Evaluation of the Impact of Superconducting Fault Current Limiters on Power System Network Protections Using a RTS-PHIL Methodology

Abstract

Planning the integration of a Superconducting Fault Current Limiter (SFCL) in an electric power network mainly consists in predicting the current limiting characteristics in any fault condition, in order to set the protection relays accordingly. Due to the very non linear behavior of the SFCL, modifications to the settings of existing protection relays are expected. To explore the potential changes, we used a Real-Time Simulation (RTS) methodology with Power-Hardware-In-the-Loop (PHIL) capabilities (i.e. circuit simulator coupled with power amplifiers for driving external physical power devices). The RTS-PHIL is a powerful approach that makes it possible to incorporate the actual transient reaction of the hardware under study without the need for developing a complicated numerical model, while the power system circuit, generally simpler in nature, can be purely simulated. In this project, the response of a commercial protection relay in the presence of a SFCL was investigated. Both the relay and a small scale shielded-core inductive limiter were coupled to the real time simulator (HYPERSIM) through single-phase linear power amplifiers and a variety of faults were applied. So far, this setup has allowed us to evaluate the impact of inserting a SFCL on overcurrent relays (OCR), in a simple radial distribution network. The results show that coordination has indeed to be slightly revised.