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System for power transformer differential protection

A power transformer and differential current protection technology, applied in the field of transformer internal fault protection devices

Inactive Publication Date: 2009-05-20
SCHWEITZER ENGINEERING LABORATORIES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when a combination of these techniques is not found to provide an appropriate solution for several specific inrush conditions, that is, safety

Method used

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  • System for power transformer differential protection
  • System for power transformer differential protection
  • System for power transformer differential protection

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Embodiment Construction

[0023] The system of the present invention, typically as part of a power transformer protective relay, comprises three differential unit arrangements. These three differential units / devices all perform the same function, and are generally considered to be related to the single-phase (A, B, or C) currents of the three-phase power transformer, that is, with these single-phase (A, B, C) currents or a selected combination thereof (such as AB, BC, CA). Therefore, in the following description, except for the first part which is concerned with the generation of the output values ​​of all three differential units, the remaining part only deals with the structure and operation of one differential unit arrangement. The other two differential unit components are structurally and functionally identical to the first unit.

[0024] In general, the differential unit arrangement of the present invention utilizes even harmonic suppression, fifth harmonic and direct current (DC) blocking funct...

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Abstract

The current transformer (CT) secondary current of the power transformer winding is used to generate the differential current. The operating current value can be obtained from this differential current value. The suppressed current value can be obtained from the processed winding current value. The second and fourth harmonic values ​​of the differential current can be obtained and added together with the value of the suppression current, which is the product of the suppression current times the slope characteristic coefficient. If the operating current value is greater than the sum of the suppressed current value and the second and fourth harmonic values, an output signal can be generated which is used as a trip signal unless it is blocked by a selected blocking signal generated by another part of the system.

Description

technical field [0001] This invention relates generally to transformer internal fault protection devices for power transformers, and more particularly to differential protection devices for transformers with harmonic suppression and blocking capabilities. Background technique [0002] Clearly, depending on the internal fault present in a power transformer, it must first be identified and then correct action taken. Immediate separation of a faulty transformer from the power system is necessary to avoid major damage to the transformer and to maintain power system stability and power quality. [0003] Several techniques have been developed to detect internal transformer faults, initially phase overcurrent protection, differential protection using differential current and gas storage / boost rate protection for arcing faults. Differential protection is now widely used For protection against internal faults in the relay. In differential protection, the operating current Iop (also...

Claims

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Application Information

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IPC IPC(8): H02H7/045H02H1/04H02H3/52
CPCH02H1/043H02H3/52H02H7/045H02H3/28H02H3/283H02H1/046
Inventor A·古兹曼卡西利亚斯H·阿尔图韦费雷尔S·E·措霍尔G·本穆约尔
Owner SCHWEITZER ENGINEERING LABORATORIES