Management of charging cycles for grid-connected energy storage batteries

The use of renewable energy requires a certain level of energy management in electricity distribution grids. Grid-connected energy storage batteries (ESBs) can be utilized to keep this level of management by charging and discharging them accordingly. Grid-connected ESB users schedule their usage based on time-of-use tariffs to follow economic charging cycles. However, charging several grid-connected ESBs during off-peak tariff interval may cause a decline of grid voltage below its limit. Therefore, this paper suggests a management scheme to maintain voltage-sag magnitude within its threshold, while minimizing the aggregated cost of charging the grid-connected ESBs. A sequential quadratic programming technique is employed to solve the objective function, considering an IEEE test system of 37 node. According to optimization results, the management scheme reduces the operational cost of different ESB penetration in the test system, taking into consideration ESB state of charge and grid voltage.