The main working principle of the de-icing technology of AC line which is based on SVC is to make a large DC current flow through the power transmission line via rectification. When the DC current exceeds the normal working current of the line, it can cause the line to heat, thus making the ice, snow, rime on the line melt and fall, and achieving the purpose of de-icing. When there is no need for de-icing, the DC de-icing mode can be switched to SVC mode by changing the main wiring connection mode, so it can be used as dynamic reactive power compensation equipment.
When the line is running under special weather conditions (for example, freezing rain), the line is prone to ice. If the line is covered with a large amount of ice for a short time and there is no time for natural de-icing, the line may collapse due to too thick ice and unbearable burden. TCR-type SVC can change the topology of valve block to a device similar to rectifier to convert the AC power supply of the line into pulsating DC power supply to the line (line outage), thus making the ice melt quickly and protecting the safety of the line.
The schematic diagram and typical engineering photos of typical DC deicing device are shown as follows: