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Title:
MMC HALF-BRIDGE SUB-MODULE CAPACITOR VOLTAGE RIPPLE MULTI-SCALE SUPPRESSION METHOD
Document Type and Number:
WIPO Patent Application WO/2022/161095
Kind Code:
A1
Abstract:
An MMC half-bridge sub-module capacitor voltage ripple multi-scale suppression method, comprising: firstly, collecting a three-phase voltage signal usj and a three-phase current signal isj on an alternating-current side, three-phase upper and lower bridge arm current signals ipj, inj, and a direct-current bus voltage signal udc; performing calculation to obtain expressions of instantaneous power Ppj and Pnj of upper and lower bridge arms; controlling the sum of the instantaneous power of the upper and lower bridge arms to be zero, so as to obtain a circulating current injection value i* cj; performing derivation on modulation functions spj and snj of the upper and lower bridge arms, and setting same to be 0 to obtain a function relationship among a moment tmax when a modulated wave reaches a peak value, m3 and φ3; and taking the maximum value of a modulation ratio and the sum of the numbers of sub-modules input into the upper and lower bridge arms at the moment t as constraint conditions, so as to obtain optimal injected third harmonics. By means of the cooperation of two injection modes, the direct-current voltage utilization rate of an MMC can be effectively improved, and it is guaranteed that the peak value of a modulated wave of the system is not increased due to circulating current injection, thereby realizing a better capacitor voltage fluctuation suppression effect.

Inventors:
LIU RUIKUO (CN)
ZOU ZUBING (CN)
ZHANG WEI (CN)
SUN CHANGPING (CN)
LIU XIQUAN (CN)
SUN YONG (CN)
Application Number:
PCT/CN2021/142796
Publication Date:
August 04, 2022
Filing Date:
December 30, 2021
Export Citation:
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Assignee:
CHINA THREE GORGES CORP (CN)
International Classes:
H02M1/15
Foreign References:
CN112787492A2021-05-11
CN110048582A2019-07-23
CN109660111A2019-04-19
US20180331632A12018-11-15
Other References:
LI ANG: "Research on Harmonic Voltages Injection and Capacitance Optimization in Modular Multilevel Converter", CHINESE MASTER'S THESES FULL-TEXT DATABASE, 15 January 2020 (2020-01-15), pages 1 - 72, XP055954025, ISSN: 1674-0246
YUAN BIN;MEI NIAN;CHEN DONG;LI TAN;ZHENG YIFEI: "Influences of Third Harmonic Injection on the Operation Characteristics of MMC System", HIGH VOLTAGE ENGINEERING, vol. 3, no. 46, 30 March 2020 (2020-03-30), pages 1060 - 1068, XP055954026, ISSN: 1003-6520, DOI: 10.13336/j.1003-6520.hve.20200331037
Attorney, Agent or Firm:
YICHANG THREE GORGES PATENT (CN)
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