Research On Battery Management System For Sodium-sulfur Battery

In recent years, development of smart grid construction and renewable energy technology gave birth to the application of energy storage technology. As one of the important aspects in energy storage technology,sodium-sulphur battery has achieved great development,100kw-level sodium-sulphur battery energy storage power station has been put into demonstration in Shanghai EXPO. As an indispensable part of the energy storage system, sodium-sulphur battery management system(BMS) directly detect and control the whole process of energy storage.The BMS monitors the physical parameters, including total voltage, cell voltage,charging and discharging current, temperature, resistance of insulation and so on, the BMS need to calculate the battery SOC under the specific algorithm,communicate with monitor PC, give orders to the temperature controllers, accomplish fault diagnosis,etc. Therefore, research on the BMS is quite necessary for operation and maintenance of energy storage system.The thesis introduces the developing situation of sodium-sulphur battery home and abroad, analyses the function and structure of the BMS. Based on the research of centralized model BMS and analysis of its function and structure, the thesis provides a flexible architecture of BMS named Distributed BMS.The system consists of two subsystems:Battery Management Unit (BMU) and Local Electric Control Unit (LECU). The subsystems communicate with each other by CAN bus.The system communicate with the monitor PC and temperature controllers by the MODBUS protocol.The thesis illustrates the function and structure of the two subsystems, and introduces the optimized scheme of BMS through comparison and analysis of a variety of hardware circuit design scheme. In the single voltage and total voltage measurement,the system adopts16high precision AD chip, greatly improves the accuracy of measurement; Current is measured by high accuracy shunt;Battery box temperiture measurement ensures the security of the system; Non-equilibrium bridge way for insulation resistance measurement guarantees the system measuring accuracy and safety.The thesis proposes the software of the two subsystem, realizing the software design of the CAN module and MODBUS module, it also puts forward the estimate strategy for battery SOC. In addition, through the commissioning and testing, the thesis analyses the indicators of the BMS, matching the system optimization parameters settings.The sodium-sulfur BMS is based on a large amount of commissioning and testing, each function of the BMS is verified, the design requirements of the project have been met.