Assessment of Directional Elements for Power Networks Connected to Inverted Based Renewable Resources: Problems and Mitigation Approach

The existing commercially available directional methods require angles of voltage, current, line, and source impedances to determine the direction of the fault. In presence of inverter-based renewables resources (IBRs) the voltage, current, and source impedance angle deviates, and it depends on the inverter controls. The inverter controls are dictated by the grid codes and interconnection agreements. Therefore, the existing methods may be mal operating for networks connected with IBRs. In this paper, a detailed study of existing methods is provided, and a mitigation approach is also proposed using only the current signal. The proposed approach is tested using EMTDC simulation of a 220kV, 200 km transmission line connected with IBRs. The proposed method is validated with field data which confirms the accuracy of the proposed mitigation approach.