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Modular multilevel converter off-grid to grid-connection control method and system

A modular multi-level, control method technology, applied in the direction of single-network parallel feeding arrangement, etc., can solve the problems of weak system damping, power fluctuation, power oscillation and so on

Active Publication Date: 2020-11-13
BEIJING SIFANG JIBAO AUTOMATION +2
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the MMC in the constant voltage and constant frequency mode has power fluctuations when it is connected to the system, and the system damping is weak and even causes power oscillations and other problems.

Method used

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  • Modular multilevel converter off-grid to grid-connection control method and system
  • Modular multilevel converter off-grid to grid-connection control method and system
  • Modular multilevel converter off-grid to grid-connection control method and system

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Embodiment Construction

[0035] The application will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, but not to limit the protection scope of the present application.

[0036] Such as figure 1 As shown, the off-grid to grid-connected control method of a modular multilevel converter of the present application is applied to multi-terminal MMC off-grid with load operation and connected to the AC power grid, which can realize the online switching of the off-grid operation mode to the AC drooping synchronization mode, the AC droop synchronous mode is switched online to the grid-connected operation mode.

[0037] The AC droop synchronization mode, that is, the MMC operates in this mode when the off-grid operation mode is ready for synchronization, this mode integrates AC voltage amplitude reactive power droop, AC voltage frequency active power droop, AC voltage amplitu...

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Abstract

The invention discloses a modular multilevel converter off-grid to grid-connected control method and system, which are applied to multi-terminal MMC off-grid on-load operation and access to an AC power grid, and the method comprises the following steps: obtaining an MMC operation control instruction; when the MMC operation control instruction is an off-grid to grid-connected switching instruction,switching the corresponding MMC from an off-grid operation mode to an alternating-current droop synchronization mode, and automatically tracking the voltage amplitude and frequency of the alternating-current power grid; and when the MMC meets the voltage amplitude and frequency requirements required by grid connection, the MMC automatically completing grid connection, and after the grid connection action is completed, switching the MMC from an alternating current droop synchronization mode to a grid connection operation mode. An alternating-current droop synchronization mode and an MMC zero-impact grid-connected control method are provided for the off-grid to grid-connected conversion process of the MMC for the distribution network, it is guaranteed that alternating-current loads carriedby the MMC supply power continuously in the off-grid to grid-connected conversion process, and meanwhile zero impact is conducted on an alternating-current power grid.

Description

technical field [0001] The invention belongs to the technical field of MMC operation control, and relates to a control method and system for off-grid to grid-connected control of a modular multilevel converter. Background technique [0002] MMC is the basic equipment that constitutes the DC distribution network. Different from the application in flexible DC transmission, in the application of distribution network, MMC needs to have multiple functions such as grid-connected operation and off-grid operation. For supply transfer and other needs, MMC needs to have the ability to seamlessly switch between grid-connected to off-grid, off-grid to grid-connected and other operating modes. [0003] In the existing MMC off-grid to grid-connected solution, MMC adopts constant voltage and constant frequency mode to follow the voltage amplitude and frequency of the system, and performs grid-connected operation when the MMC off-grid voltage and system voltage meet the grid-connected requi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/40
CPCH02J3/40
Inventor 王一马彦宾王继慷李思刘树操丰梅梅红明王皆庆游涛王立超
Owner BEIJING SIFANG JIBAO AUTOMATION
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