N.I. Voropai was a renowned expert in the field of energy systems research. He was an author, and co-author of more than 700 published research contributions. He identified and investigated the fundamental features of complex extended electric power systems. This allowed explaining multiple phenomena and processes, such as system accidents, based on clear physical representations and developing theoretical foundations for the analysis and synthesis of structurally heterogeneous power interconnections. These achievements laid off the methodological backbone of research efforts by a school of thought that still leads its field to this day. He successfully supervised over 20 PhD students. V.A. Stennikov is one of the leading experts in the field of heat and power systems, the developer of the methodology for modeling, calculating, optimizing pipeline systems in the energy sector, managing their development and operation, and district heating systems. His work significantly increases the level of validity and effectiveness of decision making on the development and reconstruction of energy systems, and their management and control. He is an author, and co-author of more than 600 published research contributions.