Non-Fault Detection Scheme before Reclosing Using Parameter Identification for Active Distribution Network

Aiming at the problem of blind reclosing in permanent fault in active distribution network, a non-fault identification method before three-phase reclosing based on parameter identification is proposed. After the three-phase trip of the fault line, the distributed generation （DG）is used to simultaneously apply three-phase symmetrical low-frequency voltage excitation to the isolated line. When there is no fault that is the transient fault arc is extinguished, the three-phase network is symmetrical and each phase equivalent circuit is consisted of its own loop resistance and inductance. But in the case of permanent fault, the three-phase is asymmetry and the fault phase equivalent circuits are related to the transition resistance and fault location etc., which cannot be characterized as the aforementioned linear relationship. Therefore, using the differences to identify the fault condition before reclosing. Based on the principle of parameter identification, the R-L network in the non-fault is used as the reference model. Using the voltage and current information on the line side during the excitation period, and the least squares algorithm is used to calculate the resistance and inductance parameters of each phase circuit. When the calculated values of the resistance and inductance are consistent with the corresponding actual values, it is determined that the arc is extinguished and there is no fault. Simulation was conducted using PSCAD in different situations, and the results showed that the proposed non-fault detection method can effectively identify the fault condition before reclosing, and it does not require additional disturbance source equipment, which is helpful for the application and practice of adaptive three-phase reclosing in distribution lines.