Symmetrical bipolar mmc-hvdc device, system and fault ride-through control method

Abstract

The invention discloses a symmetrical bi-polar MMC-HVDC apparatus, system and fault ride-through control method. The apparatus herein includes a first positive converter, a second positive converter, a first negative converter, and a second negative converter. When a pole-to-pole short circuit fault happens at a DC side, the polarity of the DC voltage of one polar converter is reversed and the polarity of the DC voltage of another polar converter stays, counter electromotive force offsets fault current, a positive power stage and a negative power stage formed through leads are intended for transmitting power, such that no power shortage is generated during pole-to-pole fault period; and when a pole-to-ground short circuit fault happens to a DC side, the amplitude and raising rate of a fault current can be suppressed by connecting to a high resistance, also the polarity of the DC voltage of the fault pole converter is reversed, the polarity of the DC voltage of the non-fault converter stays, the over-voltage of the non-fault pole is suppressed, the positive power stage and the negative power stage formed by leads are intended for transmitting power, such that no power shortage is generated during pole fault period.

Description

technical field [0001] The invention belongs to the technical field of multilevel power electronic converters, and more specifically relates to a symmetrical bipolar MMC-HVDC device, system and fault ride-through control method. Background technique [0002] The Modular Multilevel Converter Based High Voltage Direct Current (MMC-HVDC) system based on the modular multilevel converter has become a flexible DC system due to its advantages in system loss, capacity upgrade, electromagnetic compatibility, and fault management. Preferred technology in power transmission. Its development in my country is characterized by high voltage, long distance, large capacity and overhead lines. [0003] Compared with the MMC-HVDC system with symmetrical unipolar wiring, the MMC-HVDC system with symmetrical bipolar wiring has the advantages of large transmission capacity and good redundancy of system equipment. For transmission line faults, since the two converters of each pole can operate in...

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Problems solved by technology

[0007] Aiming at the defects of the prior art, the object of the present invention is to provide a symmetrical bipolar MMC-HVDC device, system and fault ride-through control method, aiming at solving the problem of using one pole switching of the symmetrical bipolar MMC-HVDC when a fault occurs in the prior art. Symmetrical bipolar MMC-HVDC has serious active power and reactive power shortage technical problems due to out-of-service converter or two-stage converter

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