A mmc circuit with dc fault clearing capability

Abstract

The invention discloses an MMC topological structure with direct current fault removing capability. Each phase comprises an upper bridge arm and a lower bridge arm; each bridge arm comprises a numberof half bridge submodules and bridge arm reactors that are connected in series, a first transistor and a fourth transistor are respectively connected to two ends of each bridge arm, a first diode is reversely connected in parallel between an emitting electrode and a collector electrode of the first transistor, a fourth diode is reversely connected in parallel between an emitting electrode and a collector electrode of a fourth transistor, an anode of a second diode is connected to the emitting diode of the fourth transistor, a cathode of the second diode is connected to the emitting diode of the first transistor, an anode of a third diode is connected to the collector electrode of the fourth transistor, and a cathode of a third diode is connected to the collector electrode of the first transistor. The MMC topological structure disclosed in the invention can help correct deficiencies of technologies of the prior art, fault currents can be rapidly cleared, and fast reclosing can be easilyrealized.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to an MMC circuit capable of clearing DC faults. Background technique [0002] As the penetration rate of distributed power supply and power electronic equipment continues to increase, the problems of traditional AC distribution network in terms of power supply efficiency, power quality and transmission capacity have become increasingly prominent. The DC distribution network will play an important role in the future power grid due to its advantages of low operating cost, flexible control, and high utilization rate of new energy. Modular Multilevel Converter (MMC) has been successfully applied in flexible direct current transmission systems. Its modular design, good scalability, low device switching frequency, good harmonic characteristics and many other advantages make it It will also have broad application prospects in the DC distribution network. [0003] Since the dis...

AI Technical Summary

Problems solved by technology

After the fault is blocked, only the capacitor of the full-bridge sub-module in the hybrid MMC circuit is introduced into the fault circuit, the capacitor is charged, and the voltage rises, so the energy imbalance between the half-bridge sub-module and the full-bridge sub-module occurs, which increases the speed of rapid reclosing Difficulty of gate

In addition, the hybrid MMC circuit is relatively complex, which increases the difficulty of sub-module packaging and industrial design

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