Webinar: Replicating hybrid microgrid solutions in Sofia's metro system – 15 May at 11am CET
Join us for a webinar on how we are improving efficiency of Sofia's metro system through solutions developed by hybrid microgrid project TIGON
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The webinar, which takes place on 15 May 2025 from 11:00 to 11:45 (CET), will offer insights into energy efficiency and grid resilience applied to a metro line in Bulgaria's capital, Sofia. The study is part of the EU-funded TIGON project which has developed and enhanced software and hardware components for the roll-out of hybrid microgrids as part of the energy transition.
Sofia Metro Line 3, operated with a 1.5 kV DC overhead electrification system and Siemens Inspiro rolling stock capable of advanced regenerative braking, currently underuses available braking energy due to infrastructure limitations. This replication case addresses this inefficiency through the implementation of wayside Energy Storage Systems (ESS) and bi-directional DC/DC power converters. The technical analysis was carried out by developing the electric rail traction system for Sofia Metro Line 3 in the MATLAB/Simulink environment.
The simulation results demonstrate the benefits of integrating ESS and bi-directional converters. The key outcomes include the following:
· A substantial increase in regenerative braking energy recovery, from approximately 15% in the current operation to nearly 90%.
· Reduction in overall grid energy consumption by around 25% per train journey.
· Improved voltage stability, significantly reducing voltage spikes and sags by approximately 66%, thus enhancing equipment longevity and operational reliability.
· Lower peak grid power demand by approximately 18%, for single-train operation and up to 22–27% for multi-train scenarios, potentially reducing infrastructure investment needs and operational costs.
The webinar preliminary agenda includes:
· Background to the TIGON hybrid microgid project (CIRCE)
· Insights from the CEA demo site—France (CEA)
· Insights from the CIEMAT demo site—Spain (CIEMAT)
· Replication study at Sofia Metro—Bulgaria (UBITECH)
· Questions & Answers
Meet the speakers
Lilly Markova (moderating) is a project manager with a BA in business management and finance at IEIT, specialising in coordinating and overseeing complex projects within the technology and innovation sectors. With a strong focus on efficient project execution and team collaboration, she ensures the successful delivery of solutions that drive progress and innovation. Lilly received her BA from the CITY College, International Faculty of Sheffield University in 2018 with excellence.
Eduardo García Martínez is an electronics engineer with a Ph.D. in renewable energy and efficiency. Since 2011, he has been with CIRCE, where he works on the research and development of electronics and power electronics systems for renewable energy integration, DC grid integration, battery energy storage systems, electric system emulation, V2G fast chargers and Wireless Power Transfer systems.
Jens Merten studied physics at Technical University in Munich and realised his diploma thesis in Ecole Polytechnique in France. His Ph.D. entitled Amorphous Silicon Photovoltaics: Physic, Technology, and Applications was achieved in Barcelona University. He held several positions related to research and development and the management of the "Solar Energy for the outer islands of Kiribati" project with 1800 PV systems installed on 18 islands. He then started at leading the Laboratory for solar systems of CEA at the French National Institute of Solar Energy (INES) in 2005. In 2019, he was elected director of INES.2S, an industrial consortium dealing with R&D projects representing with a turnover 10 M€ per year. Today, Jens Merten is Project Manager and Programme Manager for innovative solutions and architectures for solar energy systems as well as the direct solar powering of industry electricity demands.
Paula Peña Carro is a graduate researcher in the Energy Department of CIEMAT. Her professional career began in the forestry sector and then she made the leap to renewable energies in an international company in the photovoltaic sector, and subsequently focused her professional development in the field of research with micro-grids.
Nena Apostolidou is a researcher and responsible for technical management, technical implementation, participation and engagement in Research Projects. She received her Ph.D. in 2022, from the Electrical Engineering Department of the Democritus University of Thrace, Xanthi, Greece. Her research activities regard power electronics, electrical machine drives and energy management systems. Since 2018, she has been working in European Research Projects, supported by the European Regional Development Fund of the European Union and Greek national funds.
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Background to the project
TIGON is funded by the EU's Horizon 2020 Research and Innovation programme and has a budget of roughly €7m. It forms part of the EU's broader policy of building a low-carbon, climate-resilient future.
Online channels
Website: tigon-project.eu
LinkedIn: @tigon-project
Twitter: @tigon-project
Press contact
Mark Thompson
Fondazione iCons
Provided by iCube Programme