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Modular multi-level back-to-back current converter and control method thereof

A modular multi-level, control method technology, applied in the direction of AC power input conversion to AC power output, wind power generation, electrical components, etc., can solve the high requirements of capacitor capacitance, complex inverter structure, and cost Expensive and other problems, to achieve the effect of improving power quality, reducing the number, and simplifying the internal structure

Active Publication Date: 2017-01-25
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, due to the large number of sub-modules in the existing modular multi-level back-to-back converter, the internal structure of the converter is complicated, and the capacitance of the capacitor is high, so the cost of manufacturing the converter is expensive

Method used

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  • Modular multi-level back-to-back current converter and control method thereof
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  • Modular multi-level back-to-back current converter and control method thereof

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Embodiment 1

[0037] see figure 2 , Embodiment 1 of the present invention provides a modular multi-level back-to-back converter, the modular multi-level back-to-back converter includes six bridge arms A~F, and the six bridge arms A~F are cascaded to form six polygon, wherein the sixth bridge arm F is connected to the connection end R of the first bridge arm A, the connection end S of the second bridge arm B to the third bridge arm C, and the connection between the fourth bridge arm D and the fifth bridge arm E The terminal T is the three current inflow terminals on the primary side of the three-phase AC system, the connection terminal W between the first bridge arm A and the second bridge arm B, the connection terminal U between the third bridge arm C and the fourth bridge arm D, and the fifth bridge arm A The connection terminal V between the bridge arm E and the sixth bridge arm F is the three current outflow terminals of the secondary side of the three-phase AC system.

[0038] Each of...

Embodiment 2

[0046] Embodiment 2 of the present invention provides a control method for the modular multilevel back-to-back converter of Embodiment 1.

[0047] In order to ensure that the average voltage of each sub-module SM is constant, it is necessary to control the power flowing in from the primary side to be equal to the power flowing out from the secondary side. This is also the basic principle in the control method of the present invention. The specific analysis is as follows:

[0048] The average power of each sub-module SM is as follows:

[0049] P A C E = P A = P C = P E ...

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Abstract

The invention provides a modular multi-level back-to-back current converter and a control method thereof, and relates to the technical field of power electronics. The modular multi-level back-to-back current converter and the control method solve the problems of great quantity of sub modules, structure complexity and the like of the existing modular multi-level back-to-back current converter. The current converter comprises six bridge arms, wherein the six bridge arms are in cascade connection to form a hexagon; the connecting ends of the adjacent bridge arms are sequentially set into three current flowing-in ends of the primary side of a three-phase alternating current system and three current flowing-out ends of the secondary side of the three-phase alternating current system in turns. The control method comprises the following steps of measuring / calculating a current reference value between any two ends in the current converter, and active current reference values and circulating current reference values of sub modules; calculating current reference values and voltage reference values of the sub modules; balancing the voltage of the sub modules in all the bridge arms. The modular multi-level back-to-back current converter and the control method provided by the invention have wide application prospects in aspects of large-scale wind power integration, power grid interconnection, electricity transaction, urban distribution network capacity increase, electric energy quality improvement and the like.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a modular multilevel back-to-back converter and a control method thereof. Background technique [0002] The modular multilevel back-to-back converter is a modular multilevel converter with zero transmission line length. It is composed of multiple bridge arms with the same structure. The upper bridge arm and the lower bridge arm of each bridge arm They are composed of multiple sub-modules cascaded in the same number. By separately controlling the state of each sub-module, the AC voltage output by the converter can be close to a sine wave, thereby reducing the harmonic content in the output voltage and solving the problem of two-level voltage sources. The problem of series voltage equalization in the converter has broad application prospects. At present, modular multilevel back-to-back converters have been applied in asynchronous networking and back-to-back networking pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M5/458
CPCY02E10/76H02M5/4585
Inventor 罗雨朱喆许树楷杨柳魏伟
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD