Control method and control system for hybrid MMC uninterrupted operation

Abstract

The invention discloses a control method and a control system for hybrid MMC uninterrupted operation. The control method comprises the following steps: acquiring the alternating current output voltagereference values of each phase of upper and lower bridge arms, acquiring a direct current voltage reference value, acquiring the negative sequence frequency-doubled circulating current restraint reference voltage of each phase of upper and lower bridge arms, acquiring the zero sequence circulating current compensating potential reference value, and generating a driving signal. The control systemcomprises an alternating current control device, a direct current control device, a negative sequence circulating current restraint control device and a driving signal synthesis device which are usedfor acquiring the alternating current output voltage reference values of each phase of upper and lower bridge arms, the direct current voltage reference value, the negative sequence frequency-doubledcirculating current restraint reference voltage of each phase of upper and lower bridge arms, the zero sequence circulating current compensating potential reference value and the driving signal. Alternating current positive and negative sequence current can be uniformly controlled, alternating current negative sequence current and bridge arm zero sequence ring current are restricted, direct current side current is controlled, and uninterrupted operation is finally realized.

Description

technical field [0001] The invention belongs to the technical field of power transmission and distribution of electric power systems, and more specifically relates to a control method for uninterrupted operation of a hybrid MMC for AC asymmetric faults and DC faults. Background technique [0002] Modular multilevel converter (MMC) has the advantages of modular structure and easy expansion, and has been widely used in the field of flexible direct current transmission. Among various MMC topologies, the hybrid MMC based on Full bridge sub-module (FBSM) and Half bridge sub-module (HBSM) has good control characteristics. 1. The DC decoupling control method, which can not block the switching device IGBT and ride through the DC fault when the DC fault occurs, is a scheme with application prospects. [0003] At present, the modeling and control strategies of the hybrid MMC are based on the three-phase symmetrical power grid, and the probability of asymmetrical faults in the AC powe...

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Problems solved by technology

[0004] However, the above-mentioned solutions only control the electrical quantity on the AC side, and the control structure has defects, so it cannot control the electrical quantity on the DC side; moreover, none of the above-mentioned solutions has the ability to handle DC faults, and cannot guarantee that the hybrid MMC will operate in the AC side. Uninterrupted operation during symmetrical and DC faults

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