400 kV Eastern Corridor of Peloponnese

Expansion of 400 kV System to the Peloponnese

With the current load levels, the Peloponnese region exports energy during the greater part of the year. Since 2005, the Peloponnese region presents with a local maximum of 1000 MW during night time hours.

In these cases, the Peloponnese is a particularly critical region for the stability of the South System voltages, in case of loss of production in the region. Moreover, the Peloponnese is connected to the rest of the System exclusively via 150 kV lines, and therefore has a reduced transmission capacity. Specifically, to date, the Peloponnese is connected:

  • with Attica via three 150 kV heavy-duty double circuit Transmission Lines and
  • with Western Greece through two 150 kV submarine cables.

The new Megalopoli V unit is in full operation (operates up to 500 MW under special status according to Law 4533/2018), and moreover significant capacity is expected to be added from new RES Stations.

In this light, potential voltage problems and in particular the issue of absorption of the power produced by the generating Stations expected to be developed in the area, are effectively addressed with the expansion of the 400 kV System towards the Peloponnese (with beneficial effects for the entire South System).


Eastern Corridor (Megalopoli - Corinth - Attica)

A main hub of the Eastern Corridor is the High Voltage Center of Corinth, which is anticipated to be connected to the 400 kV System as follows:

  • With the Koumoundourou HVC via a new double 2Β’Β’/400 kV Transmission Line, which will either be routed alongside the existing 2B/150 kV Corinth - Koumoundourou HVC Transmission Line, or will be constructed in replacement of the Transmission Line mentioned above.
  • With the new Megalopoli HVC, through a new double 2Β’Β’/400 kV Transmission Line.



  • The expansion of the 400 kV System to Megalopoli (followed by the creation of a 400 kV Patra - Megalopoli - Corinth loop) drastically increases the transmission capacity to and from the Peloponnese, offers the opportunity for the development of RES and thermal Stations, significantly improves the voltage stability margin for the South System and shields the Peloponnese against any combination of production and load conditions. Also, it powerfully connects the Megalopoli generation center with the high load areas (Attica and Patra) and contributes in achieving an evenly distributed development of the Production and Transmission Systems in the South System. Finally, it should be noted that the development of the 400 kV System to the Peloponnese, contributes towards reducing the total losses of HETS.
Project's Timeline
Estimated completion of project
Completion of contract conclusion process