Analysis of mode current frequency after three-phase trip for transmission lines with shunt reactors

By analyzing the boundary conditions with phase-mode transformation under transient fault and permanent fault, the time-domain and complex frequency-domain composite mode networks are achieved, based on which, the low oscillation frequencies of mode currents in shunt reactor are obtained. Theoretical analysis and simulation show that, the power-frequency component, which exists in the mode current before the trips of both sides, will disappear after the trips;since then, if the fault is permanent, there may be zero, one or two low-frequency components in the mode current of shunt reactor, depending on the fault type;if the fault is transient and the arc at the fault point is extinguished, there is only one low-frequency component in the mode current of shunt reactor;the oscillation frequencies of different fault types are hardly influenced by the fault location and transition resistance. The analytical results can be applied to the criterion of fault property identification for the three-phase adaptive recloser based on the oscillation frequency of mode current.