Impacts of PV Generations on the Performance of Positive Sequence Memory Polarized Distance Relays (PROTECT)

Renewable energy sources like solar and wind are swiftly and steadily integrated into the existing power networks because of modernization in the power sector. Due to the unpredictable nature of these sources, Inverter Based Resources (IBRs) are utilized to generate power. The widespread integration of inverter-based Photovoltaic generators (PV)  into electrical grids have been encouraged by the rising popularity of renewable energy and associated technology development. Power electronic converters of IBRs are used to connect them to the grid. To prevent thermal overloads of the power electronic switches, the inverter control systems regulate and limit the maximum short-circuit current. The converter controls determine how PV generators behave during transients. The transient behaviour of synchronous generators (SGs), which are employed in conventional power systems, may differ dramatically from this. As a result, conventional protection schemes may fail in the presence of IBRs like PV generators. Positive Sequence Memory Polarized (PSMP) mho relays are widely used to detect close-in faults in transmission lines owing to their high dependability. In conventional transmission systems, the PSMP mho characteristics expand to cover a greater resistive component in the R-X (impedance) plane. As a result, a fault is reliably detected regardless of the fault resistance. As the penetration of PV increases,  fault currents are lower in amplitude and different in shape than those in classical power systems, and the PSMP mho relays may not exhibit the same behaviour as in a system with only SGs. Therefore, it is necessary to devise a new algorithm that incorporates the effects of PV generators. The study aims at developing an algorithm employing local measurements which can operate reliably in a system with and without PVs.  Grid Following (GFOL) and Grid Forming (GFOM) PV generators will be used for the study. The PVs will have Low Voltage Ride Through (LVRT) and voltage support capabilities and will adhere to IEEE 2800-2022 standard. The test cases will be simulated for a modified IEEE-39 bus system using PSCAD software, and the results will be validated using an RTDS.