Passive control method for MMC under unbalanced grid voltage

• Main Authors: SUN WEISHA, CHENG YINMAN, CHEN LU, CHENG QIMING, LI TAO
• Format: Patent
• Language: Chinese; English
• Published: 01.05.2018
• Subjects: CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERATION; REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGYGENERATION, TRANSMISSION OR DISTRIBUTION; SYSTEMS FOR STORING ELECTRIC ENERGY; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE

The invention relates to a passive control method for an MMC under unbalanced grid voltage, which comprises the steps of S1, respectively building an AC-side mathematical model and a DC-side mathematical model of the MMC based on the Kirchhoff law according to a topological structure of the MMC; S2, transforming the AC-side mathematical model of the MMC into an AC-side mathematical model under a dq two-phase rotating coordinate system according to a coordinate transformation theory; S3, building an EL model of the MMC under a condition that the grid voltage is unbalanced; S4, performing passivity judgment on the MMC under the balanced grid voltage, and adopting passive control on the MMC if the MMC is strictly passive; and S5, designing a positive and negative sequence passive controller for the MMC requiring passive control according to the EL model acquired in the step S3. Compared with the prior art, the passive control method has the advantages of no power fluctuation, high steadyspeed, good control effec