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Source-network cooperation type capacitive direct-current circuit breaker suitable for MMC direct-current power grid

A DC power grid, capacitive technology, applied in power transmission AC network, emergency protection circuit device, AC power input conversion to AC power output and other directions, can solve the problem of large breaking current, high breaking speed requirements, and large energy dissipation. and other problems, to prevent deep discharge, reduce the risk of blocking, and enhance the fault ride-through capability.

Active Publication Date: 2021-08-06
TIANJIN UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to give full play to the control capability of the converter, solve the problems of large DCCB breaking current, large energy dissipation and high breaking speed requirements in the flexible DC power grid, and propose a source network suitable for MMC DC power grids The coordinated capacitive DC circuit breaker changes the number of sub-modules input by the converter through the control strategy during the DC fault period, so that the DC voltage at the converter outlet is equal to the voltage of the pre-charged capacitor on the grid side, providing favorable breaking for fast mechanical switches condition

Method used

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  • Source-network cooperation type capacitive direct-current circuit breaker suitable for MMC direct-current power grid

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Embodiment Construction

[0034] The technical solution of the invention will be described in detail below in conjunction with the embodiments and with reference to the accompanying drawings.

[0035] The invention combines the source-side MMC active voltage regulation control strategy and the network-side circuit breaker topology structure, provides low-voltage, zero-current breaking conditions for fast mechanical switches through the cooperation of the source network, realizes the effective removal of faulty lines, and reduces the fault current to commutation current. The impact of the station avoids the collapse of the bus voltage and ensures the normal operation of the non-fault lines.

[0036]figure 1 It is the topology diagram of the ±500kV four-terminal MMC DC grid system. Among them, grid-side circuit breakers are installed on each DC line, such as figure 1 As shown, the MMC DC power grid has four converter stations MMC1, MMC2, MMC3 and MMC4, and each converter station has two converters; the ...

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Abstract

The invention discloses a source-network cooperation type capacitive hybrid direct-current circuit breaker suitable for an MMC direct-current power grid. The MMC direct-current power grid is provided with four converter stations MMC, and each converter station is provided with two converters; the converters of the four converter stations are connected to form a square-shaped structure through double-loop direct-current overhead lines; the two ends of each direct-current line connected with the converters are respectively provided with source-network cooperation type capacitive hybrid direct-current circuit breakers used for adaptively cooperating with a source-side active voltage regulation control strategy to jointly eliminate an isolation fault when the direct-current line breaks down. According to the method, the self-adaptive cooperation of the MMC active voltage regulation control strategy and voltages of pre-charging capacitors is utilized, so that low-voltage and zero-current breaking conditions are provided for a rapid mechanical switch branch, effective removal of a fault line can be achieved, the influence of fault current on the converter stations is reduced, bus voltage collapse is avoided, and normal operation of a non-fault line is guaranteed.

Description

[0001] Technical field [0002] The invention belongs to the technical field of flexible DC power grid protection and control, and in particular relates to a source-network matching capacitive DC circuit breaker suitable for MMC DC power grids. Background technique [0003] In recent years, the new generation of power transmission technology represented by flexible DC has shown great development potential in long-distance and large-capacity power transmission occasions. The emergence of modular multilevel converters (MMC) has made flexible DC transmission continue to develop in the direction of high voltage and large capacity. MMC has become the preferred converter topology for long-distance large-capacity flexible DC transmission systems. It is widely used in the field of flexible direct current transmission. [0004] Due to the large-scale development of new energy and the need for long-distance power transmission, it is an inevitable trend in the future to use overhead lin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26
CPCH02H7/268H02M1/32H02M7/4835H02M5/4585H02J3/36H02H3/087Y02E60/60
Inventor 陈晓龙韩小文李永丽李斌李博通
Owner TIANJIN UNIV
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