A direction detection method for the phase-to-phase fault of the distribution networks with BESS

With the development of renewable energy, large numbers of batter energy storage systems (BESS) have been connected to support the power grid. However, due to the charging/discharging characteristics and fault ride-through strategies of the BESS, the protection relay for the distribution networks with the BESS would have misoperation or maloperation. In response above challenges, this paper firstly analyses the negative sequence impedance of BESS under asymmetrical phase-to-phase faults and quantitatively calculate its variation boundaries. Secondly, in the case of symmetrical phase-to-phase faults, the difference between the reactive currents provided by BESS or the large power grid, as well as the active currents, were analysed and compared. Thirdly, this paper proposes a fault direction detection method based on the study of fault characteristics mentioned above. For asymmetrical faults, the proposed method detects the fault direction using negative sequence power-angle. For symmetrical faults, the proposed method uses reactive current direction and active current magnitude. Finally, the action performance of the proposed method is tested by the simulation examples in PSCAD/EMTDC.