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Thermal balance control method for modular multilevel converter

A modular multi-level, control method technology, applied in the field of power system, can solve problems such as sub-module capacitance deviation, and achieve the effect of simple algorithm

Inactive Publication Date: 2018-12-04
SHENYANG POLYTECHNIC UNIV
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  • Abstract
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Problems solved by technology

In addition, the degradation of the capacitors during operation and the replacement of a disconnected submodule can further lead to significant deviations in the capacitance of the submodule

Method used

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  • Thermal balance control method for modular multilevel converter
  • Thermal balance control method for modular multilevel converter
  • Thermal balance control method for modular multilevel converter

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Embodiment Construction

[0034] The present invention is described in detail below in conjunction with accompanying drawing and specific embodiment:

[0035] figure 1 is a typical topology diagram of a modular multilevel converter MMC. figure 1 In the topology of the modular multilevel voltage source converter (MMC), each phase has two upper and lower bridge arms, and each bridge arm is composed of n half-bridge sub-modules and a bridge arm reactor L. where U dc is the DC side voltage.

[0036] figure 2 is the block diagram of the half-bridge sub-module. figure 2 , the half-bridge sub-module is composed of two IGBTs T 1 , T 2 , two antiparallel diodes D 1 、D 2 And a capacitor, the output voltage of a single half-bridge sub-module is the capacitor voltage U SM Or it is 0, so it can output two levels of 1 and 0.

[0037] image 3 It is a flow chart suitable for the heat balance control of the modularized multilevel converter provided by the present invention:

[0038] (1) First accept the ...

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Abstract

Provided in the invention is a thermal balance control method for a modular multilevel converter. The method comprises: step one, an invested sub module number instruction Non that is needed by one bridge arm and is obtained by a converter control layer according to an NLC method is received and a change Ndiff of the sub module investment number is calculated; step two, a capacitance voltage of each sub module is measured and a minimum capacitance voltage vcmin and a maximum capacitance voltage vcmax are found out, temperatures of an IGBT and an anti-parallel diode in each sub module are measured and T1min, T2min, D1min, and D2min are found out; and step three, positive and negative properties and an arm current direction are the Ndiff are determined. According to the invention, the temperature is added into the balance algorithm based on the capacitance voltage balance algorithm, so that the modular multilevel capacitance voltages are balanced and the temperature is balanced; and on the basis of the opened sub module number during the last cycle, ranking of all sub modules is not needed during ranking, so that the algorithm becomes simple.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to a sub-module voltage equalization method for a modular multilevel converter. Background technique [0002] Recently, Modular Multilevel Converter (MMC) has been considered as a suitable technology for high power voltage source converters. Due to its scalability, high efficiency, low total harmonic distortion of the output voltage, low switching frequency, and ability to use low and medium power devices, it has been commercially implemented in high voltage DC, static synchronous compensators, and large motor drive applications. [0003] Since the MMC contains a large number of sub-modules, it is necessary to control its capacitor voltage balance to ensure the stable operation of the MMC. The capacitor voltage balance will lead to unbalanced loads of power semiconductors in different sub-modules, and the power loss of components and the balance of junction temperature betwee...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/00
CPCH02M7/00H02M1/0003
Inventor 王湘明赵盈洁邢作霞陈哲
Owner SHENYANG POLYTECHNIC UNIV
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