Transmission New Projects Department (TNPD)

The Transmission New Projects Department (TNPD) reports to the General Division of Technology, System Development & Strategy and its mission is to implement the Development Projects of the Hellenic Electricity Transmission System (HETS).

More specifically, the responsibilities of TNPD mainly focus on the following:

  1. Study, licensing and construction (with direct labour or through Contractors) of the necessary Grid reinforcements, such as new Transmission Lines (TL), upgrades of existing TLs, new Ultra-High Voltage Centers (HVC) and Substations, and expansions of existing HVCs or Substations, which are necessary for the safe distribution of capacity through the System nodes.
  2. Study, licensing and construction (with direct labour or through Contractors) of projects for the modernisation and upgrade of existing Substation and HVC infrastructure, and their corresponding control infrastructures.
  3. Study, licensing and construction (with direct labour or through Contractors) of projects involving new and/or the upgrade of existing interconnecting TLs with neighbouring countries.
  4. Study, licensing and construction (with direct labour or through Contractors) of projects for the development of the necessary infrastructures, such as reinforcements of the existing Substations - HVCs and construction of new TLs, which will allow an increased penetration of RES into the Country's electrical system to best serve the needs of the System’s Users. 
  5. Control and supervision of projects for connection to the System (TL and Substations) necessary for the inclusion of new System Users (RES production units, conventional production units, HV Customers).
  6. Participation (under the coordination of the Information Technology & Telecommunications Department), in the implementation of the necessary telecommunications links between Substations - HVCs and Energy Control Centers (ECCs), for the safer and more efficient operation of the System and the electricity market.

Among the projects implemented by the TNPD, a prominent place is held by the interconnection projects for Non-Interconnected Islands (NII) with HETS, which are IPTO’s strategic objective and correspond to more than 80% of the company’s overall investment programme.

These interconnection projects contribute greatly towards achieving national energy and environmental targets, for the following reasons:

  • The islands will no longer be isolated and their supply with energy will be ensured, thus definitively resolving their energy problem. This problem will gradually worsen after 2020 and even more after 2030 due to environmental restrictions imposed by EU law on conventional power plants (emissions limit).
  • Consumers are relieved from the high price of oil-fuelled power production on the islands, ranging for households and businesses between €500 million and more than € 800 million a year for all islands, depending on the international prices of oil.
  • The islands are environmentally upgraded, improving their environmental footprint by shutting down the oil-burning Stations, which usually operate at the boundaries or even inside residential zones, including tourist regions.
  • This will drastically contribute towards reducing the country’s dependency from oil for its energy production needs.
  • It further allows the islands themselves to become autonomous in a more cost-efficient manner, through the mild use of renewable energy sources.
  • The quality of the electricity is improved, giving a significant boost to the economy of the islands and the quality of the life of the residents and visitors.

Another fundamental goal served by the implementation of the HETS development projects is the need to push the greater penetration of RES in the context of meeting the national and the corresponding European policy, with the ultimate goal of the decarbonisation of the power production activity, as well as the contribution of the electricity industry in addressing the phenomenon of climate change. In this framework, the development of HETS is oriented towards the incorporation of the imminent increase in RES penetration, which is reflected in specific European and national objectives for 2020 and 2030. 


The TNPD is currently running a major programme of Development Projects, the most important ones being:

1. Cyclades Interconnection

The project includes exclusive GIS Substations and underground-submarine cables. It is being implemented in 4 phases: 

  • Phase A (interconnection of Syros, Paros, Mykonos with Lavrio and Evia, through Andros and Tinos) was completed in 2018. Since then, the units of the local APS were put in the reserve for emergencies and the loads of the respective islands are now being supplied by HETS. Phase A ensures the transmission of capacity from HETS to Syros for a minimum 120 MW capacity even in the case of failure of the Lavrio-Syros cable.
  • Phase B (interconnection of Naxos, and through it the closing of the Syros - Paros - Naxos - Mykonos - Syros loop), which is being completed within 2020. The upgrade of the existing interconnection with Evia was completed in 2020 (replacement of Evia - Andros - Tinos cable connection). The distribution of approximately 170 MW capacity is now ensured, from Evia to the interconnected Cyclades islands, even in the case of failure of the Lavrio-Syros cable.
  • Phase C (second connection of Lavrio with Syros) will be completed within 2020, when the full reliability of the supply of the Cyclades will be ensured for the planned project operation time frame and at N-1 conditions for the Lavrio-Syros route.
  • Phase D (interconnection of Naxos - Santorini - Folegandros - Milos - Serifos - Lavrio) is at the stage of sea floor studies and environmental licensing.


2. Crete Interconnection

The works for the interconnection of the Peloponnese with Crete are under way (rated capacity 2 x 200 MVA), with estimated completion by the end of 2020. The project includes the underground and submarine cable connection between SE Peloponnese and Chania, which is the longest submarine cable interconnection of alternating current in the world. The interconnection also includes projects of overhead TL in the Peloponnese (new circuits and extensive upgrades of existing ones), as well as Substation projects in the Peloponnese and Crete.

Also, TNPD actively participates in all stages of the Attica - Crete direct current interconnection project (rated capacity 2 x 500 MW), assisting the special purpose vehicle ARIADNE INTERCONNECTION, which is responsible for its implementation. The environmental licensing procedures have been completed and the Contractors have been selected.


3. Expansion of 400 kV System to the Peloponnese

The project consists of two 400 kV corridors, whose implementation is under way. The western corridor (connection of Megalopoli HVC-Patra-Rio-Antirrio-West Sterea Ellada) includes overhead, underground and submarine TL sections, as well as works for reactive power compensation in existing HVCs of the Peloponnese and Sterea Ellada. It will be completed during 2020.

The eastern corridor (connection of Megalopoli HVC- Corinth HVC - Koumoundourou HVC) includes overhead TLs and the new Corinth HVC. The Megalopoli - Corinth part will be completed during 2021.


4. Evia - Skiathos interconnection  

This interconnection includes overhead, underground and submarine  150 kV TL sections, and Substation projects in Skiathos and Evia. It will be completed by the end of 2021.

In general, the TNPD is responsible for the implementation of an extensive programme of projects across the country, which is included in the issued Ten-Year Network Development Plans of HETS. For example, by 2030, there is provision for implementation of projects adding up to a total € 4 bn budget.


89 Dyrrachiou Str. & Kifissou Ave,   GR 104 43  Athens

Tsirekis Konstantinos


Tel  +30 210 5192154

Fax  +30 210 5126999

E- mail