Transformer protection method based on double-side non-saturated region equivalent instantaneous inductor

Abstract

The invention relates to a transformer protection method based on double-side unsaturated zone equivalent instantaneous inductance, belonging to the electric power system primary device relay protection technical field. The invention is characterized in that: unsaturated zone equivalent instantaneous inductance at two sides of a transformer is utilized to realize transformer protection, which is a novel transformer protection method unrelated to excitation inrush current; when an internal fault of the transformer happens, equivalent instantaneous inductance in an unsaturated zone calculated from the prior secondary are all very small; when an external fault of the transformer happens, the equivalent instantaneous inductance in the unsaturated zone calculated from the prior secondary is very small on the fault side, while the equivalent instantaneous inductance is very big on the non fault side; whether a fault happens in the transformer can be judged according to the characteristic of the equivalent instantaneous inductance in an unsaturated zone calculated from two sides of the prior secondary being less than a threshold value at the same time, and internal fault and external fault can be identified; the protection has strong antisaturation capability of a current transformator.

Description

technical field [0001] The invention belongs to the technical field of relay protection for main equipment in a power system, and in particular relates to a transformer protection method based on the equivalent instantaneous inductance of a double-sided unsaturated region. Background technique [0002] There are certain defects in the principle of differential protection applied to transformer protection, but it still has an irreplaceable position as the main protection of operating transformers. Therefore, an important aspect of current research on transformer differential protection is how to improve the protection action. reliability and sensitivity. Different from the differential protection of the generator, the transformer will generate an excitation inrush current phenomenon when it is closed with no load, so that the differential protection will generate a large differential current at this time. If no blocking measures are taken for it, the differential current will...

AI Technical Summary

Problems solved by technology

Especially the criterion based on the transformer loop equation has been studied more deeply, but this method has a big weakness that the anti-current transformer saturation is very poor. If the current transformer is saturated, whether it is an internal fault , or saturation caused by out-of-area faults, will cause this type of criterion based on the transformer loop equation to malfunction

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