Superimposed Component-Based Protection Scheme for UPFC Compensated Transmission Lines

The installation of unified power flow controller (UPFC) in a transmission line affect the transient as well as steady-state components of the current and voltage signals. In such situation the conventional distance relays find difficulty to protect such compensated lines. This paper presents a fast and accurate fault detection, classification and section identification technique for a UPFC compensated line based on superimposed principle. In this work, the superimposed components of current signals are taken as features for performing the detection and classification task. For fault section identification, the voltage and current superimposed components are used together. Performance of the proposed technique is assessed for numerous test cases by generating data on a 230 kV UPFC compensated two machine system through EMTDC/PSCAD. The obtained results clearly show that using the proposed protection scheme fast and accurate fault detection, and classification as well as fault section identification can be accomplished in transmission lines installed with UPFC at the mid-point of the line.