Auto-tuned Solution to Wide Area Coordination Issues of Distance and Directional Time Overcurrent Relay Settings

Abstract

Relay coordination is an extremely difficult, yet vital part of a comprehensive protection strategy for modern power systems. With the recent introduction of PRC-027-1 [14] and its requirement for coordination to be reevaluated at regular intervals, innovation to reduce the burden and resources required for this activity is essential. Achieving coordination and ensuring that relays operate in a predictable manner can be quite a challenging activity, especially in highly coupled power systems with tight loops in the topology structure. In [3] we presented an early prototype of a coordination autotuner framework and demonstrated its use for the automatic generation of tuned pickup and time dial settings for direction time overcurrent relays on a mix of synthetic and real world grids.In this paper, we present improvements we have made to our autotuner framework, moving us significantly closer to a general purpose coordination autotuner, capable of performing the mundane, iterative work required during coordination studies, with guidance and feedback from the protection engineer tasked with the effort. We focus on several key areas including support for additional coordination constraints (for implementing specifics of a utility’s standard), allowing more tunable parameters (e.g., overcurrent curve) and alternative methods to calculate them, fault studies with contingencies, and incorporation of distance element responses. We show usage of each in the experiments, demonstrating how they allow us to better support common cases encountered in real world coordination studies. Together, these new capabilities address a large number of simplifying restrictions in our previous work, making us increasingly confident that autotuning-assisted coordination studies is a viable and important advancement quickly coming on the horizon in system protection.