Abstract: To improve the anti-icing ability is vital for safe operation of the line. The paper analyzes the environment and waveform record of the ground wire disconnection fault field of ±800 kV ultra-high voltage(UHV) DC line, makes static analysis of the ground wire fracture,conducts scanning electron microscope and breaking force test, and carries out the simulation calculation of guide wire spacing. According to the test and simulation calculation, there is a big difference of the ground wire icing thickness of UHV DC. When the ground wire icing thickness increases, the spacing between conductors and ground wires gradually decreases which is likely to contribute to discharge because of insufficient air gap under the strong wind. The reason for this UHV line fault is that the insufficient air gap of ground wires caused by icing contributes to discharge to burn and break ground wires. The line icing of micro-terrain region is possible to exceed the design value, so factors such as the actual on-site icing thickness, ground wire icing thickness differential value, micro-meteorology and micro-topography of fault section should be taken into consideration to ensure operation of the line.

    Key words: ±800 kV ultra-high voltage DC line; ground wire; icing; disconnection; fault analysis