Setting method and device for transformer differential quick-break protection

Abstract

A transformer differential quick-break protection setting method and device. The method establishes an equivalent power system transformer differential quick-break protection setting model according to the system parameters, transformer parameters and current transformer parameters of each side of the power system in the maximum operating mode; When the transformer excitation inrush current is the largest, calculate the differential current; set a three-phase short-circuit fault on the low-voltage side outside the protection zone, and consider the saturation of the current transformer, and calculate the differential current of the transformer; in the normal operation mode of the power system, re-establish the equivalent system and calculate Protect the differential current when the metallic two-phase short circuit occurs at the installation. According to the above three current values, the preset threshold and the setting range of the differential quick-break protection, the setting value of the transformer differential quick-break protection can be determined. The present invention also provides a transformer differential quick-break protection setting device, which determines the fixed value of the transformer differential current through a computer program under the condition of satisfying regulations, thereby improving the reliability of power supply.

Description

technical field [0001] The invention relates to a setting method and device for transformer differential quick-break protection, which belongs to the technical field of relay protection for power systems. Background technique [0002] At present, the main protection of transformers based on electrical quantities is generally differential protection, including differential quick-break protection and proportional differential protection. The principle of differential protection is Kirchhoff's current theorem, that is, when the transformer is faulty outside the transformer area, the current vector sum of each branch of the transformer is zero, and when the transformer is faulty inside the transformer area, the vector sum of each branch of the transformer is not zero. In order to prevent maloperation of proportional differential protection, the proportional differential protection has anti-maloperation measures such as braking coefficient, second harmonic blocking, and discontin...

AI Technical Summary

Problems solved by technology

[0004] First, the fixed value of the differential quick-break protection is only set based on the experience of the adjuster, without considering some special circumstances, and the differential quick-break protection has a greater risk of refusal or misoperation

[0005] Second, during the operation of the actual power system, too many out-of-area faults have occurred, causing saturation of the current transformer, resulting in misoperation outside the differential quick-break protection area

In my country's power grid, there have been many accidents of differential quick-break protection misoperation due to unreasonable setting of differential quick-break protection.

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