## Nomenclature
### Acronyms
* _CFR_ (2016) CFR Title 10 Chapter II Part 431, Energy Efficiency Program for Certain Commercial and Industrial Equipment, Appendix A of Subpart K-Distribution Transformers. US Regulations. 2016. Available online: [[https://www.ecfr.gov/current/title-10/chapter-II](https://www.ecfr.gov/current/title-10/chapter-II)]([https://www.ecfr.gov/current/title-10/chapter-II](https://www.ecfr.gov/current/title-10/chapter-II)) /sub chapter-D/part-431/subpart-K?toc=1 (accessed on 15 March 2022). * Efficiency-Transformers-Program.aspx (accessed on 15 March 2022). IEC TS 60076-20:2017; Power Transformers--Part 20: Energy efficiency. International Electrotechnical Commission (IEC): Geneva, Switzerland, 2017. Available online: [[https://cdn.standards.iteh.ai/samples/18643/38c24f902a05425](https://cdn.standards.iteh.ai/samples/18643/38c24f902a05425) aa8607a40a339c92c/IEC-T-S-60076-20-2017.pdf]([https://cdn.standards.iteh.ai/samples/18643/38c24f902a05425](https://cdn.standards.iteh.ai/samples/18643/38c24f902a05425) aa8607a40a339c92c/IEC-T-S-60076-20-2017.pdf) (accessed on 15 March 2022). * [29] Baggini, A. Overview of IEC/TS 60076-20 Ed. 1.0: Power Transformers--Part 20: Energy Efficiency. In Proceedings of the Workshop on Reducing Losses in Power Distribution through Improved Efficiency of Distribution Transformers, Jeju, Korea, 28 March 2017. * [30] Almeida, A.; Santos, B.F.; Martins, F.M.L. Energy-efficient distribution transformers in Europe: Impact of Ecodesign regulation. _Energy Effic._**2015**, \(9\), 401-424. [CrossRef]
* [31] Tran, Q.T. ; Davies, K.; Roose, L.; Wiriyakitikun, P.; Janjampop, J.; Riva Sanseverino, E.; Zizzo, G. A Review of Health Assessment Techniques for Distribution Transformers in Smart Distribution Grids. _Appl. Sci._**2020**, _10_, 8115. [CrossRef]
* [32] Leon-Martinez, V.; Andrada-Monros, C.; Molina-Canareno, L.; Cano-Martinez, J.; Penalvo-Lopez, E. Decarbonization of Distribution Transformers based on Current Reduction: Economic and Environmental Impacts. _Energies_**2021**, _14_, 7207. [CrossRef]
* [33] Leon-Martinez, V.; Montana-Romeu, J. Formulations for the Apparent and Unbalanced Power Vectors in Three-Phase Sinusoidal Systems. _Electr. Power Syst. Res._**2018**, _160_, 37-43. [CrossRef]
* [34] Sustainability Report 2020. Red Electrica, Spanish Operator. 2021. Available online: [[https://www.ree.es/es/publicaciones/info](https://www.ree.es/es/publicaciones/info)]([https://www.ree.es/es/publicaciones/info](https://www.ree.es/es/publicaciones/info)) rme-sostinibilidad-2020 (accessed on 15 March 2022). * [35] Circular 3/2020, of 15 January of the National Markets and Competition Commission, which Establishes the Methodology for Calculating Electricity Transmission and Distribution Tolls. Spanish Official State Bulletin (BOE), N\({}^{\circ}\) 21, 24 January 2020; pp. 6953-6980. Available online: [[https://www.boe.es](https://www.boe.es)]([https://www.boe.es](https://www.boe.es)) (accessed on 15 March 2022). * [36] New Penalties for Capacitive Reactive Energy. 2020. Available online: www.casel.es (accessed on 15 March 2022). * [37]_IEC Standard 60076-1:2011_; Power Transformers--Part 1: General. International Electrotechnical Commission (IEC): Geneva, Switzerland, 2011. * [38] Jeon, S.-J. ; Willems, J.L. Reactive power compensation in a multi-line system under sinusoidal unbalanced conditions. _Int. J. Circuit Theory Appl._**2010**, _39_, 211-224. [CrossRef]
* [39] Grana-Lopez, M.A. ; Garcia-Diez, A.; Filgueira-Vizoso, A.; Chouza-Gestoso, J.D. ; Masdias-Bonome, A. Study of the Sustainability of Electrical Power Systems: Analysis of the Causes that Generate Reactive Power. _Sustainability_**2019**, _11_, 7202. [CrossRef]
* [40] Blasco, P.A. ; Montoya-Mira, R.; Diez, J.M. ; Montoya, R.; Reig, M.J. Compensation of Reactive Power and Unbalanced Power in Three-Phase Three-Wire Systems Connected to an Infinite Power Network. _Appl. Sci._**2020**, _10_, 113. [CrossRef]
* [41] Montoya-Mira, R.; Blasco, P.A. ; Diez, J.M.