Study of overvoltage and insulation coordination of UHV DC transmission line

In order to determine the insulation level of DC transmission line, one UHV DC transmission project is taken as an example in this paper. PSCAD program is used to establish the simulation calculation model. Multiple fault points on the fault line are selected. The induced overvoltage amplitude, distribution along the line and the maximum overvoltage envelope of healthy pole transmission line corresponding to the failure point are calculated to determine 2% statistical overvoltage. The influence of DC filter parameters, grounding resistance and grounding position on overvoltage are analyzed. According to the DC filter scheme, the DC line insulation coordination is analyzed, and the air gap of transmission line tower is determined. The calculation results provide the references for the designation and construction of UHV DC transmission projects.