Battery management system development in hybrid grid

Abstract

With the rapid upgrade of the intelligent hybrid grid and electric transportation, the significant amount of attention has taken place on battery management system (BMS) to make the batteries safe and efficient. Batteries in the battery array have a wide application in the voltage stabilization on DC side of hybrid grid. Whereas, the reliable battery management system for battery array is a challenging task due to chemical reactions, temperature and voltage effects for the state of charge (SOC) estimation and cell balancing. And it also requires careful monitoring to ensure that batteries in the battery array are not in over-charged or under-charged conditions.

To maintain the safety and reliability of the battery array, state monitoring and evaluation, ModBus system communication and remote database using Structured Query Language (SQL) for future data analysis and control algorithm development have been achieved in this cost-effective and user-friendly BMS. The customised BMS has fulfilled the concerns for the current lead-acid battery array in Water & Energy Research Lab under school of Electrical and Electronic Engineering. Through the literature review, the essential knowledge of ModBus protocol, the physical characteristics of a lead-acid battery, conventional functions of BMS and the latest state-of-the-art methodologies for the SOC estimation of batteries with related works on evaluation of SOC estimation error, and fundamental SQL commands are reviewed. The necessary hardware parts, such as lead-acid batteries, the solar panel simulator – TopCon DC programmable power supply as the battery charger, variable DC load, voltage sensors and current sensor are studied and customized. An Ethernet ModBus technology - EDAM5017 as the data acquisition (DAQ) offering a high-performance embedded measurement advantage is also brought in the project. Software techniques related to LabVIEW and MySQL Workbench to develop the graphical user interface (GUI) and remote database are achieved. The detailed design, problems encountered and solutions, results and discussions, recommendations to construct the final prototype are described in this final report.