DC power transmission system for power transmission by adopting three-phase AC cable

Abstract

The invention discloses a DC power transmission system for power transmission by adopting a three-phase AC cable. The DC power transmission system comprises: a rectification converter station, which is used for converting three-phase alternating current output from a sending end AC power grid into first bipolar direct current; a rectification-side current and voltage conversion unit, which is used for converting the first bipolar direct current into three-phase direct current and outputting the three-phase direct current to a three-phase AC cable, wherein the positive and negative polarities of phases of the three-phase direct current change periodically; an inversion-side current and voltage conversion unit, which is used for receiving the three-phase direct current through the three-phase AC cable and converting the three-phase direct current into second bipolar direct current; and an inversion converter station, which is used for converting the second bipolar direct current into three-phase direct current and conveying the three-phase direct current to a receiving end AC power grid. The system has the high capacity of power transmission, the positive and negative polarities current and voltage of each phase on the three-phase AC cable change periodically, the insulating characteristic of a power transmission line will not be affected, and the functioning safety of the power transmission line is high.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a DC power transmission system using a three-phase AC cable for power transmission. Background technique [0002] The rapid development of social economy has promoted the rapid growth of power load, and at the same time, it also puts forward higher requirements for the transmission capacity of the power grid. On the one hand, with the development and construction of modern cities becoming more and more mature, there are more and more constraints on the power supply construction and power supply lines of the power supply system; As a result, the cost of requisitioning new power supply lines is getting higher and higher. Therefore, it is necessary for grid construction to be able to transmit greater power on the basis of existing power supply lines. [0003] In order to transmit more electricity, the method of transforming the original power supply line and converting it...

AI Technical Summary

Problems solved by technology

[0004] However, whether it is a bipolar DC transmission system, a three-pole DC transmission system or an extended bipolar DC transmission system, the voltage on some AC cables in the system will always remain in the positive or negative state. Under the action of the DC high-voltage electric field, It is easy to cause serious space charge accumulation in the insulating medium or on the interface of the AC cable. If the space charge density is high enough, the local electric field may even exceed the breakdown field strength of the insulating medium, resulting in the destruction of the insulating medium in the AC cable, resulting in serious Affects the insulation properties and operational safety of transmission lines

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