Current active transfer mmc power electronic transformer with fault blocking capability

Abstract

The invention discloses a current active transfer type MMC power electronic transformer with a fault blocking capability. The current active transfer type MMC power electronic transformer comprises amodular multilevel converter, which comprises an A-phase upper bridge arm, an A-phase lower bridge arm, a B-phase upper bridge arm, a B-phase lower bridge arm, a C-phase upper bridge arm and a C-phaselower bridge arm, wherein each of the A-phase upper bridge arm, the A-phase lower bridge arm, the B-phase upper bridge arm, the B-phase lower bridge arm, the C-phase upper bridge arm and the C-phaselower bridge arm comprises an inductor and a plurality of half-bridge sub-modules HB connected in series, and the modular multilevel converter further comprises a cutoff branch, an energy absorption branch and a bridge arm blocking branch. According to the invention, the defects that the half-bridge MMC cannot block a direct-current short-circuit fault and a scheme of adopting a direct-current circuit breaker or an improved sub-module is immature in technology, too high in cost, complex in control and the like are overcome, the direct-current short-circuit fault can be quickly eliminated, fewadditional power electronic devices are added, and the control is simple.

Description

technical field [0001] The invention relates to the technical field of modularized multilevel converters, in particular to an active current transfer type MMC power electronic transformer with fault blocking capability. Background technique [0002] MMC (Modular Multilevel Converter) has the advantages of dynamic reactive power support, active and reactive power control decoupling, and excellent output harmonic characteristics, so it is widely used in the field of flexible DC power transmission and distribution. However, the unique " The characteristics of "low damping" and "low inertia" lead to its rapid development of faults; at the same time, considering the needs of various forms of long-distance and large-scale new energy grid integration, it is more appropriate to use overhead lines as a transmission method. But overhead lines are more prone to short-circuit faults than cables. If the converter still uses the half-bridge MMC, the fault current cannot be cleared even i...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a current active transfer type MMC power electronic transformer with fault blocking capability for the above deficiencies, which solves the problem that the half-bridge type MMC cannot block DC short-circuit faults, adopts DC circuit breakers or improves sub-modules The solution also has shortcomings such as immature technology, high cost, and complicated control. It can quickly clear DC short-circuit faults, and has few additional power electronic devices and simple control.

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