A DC fault ride-through control method for hybrid modular multilevel converters

Abstract

The invention relates to a DC fault ride-through control method for a hybrid modular multilevel converter. The control method of the present invention realizes the balance of the capacitance voltage of the half-bridge and full-bridge structural sub-modules in the bridge arm during the steady state by controlling the input and removal of the half-bridge and full-bridge structural sub-modules in the bridge arm; Effective control of DC current voltage. Based on the effectively operating half-bridge and full-bridge sub-modules, by tracking the capacitance voltage of the half-bridge sub-modules and full-bridge sub-modules in the same bridge arm, and monitoring the fault status of the DC side, dynamically allocate the half-bridge sub-modules in the same bridge arm Modules and full-bridge sub-modules input number instructions. The invention realizes the voltage balance control of the half-bridge and full-bridge structure sub-modules in each bridge arm of the hybrid modular multilevel converter during the steady state, and at the same time ensures the effective control of the AC side current during the DC bipolar fault period, The continuous operation of the converter can be guaranteed, and the converter will not be blocked due to failure.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission in power systems, in particular to a direct current fault ride-through control method for a hybrid modular multilevel converter. Background technique [0002] The half-bridge and full-bridge structure sub-module hybrid modular multilevel converter (Cell Hybrid Modular Multilevel Converter, CH-MMC) adopts a new type of multilevel topology that is currently more popular in the world. Its core unit—submodule (Sub Module, SM) is divided into two types. One is a half-bridge sub-module (Half Bridge Sub-Module, HBSM, figure 1 3); the other is a full bridge sub-module (Full Bridge Sub-Module, FBSM, figure 1 4). Several half-bridge structure sub-modules are cascaded to form a half-bridge structure sub-module valve section (HBSM Valve); several full-bridge structure sub-modules are cascaded to form a full-bridge structure sub-module valve section (FBSM Valve); The structural...

AI Technical Summary

Problems solved by technology

[0007] The fundamental shortcomings of the above two control methods are: first, the robustness of the group control method is insufficient; second, the DC transient fault still needs to block the converter

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