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Large difference protection method based on second harmonic excitation surge current of converter transformer

A technology of converter transformers and second harmonics, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as protection malfunctions, and achieve the effect of avoiding malfunctions

Active Publication Date: 2015-01-28
STATE GRID CORP OF CHINA +2
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AI Technical Summary

Problems solved by technology

[0017] The purpose of the present invention is to provide a large difference protection method based on the second harmonic excitation inrush current of the converter transformer to solve the problem of protection malfunction when a single-phase ground fault occurs in the valve side area of ​​the converter transformer

Method used

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  • Large difference protection method based on second harmonic excitation surge current of converter transformer
  • Large difference protection method based on second harmonic excitation surge current of converter transformer
  • Large difference protection method based on second harmonic excitation surge current of converter transformer

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Embodiment Construction

[0030] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0031] When a single-phase ground fault occurs in the valve side area of ​​the converter transformer, the large difference protection adopts the large difference protection differential current, the Yn / Y converter transformer differential protection differential current and the Yn / D converter transformer differential protection middle differential current The content of the second harmonic in the comprehensive discrimination to identify the excitation inrush current, the discriminant equation is as follows:

[0032] (1) When the second harmonic content of the large difference protection is greater than the second harmonic coefficient of the large difference protection

[0033] I op.2 >K 2 *I op.1 Formula 6

[0034] In the formula: I op.2 is the second harmonic in the large difference flow, I op.1 is the fundamental wave in the large difference flow, ...

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Abstract

The invention relates to a large difference protection method based on second harmonic excitation surge current of a converter transformer. When a single-phase earth fault is generated in a valve side area of the converter transformer, second harmonic content in differential current in large difference protection, differential current in differential protection of a Yn / Y converter transformer and differential current in differential protection of a Yn / D converter transformer is adopted for comprehensive recognition to recognize excitation surge current, so that the resulting protection maloperation is effectively avoided. The method is simple and reliable to realize and lower in realization threshold, can be realized on the original protection device platform, and has a very high popularization value.

Description

technical field [0001] The invention relates to a large difference protection method based on the second harmonic excitation inrush current of a converter transformer, and belongs to the technical field of high-voltage direct current transmission systems. Background technique [0002] The converter transformer is one of the key equipment in the HVDC power transmission system. At present, the ideal configuration of the domestic HVDC power transmission project is to use a 12-pulse converter and configure 6 single-phase double-winding converter transformers to form Yn / Y and Yn / D two single-phase transformer groups, the network side windings are connected in star connection, the neutral point is directly grounded, the outgoing lines are connected in parallel to the AC power grid, and the valve side windings are Y-type connection and D-type connection respectively. [0003] At present, the differential current of large differential protection of HVDC converter transformer adopts...

Claims

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Application Information

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IPC IPC(8): H02H7/045
Inventor 张红跃熊章学宋红涛牛志雷刘家军杜延辉路振宇赵艳茹徐玉洁胡晓静王二军曹雪兰安友彬苏金国张艳浩
Owner STATE GRID CORP OF CHINA
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