At The Edge of The Mathematical Limit: A Multi-Dimensional Protection Approach To Enhance Sensitivity In Impedance-Based Relaying

Enhancing the sensitivity of relay protection in high impedance fault scenarios remains a critical practical challenge, particularly for transmission lines susceptible to faults caused by vegetation, which can increase the risk of forest fires. Impedance-based protection schemes, widely studied for their adaptability, are often modified to improve performance under such conditions. This paper investigates the mathematical limitations inherent in impedance relay algorithms, demonstrating that a fundamental sensitivity threshold exists, irrespective of the equation embedded in the protection algorithm. The proposed solutions leverage multi-dimensional analysis and modes classification to help reach this limit by employing unified operating characteristics and comprehensive data utilization, to maximize relay sensitivity and operational reliability.