Techno-economic Optimum Control of Grid-connected Residential Battery Energy Storage Units

Abstract

A method for cycling residential battery energy storage (BES) units coupled with photovoltaic (PV) systems is presented. The primary purpose of the BES unit is to store the excess energy from the PV system for later utilization or selling to the grid if the utility provides competitive feed in tariff. The scheduling of the BES unit is determined by a local energy management system (EMS). The EMS charges the BES unit mostly during the period when the network is prone to overvoltage risks due to the reverse power flow. The discharging of the battery is done considering the electricity tariff, so that the economic benefits from the system is maximized. If the over- or under-voltage problems still persist, then the reactive power capability of the converters are utilized. This is done by a central control system. It calculates the required reactive power set points, which results the minimum total reactive power support from the converters. The results from a simulation study is presented, where the proposed method is applied for the IEEE European LV test feeder. The results show that the proposed method can maximize the economic benefits for the system owner while providing required voltage support for the grid.