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A method and device for controlling pressure equalization of mixed twin modules MMC

A voltage equalization control, dual sub-module technology, applied in the output power conversion device, electrical components, AC power input into DC power output and other directions, to achieve the effect of capacitor voltage balance

Active Publication Date: 2019-02-01
XUJI GRP +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the pressure equalization control strategy of the conventional MMC system cannot meet its pressure equalization requirements, so it is urgent to propose a system voltage equalization control strategy suitable for the hybrid twin module MMC

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  • A method and device for controlling pressure equalization of mixed twin modules MMC
  • A method and device for controlling pressure equalization of mixed twin modules MMC
  • A method and device for controlling pressure equalization of mixed twin modules MMC

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Embodiment Construction

[0042] In order to make the purpose, advantages and technical solutions of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] Such as figure 2 , image 3 As shown, the hybrid twin sub-module consists of 4 IGBTs and 2 module capacitors. The hybrid twin sub-module can be approximated as a combination of two half-bridge units. The following table shows the working status of the hybrid twin sub-module.

[0044] Table 1 Working status table of hybrid twin sub-module

[0045]

[0046] It can be seen from the above table that the hybrid twin sub-module can output 4 kinds of voltages, which are dual capacitor voltage, single capacitor voltage, zero voltage and negative capacitor voltage. Moreover, when the number of input sub-modules is positive, the output voltage of the sub-module corresponds to three states: single-capacitor voltage, double-capacitor voltage, ...

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Abstract

The present invention proposes a hybrid dual sub-module MMC voltage equalization control method and device. For any bridge arm, according to the current direction of the bridge arm, the positive or negative of the sum of the voltage differences in the modules of the entire bridge arm and the positive or negative of the number of input sub-modules , sorting the comprehensive voltage index of each sub-module, and determining the corresponding output state of each sub-module; the comprehensive voltage index is related to the capacitor voltage in the module and the capacitor voltage difference in the module. The present invention is based on the comprehensive voltage index-based sorting voltage equalization control between modules, which realizes the effect of capacitor voltage balance inside the module and capacitor voltage balance between modules, and can be used in various working conditions such as start-up, normal operation, and fault ride-through of the mixed twin-module MMC system Both can achieve a good pressure equalization effect.

Description

technical field [0001] The invention belongs to the technical field of flexible direct current transmission of electric power systems, and in particular relates to a method and device for controlling voltage equalization of a hybrid twin module MMC. Background technique [0002] The DC short-circuit fault is the most common fault in the MMC-HVDC system. The MMC converter based on the half-bridge sub-module, such as Figure 1-a As shown, in the event of a DC bipolar short-circuit fault, it is impossible to cut off the energy feeding circuit of the AC system to the DC short-circuit point by blocking the sub-module IGBT, and the AC circuit breaker or DC isolating switch must be quickly tripped to clear the fault current, which not only increases the system The cost increases the technical requirements for the equipment, and also reduces the system commissioning rate and slows down the failure recovery speed. [0003] At present, most projects use DC cable laying lines, which ar...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/00H02M7/219
CPCH02M7/00H02M7/219H02M7/4835
Inventor 张浩吴金龙王先为杨美娟刘欣和李道洋姚为正范彩云
Owner XUJI GRP
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