Virtual impedance based DC-side fault current suppression method of modular multilevel converter (MMC)

A technology of virtual impedance and fault current, which is applied in the field of power transmission and distribution to achieve the effect of suppressing the rising speed

Active Publication Date: 2016-06-01
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The suppression of the fault current when the DC side of the MMC is faulty is realized through the control method, which is hardly involved in the existing research

Method used

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  • Virtual impedance based DC-side fault current suppression method of modular multilevel converter (MMC)
  • Virtual impedance based DC-side fault current suppression method of modular multilevel converter (MMC)
  • Virtual impedance based DC-side fault current suppression method of modular multilevel converter (MMC)

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Embodiment Construction

[0011] A virtual impedance-based MMC DC-side fault current suppression method involved in the present invention will be described in detail below. It should be emphasized that the following description is only exemplary and not intended to limit the scope of the invention and its application.

[0012] The technical problem to be solved by the present invention adopts the virtual impedance control strategy, based on the existing DQ decoupling control strategy, by adding the feedback link of active power control on the D axis, the system transfer function is corrected, and the feedback control is mapped to the primary system to form The virtual impedance parallel circuit can equivalently increase the DC bus impedance, thereby effectively suppressing the instantaneous rising speed of the DC current and the bridge arm current when a fault occurs on the DC side of the MMC. The present invention adopts following technical scheme to realize:

[0013] Step 1: Use the current sensor t...

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Abstract

The invention relates to a virtual impedance based DC-side fault current suppression method of a modular multilevel converter (MMC), belonging to the technical field of power transmission. A DC-side fault of the MMC can cause overcurrent of a switching device; and based on a traditional control strategy, a virtual impedance parallel circuit in a primary system is mapped to a controller by a feedback function, DC bus impedance is equivalently risen, thus, instantaneous rising speed of a fault current when a fault occurs in a DC side of the MMC is effectively prevented without increasing the fault current rising speed of other types of faults. In the core scheme, firstly, the DC bus voltage and current of a MMC system and the active power of a PCC point of an AC side are measured in real time; secondly, if the virtual impedance circuit is connected in series to a DC bus, the DC voltage deviation and the active power deviation are calculated when the DC current passes through the virtual circuit; and finally, the associated deviation correction quantity is additionally added to a measurement value of an active power type control quantity of a DQ decoupling controller for correction.

Description

technical field [0001] The invention belongs to the technical field of power transmission and distribution, and in particular relates to a virtual impedance-based MMC DC side fault current suppression method. Background technique [0002] Modular multilevel converter (ModularMultilevelConverter, MMC) has the advantages of high power transmission capacity, no need for a large number of IGBTs to be crimped and connected in series, low device withstand voltage change rate, and good harmonic characteristics, and has gradually become the development trend of flexible DC power transmission. . [0003] The fault of the DC side of the MMC will cause a large charge and discharge of the converter sub-modules at the sending end and the receiving end, and then cause the overcurrent of the switching device. Compared with AC faults, faults on the DC side of the MMC evolve very quickly after occurrence, which can easily affect the normal operation of the AC and DC sides of other connected...

Claims

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Application Information

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IPC IPC(8): H02M1/32
Inventor 赵成勇张帆苑宾许建中
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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