The main purpose of this HVDC interference analysis project was to investigate the inductive and DC stray current effects of a few different HVDC transmission line systems during lightning-initiated faults as well as steady-state monopolar operations on adjacent metallic pipelines. Simulation forecasts in this project revealed different levels of DC stray current interference on nearby pipelines during monopolar operations based on the configuration of the HVDC system under study. Conversely, induced transient waveforms during fault scenarios were within the expected range compared to previous staged fault field measurements performed in the past project. Conducting these simulations will provide increased confidence when undertaking mitigation design by highlighting interference hot spots, therefore assisting with the design of more efficient mitigation systems to address both personnel safety and pipeline integrity concerns.
Back in 2018, we published a paper on a joint industrial R&D project, during which we performed detailed field measurements on selected pipeline segments in close vicinity to a High Voltage Direct Current (HVDC) transmission line during planned staged fault tests on the power line [1]. Induced voltages on these pipelines were recorded during the HVDC staged fault process, which was conducted by the utility company. The measurement results from these tests were used for further validation or modification of an existing industrial guideline that focuses on the influence of HVDC power lines on metallic pipelines. Verification of future modeling results was another expected outcome of this study. A pre-field laboratory test was conducted to ensure accurate calibration and functionality of equipment prior to the actual staged fault field testing. To check the functionality of the digital triggering on the data logging unit and choose an appropriate triggering level and methodology, a typical touch voltage waveform based on previous simulation forecasts was used. The test setup during the HVDC staged fault testing consisted of an arrangement of ground rods, a differential high voltage probe and the data logging unit used in order to capture the transient fault waveforms on the pipelines. Using the staged fault current waveforms provided by the utility company, the total interference fault state touch potentials along the selected pipeline segments were simulated. Simulated waveforms were in close agreement with measured waveforms in terms of overall outline.
