Battery Protection Scheme Integrated with Demand Side Management in Stand Alone Hybrid Microgrid

Energy produced from conventional sources like coal and diesel is inadequate due to ever increasing demand for power. Generation of power from renewable energy sources to meet the gap of supply and demand is intermittent in nature. Hence there is need for storage of energy from renewable sources to ensure continuity of supply. Secondary batteries based on electrochemical principle are commonly used for energy storage in hybrid energy generation systems, portable devices, electric vehicles etc. Since batteries are also becoming the primary source of power for many small to large power applications, it is necessary to protect batteries from over charging and over discharging to ensure their efficient operation. Thus, battery protection system with Battery Management System (BMS) has become an integral part of all applications. The functions of BMS include monitoring and charging. Hybrid energy systems have also incorporated the energy management function into the BMS to ensure efficient and continuous power supply. Monitoring of batteries involves determination of state-of-charge (SOC), state-of-health (SOH), temperature monitoring and cell balancing. The types of charging include constant current, constant voltage and pulse charging. Energy management involves coordination of sources and loads for maximum utilization of available power. This thesis deals with some aspects of each of these three components, i.e., monitoring, charging and source/load management, of a BMS. In particular, monitoring of battery from the source side is examined for online determination of SOC and SOH.