An Adaptive Approach for Protecting Transmission Line Connecting Converter-Interfaced Solar Plants

Exponentially growing inverter-based resources (IBRs) are required to address the expanding global demand for electrical energy. To meet the criteria of the utility grid codes (GCs), several control techniques are utilized in IBR. For the protection of high-voltage transmission lines, distance protection is commonly used. The various control schemes employed in grid-connected renewable resources severely impact conventional distance protection. System non-homogeneity is caused by the phase angle modulation of the fault current, which malfunctions the distance relay. This paper proposes an adaptive distance protection approach for the transmission line connecting inverter-based resources. The proposed approach estimates the dynamic positive sequence impedance of the IBR to compute the phase angle of the faulted loop current to obtain the line impedance up to the fault location from the relaying point. The functionality of the adaptive scheme has been verified with the Mho relay on the transmission line connecting the solar power plant to the remote grid modelled in PSCAD/EMTDC.