Interference of Unipolar Discharge of Gongle Grounding Pole on Changning Gathering and Transmission Trunk Line

The on-site test piece method was used to test the influence of 870 A anode discharge and 2 900 A cathode discharge of the Gongle grounding electrode on the DC interference parameters of a nearby buried steel pipeline. By analyzing and processing the test data, the interference effects of ultra-high voltage direct current transmission lines on buried pipelines under different discharge conditions during single pole operation were studied. The results show that the relative positions of stray currents flowing in and out of the pipeline remain basically unchanged, but in opposite directions, and the degree of interference increased with the increase of discharge current. When the anode of the grounding electrode discharged, the length of the positive displacement segment of the tube ground potential was relatively long, and the impact range was relatively wide. When the cathode of the grounding electrode 2 00 A was discharged, at a distance of 17 km from it, compared to the blank tube, the maximum positive deviation of the power-off potential reached 0.392 V, and the current density flowing out of the test piece was 1.28 A/m². The three sections of pipeline separated by insulation joints had their own inflow and outflow zones, and there were positive and negative sudden changes in the ground potential of the pipes on both sides of the insulation joint. The insulation joint was a high-risk point for corrosion.