A Novel Modular Multilevel Converter Sub-module Topology Circuit and Its Control Method

Abstract

A novel modular multilevel converter sub-module topology circuit and its control method. The invention relates to the field of DC transmission and distribution protection and control of power systems, in particular to an MMC sub-module topology circuit with DC side fault ride-through capability and a control method thereof. Provided are a new modular multilevel converter sub-module topology circuit and a control method thereof with high modularization degree, higher reliability, stronger forward and reverse fault suppression current capability, and more balanced. Including an incoming line port X and an outgoing line port Y, at least two half-bridge sub-modules are connected in series between the incoming line port X and the outgoing line port Y, the half-bridge sub-module has an input port, an output port 1 and an output port 2, The power switch device can be IGBT or MOSFET. The invention has strong fault current suppression ability.

Description

technical field [0001] The invention relates to the field of protection and control of direct current transmission and distribution of power systems, in particular to an MMC sub-module topology circuit with direct current side fault ride-through capability and a control method thereof. Background technique [0002] With the continuous increase of new energy power generation and DC load, the application of DC transmission and distribution network and AC-DC hybrid distribution network is getting more and more attention. The modular multilevel converter (MMC) is popular at home and abroad because of its simple modular structure, good scalability, low switching frequency, low loss, good harmonic characteristics and power quality regulation ability. Scholars welcome, and are widely used in DC transmission system and DC power distribution system. However, although the MMC with the traditional half-bridge sub-module structure has a low number of components and low cost and loss, i...

AI Technical Summary

Problems solved by technology

[0008] 1. Regardless of whether the fault current is forward or reverse, the fault current will flow through the anti-parallel diode in the MMC power switch sub-module, which will easily cause damage to the MMC power switch sub-module and reduce the reliability of the converter

[0009] 2. The switching device T in the circuit 3 and diode D 8 The withstand voltage is twice the withstand voltage of the switching device in the half-bridge module, that is, twice the capacitor voltage of the sub-module. Therefore, it is necessary to select a switching device with a higher voltage level, or use multiple switching devices in series to increase the configuration. cost, difficult to configure

Features that cannot be truly modularized

[0010] 3. When the fault current reverses at the same time, only C 1 and C 2 Two sub-module capacitors are connected in series to the MMC bridge arm, C 3 and C 4 is bypassed, therefore, the fault current suppression ability is weak

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