Method for increasing capacity of flexible direct-current power transmission system and apparatus thereof

A power transmission system and flexible DC technology, which is applied in the direction of converting irreversible DC power input into AC power output, and can solve problems such as electromagnetic interference, transmission capacity constraints, IGBT flow capacity, and dynamic voltage equalization.

Active Publication Date: 2014-04-09
STATE GRID CORP OF CHINA +2
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AI Technical Summary

Problems solved by technology

The main problems of the two-level VSC are the high switching loss caused by the high switching frequency, the static and dynamic voltage equalization and electromagnetic interference caused by the IGBT series connection
The main problems of the three-level VSC are the voltage equalization on the DC side and the influence of the third harmonic current on the neutral point of the DC side.
[0007] Although the above method can reduce the use of IGBTs in the case of outputting the same number of levels, it still cannot improve the transmission capacity of the converter when the device current and DC cable voltage are used to the limit, that is, the transmission capacity is still limited by the IGBT flow capacity

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  • Method for increasing capacity of flexible direct-current power transmission system and apparatus thereof
  • Method for increasing capacity of flexible direct-current power transmission system and apparatus thereof
  • Method for increasing capacity of flexible direct-current power transmission system and apparatus thereof

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Embodiment Construction

[0048] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0049] The invention provides a method for improving the capacity of a flexible direct current transmission system. The method is connected in series in the upper and lower bridge arms of each phase of a modular multilevel converter without increasing the current limit of the device and the rated voltage of the direct current cable. The full-bridge sub-module uses the ability of the full-bridge sub-module to output negative voltage to balance the DC voltage output by the modular multi-level converter while adjusting the AC output voltage of the modular multi-level converter to improve the modular multi-level converter. The transmission capacity of the streamer. The capacity improvement design method of the flexible DC system is as follows:

[0050] 1. Assume that the capacity of the voltage source modular multilevel con...

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Abstract

The invention relates to the technical field of flexible direct-current power transmission, particularly to a method for increasing the capacity of a flexible direct-current power transmission system and an apparatus thereof. According to the invention, by adding a full-bridge sub-module (FBSM) which can generate negative voltage into a bridge arm of a modular multilevel converter (MMC), direct-current output voltage of a transverter is balanced while alternating-current output voltage of the transverter is adjusted, thereby increasing the transmission capacity of the transverter. The method does not have higher requirements on the through-current capability of IGBT elements and proceeding from conventional engineering technologies, the application of flexible direct-current power transmission technologies in practical engineering is substantially optimized.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission (VSC-HVDC), in particular to a method and a device for increasing the capacity of a flexible direct current transmission system. Background technique [0002] Due to its excellent controllability and flexibility, the flexible direct current transmission technology (VSC-HVDC) based on voltage source converter has developed rapidly in recent years. Both foreign companies ABB and Siemens have mastered the core technology in the field of flexible direct current transmission, and my country also completed the first demonstration project of flexible direct current transmission in Asia in July 2011. With the increase in power demand and the stringent requirements for system stability, the engineering applications of flexible DC transmission will continue to increase. [0003] For long-distance large-capacity power transmission, from an economic point of view, DC transmission...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/49
Inventor 季兰兰王海田孔明张海峰阎发友杨杰
Owner STATE GRID CORP OF CHINA
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