Superimposed Quantities-Based Protection for Transmission Lines with Inverter-Based Resources

This study analyzes the effects of inverter-based resources (IBR) on protective relays based on time-domain superimposed quantities. It examines a filtering method to enhance the security of the relay. The superimposed quantities, often referred to as incremental quantities, are instantaneous components of voltages and currents that are generated by faults. The directional component determines the direction of the fault by evaluating the transient energy quantities, which are derived from the relative polarities of the transient voltages and currents. Ensuring accurate indication of the correct direction becomes crucial when nonlinear fault current supplied by IBRs influences the current quantities. The instantaneous control response of an IBR influences the current quantities by changing their magnitude and phase angle. This study presents an analysis of the superimposed quantities in response to fault currents supplied by IBRs. It examines a filtering methodology based on a decoupled double synchronous reference frame (DDSRF) for improving the security of the superimposed-based relays.