Distance Protection Relaying Under the Impact of Grid-Following Inverter-Based-Resources

Inverter-based-resources (IBRs) form the link between the electrical grid and renewable energies, HVDC lines or battery storage systems. The type of IBR control defines the role of their grid behavior under normal operation as well as in the event of a grid fault. The state of the art is grid-following (GFL) control mode. Grid protection must remain secure and dependable despite the change in grid behavior by IBRs. This paper proposes a precise analytical explanation and understanding of the impact of GFL IBRs on distance protection relaying and algorithms. This is essential for developing countermeasures against relay malfunction based on IBR in-feeds. The analysis is done in symmetrical components, as this is combining classical fault analysis and typical GFL IBR control in the best way. The distance protection algorithm and the resulting measurement errors are converted into modal components. The analysis shows that active and reactive power control of GFL IBRs in the positive and negative sequence domain lead to considerable measurement errors of distance relays. Countermeasures are developed and presented based on the analytical explanation. They include the low-voltage fault-ride-through behavior and settings of distance protection relays. All results are evaluated and confirmed in a real-time protection test lab.