Phase imbalance impact on operating envelope for low-voltage distribution grid

Distribution System Operators must ensure safe operation of the Low Voltage distribution grid in the face of upcoming challenges posed by new assets (e.g. photovoltaic panels, electric vehicles) and new activities (e.g. energy sharing, frequency reserves). This task is further complicated by the fact that end-users may be unevenly connected to the phases without Distribution System Operators being aware of it. This can lead to unexpected voltage or current congestions. This paper presents an innovative method, a relaxed unbalanced three-phase optimal power flow, to compute the maximum day-ahead flexibility per end-user that can be unlocked while ensuring safe use of the low voltage grid, i.e. the operating envelope. Additionally, the paper shows results that controlling reactive power on the LV network could not increase flexibility potential and counteract imbalances caused by unevenly distributed phase connections.