Unidirectional direct current-direct current autotransformer

Abstract

The invention discloses a unidirectional direct current-direct current autotransformer for transmitting a direct-current power between two direct-current systems in a unidirectional mode. On the basis of optimized designs of a converter, a rectifier, and an alternating-current link, defects of large converter capacity, large alternating-current link capacity, and high running losses according to the existing unidirectional direct current-alternating current-direct current conversion technology can be overcome. A voltage source type converter is used for controlling an alternating-current voltage of the unidirectional direct current-direct current autotransformer, thereby realizing controlling of a direct-current power transmitted between a low-voltage first direct-current system and a high-voltage second direct-current system or a direct-current power transmitted between a high-voltage second direct-current system and a low-voltage first direct-current system and thus realizing power transmission between the two direct-current systems. Moreover, the unidirectional direct current-direct current autotransformer has the advantage of configuration of the bidirectional direct-current fault isolation capability. In addition, the invention discloses corresponding high-voltage-side and low-voltage-side direct-current fault isolation methods.

Description

technical field [0001] The invention belongs to the technical field of electric power transmission and distribution, and more specifically relates to a unidirectional DC-DC autotransformer, which is used to unidirectionally transmit DC power from one DC system to another DC system. Background technique [0002] With the development of modular multilevel converters, the use of modular multilevel converters to construct DC power grids has become a hot spot in the power industry in recent years. The interconnection of DC power grids in various regions is an urgent problem to be solved. Due to the different functions of the DC power grids in each region, the different technologies adopted, and the different years of construction, the rated DC voltages of the DC power grids in each region will not be completely consistent. In order to interconnect DC grids of different voltage levels, a DC-DC converter is required. [0003] DC-DC converters and DC-DC autotransformers are usuall...

AI Technical Summary

Problems solved by technology

It can be seen that since all transmitted DC power needs to undergo two-stage AC / DC conversion, the rated capacity of the voltage source converter and uncontrolled rectifier used in this unidirectional DC-AC-DC conversion technology is equal to the rated transmission power , the rated capacity of the AC link is also equal to the rated transmission power, so there are defects in the high investment cost of the converter, the high cost of the AC link, and the large operating loss

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