Superimposed Energy-based Fault Detection and Classification Scheme for Series-compensated Line

This article presents a fault detection and classification scheme for a series-compensated transmission line that is based on post-fault superimposed energy. The derivations of the scheme presented in this article are obtained with consideration of both the real and reactive components of the power system. However, the criterion depends only on the real components of the power system. For a forward fault, superimposed energy is negative, whereas it is positive for a reverse fault. If the relays of both ends detect forward fault, it is an internal fault; else, it is an external fault. The magnitude of superimposed energy depends on the fault type, location, and resistance, which makes it difficult to classify the type of fault as a fixed threshold cannot be set. Therefore, to classify the type of fault, energy coefficients have been introduced that depend on the superimposed energy measured at the relay. To test the capability of the superimposed energy based scheme, the test system has been simulated in PSCAD/EMTDC (Manitoba HVDC Research Centre) and an algorithm has been implemented in MATLAB (The MathWorks, Natick, Massachusetts, USA). Results proved that the scheme is accurate and robust against different system conditions and uncertainties.