Submodule grouped voltage-sharing control method for modular multi-level current converter

Abstract

The invention discloses a submodule grouped voltage-sharing control method for a modular multi-level current converter, and belongs to the technical field of power transmission and distribution. According to the technical scheme, the method comprises the following steps: performing average grouping on submodules according to the number of bridge arm submodules, and acquiring voltage values of each group of submodules; calculating total voltage of each group, a bridge arm voltage sum and energy balance factors of each group, obtaining the number of submodules to be switched according to a modulation strategy, and calculating the number of submodules to be switched of each group; and finally, sequencing each group of submodules according to the voltage values, and switching each group of submodules according to the number of submodules to be switched of each group. The method has the beneficial effects that on the premise that the current converter runs normally, an energy balance factor is introduced, and the bridge arm submodules are subjected to a grouped voltage-sharing strategy, so that the aims of increasing the capacitance and voltage sequencing speed of the submodules, balancing energy between the modules and improving the capacitance and voltage fluctuation situation of the submodules can be fulfilled.

Description

Technical field [0001] The invention belongs to the technical field of power transmission and distribution, and particularly relates to a sub-module grouping voltage equalization control method of a modular multilevel converter. Background technique [0002] In recent years, high-voltage and high-power fully controlled power electronic devices such as IGBTs and IGCTs have been widely used in long-distance power transmission systems and low-voltage distribution networks, especially in high-voltage direct current transmission based on voltage source converters (VSC- HVDC) technology. Compared with the traditional two-level and three-level VSC-HVDC, the modular multi-level converter (MMC) (sub-module is a half-bridge structure) topology proposed by Siemens has the advantages of direct series connection without a large number of IGBTs, and the device withstands voltage The current change rate is low, and no filter is needed. At the same time, under the same voltage level, it needs ...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the technical problems that when the modular multi-level converter described in the background technology realizes a higher level, the number of bridge arm sub-modules is too large, the sorting speed of the sub-module capacitor voltage is slow, and the energy balance of the sub-modules is difficult, the present invention proposes A sub-module group voltage equalization control method for modular multilevel converters

Images