**6. Conclusions**

In this paper, a novel algorithm for detecting secondary arc extinction in shunt compensated transmission lines was presented. Using the Hilbert–Huang transform (HHT), the absolute value of all frequency contents below 60 Hz of the fault phase was calculated. Secondary arc extinction was then detected using a global threshold value. The algorithm was tested on a transmission line for different fault location, line loading, and various shunt reactor configurations, designs, compensation rates, and placement. The test results validate the algorithm's performance as well as its independence of the shunt compensation configuration. The main features of the algorithm can be summarized as follows:


**Author Contributions:** Methodology, validation, writing—original draft preparation, A.G.B.; Review and editing, supervision, N.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
