Isolated modular multi-level converter

Abstract

The invention discloses an isolated modular multi-level converter, which comprises three phase units linked to high-voltage direct current ports (PH, NH) in parallel; every phase unit is composed of upper and lower bridge arms; outgoing lines of electric joint points (N1, N2, N3) of the upper and lower bridge arms of three phase units are high-voltage alternating current ports (a, b, c) after linking with filter inductors in series; every bridge arm is composed of a single-grade high frequency isolating type submodule with high-voltage direct current side fault current blocking ability and a bridge-arm reactor Lm; the single-grade high frequency isolating type submodule comprises a front grade part, a high-frequency transformer part and a back grade part; the back grade part can block failed current when the high-voltage direct current side has short-circuited failure, thus the failure at the direct current side is removed. The converter structure is simple, and the converter has the advantages that the isolated modular multi-level converter is free from the high-voltage-free side capacitor and voltage-sharing control, and others; the high-voltage direct current side failure voltage can be rapidly cut off.

Description

technical field [0001] The invention relates to the technical field of isolated modular multi-level power conversion, in particular to an isolated modular multi-level converter with high-voltage DC side fault current blocking capability. Background technique [0002] The isolated modular multilevel converter has the advantages of no need for high-voltage side capacitor support and voltage equalization control. However, when a short-circuit fault occurs on the high-voltage DC side, even if the active switch tubes of the subsequent stage are all turned off, the high-voltage AC side passes through the active switch. The diodes connected in anti-parallel will still feed short-circuit current to the fault point, which is equivalent to a three-phase AC short-circuit fault. In severe cases, the switch tube will be damaged and the converter will not work properly. Contents of the invention [0003] In order to solve the above problems, the present invention provides an isolated mo...

AI Technical Summary

Problems solved by technology

[0002] The isolated modular multilevel converter has the advantages of no need for high-voltage side capacitor support and voltage equalization control. However, when a short-circuit fault occurs on the high-voltage DC side, even if the active switch tubes of the subsequent stage are all turned off, the high-voltage AC side passes through the active switch. The diodes connected in anti-parallel will still feed short-circuit current to the fault point, which is equivalent to a three-phase AC short-circuit fault. In severe cases, the switch tube will be damaged and the converter will not work normally.

Images