismethod can ensure the system operation stable, reliable and optimizes economicperformance. It is verified effective through the MATLAB/Simulink.The battery is a crutial element for the reliable operation of the microgrid. It issignificant to analyse the external characteristic and establish accurate model of the batteryfor its effective management and reliability enhancement of the DC microgrid. Howeverthe models proposed formerly are not suitable for the research on the control method ofDC microgrid. The experimental platform of battery was set up, and then the research onexternal characteristics of valve-regulated lead-acid battery is conducted based on it. Asimple modeling method of the external characteristic of battery is proposed, and then thecharge and discharge voltage characteristic model is established. The model can reflect thenonlinear variation regulation of the battery voltage and also estimate the battery state ofcharge and discharge accurately.The control method of battery is optimized based on the mathematical model of theexternal characteristic of battery and the effective management of the battey is realizedsimply. The autonomous control method based on the DC bus voltage is improved. Theoperation cases increase when considering the battery capacity is limited. The optimizedcontrol method of the battery and the improved autonomous control method based on itare verified through MATLAB/Simulink.