A layered direct current transmission system

Abstract

The invention belongs to the field of power system power transmission and distribution, and provides a layered direct current power transmission system for transmitting a large amount of renewable energy power generation distributed in different regions to a load center. The system consists of a high-voltage converter station and several low-voltage converters. Station interconnection, the high-voltage converter station is composed of high-end converters and low-end converters in series. The low-end converters are connected to the DC side of one or more low-voltage converter stations through the DC transmission line, the AC side of the low-voltage converter stations is connected to the AC system of each low-voltage converter station, and the high-end converters of the high-voltage converter stations are connected. , The AC side of the low-end converter is connected to the AC system where the high-voltage converter station is located. The topology of the invention can more conveniently arrange the geographical location of each renewable energy power station, realize AC side isolation of each renewable energy power station, and reduce the total capacity of the voltage source type converter in the whole system.

Description

technical field [0001] The invention belongs to the field of power system power transmission and distribution, and in particular relates to a layered direct current power transmission system, which is used for transmitting a large amount of renewable energy power generation distributed in different regions to a load center. Background technique [0002] my country is currently facing a severe haze problem. One of the main reasons for the haze problem is that my country is overly dependent on fossil energy such as coal combustion. Vigorously developing solar power, wind power, hydropower and other renewable energy power generation is the solution to my country's haze problem. fundamental measures. The northwest region of my country has a large number of wind power and solar power generation resources, and the southwest region has a large number of hydropower, wind power and solar power generation resources. Taking the five provinces of Inner Mongolia, Xinjiang, Gansu, Qinghai...

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Problems solved by technology

[0006] 1. It is necessary to build a large-capacity voltage source converter station to facilitate access to wind power, photovoltaic power generation and other new energy power generation systems, which brings high costs and high losses;

[0007] 2. Each power station needs to be connected to the AC side of the voltage source converter station through its own long-distance AC transmission line. Since the long-distance AC transmission line will generate a large amount of reactive power, and the AC transmission line is a three-phase line, Each AC transmission line contains 3 wires, resulting in large loss of transmission lines, high cost, and difficulty in line erection;

[0008] 3. Since each power station is interconnected through AC transmission lines, any AC fault will affect all power stations, resulting in poor system stability and reliability

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