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Control method of modular multilevel converter based on power frequency fixed switching frequency

A modular multi-level, switching frequency technology, applied in the direction of converting AC power input to DC power output, output power conversion devices, electrical components, etc., can solve the problem of high switching frequency and unseen multi-level converters Issues such as control strategy, instability, etc.

Inactive Publication Date: 2014-05-28
XI AN JIAOTONG UNIV
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Problems solved by technology

However, the problem with this method is that the switching frequency is high and not fixed
The author of this paper has not seen a good control strategy for modular multilevel converters based on fixed switching frequency of line frequency

Method used

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  • Control method of modular multilevel converter based on power frequency fixed switching frequency
  • Control method of modular multilevel converter based on power frequency fixed switching frequency
  • Control method of modular multilevel converter based on power frequency fixed switching frequency

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Embodiment Construction

[0073] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0074] refer to figure 1 , 2 , 3, 4, the control method based on the power frequency fixed switching frequency modular multilevel converter in the present invention includes the modulation strategy that periodically shifts the pulse waveform and the capacitance of the rising or falling edge of the exchange pulse waveform Voltage balance control method. Specific steps are as follows:

[0075] The present invention provides a control method for a modular multilevel converter based on power frequency fixed switching frequency, which includes the following steps:

[0076] 1) Compile the initial parameter table of the pulse waveform:

[0077] 1.1. According to the characteristics of the pulse waveform in a power frequency cycle, set a set of parameters representing the pulse waveform as (γ k ,w k ), where γ k is the position of the center point of the pulse waveform,...

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Abstract

The invention discloses a control method of a modular multilevel converter based on a power frequency fixed switching frequency. The control method includes the steps that the modulation strategy that impulse waveforms are moved periodically is adopted, so that the characteristics of four impulse waveform parameters in one group are determined; specific values of the impulse waveform parameters are determined by referring to the latest level modulation strategy, fine adjustment is conducted on the impulse waveform parameters by the utilization of an impulse waveform parameter vector mode and according to an active energy equipartition principle, an impulse waveform parameter table is compiled, and under the condition that the total distortion rate of voltage harmonic is guaranteed, and automatic balancing of module absorbing power is achieved. A modulation ratio is determined by detecting the actual value of a power grid voltage and the actual value of a power grid current, the table is looked up according to the modulation ratio to obtain the impulse waveform parameters, then the impulse waveforms are moved periodically according to the corresponding principle and the number of sub-module cascades to obtain sub-module switching signals when capacitor voltage control does not exist, the control over the modular multilevel converter based on the power frequency fixed switching frequency is realized, and good reference value is provided for engineering application.

Description

technical field [0001] The invention relates to a high-voltage power quality controller in a modular multi-level topology structure and the field of high-voltage direct current transmission, in particular to a control method for a modular multi-level converter based on a fixed switching frequency of power frequency. Background technique [0002] With the progress of society and the development of industry, there are two major characteristics of the modern power system: the huge power transmission and distribution system, and the continuous improvement of the voltage and power level of the power system. First of all, the demand for electricity in modern society is increasing. In order to meet the increasing demand of users for electricity, the power system has become larger and wider, and the coverage area has become wider and wider. This brings challenges to the stability of the power system. At the same time, due to my country's vast territory and unbalanced distribution o...

Claims

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Application Information

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IPC IPC(8): H02M7/219
Inventor 刘进军杜思行刘腾
Owner XI AN JIAOTONG UNIV
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