Impact of Resistive SFCLs on Superimposed Quantities in Power System Faults

Superimposed quantities, also known as delta quantities, are the transient signatures of fault currents and voltages that can be utilized by protective relays to achieve fast fault detection for electric power grid applications. With the installation of superconducting fault current limiters (SFCLs) on power transmission lines, the profiles of superimposed quantities in power system faults are affected due to the altered impedance properties at transmission line terminals, which may further affect protective relay performance. In this article, we investigate the impact of a resistive SFCL on superimposed quantity profiles. The equivalent circuit of a resistive SFCL connected to an electric power transmission system is first illustrated based on which the simulation model is established in an electromagnetic transients program. Various types of power transmission line faults are simulated. The superimposed current and voltage quantities at transmission line terminals are obtained. The simulation results demonstrate that the acquired superimposed quantities are significantly affected by the SFCL. Possible consequences to protection functions are discussed.