MMC control method under unbalanced power grid voltage based on Lyapunov function

A technology of grid voltage and control method, applied in the direction of power transmission AC network, electrical components, circuit devices, etc., can solve the problems of voltage fluctuation, power fluctuation, affecting system stability and power quality, etc.

Active Publication Date: 2018-09-25
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when the grid voltage is unbalanced, for the outside of the MMC, problems such as current three-phase asymmetry and power fluctuations will occur on the AC side, and the voltage on the DC side will also fluctuate, which seriously affects the stability of the system and power quality.

Method used

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  • MMC control method under unbalanced power grid voltage based on Lyapunov function
  • MMC control method under unbalanced power grid voltage based on Lyapunov function
  • MMC control method under unbalanced power grid voltage based on Lyapunov function

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Embodiment

[0091] Such as figure 1 The topology diagram of MMC is shown. The modular multilevel converter (MMC) includes three bridge arms a, b, and c. Each bridge arm is composed of upper and lower bridge arms. Each bridge arm is composed of multiple sub-modules. The topology of the module is as follows figure 2 shown.

[0092] A kind of MMC control method under unbalanced grid voltage based on Lyapunov function, this method comprises the following steps:

[0093] (1) Establish MMC mathematical model;

[0094] (2) obtain the steady-state value of the MMC switch function according to the MMC mathematical model;

[0095] (3) Determine the fluctuation amount of the MMC switch function based on the Lyapunov function;

[0096] (4) Determine the control value of the MMC switch function according to the steady-state value of the MMC switch function and the magnitude of the fluctuation of the MMC switch function, and control the work of the MMC according to the control value of the switch ...

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Abstract

The invention relates to an MMC control method under unbalanced power grid voltage based on a Lyapunov function. The method comprises the following steps: (1) an MMC mathematical model is built; (2) according to the MMC mathematical model, the steady-state value of an MMC switching function is acquired; (3) based on the Lyapunov function, the fluctuation quantity of the MMC switching function is determined; and (4) according to the steady-state value of the MMC switching function and the fluctuation quantity of the MMC switching function, the control value of the MMC switching function is determined, and according to the control value of the switching function, the MMC is controlled to work. Compared with the prior art, the method has the advantages that the response speed is quick, the robustness is strong, the system has a simple structure, the physical meaning is clear, the cost is low, realization is easy and the like.

Description

technical field [0001] The invention relates to an MMC control method, in particular to a Lyapunov function-based MMC control method under unbalanced grid voltage. Background technique [0002] Compared with AC transmission, DC transmission has many advantages, such as: it can quickly and accurately control the transmission power to improve the stability of the system; when using DC transmission, there is no need to consider the frequency and phase of the connected AC system. Relying on the DC transmission system of the modular multilevel converter (MMC), a large number of levels is realized, and the power quality is high; and a common DC side can be provided, which is easy to realize back-to-back connection. However, when the grid voltage is unbalanced, for the outside of the MMC, problems such as current three-phase asymmetry and power fluctuations will occur on the AC side, and the voltage on the DC side will also fluctuate, which seriously affects the stability of the sy...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36H02J3/26H02J3/24
CPCH02J3/24H02J3/26H02J3/36H02J2003/365H02J2203/20Y02E40/50Y02E60/60
Inventor 程启明孙伟莎陈路李涛魏霖沈磊王玉娇
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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