Transformer short window negative sequence differential protection method and device based on split-phase reference

By installing current transformers on each side of the transformer, using a short-window algorithm to calculate the negative sequence current, and combining the effective values ​​of differential current and braking current for discrimination, the problem of insufficient sensitivity of transformer longitudinal differential protection in the event of minor faults is solved, and a fast and sensitive fault response is achieved.

CN117060339BActive Publication Date: 2026-06-05NR ELECTRIC CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
NR ELECTRIC CO LTD
Filing Date
2022-05-05
Publication Date
2026-06-05

AI Technical Summary

Technical Problem

Existing transformer differential protection has insufficient sensitivity in the event of minor faults and slow negative sequence calculation speed, which affects the protection's speed of operation.

Method used

The short-window negative sequence differential protection method based on phase-separated reference is adopted. By installing current transformers on each side of the transformer, the negative sequence current is calculated using the short-window algorithm. The protection action is determined by combining the effective values ​​of differential current and braking current. The calculation time window only requires 1/6 cycle.

Benefits of technology

It improves the sensitivity and speed of minor faults in the transformer area, overcomes the braking effect of load current on conventional differential protection, and quickly responds to faults.

✦ Generated by Eureka AI based on patent content.

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    Figure CN117060339B_ABST
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Abstract

The application provides a transformer short window negative sequence differential protection method and device based on a split-phase reference. The protection method comprises: obtaining current sampling values of each side of a transformer; calculating negative sequence current sampling values according to the current sampling values; calculating adjusted current sampling values according to the negative sequence current sampling values; calculating adjusted current effective values according to the adjusted current sampling values; calculating differential current effective values according to the adjusted current sampling values; calculating braking current effective values according to the adjusted current effective values; and determining whether to start a protection action based on the differential current effective values and the braking current effective values.
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