Novel direct-current power electronic transformer with direct-current short-circuit fault protection capability

Abstract

The invention discloses a novel direct-current power electronic transformer with a direct-current short-circuit fault protection capability. The novel direct-current power electronic transformer is mainly applied to voltage conversion and power management among a medium-voltage direct-current bus, a high-voltage direct-current bus and a low-voltage direct-current bus. The power electronic transformer comprises a cascaded isolation DC / DC converter, a switching circuit and an energy consumption circuit, and the cascaded DC / DC converter adopts an input-series output-parallel connection mode so asto meet the use requirements of high voltage and high power in a power grid. The switching circuit is connected in series with the cascaded direct-current converter and is used for realizing connection and disconnection of the power electronic transformer; and the energy consumption circuit is connected in parallel with the cascaded direct-current converter and is used for realizing consumption and transfer of grid-side energy. The power electronic transformer provided by the invention is simple to control, and can realize active isolation and self-protection of faults when direct-current faults occur in input / output side lines, so that the dependence on a direct-current circuit breaker is reduced, and the construction cost of a power grid is reduced.

Description

technical field [0001] The invention relates to a novel direct-current power electronic transformer topology with direct-current short-circuit fault protection capability, which is suitable for fields such as flexible direct-current power grids, direct-current micro-grids, new energy grid-connected and the like, where medium and high-voltage direct current conversion is used. Background technique [0002] In recent years, flexible DC transmission technology and its application in DC grids have gradually become a research hotspot and have received extensive attention. Power Electronic Transformer (Power Electronic Transformer, PET) or also known as Solid State Transformer (Solid State Transformer, SST), as a key link in the flexible DC distribution network, can realize the voltage and voltage between the high and low voltage DC distribution network or microgrid. The flexible control and rapid management of power has important theoretical value and engineering significance. ...

AI Technical Summary

Problems solved by technology

However, when the voltage ratio is too large, this topology lacks electrical isolation inside and cannot block the fault current, so it is not suitable for high-power applications.

At the same time, the manufacturing process of high-voltage and large-capacity DC circuit breakers is still immature, and it is still difficult to realize the fault protection strategy based on DC circuit breakers

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