Communication method between sub-module controller and upper controller suitable for modular multilevel converter

Abstract

The invention discloses a method applicable to communication between a sub-module controller and an upper layer controller of a modular multi-level converter. The modular multi-level converter is composed of six bridge arms in three phases, each phase comprises an upper bridge arm and a lower bridge arm, and each bridge arm comprises N sub-modules in series connection and an alternating-current reactor. The communication method includes the steps that high-speed information interaction between the upper layer controller and the sub-module controller is completed through two optical fibers, the first optical fiber forms a channel from the upper layer controller to the sub-module controller, and the upper layer controller sends command information to the sub-module controller through the channel; the second optical fiber forms a channel from the sub-module controller to the upper layer controller, and the sub-module controller sends sub-module capacitance and voltage information and sub-module state information to the upper layer controller through the channel. On the premise that a synchronization mechanism between sub-modules is not added, multiplexing of the optical fibers is achieved, the number of the used optical fibers between the sub-module controller and the upper layer controller is reduced to two from three, and thus economic cost and space cost are saved. Moreover, the method is applicable to three-level control and two-level control schemes of a modular multi-level converter system and has certain promotional value.

Description

technical field [0001] The invention relates to a communication method between a sub-module controller and an upper-layer controller suitable for a modular multilevel converter (MMC), and belongs to the technical field of power systems. Background technique [0002] The modular multilevel converter (ModularMultilevelConverter, MMC) is a voltage source converter with a new topology. MMC is a three-phase six-arm converter. Each phase is composed of upper and lower bridge arms. Each bridge arm is composed of N sub-modules connected in series and an AC reactor. Each sub-module is a two-port unit but does not have to Limited to half-bridge or full-bridge structures. The traditional half-bridge sub-module includes a half-bridge structure composed of two insulated gate bipolar transistors (IGBT1, IGBT2) connected in series with anti-parallel diodes, and a capacitor connected in parallel with the half-bridge. [0003] In view of the fact that MMC not only retains the highly modula...

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Problems solved by technology

[0009] The purpose of the present invention is to overcome the shortcomings of the existing MMC system-level control, such as the large amount of fiber usage, and provide a communication between the sub-module controller and the upper-layer controller suitable for modular multilevel converters (MMC) method

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