Circulating-current restraining method for three-phase modular multilevel convertor

A multi-level converter and circulating current suppression technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the high cost of inductance, increase the high-voltage reactor, increase the Circulation impedance and other issues

Inactive Publication Date: 2010-10-06
ZHEJIANG UNIV
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Problems solved by technology

[0005] However, the above-mentioned method of only increasing the value of the bridge arm inductance to suppress the circulating current only passively increases the circulating current impedance, and it is impossible to completely eliminate the circulating current, and t

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  • Circulating-current restraining method for three-phase modular multilevel convertor
  • Circulating-current restraining method for three-phase modular multilevel convertor
  • Circulating-current restraining method for three-phase modular multilevel convertor

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Embodiment Construction

[0034] The specific implementation of the present invention will be described in detail below in conjunction with the drawings and examples, but the present invention is not limited by the specific examples.

[0035] Such as figure 1 As shown, the three-phase modular multilevel converter consists of six bridge arms in three phases a, b, and c, and each phase has two upper and lower bridge arms. Each bridge arm 1 consists of a bridge arm series inductor L 0 It is formed by cascading with N submodules 2. The sub-modules SM1~SMN have the same structure, and each sub-module 2 consists of a first power electronic switch T 1 , the second power electronic switch T 2 (T 1 , T 2 Select a power electronic switch with self-shutoff capability, usually IGBT, IGCT, GTO, etc., the present invention uses IGBT), a diode D connected in antiparallel with the first power electronic switch 1 , a diode D connected in antiparallel with the second power electronic switch 2 And the DC capacitor...

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Abstract

The invention discloses a circulating-current restraining method for a three-phase modular multilevel convertor. The method comprises the following steps of: processing detected bridge current by utilizing fundamental frequency-doubled rotating coordinates transform based on negative sequences, and then performing signal processing and feedforward compensation link so as to acquire an additional control signal used for restraining circulating current; subtracting the additional control signal from a half of a DC voltage value, superposing an output voltage reference signal on the AC side of the existing converter to acquire a bridge voltage reference signal, and performing pulse width modulation to acquire trigger pulses of various bridges of the converter to ensure that the converter outputs corresponding voltage. The circulating-current restraining method can restrain the circulating current in the converter in a low level under the condition of not increasing the inductance of the bridges so as to basically eliminate the distortion of the bridge current to make the bridge current restored into sinusoidal waveform.

Description

technical field [0001] The invention relates to the technical fields of flexible power transmission and distribution of power systems, power electronics and user power, and in particular to a method for suppressing circulation of three-phase modular multilevel converters. Background technique [0002] Modular multilevel converter (MMC) is a multilevel converter topology that has attracted much attention in recent years. It uses multiple submodules (submodules, SM) cascaded, and by controlling the input and disconnection states of each submodule separately, it can make the AC voltage waveform output by the converter contain many voltage steps to approach the sine wave to the maximum extent. Thereby reducing the harmonic content in the output voltage and reducing the waveform distortion to meet the harmonic requirements of the power grid. [0003] The basic structure of a three-phase modular multilevel converter (such as figure 1 Shown) is composed of three-phase six bridge ...

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Application Information

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IPC IPC(8): H02J3/01
CPCH02M2001/0003H02M2007/4835H02M1/14H02M1/0003H02M7/4835
Inventor 徐政屠卿瑞翁华黄弘扬薛英林
Owner ZHEJIANG UNIV
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