Sub-module topology structure and method for flexible DC power transmission converter valve

Abstract

The invention provides a sub-module topology structure and method for a flexible DC power transmission converter valve. The sub-module topology structure comprises a full-bridge structure sub-module (1) and a half-bridge structure sub-module (2) which are mutually connected, wherein an AC end A2 of the full-bridge structure sub-module (1) is connected with a DC end positive electrode D21 of the half-bridge structure sub-module (2), and a DC end negative electrode D12 of the full-bridge structure sub-module (1) is connected with a DC end negative electrode D22 of the half-bridge structure sub-module (2) through a diode D7. Through an additional diode, the full-bridge and half-bridge hybrid topology is reconstructed into a new topology capable of inhibiting a fault current, in the fault current inhibition process, voltage balance can be automatically kept in two capacitors of the sub-module, and problems of voltage imbalance and the overhigh withstanding voltage can be avoided.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission and power electronics application, in particular to a sub-module topology structure for a flexible direct current transmission converter valve. Background technique [0002] The flexible DC transmission system based on the MMC voltage source converter has excellent performances such as power supply to passive systems or weak AC systems, fast independent control of active power and reactive power, easy construction of multi-terminal networks and environmental friendliness, and the transmission voltage of MMC-HVDC systems The harmonic content is extremely low, and there is no need to configure additional filters, which makes the MMC-based flexible DC transmission have broad application prospects in the field of power transmission. The core component of MMC-HVDC is the power sub-module on the bridge arm (hereinafter referred to as the sub-module). Currently, the commonly ...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the problems described in the background technology, the present invention provides a sub-module topology structure for flexible direct current transmission converter valves. Based on the patent CN201420288038, the hybrid topology of the full bridge and the half bridge is modified by an additional diode. A new topology that can suppress the fault current, and in the process of suppressing the fault current, the two capacitors in the sub-module automatically maintain voltage balance, avoiding the problems of voltage imbalance and high withstand voltage

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