A MMC zero DC voltage fault ride-through control method under asymmetric state of bridge arm parameters

A technology of DC voltage and control method, applied in the direction of converting AC power input to DC power output, electrical components, power transmission AC network, etc., can solve the problems of difficult voltage equalization of bridge arm sub-modules and non-zero DC side output voltage.

Active Publication Date: 2019-10-11
XI AN JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the problem that when the full-bridge MMC bridge arm parameters are asymmetrical, it is difficult to equalize the voltage of the upper and lower bridge arm sub-modules during the zero DC voltage fault ride-through process, and the output voltage of the DC side is not zero, the present invention proposes a bridge arm parameter asymmetry The MMC zero-DC voltage fault ride-through control method in the state ensures that the MMC clears the fault current during the zero-DC voltage fault ride-through process, continues to provide reactive power support to the AC system, and maintains the energy balance of the sub-modules

Method used

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  • A MMC zero DC voltage fault ride-through control method under asymmetric state of bridge arm parameters
  • A MMC zero DC voltage fault ride-through control method under asymmetric state of bridge arm parameters
  • A MMC zero DC voltage fault ride-through control method under asymmetric state of bridge arm parameters

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Embodiment

[0048] According to the description of the present invention, the three-phase symmetrical capacitor voltage self-balancing topology is applied in the simulation example as figure 1 As shown, the AC side is connected to the rated voltage of the 380V AC grid, and the rated voltage of the DC side is 700V; an 11-level structure is adopted, that is, the upper and lower bridge arms of each phase are composed of 10 sub-full bridge modules, the sub-module capacitance is 3300μF, and the sub-module capacitance The rated voltage is 70V; the bridge arm reactor is 20mH; when the bridge arm parameters are completely symmetrical, both the traditional control method and the method proposed by the present invention can realize energy balance. Set the loss of the lower bridge arm of phase A to increase by 10W, that is, the parameters of the upper and lower bridge arms of phase A are asymmetrical. The matlab / Simulink simulation results are as follows. After the system runs stably, refer to Figu...

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Abstract

The invention discloses an MMC zero-DC voltage fault ride-through control method under the condition of bridge arm parameters asymmetric topology; in the process of zero DC voltage fault ride-through, the auxiliary circuit between the bridge arms maintains the energy balance of the three upper bridge arms and the energy balance of the three lower bridge arms; and then adjusts the voltage deviation of the upper and lower bridge arms to make the overall voltage balance of all modules , to ensure that the fault current is cleared during the MMC zero-DC voltage fault ride-through process, continue to provide reactive power support to the AC system, and maintain the energy balance of the sub-modules, especially when the MMC bridge arm parameters are asymmetrical, the topology and its control method can still achieve 6 Each bridge arm shares the voltage deviation caused by the asymmetry of the bridge arm parameters, maintains the overall balance of energy, limits the short-circuit current to a very low level, and achieves zero DC voltage fault ride-through.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission, and in particular relates to an MMC zero direct current voltage fault ride-through control method under a state of bridge arm parameter asymmetry. Background technique [0002] Flexible DC transmission technology (voltage sourced converter based high voltage direct current, VSC-HVDC) is one of the key technologies for building Energy Internet and DC distribution network. Modular multilevel converter (MMC) relies on the static The advantages of voltage equalization, high efficiency, and low electromagnetic interference have become the main topology of the flexible HVDC converter station. During the development of VSC-HVDC technology, DC short-circuit fault ride-through is one of the important issues currently facing. Although the half-bridge sub-module used in the traditional MMC topology has the advantages of low cost and high efficiency, it does not have DC fault rid...

Claims

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Application Information

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Patent Type & AuthorityPatents(China)
IPC IPC(8): H02M7/483H02M1/32H02J3/36
CPCH02J3/36H02M1/32H02M7/483H02M1/322H02M7/4835Y02E60/60
Inventor王跃段国朝尹太元尹诗媛周晖王璋
OwnerXI AN JIAOTONG UNIV