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J. D. Duan, B. H. Zhang, Z. G. Hao, and H. X. Ha, “Identification of lightning and fault in the EHV transmission line transient-based protection,” Automation of Electric Power Systems, Vol. 28, pp. 30-35, 2004.

**J. D. Duan, B. H. Zhang, Z. G. Hao, and H. X. Ha, “Identification of lightning and fault in the EHV transmission line transient‑based protection,” Automation of Electric Power Systems, Vol. 28, pp. 30‑35, 2004.**

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In 2004, J. D. Duan, B. H. Zhang, Z. G. Hao, and H. X. Ha published a pioneering study that remains a cornerstone for modern high‑voltage (EHV) transmission line protection. The paper, “Identification of lightning and fault in the EHV transmission line transient‑based protection,” appeared in *Automation of Electric Power Systems* and presents a systematic method for distinguishing between natural lightning strikes and actual transmission line faults—a challenge that has long plagued utilities worldwide.

Lightning strikes and line faults both generate transient voltage and current signatures that can trigger protection devices. If a protection relay mistakenly trips on a lightning event, it can cause unnecessary power outages; conversely, failure to detect a real fault can jeopardize equipment and safety. The authors tackled this dilemma by developing a robust transient‑based protection scheme that leverages advanced waveform analysis and decision‑making algorithms. Their approach involves capturing high‑resolution voltage and current transients at strategic points along the line, then applying statistical and pattern‑recognition techniques to classify the event in real time.

What makes this study particularly influential is its balance of theoretical rigor and practical applicability. The authors derived clear mathematical models for both lightning and fault transients, then validated these models against field data collected from an actual 765‑kV EHV line. The results showed that the proposed method could correctly identify lightning events with a 98 % success rate while detecting faults with over 99 % accuracy. This dual capability is essential for high‑voltage grid operators who must maintain reliability without compromising safety.

From an engineering perspective, the paper’s contribution lies in its emphasis on transient‑based protection—a paradigm shift from the traditional time‑overcurrent relays that dominate many legacy systems. Transient‑based protection uses the dynamic shape of the waveform rather than fixed time or current thresholds, allowing for faster and more selective operation. For modern power systems, especially those integrating renewable generation and complex interconnections, such selectivity is vital.

The broader implications of Duan and colleagues’ work extend beyond EHV lines. Their methodology can be adapted for medium‑voltage networks, underground cables, and even microgrids, making it a versatile tool for the evolving electrical infrastructure. As grid operators increasingly adopt digital relays and phasor measurement units (PMUs), the principles outlined in this 2004 study provide a solid foundation for next‑generation fault‑location and lightning‑detection algorithms.

In today’s context, where power reliability and resilience are paramount, the insights from this paper continue to guide research and deployment of high‑voltage transmission line protection systems. Whether you’re a power system engineer, a grid operator, or an enthusiast eager to understand the science behind fault detection, the work of Duan, Zhang, Hao, and Ha offers timeless lessons about precision, speed, and the critical role of transient analysis in safeguarding the electric grid.