Technology determination method for changing crosslinked polyethylene cable alternating current line into direct current operation

Abstract

The invention provides a technology determination method for changing crosslinked polyethylene cable alternating current line into direct current operation. The method comprises the following steps: designing a crosslinked polyethylene cable alternating current operation scheme, calculating long-term allowed rated current-carrying capacity of a crosslinked polyethylene cable and a temperature difference between two insulated ends of the crosslinked polyethylene cable in full load operation, testing a characteristic parameter of the crosslinked polyethylene cable under direct current voltage, calculating long-term allowed direct current work voltage of the crosslinked polyethylene cable, calculating transmission capacity of a crosslinked polyethylene cable line and determining whether the crosslinked polyethylene cable satisfies a requirement of direct current operation, and checking a grounding mode of a direct current operation line of the crosslinked polyethylene cable. According to the method in the invention, present cable insulation can bear various voltage of operation under designed direct current voltage, an electrical property of the cable insulation satisfies a requirement, simultaneously present resource can be fully utilized, and long-term reliable economic transmission of electric energy is realized.

Description

technical field [0001] The invention relates to the technical field of cable line operation, in particular to a technical determination method for changing an AC line of a cross-linked polyethylene cable to a DC operation. Background technique [0002] Compared with AC transmission, DC transmission has many advantages: 1) High transmission efficiency and low line loss. 2) It is convenient to adjust the current and change the direction of power transmission. 3) DC lines use less wires, lower investment costs, and save money for long-distance power transmission than AC. 4) The length of the DC cable is not limited by the capacitive current, which is more beneficial for crossing the strait and transmitting power to islands. 5) The DC transmission line can be used as the connecting line of the two power grids, even when the frequency of the two power grids is different, it can also reduce the short-circuit current between the main line and the power grid. 6) The corona radio ...

AI Technical Summary

Problems solved by technology

2) DC cables have no capacitive charging current, and theoretically the transmission distance can be infinitely long

Without strict technical judgment, the long-term operating voltage, load current, and transmission capacity of the AC XLPE cable line after it is changed to DC operation cannot be accurately determined.

If the operating voltage and current values ​​are too high, or the grounding method of the system cannot meet the requirements for operation under DC voltage, it will cause the cables that can run safely for a long time to fail in a short period of time, causing unexpected power outages; and if the voltage and current values ​​are too high Low, on the one hand, it will cause low utilization rate of cables and waste of assets; on the other hand, it will not only fail to improve line performance, but may even fail to meet the original transmission capacity requirements. Therefore, for XLPE AC cable lines to be changed to DC operation Feasibility requires full theoretical analysis and technical judgment, and the design of operating parameters under DC voltage also requires systematic test checks as a basis

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