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Directional protection scheme using impedance approach for transmission lines.

Ahmed R Adly¹, Mahmoud A Elsadd², Mahmoud M Elgamasy³

¹Nuclear Search Center, Egyptian Atomic Energy Authority, Cairo, Egypt. ahemd_adly@yahoo.com.

Scientific Reports

|June 20, 2025

Summary

This study presents a novel fault direction identification technique for transmission line protection using a positive impedance approach. The method accurately determines fault direction even under challenging conditions like high resistance and CT saturation.

Keywords:

Digital protection Directional relay Transmission lines Z-matrix

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Area of Science:

Electrical Engineering
Power Systems Protection

Background:

Accurate fault direction identification is critical for transmission line protective schemes.
Existing methods face challenges with high resistance, noise, and system variations.

Purpose of the Study:

To develop and validate a new directional protection technique for transmission lines.
To assess the proposed scheme's performance under diverse fault scenarios.

Main Methods:

Utilizing instantaneous positive sequence voltage and current components.
Calculating the impedance matrix (Z matrix) for fault direction determination.
Employing ATP-EMTP software for simulation and verification.

Main Results:

The proposed positive impedance approach successfully determines fault direction.
The scheme demonstrates robustness against high fault resistance, far-end faults, and cross-country faults.
Performance remains reliable despite power flow changes, single pole tripping, CT saturation, and noise.

Conclusions:

The presented directional protection technique is feasible and accurate.
The method offers a reliable solution for transmission line protection, outperforming existing schemes in various challenging conditions.