Research On Energy Storage Battery Management System

With the fast development and application of renewable energy resource, micro-grid and distributed generation are widely studied all over the word, which leads the traditional power system evolves to the smart grid. To deal with the intermittent nature of these resources, large-scale energy storage system is necessary to ensure the stability of the power system. This dissertation mainly focuses on energy storage battery management technology for battery energy storage system, and studies the related technology to make energy storage battery pack run safely and efficiently with long lifespan.Based on a review of existing research works, this dissertation studies the battery management system for energy storage system using Lead-carbon battery in four aspects, including battery modeling and simulation, SOC estimation, battery balancing method and system architecture realization.The model and simulation for Lead-carbon battery is firstly discussed in the second chapter. Lead-carbon battery model with variable parameters is built based on PNGV model. And battery circulating charge and discharge tests of full SOC range are conducted to acquire data for battery parameters fitting. Then, battery model with variable parameters is obtained, which fits well with the data acquired by battery charge and discharge tests and provides basis for SOC estimation.The SOC estimation with Kalman filtering based on SOC-OCV curve is proposed based on PNGV model. Battery OCV is obtained through Kalman filter algorithm when battery current and terminal voltage are taken as input. Battery SOC is obtained by SOC-OCV curve, and the battery parameters are got from the relationship table between battery parameters and the battery SOC, which are then used for SOC estimation of next period. Finally, the real-time SOC estimation is acquired through such iterations.Active battery balancing methods for charging and discharging period are studied in the fourth chapter. Active battery balancing method using auxiliary charger combined with passive battery balancing is realized in BMU consisting of LTC6803-4 AFE, which is also implemented in BMS consisting of BQ76PL536A-Q1 AFE.To meet the requirements of BMS and modularization of the battery pack, a distributed battery management system is proposed, and its software architecture and hardware implementation are discussed. Each battery module has its individual battery management module to process information and make strategy inter the module and communicate with other module and host. Different battery modules are independent from each other, but they also communicate with each other. The proposed architecture is modular designed and is easy for circuit implementation, replacement and system extension, which is also suitable for smart battery application in the future.