Special protection system to cope with the unavailability of sampling values from an entire substation

摘要

A special protection system is proposed to respond to a challenge such as that a substation must be immediately taken out of service or only be protected by a remote backup protection without selectivity if the sampling system of this substation breaks down or the samplings are unavailable even though the GOOSE channel is functioning normally. After the special protection system perceives an abnormality of the sampling system of the substation, it first locates the rough fault region using a wide area measurement system based current differential protection scheme of the sound side of the lines connected to the substation with an abnormal sampling system. Then, a novel compensation voltage difference scheme is proposed to determine the faulty line within the recognized rough fault region. Combined with the zone I distance protection scheme, a comprehensive special protection scheme to address a serious sampling abnormality is proposed. Theoretical analysis and PSCAD and MATLAB based simulation studies show that the proposed scheme has the advantages of high reliability, sensitivity and capability of withstanding a fault resistance.