A square wave power transmission system for improving the transmission capacity of AC cable lines

Abstract

The invention provides a square wave power transmission system for improving the transmission capacity of an alternating-current cable line. The system comprises a transmitting terminal voltage source converter, a transmitting terminal interelectrode power coordination control device, a receiving terminal interelectrode power coordination control device, and a receiving terminal voltage source converter, wherein the output end of the transmitting terminal voltage source converter is connected with the transmitting terminal interelectrode power coordination control device, the transmitting terminal interelectrode power coordination control device is connected with the receiving terminal interelectrode power coordination control device through the alternating-current cable line, and the receiving terminal interelectrode power coordination control device is connected to a receiving terminal alternating-current system through the receiving terminal voltage source converter. According to the system, reformation of capacity expansion of the alternating-current cable line is realized by means of the good control performance of the modularized multi-level voltage source converters as well as an interelectrode voltage change-over switch and an interelectrode current commutation switch, the influence of space charge accumulation on cable line insulation is reduced, dynamic reactive power compensation and harmonic suppression are realized, and the system has great significance for solving the contradiction between ever-growing loads and increasing difficulties in new line construction.

Description

technical field [0001] The invention relates to a power transmission system, in particular to a square-wave power transmission system that improves the transmission capacity of AC cable lines based on MMC. Background technique [0002] In recent years, my country's urbanization has further accelerated, and urban electricity loads have continued to grow. Objectively, the scale and transmission capacity of the power grid are required to maintain continuous development. However, the following problems generally exist in urban power grids. [0003] The city's electricity load has increased, the transmission capacity of AC lines is insufficient, and the line corridors are scarce. For heavy-duty AC lines, it is impossible to greatly increase the transmission capacity by installing FACTS devices, and new lines encounter increasing resistance, especially for line projects into cities, which are difficult to get support in terms of land acquisition and environmental protection. The ...

AI Technical Summary

Problems solved by technology

[0008] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a square wave power transmission system based on MMC to increase the transmission capacity of AC cable lines, which utilizes the good control performance of modular multi-level voltage source converters, and cooperates with inter-pole voltage conversion The switch and the inter-electrode current transfer switch have solved the problem of increasing the capacity of the AC cable line, reducing the impact of space charge accumulation on the insulation of the cable line, and have functions such as dynamic reactive power compensation and harmonic control. The growing contradiction with the increasingly difficult new lines is of great significance

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