为了避免配电线路相间故障跳闸后自动重合闸盲目重合于永久性故障带来的危害，提出了一种基于参数辨识的配电网相间永久性故障的识别方法。该方法在配电线路相间故障三相跳闸后，依次对停电线路的3个相间回路主动施加低频电压扰动信号，利用激励侧的电流和电压信息建立相间回路的参数方程，采用参数辨识的思想进行相间回路状态的甄别。以无故障相间回路为计算模型，依据电阻和电感参数的识别值与实际回路中真实值之间的偏差判别故障性质。当识别值与真实值偏差较大时，则实际相间回路模型与计算模型不一致，判为永久性故障。PSCAD建模仿真计算结果表明，所提出的永久故障判别方法能够有效辨识故障性质，且基本不受过渡电阻和故障位置等因素影响，有助于实现配电网三相自适应重合闸。

In order to avoid the damage caused by the blind recloser of the automatic reclosing in the permanent fault after the phase-to-phase fault trip of the distribution line, this paper proposes a method for identifying permanent faults between phases in distribution networks based on parameter identification. This method is used after the three-phase tripping of the power distribution line, the low-frequency voltage disturbance signal is actively applied to the three phase-to-phase loops of the power failure line in turn, the current and voltage information of the excitation side are used to establish the parameter equation of the interphase loop, and the parameter identification idea is used to screen the state of the interphase loop. The fault-free phase-to-phase loop is used as the calculation model. The nature of the fault is judged according to the deviation between the identification value of the resistance and inductance parameters and the true value in the actual loop. When the recognition value deviates greatly from the true value, the actual phase-to-phase loop model is in line with the calculation model, and it is judged as a permanent fault. The simulation calculation results based on PSCAD show that the permanent fault identification method studied in this paper can effectively identify the nature of the fault, and is basically not affected by factors, such as transition resistances and fault locations which is helpful to realize the three-phase adaptive reclosing of the distribution network.