The Territorial Transmission Branch Constanta (TTB Constanta) has the mission of ensuring the functioning of the National Electricity System (NES) in the south-eastern area of Romania in safe and stable conditions, as well as ensuring the electricity transmission services meeting the quality and safety standards of the NES.

TTB Constanța operates on the entire territory of four counties: Constanța, Tulcea, Galați, Brăila and partially on the territory of Ialomița and Vrancea counties, having under its management an electricity transmission grid consisting of 1143.08 kilometers of overhead power lines (OHL), at voltages of:

• 750 kV - 3,108 km – works at 400 kV;
• 400 kV - 988,11 km;
• 220 kV - 151,86 km,

As well as 12 Electrical Substations:

1. 400/110/10 kV Constanța Nord Electrical substation;

2. 400/110/20 kV Medgidia Sud Electrical substation;

3. 400 kV Cernavodă Electrical substation;

4. 400/110 kV Tariverde Electrical substation;

5. 400 kV Stupina Electrical substation;  

6. 400/110/20 kV Tulcea Vest Electrical substation;

7. 400 kV Isaccea Electrical substation;  

8. 400 kV Rahman Electrical substation;

9. 400/220/110/20 kV Lacu Sărat Electrical substation;

10 400/110/20 kV Smârdan Electrical substation;

11. 220/110 kV Filești Electrical substation;  

12 220/110 kV Barboși Electrical substation.

The main objectives of TTB Constanța, according to the strategic objectives of the Company from the ETN Development Plan:

• The safe operation of the NES and the transmission of the power energy at the quality level corresponding to the normal conditions of the TSO license granted by NRA, the technical code of the ETN and the Standard Performance for the Power Energy Transmission and System Services (OTS).
• The technical and operational management of the SEN, so as to ensure continuous supply and under standard conditions of power energy quality, safety and stability in operation.
• Consolidating the ETN and increasing the efficiency in operation of the ETN.
• Optimizing the maintenance budget.
• Optimizing the organizational structure and the average number of staff, increasing work productivity. 

Achievements of TTB Constanța and historical landmarks:

In December 2022, the expansion of the 400 kV Cernavodă substation was completed with the connection of the 400 kV  OHL d.c. Cernavodă-Stâlpu, with an input/output circuit in the 400/110/20 kV Gura Ialomiței substation. This project, included in the "Black Sea Corridor" cluster, leads to the increase of the interconnection capacity between Romania and Bulgaria by strengthening the infrastructure that will support the transmission of power flows from intermittent renewable sources installed on the Black Sea coast to the consumption and storage centers.

In the same year, the newly installed 250MVA transformer in the 400/110 kV Smârdan substation, instead of the old T2 transformer, was put into operation, in order to consolidate the transmission grid and increase the evacuation capacity from the Dobrogea area to the rest of the system.

Also, in the spring of 2022, in the 400/110/20 kV Medgidia Sud substation, the first stage of the project to create the input-output connection of Stupina-Varna OHL and 400 kV OHL Rahman-Dobrudja was completed. The project contributes both to the consolidation of the ETN and to the increase of the cross-border interconnection capacity by increasing the exchange capacity on the southern interface of Romania, across the border with Bulgaria.

• 1893 – The establishment of the anonymous gas and electricity lighting exploitation company Galati
• 1956 - The first 110 kV line Borzești - Focșani - Galați (Filești station) and the connection of the southern part of Moldova to SEN, project carried out in the period 1954-1956
• 1965 – Placing in service the first 220 kV Borzești - Galați line, built between 1962 and 1964
• 1972 - Placing in service on the territory of Dobrogea of the 400 kV Vulcănești - Dobrudja OHL
• 1973 - December – Placing in service the 220/110 kV Lacu Sărat substation
• 1976 – Placing in service the 220/110 kV Constanța Nord and Tulcea Vest substations and the related OHL, with a gauge of 400 kV
• 1977 – Placing in service the 400 kV Lacu Sărat substation, and implicitly of the 400/220/110/20 kV Lacu Sărat substation, after making the connections between the two substations
• 1981 November – The transition to 400 kV of the 220 kV Constanța Nord substations and respectively of Gura Ialomiței - Constanța Nord OHL
• 1982 - The 220 kV Tulcea Vest substation and the Lacu Sărat - Tulcea Vest OHL are being switched to 400 kV.
• 1985 - Closing the loop 400 kV Constanța - Tulcea.
• 1986 – Placing in service the 750/400/15.75/20kV Isaccea substation, as a NES interconnection substation with Bulgaria and Ukraine. A polygonal scheme was adopted, namely a quadrilateral which has two autotransformers in the opposite nodes.
• 1986 – Building the 750 kV lines, project carried out in the period 1983-1986.
• 1994 – Placing in service the 400/110 kV Medgidia Sud substation for internal services of CNE Cernavodă.
• 1994 – Placing in service the 400 kV Cernavodă trafo substation (connection to the power energy system of the two 180 MVAR reactance coils)
• 1996 - April – Placing in service the first nuclear reactor and generating set at CNE - Cernavodă - 706 MW
• 1996 – July, 11 - Paralleling of CNE Cernavodă with the National Electricity System in the 400kV interconnection substation Cernavodă.
• 2001 Smârdan subtation 400 kV PIF reactance coil 100 MVAR type ELIN
• 2004 May – Placing in the Isaccea-Vulcănești and Isaccea-Dobrudja 400 KV LEA following the sectioning and introduction of the Vulcănești-Dobrudja 400 kV OHL into the Isaccea substation.
• 2004 – Placing in service the 400/110/10 kV Constanța Nord substation, refurbished with ABB Romania equipment
• 2009 – Placing in service the re-engineered, 400 kV Cernavodă substation, for discharging the power energy produced by CNE Cernavodă into the NES
• 2013 – Placing in service the refurbished 400/220/110/20 kV Lacu Sărat substation, project carried out between 2009 and 2013
• 2014 – Placing in service the refurbished 220/110 kV Barboși substation, project carried out in the period 2013 – 2014
• 2012 – Placing in service the new 400 kV Stupina connection substation, connected to the NES through the sectioning of the 750 kV Isaccea – Varna OHL
• 2012 – Placing in service the new 400 kV Rahman connection substation, connected to the NES through the sectioning of the 400 kV Isaccea - Dobrudja OHL
• 2014 – Placing in service the new 400 kV Tariverde connection substation, connected to the NES through the sectioning of the 400 kV OHL Constanța Nord – Tulcea Vest.
• 2014 - The installation of the third 400/110 kV 250 MVA transformer in Tulcea Vest substation increased the injection power from the EDN to the ETN for taking over the production from the wind power plants connected to the EDN and allowed operation with the 110 kV grid from Tulcea area "unlooped" by the grids in Constanța-Medgidia area.
• 2016 – Placing in service the refurbished 400/110/20 kV Tulcea Vest substation.
• 2019 – Placing in service the extended 400 kV Isaccea substation, according to stage I of the refurbishment.

The importance of the activity carried out results from the fact that in the consumption area of the branch there are powerful industrial centers, the Cernavodă Nuclear Power Plant, the "Liberty Galați SA" steel plant, the "Alum Tulcea S.A." alumina refinery, the "FERAL Tulcea S.R.L." ferroalloy factory, and some installations have a special importance or unique character in the Romanian power energy system.

Thus the 400/220/110/20 kV Lacu Sărat power station with its 41 cells is the largest station in Romania.

Forward-looking guidelines, in accordance with the development strategy:

To preserve the adequacy of the grid to be properly dimensioned for the power energy transmission forecasted to be produced, imported, exported and transited under the conditions of the changes that have occurred, were included in the ETN Development Plan for ten years, and will be carried out, two categories of investments: re-technology of the existing substations and the expansion of ETN.

The appearance of new production capacities, especially based on renewable sources, with intermittent operation and priority mode, connected both to RET and to the distribution grid, determines the need to strengthen RET in the next period.

At the level of TTB Constanța, the following projects are planned for the modernization and refurbishment of existing ssubstations:

1. Refurbishment of the 400/110 kV Smârdan substation, in progress.
2. Refurbishment of the 400/110 kV Filești sustation, in progress.
3. Refurbishment of the 110/20 kV Medgidia Sud sustation.
4. Refurbishment of the 400 kV Isaccea substation stage II.
5. Replacement of T1 and T2 in the 400/110 kV Constanța Nord substation.

Moreover, in the area of Dobrogea, due to the potential given by the meteorological conditions, there is already a large installed power in the wind power plants which, in addition to the power installed in the CNE Cernavodă, makes this area to have a overcapacity in terms of transited power energy at national level.

To increase the transmission capacity in the eastern area and integrate into the system the power generated from renewable sources and other sources in Dobrogea, the following projects for the expansion and consolidation of RET are being considered:

1. Input-output connection of 400 kV OHL Stupina-Varna and 400 kV OHL Rahman – Dobrudja in the 400/110 kV Medgidia Sud substation: stage I, of the 400 kV Medgidia Sud substation's extension was completed in 2022 and follows stage II - their connection.
2. The equipment of Circuit 2 for the new 400 kV OHL d.c. (1 c.e.) Smârdan–Gutinaș;
3. The realization of 400 kV OHL d.c. (1 c.e.) Medgidia South – Constanța North.
4. The transition of 400 kV OHL Isaccea – Tulcea Vest from single to double circuit.
5. The increasing the transmission capacity of 400 kV OHL Cernavodă-Pelicanu on the 53 km section with a smaller subsection.
6. The replacement of T2, 250 MVA with a new transformer in the 400/110 Medgidia Sud substation.
7. The installation of a new transformer, T3 in the 400/110 kV Medgidia Sud substation.
8. The installation of a third transformer in the 400/110 kV Smârdan substation.

The activity carried out at the TTB Constanța level contributes to the increase of the cross-border interconnection capacity by increasing the exchange capacity on the southern interface of Romania (the border with Bulgaria) for the transmission of power from intermittent renewable sources installed on the Black Sea coast to the consumption and storage centers.

In this sense, two grid development actions were established: 400 kV OHL d.c. (1 c.e.) Smârdan - Gutinaș which, together with the work already completed in December 2022, 400 kV OHL d.c. Cernavodă - Stâlpu with an input-output circuit in the 400/110 kV Gura Ialomiței substation, make up the "Black Sea Corridor" project.

As a result of this project's implementation - which contributes significantly, by increasing the interconnection capacity between Romania and Bulgaria, to increasing the sustainability of the infrastructure that will support the transmission of power flows - the integration's consolidation within the regional and European power energy market will be achieved, which will allow the increase power energy exchanges in the area.

Manager:	Florin Gavrilă
Address:	Bd.Alexandru Lapusneanu, nr.195A, bl .LAV1,Constanta, Cod 900472
Phone:	0040241 607 505
Fax:	0040241 607 550