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Mixed double sub-module MMC voltage balancing control method and device

A technology of voltage equalization control and dual sub-modules, which is applied in the output power conversion device, electrical components, and the conversion of AC power input to DC power output, etc., to achieve a good voltage equalization effect.

Active Publication Date: 2017-06-13
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

Method used

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  • Mixed double sub-module MMC voltage balancing control method and device
  • Mixed double sub-module MMC voltage balancing control method and device
  • Mixed double sub-module MMC voltage balancing control method and device

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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 invention provides a mixed double sub-module MMC voltage balancing control method and device. For any bridge arm, comprehensive voltage indexes of each sub-module are ranked according to the current direction of the bridge arm, plus or minus of the sum of voltage differences in modules of the whole bridge arm and plus or minus of the number of input sub-modules, and the output states corresponding to the sub-modules are determined; the comprehensive voltage indexes are relevant to the plus or minus of capacitor voltage sum in the modules and the capacitor voltage difference in the modules. Based on voltage balancing control of inter-module ranking of the comprehensive voltage indexes, the effects of capacitor voltage balance in the modules and capacitor voltage balance between the modules are achieved, and a good voltage balancing effect can be achieved under multiple working conditions of start, normal operation, fault ride-through and the like of a mixed double sub-module MMC system.

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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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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