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Passive control method for MMC under unbalanced grid voltage

A grid voltage and passive control technology, applied in the direction of circuit devices, AC network circuits, multi-phase network asymmetry reduction, etc., can solve the problems of affecting output characteristics, current and power fluctuations, increasing converter losses, etc.

Inactive Publication Date: 2018-05-01
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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Problems solved by technology

However, when the grid voltage is unbalanced, for the outside, the current and power of the AC side will fluctuate, and the voltage of the DC side will also fluctuate, seriously affecting the stability of the system and power quality; for the inside, the bridge arm will appear to contain a large number of The circulating current of the harmonic component will also fluctuate the capacitor voltage of the sub-module, which increases the loss of the converter and affects the output characteristics

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  • Passive control method for MMC under unbalanced grid voltage
  • Passive control method for MMC under unbalanced grid voltage
  • Passive control method for MMC under unbalanced grid voltage

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Embodiment Construction

[0113] The technical solutions in the embodiments of the present invention are clearly and completely described below in combination with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0114] The present invention relates to a kind of MMC passive control method under unbalanced grid voltage, and this method comprises the following steps:

[0115] Step 1: Establish the mathematical models of the MMC AC side and DC side;

[0116] MMC consists of six upper and lower bridge arms, and each bridge arm has the same number of sub-modules (Sub-Module, SM), such as figure 1 shown. The SM consists of two IGBT half-bridges with antiparallel...

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Abstract

The invention relates to a passive control method for an MMC under unbalanced grid voltage, which comprises the steps of S1, respectively building an AC-side mathematical model and a DC-side mathematical model of the MMC based on the Kirchhoff law according to a topological structure of the MMC; S2, transforming the AC-side mathematical model of the MMC into an AC-side mathematical model under a dq two-phase rotating coordinate system according to a coordinate transformation theory; S3, building an EL model of the MMC under a condition that the grid voltage is unbalanced; S4, performing passivity judgment on the MMC under the balanced grid voltage, and adopting passive control on the MMC if the MMC is strictly passive; and S5, designing a positive and negative sequence passive controller for the MMC requiring passive control according to the EL model acquired in the step S3. Compared with the prior art, the passive control method has the advantages of no power fluctuation, high steadyspeed, good control effect and the like.

Description

technical field [0001] The invention relates to the technical field of MMC converter control, in particular to an MMC passive control method under unbalanced grid voltage. Background technique [0002] Compared with AC transmission, DC transmission has many advantages. For example, using DC transmission can quickly and accurately control the transmission power, thereby improving the stability of the system; when using DC transmission, there is no need to consider the frequency and phase of the connected AC system. With the rapid development of renewable energy power generation such as large wind farms in recent years, the advantages of direct current transmission have been widely explored and are increasingly used in modern power transmission. With the development of power electronic devices, DC transmission technology is becoming more and more advanced, from two-level converters to three-level converters to today's modular multi-level converters, modular multi-level convert...

Claims

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Application Information

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IPC IPC(8): H02J3/26
CPCH02J3/26H02J2203/20Y02E40/50
Inventor 程启明孙伟莎程尹曼陈路李涛
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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