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

Abstract

The invention discloses a transformer protection method based on the equivalent instantaneous inductance of a double-sided unsaturated region, which belongs to the technical field of relay protection for main equipment in a power system. It is characterized in that the transformer is protected by using the equivalent instantaneous inductance in the non-saturation area on both sides of the transformer, which is a new transformer protection method independent of the excitation inrush current. The equivalent instantaneous inductance is very small; when an external fault occurs to the transformer, the equivalent instantaneous inductance calculated from the primary and secondary sides in the unsaturated region is very small on the fault side and very large on the non-fault side. Whether the equivalent instantaneous inductance in the unsaturated region calculated on both sides is less than the threshold value at the same time can directly determine whether the transformer has a fault, and distinguish the fault inside the zone from the fault outside the zone. The protection itself has a strong resistance to current mutual inductance device saturation capability.

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...

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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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