He is since 1984 a faculty member and since 1995, full professor in Power Systems at the Electrical and Computer Engineering School of the National Technical University of Athens. He is Director of the Postgraduate Programme of “Energy Production and Management”. He is Director of the Energy Systems Laboratory and founder of the "SmartRue" research unit. From April 2015 to September 2019 he was Chairman and until June 2018, CEO of the Hellenic Distribution Network Operator (HEDNO). From February 2007 until September 2012 he was executive Vice-Chair and Deputy CEO of the Public Power Corporation (PPC), responsible for the Transmission and Distribution Divisions. He is Fellow Member of IEEE, past Chair of the Power System Dynamic Performance Committee (PSDPC) and currently Editor in Chief of the IEEE Trans on Power Systems. He is honorary member of CIGRE and past Chair of CIGRE SC C6 “Distribution Systems and Distributed Generation”. He is vice-chair of the EU Technology and Innovation Platform on Smart Networks for Energy Transition. He has participated in more than 60 RD&D projects funded by the EU Commission, electric utilities and manufacturers for both fundamental research and practical applications. He is author of the book “Microgrids: Architectures and Control” and of more than 200 journal publications and 500 conference proceedings papers. He is included in the 2016, 2017 and 2019 lists of the top 1% most cited researchers.