Research on load transfer melt-icing technology of transmission lines: Its critical melt-icing thickness and experimental validation

Transmission line icing poses a long-term threat to the safety of power grid operation. DC large current melt-icing technology is the most effective transmission line ice damage defense method. However, it still has certain shortcomings, such as the need for power outage during melt-icing, additional access to melt-icing equipment and the significant manual input, and so on. With respect of this issue, this paper proposes to increase the current density of the ice-covered conductor to melt the ice by load transfer melt-icing technology when the wire ice thickness reaches the critical melt-icing thickness. Considering the actual situation which wire keep on twisting while icing to form circular ice under natural icing conditions, the critical melt-icing thickness of load transfer melt-icing technology is proposed, and the influence of ambient temperature, wind speed, liquid water content in the air and the diameter of the conductor is analysed. The LGJ-400/35 wire and LGJ-300/50 wire were selected for laboratory and field in natural experimental validation. Laboratory experimental and natural field experi-mental results show that the average value of the calculation error is within 10%. Under the critical melt-icing thickness, keeping the current density of the ice-covered conductor is 2 to 2.5 times of the economic current density through load transfer melt-icing technology can meet the practical engineering applications needs of transmission line melt-icing, which can replace the use of DC large current melt-icing technology.