Control of distributed energy storage systems for minimum reverse flow in a distribution grid with high share of photovoltaic

Due to the increasing numbers of photovoltaic (PV) systems installed at the low-voltage (LV) level, reverse power flow (RPF) between the LV and the medium-voltage (MV) grid occurs more frequently and with higher magnitudes. This poses a threat to grid security as RPF can cause overvoltage and thereby potentially damage system equipment. This paper proposes a method of reducing RPF and increasing the local consumption of renewable energies (RES) by collectively controlling distributed residential battery energy storage systems (BESS) in a LV grid. For this purpose, the charging and discharging powers of the BESS are set correlating to the expected RPF and power demand at the transformer level by using a linear optimization algorithm and a forecast of the power flow at the transformer. This method aims at RPF shaving by charging the BESS and at covering the power demand by discharging. Comparisons with BESS controlled individually at the household level show, that the proposed method leads to a more effective reduction of reverse power peaks.