Stamatopoulos, Athanasios

Industrial PhD Banedanmark 

PROJECT TITLE:Technologies for the Power Supply of Electric Railways in Denmark  

PhD period: 2015.05.18 - 2018.05.17.
Section: Electric Power Systems
Research Programme: Modern Power Transmission Systems
Supervisor: Filipe Miguel Faria Da Silva 
Co-Supervisors: Claus Leth Bak, Philip C. Kjær and Hans Henrik Vikelgaard (Banedanmark)
Contact information

Collaborators: Banedanmark and
Funding: Banedanmark and Innovationsfonden.


Railway electrification has been widely adopted over the last decades due to the undeniable advantages over the diesel-powered trains (speed, efficiency, environmental compatibility etc.). Toward this direction, the Danish railway organization has decided to electrify 1300 km of new and existing lines by 2026. However, rail electrification comes with several challenges due to the nature of the traction load. Electric trains are seen as single-phase, non-linear, variable loads by the HV three-phase network. Major consequence of this is the voltage unbalance at the Point of Common Coupling (PCC). Unbalancing the network is highly undesirable as it may, if severe enough, damage equipment or reduce its lifetime, mainly electric rotating machines. Other equipment, such as HVDC lines, signaling and communication systems, and protection relays, can be also seriously affected.

Danish HV system is strong at the moment and the disturbances registered at the connection nodes are still below the limits, imposed by transmission system operator (TSO), However, this may no longer be true in future for two main reasons:

  • The electrification of new lines will radically change the load profiles resulting in higher power unbalance
  • The increasing penetration of renewable energy sources together with the disconnection of thermal power plants will reduce the short-circuit power of the transmission network and make it more prone to voltage unbalance

The objective of the project is primarily to estimate the impact of the railway electrification on the HV grid, accounting all foreseeable changes in both the railway and the HV grid. Subsequently, countermeasures will be investigated, including traditional compensation solutions (phase-rotation, Scott-transformer, LeBlanc-transformer etc.) as well as more advanced power electronics-based methods (Static Var Compensators, (SVC), Railway static Power Conditioners, (RPC)). Finally, the most optimal long-term solutions for various railway sections are to be identified, considering other power quality issues (harmonics, voltage flicker) as well as cost analysis. 


Publications in journals and conference papers may be found at VBN.