Improved method of MMC direct voltage protection

A DC voltage and AC voltage technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of DC protection malfunction, threats to system safe operation, imperfect DC protection principle and setting method, etc., to solve DC voltage protection. The effect of malfunction and improved reliability

Inactive Publication Date: 2018-03-30
NORTHEAST DIANLI UNIVERSITY +2
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  • Description
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Problems solved by technology

However, due to the similarity between DC transients and DC faults caused by AC faults, and the imperfection of DC protection principles and setting methods, AC faults may cause DC protection malfunctions
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  • Improved method of MMC direct voltage protection
  • Improved method of MMC direct voltage protection
  • Improved method of MMC direct voltage protection

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Embodiment Construction

[0041] In the present invention, the DC transient state caused by the AC fault is similar to the DC fault, and the DC protection principle and setting method are not perfect, and the DC protection may malfunction when the AC fault occurs. According to the on-site feedback of the flexible DC power transmission project, when AC faults occur, DC protection misoperation accidents occur from time to time, which poses a threat to the safe operation of the system.

[0042] In order to solve the above technical problems, the present invention proposes an improved MMC DC voltage protection criterion, the main content of which is to increase the AC voltage as the blocking criterion for DC voltage protection.

[0043] The method comprises the steps of:

[0044] 1. A method of improving MMC DC voltage protection by adding a blocking criterion. The main content is to increase the AC voltage as a blocking criterion for DC voltage protection. It is characterized in that it can avoid the prot...

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Abstract

The invention discloses an improved method of MMC direct voltage protection and belongs to the high-voltage direct current power transmission technology field. Through increasing an alternating voltage as an atresia criterion of direct voltage protection, the improved method of MMC direct voltage protection, which can be used to solve a direct current protection misoperation accident, is realized.The method comprises the following steps of through carrying out qualitative analysis on a MMC-HVDC system mathematic model, determining the atresia criterion of the direct voltage protection; determining an alternating voltage setting value Uac_set in the direct voltage protection; and improving the direct voltage protection. Based on a condition of deepening MMC-HVDC mathematical modeling, direct current protection configuration when the MMC-HVDC alternating current system has a fault is further studied, and an obvious engineering application value and practical significance are possessed.

Description

technical field [0001] The invention belongs to the technical field of high voltage direct current transmission. Background technique [0002] As a new type of flexible DC transmission technology, the high-voltage DC transmission technology based on modular multilevel converters (MMC-HVDC) has a short research time and lack of practical engineering applications, so further research is needed on this technology. The current literature available for reference mainly focuses on the steady-state control mechanism such as modeling and simulation of the MMC-HVDC system, modulation strategy, etc., and the research on protection also focuses on the fault analysis of the DC side. In the modular multi-level HVDC flexible transmission system, the AC system and the DC system are respectively configured with protection. When the DC system fails, the DC protection quickly removes the fault to ensure that the DC equipment is not damaged; similarly, the AC protection works quickly after th...

Claims

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Application Information

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IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 李国庆娄剑王鹤王振浩于华楠刘芮彤杨滢璇韩子娇
Owner NORTHEAST DIANLI UNIVERSITY
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