**2. Short Review of Contributions**

Adaptive protection: The idea of adaptive protection, where relay settings are modified in response to changing system configuration or operating conditions, has been present in the technical literature for quite some time. While in the past its practical application was not perceived as critical and was also limited by technological constraints, the development of numerical multifunctional relays accompanied by digital communications, as well as increased system-fault-level variability, has enabled adaptive protection to progress to practical applications. In this issue, we include two papers [1,2] which propose adaptive solutions for both high-voltage transmission systems and distribution-level microgrids.

Protection of DC systems: There are many situations where DC electricity systems are preferable to AC systems, especially when considering rapid advances in power electronic converter technologies and the utilisation of energy sources which naturally produce DC power, such as photovoltaics or batteries. Both HVDC and LVDC systems are being developed, and the protection of such networks has a separate set of challenges in terms of ultra-fast fault detection and classification requirements, fault-ride through capabilities, and DC fault current breaking. Therefore, we are pleased to present four papers [3–6] that tackle various aspects of DC network protection.

Enhanced/unconventional protection-systems: There is always a plethora of papers that aim to improve the operation of conventional protective methods, either by utilising advanced processing techniques or by taking advantage of emerging technological developments (e.g., distributed sensing technologies). This issue is no exception. You will find some fine examples of unconventional thinking and innovation in most of the presented papers (e.g., [3,5,7,8], to highlight a few).

**Citation:** Dy´sko, A.; Tzelepis, D.Protection of Future Electricity Systems. *Energies* **2022**, *15*, 704. https://doi.org/10.3390/ en15030704

Received: 14 December 2021 Accepted: 17 January 2022 Published: 19 January 2022

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Protection of superconducting transmission systems: Due to the introduction of superconducting cables, long-distance, superconducting electricity transmission has recently become a reality. Due to their unique physical characteristics, such cables require special attention when it comes to protection. We are pleased to present one paper [9] which specifically addresses this new, exciting area of research.

Lightning protection: Last but not least, we present one paper which addresses an important aspect of lightning protection in building integrated photovoltaic modules [10].
