抄録
This paper relates to the magnitude of the DC transient component and that of the AC fundamental component contained in line current caused by power system faults. The condition that the former could exceed the latter can be expressed graphically by the region inside the circles on the plane with P-Q coordinates where P-Q corresponds to power flow in the line before fault occurrence. The circles for various faults in power systems with singlle-circuit and double-circuit transmission lines are shown.
