Mixed bipolar direct current (DC) transmission system

Abstract

The invention discloses a mixed bipolar DC transmission system. The system comprises a rectification converter station and an inversion converter station which are connected through a DC transmission line, wherein the rectification converter station is formed by two thyristor converters through serial connection, and the serial connection node is grounded; and the inversion converter station is formed by two modular multilevel converters (MMCs) through serial connection, the serial connection node is grounded, and positive and negative ends after serial connection are connected with one-way connection power devices. The system has the advantages of low cost and loss, high reliability and the like of the existing thyristor converter, flexible control of the MMCs, low harmonic, active-reactive power decoupling control, low dependence on an alternating current system and the like; and the system is divided into positive and negative poles, so that operating reliability is strengthened, and the power devices provided with the one-way connection capacity and additionally arranged at outlets of inverters can effectively handle DC faults. The system is suitable for occasions such as high-power long-distance high-voltage DC transmission and island current delivery, provided with broad development space, and worthy of being popularized vigorously.

Description

technical field [0001] The invention belongs to the technical field of electric power system transmission, and in particular relates to a hybrid bipolar direct current transmission system. Background technique [0002] With the development of electric power science and technology, the cost of traditional high-voltage DC transmission systems based on thyristor converters has been reduced year by year, the reliability of power transmission has been continuously improved, and the losses in stations have gradually decreased. At present, the traditional HVDC power transmission system based on thyristor converters has been widely used in large-capacity long-distance power transmission, island power transmission, and back-to-back interconnection of asynchronous grids. However, the traditional HVDC power transmission system based on the thyristor converter has the following three main defects: (1) The inverter side is prone to commutation failure; since the thyristor, the main compo...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the above-mentioned technical defects existing in the prior art, the present invention provides a hybrid bipolar direct current transmission system, which combines the advantages of the thyristor-based converter and the MMC-based direct current transmission topology; solves the commutation failure on the inverter side and the The DC side cannot self-clean faults and other technical problems, the floor space is small, and the grounding method is easy to design

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