High-voltage direct-current transmission line protection method and device for distinguishing internal and external faults of smoothing reactor

The invention discloses a high-voltage direct-current transmission line protection method for distinguishing internal and external faults of a smoothing reactor. The method comprises the steps: obtaining the difference value of a rectification side current according to the current values of the rectification side of a high-voltage direct-current transmission line at the current moment and the previous moment; obtaining the difference value of the current of the inversion side according to the current moment and the current value of the delay inversion side of the high-voltage direct-current line transmission channel; calculating a differential asynchronous differential quantity according to the differential value of the rectification side current and the differential value of the inversionside current, and if the differential asynchronous differential quantity is greater than a differential asynchronous differential relay constant value, judging that a fault occurs in the high-voltagedirect-current transmissi