Voltage compensation device and method for end-to-end direct-current power transmission system

Abstract

The invention provides a voltage compensation device and method for an end-to-end direct-current power transmission system. The device comprises a positive electrode compensation module, a metal loopconnection module, a negative electrode connection module, an inter-line connection module and a control system, wherein the positive electrode compensation module and the negative electrode connection module are respectively connected to a positive electrode power transmission line and a negative electrode power transmission line, the metal loop connection module is connected to a metal loop, oneend of the inter-line connection module is connected with the positive electrode compensation module, the other end of the inter-line connection module is connected with the metal loop and the negative electrode power transmission line, the control system is respectively connected with each module and is used for controlling each module to realize compensation of voltage drop, so that the systemloss is reduced, and the design requirement of the converter is reduced. According to the invention, the compensation device provided by the invention is simple and reliable in structure and low in operation difficulty, and can be widely applied to a two-end bipolar direct-current power transmission system or a multi-end direct-current power transmission system and a direct-current power grid.

Description

technical field [0001] The invention relates to the technical field of direct current transmission, in particular to a voltage compensation device and method for an end-to-end direct current transmission system. Background technique [0002] For the end-to-end DC transmission system using metal loops, when the positive transmission line or the negative transmission line fails or is overhauled, it can be switched to an independently operating unipolar DC transmission system, so it has higher reliability when applied to long-distance power interconnection scenarios. Reliability and operational flexibility. The metallic return wire is a low-insulation neutral wire that is placed between the positive and negative transmission lines. Metal return wires are usually grounded at one end and subjected to the voltage drop caused by the maximum current flowing through them at the other end. When the end-to-end DC transmission system using metal loops is in bipolar operation, the curr...

AI Technical Summary

Problems solved by technology

When the operation mode of the end-to-end DC transmission system using metal return lines is changed from bipolar operation mode to unipolar operation mode, due to the long-distance power interconnection transmission distance, there will be a significant voltage drop along the metal return line, increasing The loss of the positive and negative transmission lines is reduced; furthermore, the DC voltage at the outlet of the converter is greatly reduced, while the neutral point voltage of the metal return line is significantly increased, which leads to higher requirements for the design of the electrical parameters of the converter station. Require

In addition, whether it is a bipolar operation mode or a unipolar operation mode, for long-distance power transmission, there will be power loss along the transmission line, resulting in a large voltage drop

Generally, the voltage adjustment can be realized by changing the transformer tap installed between the converter and the power system. However, due to the small voltage adjustment range of the transformer tap, the current flowing through the transmission line will still be caused in the case of long-distance power transmission. Larger, resulting in large losses in the end-to-end DC transmission system

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