Method for eliminating defects of main insulation of cold insulation superconducting cable and system structure for realizing method

Abstract

The invention discloses a method for eliminating defects of main insulation of a cold insulation superconducting cable. The method comprises the following steps of: assembling a cable body, and connecting the two ends of the cable body with cable terminals or cable end sockets in a sealed mode; connecting a conductor which passes through the cable body with an external power supply by using a group of current leads, switching on the external power supply, heating, and ensuring that the heating temperature of the heated cable body is between 50 and 180 DEG C; vacuumizing and detecting vacuum degree; keeping the heating temperature stable until absolute vacuum degree in a cable cavity reaches the order of magnitude of below 10<-1>Pa, charging inert gas into the cable cavity to ensure that the absolute vacuum degree reaches over 0.1Mpa, and maintaining for 2 to 24 hours; repeating the steps to accomplish gas displacement; and maintaining the seal, and continuously charging the inert gas to ensure that gas pressure in the cable cavity is higher than the atmosphere to accomplish the defect elimination of the main insulation of the cable. A system structure for realizing the method comprises a superconducting cable core, a low temperature thermostat and the cable terminals or the end sockets special for cables, wherein a group of gas inlets / outlets are formed in the cable cavity which is formed by the cable terminals or the end sockets special for the cables and the low temperature thermostat.

Description

technical field [0001] The invention belongs to the application field of superconducting power technology, and in particular relates to a method for eliminating defects of a cold-insulated superconducting cable and a system structure for realizing the method. Background technique [0002] The cable core of the cold insulated superconducting cable has an independent and complete power transmission structure, including an inner support tube, a superconducting conductor, an insulating layer and a shielding layer, and its working low temperature environment is provided by a thermostat. When the cold-insulated superconducting cable is in operation, its main insulation is in a low-temperature liquid nitrogen environment (about 77K). Since insulating materials such as rubber and cross-linked polyethylene (XLPE) cannot be used at liquid nitrogen temperatures, the main insulation of cold-insulated superconducting cables cannot be made of such materials, so the overall insulation cann...

AI Technical Summary

Problems solved by technology

Because the structure of the cryostat is very complicated, whether it is extruded in situ on the cable core, or the cable core is assembled through the tube after the cryostat is fabricated, the cable core will inevitably be In contact with the atmosphere, the insulating layer will absorb moisture in the air, resulting in deterioration of insulation performance

Secondly, the insulating oil cannot be used in the environment of liquid nitrogen, because the insulating oil will solidify at low temperature, even if the cable is impregnated, it will leave a new air gap in the insulation due to the shrinkage of the insulating oil

Moreover, when the cable is in normal operation, the insulating oil cannot be replenished and the newly formed insulating air gap cannot be filled.

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