A new dual slope differential relaying scheme for the protection of various busbar arrangement

The protection of busbar demands high integrity and high speed relaying scheme. This paper presents an idea of dual slope differential relaying scheme for the protection of various fault conditions on busbar. Fast Fourier Transform (FFT) technique is used to provide the operating quantity for the dual slope differential relay. The operating criterion of the relay depends on the relationship between differential current (I_DIFF) and restraining current (I_REST = I_BIAS). Various power system components such as generator, transmission lines, relay, etc. have been modeled in PSCAD/EMTDC software package. In order to validate the proposed scheme, fault data have been generated by modeling a part of Indian power system network. The proposed protective scheme operates only for the internal fault, and it remains stable during any out of zone fault as well as normal load condition. Moreover, it operates for high resistance in-zone fault and is unaffected by Current Transformer (CT) saturation in case of an external fault. Simulation results and relay response for different types of fault are included in the paper.