North-South Interconnections in Central-East and South-East Europe

Building power bridges between Eastern and Western Europe; relieving the bottlenecks in Central Europe; see what grid development the Central East and the South East regions are facing.

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This document addresses grid development issues in the geographical area covered by the North-South electricity interconnections in Central Eastern and South Eastern Europe (‘NSI East Electricity’) established by Regulation (EU) No. 347/2013 on guidelines for trans-European energy infrastructure (‘The Energy Infrastructure Regulation’).

It bases on the achievements of TSOs’ efforts striving to ensure adequate and timely grid development while closely coordinating within three ENTSO-E Regional Groups: Continental Central East, Continental Central South and Continental South East, the perimeter of which is shown on Fig 1.1.

Figure 1‑1 ENTSO-E System Development Regions

Main Drivers For Grid Development

Main Challenges

The following trends can be observed over the coming 15 years and beyond:

Dynamic RES development

Dynamic RES development (especially wind and solar) according to EU objectives. A particularly intensive up-growth of the Wind energy is taking place mostly in the northern regions (i.e. Germany and the North Sea), but it is also significant in the western (like GB and France) and southern European regions (i.e. Italy, Greece). The core development area of the solar energy lies in southern part (Italy, Greece) but also in France and southern Germany.

Vast number of variable renewable resources located at the different corners of the region and far from the load centers results in high and volatile bulk power flows, basically in the direction North-to-South and Central East-to-South East, and is also quite challenging to the system security and frequency control as the system must provide suitable back-up generation at any moment of time. Far distance RES-electricity transports, especially via HVDC lines, will facilitate using RES energy where it is most needed, increasing its value for the region

Conventional generation

Conventional generation like combined cycle gas turbines and traditional coal plants is still under development in Poland, Czech Republic and West Balkan, even though the European electricity market conditions in general are less favorable for such power generation for the time being. Some countries are planning to phase out nuclear power plants totally (DE, CH) or partially (FR) while Czech Republic, Poland, Slovakia, Hungary, Romania and Slovenia still intend to significantly increase their share in the nuclear energy market. Another phenomenon to be carefully monitored from the system security perspective is linked to the dismissal or mothballing of a significant amount of conventional generation (especially from oil, coal and gas thermal power). This is a market driven trend, mainly due to the development of new RES capacity and slowing down in the evolution of the electricity demand, which is expected to keep on further in the next years.

Storage development

Storage plants can be used in order to facilitate the efficient use of RES. Considerable storage potential is available in the very center of the eastern and south central region through the hydro pumped storage potential located mainly in the Alps. Further opportunities could be considered concerning development of distributed storage systems within or near peripheral areas with expected higher RES penetration to reduce local congestions. In this respect, some network development projects are aimed also to better integrate storage projects in the power system.

Climate change mitigation

Climate change mitigation and competition will require energy efficiency measures such as transfer from fossil-fuel based end-users to CO2-free energy sources. The electricity peak demand growth forecast based on the future scenarios varies between moderate and rapid by the year 2030.

Market integration

Versatile market flows across Europe and following price signals instantly result in triggering further grid development. This is of major relevance for the bidding zones (within a Country or among different Countries) characterized by limited competition due to lack of transmission capacity with neighboring areas endowed with more competitive RES or thermal power resources.

Improving the interconnection of the sparse networks

In the eastern and south central region there are a lot of projects designed to cope with insufficient interconnection transmission capacities on particular profiles, to fulfil the essential characteristics of the common European market. This is relevant especially for the Balkan area and for the integration of the Italian peninsula and the main Islands in the European bulk power system.

Security of Supply improvement

The energy transition of the regional power system leads to increased high north-south power flows. In order to ensure security of supply and to improve system stability not only new DC and AC grid expansion measures are needed, but also additional reinforcements in the area of voltage control such as VAR-compensation. In order to prevent a lack of supply it is essential to increase transmission capacities between European countries and within market zones, especially concerning Islands or areas which are less interconnected such as not strongly meshed network portions .

Main bottlenecks

The actual overview of the pan European situation including main regional boundaries is shown in Fig 2.1.

Figure 2-1 Main bottlenecks in eastern and south central region (marked area)

Based on the expected evolution of the power system in the coming years as well as actual constraints analysis it was possible to identify several barriers already (indicated in the figure with yellow and grey boundaries).

Due to ongoing market integration processes the main boundaries refer mostly to the Italian borders: northern and the one between Italy and the Balkans and the internal bottlenecks among the six different Italian price zones.

Significant power flows throughout Germany (north-south power flows) and towards Austria have already generated a need for the transmission capacity increase within the same price zone.

In order to efficiently integrate the dispersed generation units (RES) and improve the correlation to the public and mature applications for connecting large generation plants, storage, and areas with high penetrations of RES it is necessary to relate such critical sections to the actual boundaries as well. According to such an approach the primarily concerned boundaries are:

  • the connection of offshore wind in North Sea and Baltic Sea in Germany;
  • the connection of additional hydro power plants in Austria and the connection of wind in eastern part of Austria;
  • integration of renewable generation expected especially in Germany, in Italy and in South-Eastern Europe.

Generally it can be stated, that the actual generation capacity is sufficient to balance the load. Nonetheless, security of supply still remains a concern, especially locally, in peripheral areas with scarcely meshed network (like Italian main Islands and Corsica).

Grid Development in the Region

Project portfolio

The table below lists the boundaries with the specific drivers for grid development in each case and link the projects that are assessed in TYNDP2016.

All the projects listed were classified according to their status (Mid-Term projects are marked in red, long-term ones are in blue and the future projects are marked in black).



Proposed solutions

Name of the project

PCI label

Main Benefit

Italian Northern boundary1

Integration of the Italian peninsula. High north to south flows triggered by power exchanges at the Italian Northern border, mainly from the Alps area and Germany.

p. 150

Interconnection Italy-Slovenia


Increase SI-IT capacity by about 1000 MW

p. 26


Austria - Italy

3.2.1 and 3.2.2


Increase AT-IT capacity by about 1100 MW via two new single circuit cross-border lines and closure of the 380-kV-Security Ring in Austria

p. 210

Wurmlach (AT) - Somplago (IT)


Increase AT-IT capacity by about 150 MW


Integration of the Italian peninsula and the Balkans in the European market/system

p. 28

Interconnection Italy - Montenegro


To realize 2X600 MW transmission capacity cables to interconnect Italy and the Balkan system is of major importance to integrate the central-eastern and south-eastern markets with the Italian market. The link will contribute as well to improve the security of the two interconnected areas.

Italy-center/Italy north

Removal of the bottlenecks between market zones internal to Italy to better integrate Italy in the European market

p. 33



Central Northern Italy



Increase the transmission capacity between IT Center and IT north by about 400-600 MW

Italy-South/Italy central

Removal of the bottlenecks between market zones internal to Italy to better integrate Italy in the European market.

p. 127



Central Southern Italy


Increase the transmission capacity between IT South and IT center market zones by about 1200 MW

Slovenia - Hungary

RES integration in the South East and Central East Europe, new electricity corridors and possibility to access the new energy market

p. 141

Slovenia-Hungary corridor

3.9.1, 3.9.2, 3.9.3 and


Increase the transmission capacity between Slovenia and Hungary by about 1100 MW

Austria – Germany


Integration of RES generation mainly in Germany and connection with pump storage power plants in the Alps


p. 47

Austria - Germany

2.1, 3.1.1, 3.1.2

Increase of the interconnection capacity between Austria and Germany by approximately 2900 MW




Increase of the interconnection capacity between Austria and Germany by approximately 1500 MW

p. 198

Area of Lake Constance


Increase of the interconnection capacity between Austria and

Germany by approximately 1000 MW

Poland - Germany

Market integration and decreasing of unscheduled flow from DE to PL, PL to CZ and PL to SK by increasing of controllability on entire synchronous profile.

p. 94

GerPol Improvements


Enhancement of market capacity on Polish synchronous profile - PL/DE as well as PL-CZ/SK border in case of both import (3500 MW) and export (2000 MW)

p. 229

GerPol Power Bridge II


p. 230

GerPol Power Bridge I

Czech - Germany

Security of Supply improvement in the CZ southern regions and connection of potential power generation capacities in the region and facilitation of power flows in the north-west and west-east direction.

p. 35

CZ Southwest-east corridor

3.11.3, 3.11.4 and 3.11.5

Enhancement of transmission capacity inside CZ by 2x1730 MVA by building new AC 400 kV OHL between Kocin-Mirovka, Kocin-Prestice and Mirovka-Cebin

, RES integration in the Karlovary region and accommodation of the prevailing power flows in the north-west and west-east direction, Security of Supply improvement in the CZ western region

p. 200

CZ Northwest-South corridor

3.11.1 and 3.11.2

Enhancement of transmission capacity inside CZ about 2x1730 MVA, by building new 400 kV substations and AC OHL between Vernerov-Vitkov, Vitkov-Prestice and Mirovka-V413


Internal German projects



RES integration, Security of Supply improvement in particular DE regions


p. 205

N-S transmission DE_par_line_1


Increase of the transmission capacity between Thuringia (area with increasing RES generation), and Bavaria (area with decreasing conventional power generation)

p. 235

HVDC Brunsbüttel/Wilster to Großgartach/Grafenrheinfeld


Increase of the transmission capacity about 4 GW between Northern Germany to Bavaria / Baden-Württemberg by HVDC connection construction

p. 254



Increase of the transmission capacity about 2 GW between Region of Osterath and Region of Philippsburg by HVDC connection construction, where DC circuits will be on the same pylons as AC lines

p. 130

HVDC Wolmirstedt to area Gundremmingen


Increase of the transmission capacity about 2 GW between North-East Germany (are with RES generation) and South of Bavaria (area with high consumption) by HVDC connection construction

Slovakia - Hungary


Improvement of the secure and reliable operation at the SK-HU profile, market integration as the SK-HU profile is the part of the 4M MC market coupling and accommodation of the North - South RES power

flows in CCE region

p. 48

New SK-HU intercon. - phase 1

3.16 and 3.17

Increase of the transfer capacity on the SK-HU cross-border profile.

p. 54

New SK-HU intercon. - phase 2



Support market integration in SE Europe.


2nd BG-GR interconnector and South BG corridor


Increase transfer capacity in the predominant North-South direction, between Bulgaria and Greece.


Support  the large scale integration of RES in the area of the Black sea coast in Romania and Bulgaria


Black Sea corridor


Increase transfer capacity in the predominant North-South direction, between Bulgaria and Romania


Support market integration and the large scale integration of new RES in the region of South-West Romania and  North-East Serbia.


Mid Continental East Corridor


Increase transfer capacity along the East-West corridor in the South Eastern and Central Europe.

Table 3-1 Project portfolio of the eastern and south central region

Boundary adequacy

The analysis of the target capacities is to be considered as the starting point for the assessment of the transmission adequacy and the identification of any further network development needed for 2030 and beyond.

The target capacity for every boundary corresponds essentially to the maximum transmission capacity value, which is able to bring enough benefits to outweigh costs. Then, comparing the target capacity and the project portfolio for every boundary, a transmission adequacy indication could be evaluated.

In order to identify a wider spectrum of further potential needs, it is recommendable to analyze the transmission system under the different development conditions portrayed in the four 2030 visions, leading to intensified interactions between market areas, higher usage of the transmission capacity and therefore to a higher target capacity.

The transmission adequacy prospect along the corridor is depicted in the Figure 3.1.

Figure 3-1 Main boundaries of the region

  1. Interconnections between Italy and France and between Italy and Switzerland are described in the Insight Report: North-South Interconnections in Western Europe.