基于等值阻抗相位特征的带并补电抗线路单相自适应重合闸故障识别方法

Aiming at the problem that the AC transmission line of hybrid AC/DC system recloses on fault blindly and causes DC side commutation failure, a single-phase adaptive reclosure scheme for identifying fault properties using the equivalent impedance characteristics of fault phase is proposed. In the case of transient faults, the equivalent impedance on the line side of the fault phase is mainly composed of ground capacitance, and the equivalent impedance is capacitive. When the arc is extinguished, the variable quantity of impedance phase increases sharply. In the case of permanent faults, the equivalent impedance on the line side of the fault phase consists of ground capacitance and transition resistance. The equivalent impedance presents the characteristics of resistance-capacitance or resistance-inductance. Therefore, the transient fault equivalent model is taken as the baseline model and the equivalent impedance is calculated using power frequency phasor fast extraction algorithm. Finally, the transient faults and permanent faults are distinguished based on equivalent impedance characteristic difference of the fault phase. A large number of simulation results show that the proposed method is suitable for transmission lines with shunt reactors, able to identify single-phase fault properly and confirm fault arc extinction time quickly, reducing the possibility of commutation failures caused by blind reclosure on the faults and possessing an excellent ability to withstand transition resistance.