A digital distance relay using negative sequence current

The configuration and performance of a recently developed digital distance relay using negative sequence current for remote backup protection are described. Since relays for remote backup protection are designed for remote faults, the fault current that is input to the relay is small due to the influence of current distribution factors. This in turn makes the relay sensitive to the effects of load current. In order to resolve this problem, a distance relay using negative-sequence current has been developed and put into use. The characteristics of this relay are: (1) the effects of load current are reduced, so the relay rarely maloperated due to load current during a fault; and (2) the hardware configuration of a digital relay that performs calculation on a negative component is simple and thus relatively error-free