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Detection method of commutation failure of direct-current power transmission system

A technology for DC transmission system and commutation failure, which is applied in the field of multi-feed systems and can solve problems such as difficulty in detecting commutation failure

Inactive Publication Date: 2015-08-05
STATE GRID CORP OF CHINA +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method for detecting commutation failure in a direct current transmission system to solve the problem in the prior art that commutation failure caused by voltage distortion is difficult to detect

Method used

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  • Detection method of commutation failure of direct-current power transmission system
  • Detection method of commutation failure of direct-current power transmission system
  • Detection method of commutation failure of direct-current power transmission system

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Embodiment Construction

[0026] Firstly, the creation process of the present invention is analyzed.

[0027] According to the prior art, it is known that the arc extinguishing angle has the following relationship during the inverter commutation process:

[0028] cos γ = cos β + 2 X i I d E i - - - ( 1 )

[0029] In the formula, β is the trigger lead angle of the inverter; γ is the arc-extinguishing angle of the inverter, and X i is the commutation reactance of each phase of the AC system, I d is the direct current, E i is the effective value of the AC side line voltage of the inverter. The commutation reactance is an inherent parameter of the converter transformer....

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Abstract

The invention relates to a detection method of a commutation failure of a direct-current power transmission system. For a converter station, a converter extinction angle gamma provided by a system is calculated, the converter extinction angle gamma provided by the system is compared with a minimum extinction angle value gamma min that is needed by the converter itself so as to determine whether a criterion of gamma being larger than gamma min is met; a maximum voltage time area Sv provided by an alternating-current line voltage and a commutation area S needed by the converter during the commutation process are calculated, and whether a criterion of Sv being larger than S is met is determined; and as long as one of the criteria is met, occurrence of a commutation failure at the system is determined. According to the invention, the extinction angles and the commutation area are used for determination and the commutation process of the multi-infeed direct-current power transmission system can be reflected simultaneously, visual, and completely from two aspects. Phenomena of voltage drop and voltage distortion can be detected accurately and thus the occurrence trend of the commutation failure can be detected, thereby providing the basis for the protection strategy of the converter. And a reference frame is also provided for commutation failure prevention measures like reactive compensation.

Description

technical field [0001] The invention relates to a method for detecting phase commutation failure of a direct current transmission system, which is especially suitable for multi-infeed systems. Background technique [0002] Thyristor is a semi-controlled power electronic device with mature technology. Due to its large capacity and high withstand voltage, most of the current HVDC transmission systems use thyristor as the basic commutation unit. However, since the thyristor converter adopts the grid commutation technology and the characteristics of the thyristor itself, commutation failure is a fault that cannot be completely eliminated for the HVDC transmission system. [0003] Due to the characteristics of my country's uneven energy distribution and large differences in economic development levels, HVDC transmission is of great significance to my country's modernization. In recent years, a number of high-voltage direct current transmission lines have been put into operation ...

Claims

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Application Information

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IPC IPC(8): G01R31/08
Inventor 张军王先为吴金龙行登江
Owner STATE GRID CORP OF CHINA
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