A relay scheme of double-circuit lines based on directional traveling wave

Through analyzing the character of electric quantity after fault,a protection scheme of double-circuit lines is presented based on directional traveling wave,which utilizes characters of directional traveling wave of two ends of lines to identify internal,external fault and fault line.This scheme can protect the whole line and is unlimited to lines number of bus.It can act correctly in the situation of one line operation of double-circuit lines.Comparing with the protection using main frequency quantity,it not only acts rapidly and is immune to CT saturation.The simulation verifies the feasibility of scheme.