Study on Free-oscillation Components Characteristics and Single-phase Adaptive Reclosure in Reactored Transmission Lines

Based on the characteristics analysis of the free-oscillation components in single-phase faults under transient fault and permanent fault for transmission lines with shunt reactors, this paper proposed a single-phase permanent fault identification criterion using the amplitude of the free-oscillation component in the tripped phase current from the shunt reactor. In the case of a transient fault, the current from shunt reactor in the opened phase consists of low-frequency oscillation component and power-frequency component. But for permanent fault, the current contains only power-frequency periodic component. Therefore, a method uses a prescribed fitting function of the tripped phase current from shunt reactor to acquire the amplitudes of low-frequency component and power-frequency component, and than utilizes the amplitudes to distinguish the permanent faults from transient faults. The criterion is simple and reliable, as it only uses the tripped fault phase current with high precision. ATP simulations show that the criterion is correct and effective, and promised to improve the success rate of the quick single-phase adaptive reclosure.