Investigating A Transmission Line Misoperation Caused By Ibr Penetration

Abstract— Negative sequence directional elements are used in transmission line protection to determine whether a fault occurs in the forward or reverse direction of the relay. These negative sequence directional elements are set under the assumption that there is sufficient negative sequence current. However, when considering inverter-based resources (IBR), the negative sequence fault response is inconsistent. This paper describes a misoperation event that occurred on a Dominion Energy Virginia transmission line resulting from the lack of negative sequence current from an IBR facility. During the event, a B-G fault occurred due to a failed arrestor at a tapped distribution transformer on the transmission line. The remote end of the transmission line detected the fault and issued a transfer trip signal to the local end of the line near the IBR facility; however, the signal was never received. The local relay never tripped for the fault because of the lack of negative sequence current. This paper also addresses how the data was analyzed and makes recommendation for fixes to the transfer trip communication and logic for IBR sites with weak sources.

Keywords—Inverter based resources, negative sequence directional elements, transfer trip.