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

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...

AI Technical Summary

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

Images