Optimal Scheduling of Microgrid with Variable Current for Energy Storage

The energy storage unit plays an important role in balancing power fluctuations of microgrid. Unreasonable battery scheduling will cause more life loss and increase the replacement cost of the battery. Therefore, prolonging the life of the battery becomes one of the key factors to improve the microgrid economy. According to terminal voltage characteristics of lithium batteries in the process of charging and discharging, this paper proposes an optimal scheduling method of isolated microgrid with variable current for energy storage, in order to reduce the damage of battery life caused by the polarization and over-discharge phenomenon. According to the relationship between the state of charge (SOC) and the terminal voltage of the battery, the charging or discharging current in different SOC is dynamically adjusted during the scheduling process. In addition, a scheduling strategy coordinating the power output of the battery and the micro gas turbine (MGT) is proposed to reduce the mechanical wear and tear of the MGT as well as decrease the life loss of the battery. The results of simulation show that the proposed microgrid scheduling strategy with variable current for energy storage can effectively extend the battery life and reduce the operation cost of the microgrid.