State power grid operator Elektromre?a Srbije (EMS) has invested EUR 30 million in two overhead power lines in the Banat region of Vojvodina. which will enable the integration of 2.8 GW of wind farms that are in different phases of the connection process. This demonstrates that EMS is ready to meet the demand for the connection of new green power plants. However, she also said it will be a challenge to secure some EUR 60 million a year needed to ensure the transmission system can keep pace with the increasing demand for renewables integration.

Jelena Mateji? also talked about new requests for the connection of solar and wind power plants, the power grid operator’s experience with the variable output of wind farms that are already connected, as well as the completion of the Trans-Balkan Electricity Corridor.

Investors are announcing the construction of green energy power plants with a capacity of between several hundred megawatts and several gigawatts.

How prepared is EMS to integrate new wind farms, solar parks, hydropower plants?

As the national transmission system operator, EMS is channeling its infrastructure investments taking into account several key objectives, including the integration of renewable energy sources. In line with this, and in an effort to meet the objectives of the Energy Sector Development Strategy of the Republic of Serbia until 2025 with projections until 2030, EMS has completed two capital infrastructure projects in southern Banat: a double-circuit 400 kV overhead power line between the Pan?evo 2 substation and the Romanian border (Section1 of the Trans-Balkan Electricity Corridor) and a 110 kV overhead line between the Bela Crkva substation and the Veliko Gradište substation.

EMS invested nearly EUR 30 million of its own funds in these two projects alone. I’m telling you this because these projects are significant precisely because their implementation has enabled the integration of a certain number of wind farms in this region, where there are currently a total of 2.8 GW of wind power plants in different phases of the connection process. So, we’re ready. We are working and we are looking at all the needs of investors, as well as the capacities of our system and, after all, of Serbia as a country.

How much does EMS need to invest in the connection of new capacities?

Over the coming period, EMS will need to make massive investments to enable a greater level of renewable energy integration. The necessary annual investments that would enable the adequate development of EMS’ transmission system, with the necessary maintenance of the existing grid, are analyzed in a study on a long-term development of Serbia’s power transmission system until 2035, produced by Electrical Engineering Institute Nikola Tesla, as a consultant.

We expect significant support from the state budget for future investments given that these are capital and strategic projects that will help achieve national goals

Based on the results of the study, and available data from practical experience, it has been determined that it is necessary to invest nearly EUR 60 million a year in order to ensure that the development of the power transmission system can keep pace with the increasing demand for renewable energy integration. Otherwise some projects could be delayed, limiting EMS’ capacity to respond adequately to the energy transition.

How are you going to secure the necessary funding?

These are clearly significant investments that require sizeable funds. EMS has experience in implementing major infrastructure projects, and over the years it has relied on its own funds as well as loans and credit arrangements with international financial institutions. It will be the same with these investments, but this time around we certainly expect significant support from the state budget given that these are capital and strategic projects that will help achieve our national goals.

What other parts of the transmission system is EMS currently investing in?

We aim to ensure the greatest possible stability and security of supply for electricity consumers, as well as an unimpeded integration of the greatest possible capacity of renewable energy sources.

Projects that should be mentioned are the construction of a 400 kV overhead line between the Kragujevac 2 substation and the Kraljevo 3 substation (Section2 of the Trans-Balkan Corridor), as well as a double-circuit 400 kV overhead line between the Obrenovac substation and the Bajina Bašta substation (Section 3 of the Trans-Balkan Corridor). The completion of these projects will enable an unimpeded offtake of electricity from hydropower capacities in the Drina-Lim river basin, where the current installed capacity exceeds 1.1 GW.

EMS is also working on the rollout of new technologies

Additionally, a significant portion of EMS’ investments is channeled towards the further development of the transmission system in southern Banat and an increase of the transmission capacity between this area and the rest of the country, including, first and foremost, the BeoGrid2025 project, which entails the construction of a new 400/110 kV substation called Beograd 50 and a new double-circuit 400 kV overhead line that will connect this facility with southern Banat. This will open up another corridor for supplying electricity produced from renewable energy sources to consumers in the Srem region.

In parallel with infrastructure development, EMS is working on the rollout of new technologies. We have completed a pilot project of installing a Dynamic Line Rating (DLR) device with the aim of making the existing infrastructure more flexible amid intensified renewable energy integration. This technology can be considered an operational solution to problems arising from increased electricity generation at wind power plants due to high wind speeds.

What is EMS’ experience with the 400 MW of wind capacities that are already connected to the grid?

At the moment, there are four wind farms connected to the transmission system – ?ibuk 1, at 400 kV, Kova?ica, at 220 kV, and Alibunar and Košava, at 110 kV – whose total installed capacity is 374 MW. The share of these four wind farms in overall electricity production in Serbia in 2020 was 2.6%. The experience so far has been positive and there have been no problems on the grid due to the operation of these wind farms.

How problematic for the transmission system is the intermittency of this energy source?

Given the current share of these wind farms in overall electricity production, and the combined installed capacity of all power plants connected to the grind, the intermittency of these sources does not affect the stability of the transmission system.

EMS has a good relationship with all four wind farms, which is defined in agreements on the operation of these facilities. These agreements set out the responsibilities and obligations regarding the operation of these specific sources of electricity.

In line with the best practices of European grids where renewable energy sources have a significant impact on the functioning of the system, EMS has established a forecasting process for electricity generation from renewable energy sources in order to minimize the impact of their intermittency. For now these forecasts, which are made on a daily and weekly basis, are within the set limits (the average error is about 10% of the installed capacity), which provides satisfactory parameters for management in real time.

What is the total installed capacity of new facilities whose connection is pending?

At the moment, the requested capacity for connection is 4,274 MW for wind farms, 637 MW for solar power plants, and 750 MW for thermal power plants.

What is your assessment of the feasibility of these projects?

The offtake of electricity produced at power plants using renewable energy sources, from the standpoint of the transmission system operator’s jurisdiction, will be enabled in line with the newly adopted regulatory framework, and at a pace at which investors can realize their wind and solar projects and the defined connection procedure.

At what stage is the construction of the Trans-Balkan Corridor?

It is well known that this project is a strategic investment of regional and European significance. The Trans-Balkan Corridor is primarily aimed at ensuring Serbia’s national energy security and replacing the outdated lower-voltage network (220 kV) with a higher-voltage system whose capacity is many times bigger. The project will also improve the security of supply in western and central Serbia. Thanks to its geographical position and planned investments in new interconnections, the Trans-Balkan Corridor is at the same time a kind of a link between the East and the West, connecting the markets of eastern and western Europe.

The project consists of four sections. Section 1, which involved building a double-circuit 400 kV overhead line between Pan?evo and the Romanian border and equipping  the 400 kV field at the 400/220/110 kV Pan?evo 2 substation, was completed and put in operation in December 2017, and was financed entirely with EMS’ own funds.

When it comes to Section 2 – the construction of a 400 kV overhead line between Kragujevac 2 and Kraljevo 3 (60 kilometers in length), the upgrade of the 220/110 kV Kraljevo 3 substation into a 400/220/110 kV substation, and the fitting of the 400 kV field at the 400/110 kV Kragujevac 2 substation – the works were launched in 2020. The transmission line is expected to be completed this year, while works on Kraljevo 3 should be finished in 2022, marking the completion of the entire Section 2.

Section 3 (building a double-circuit 400 kV overhead power line between the Obrenovac and Bajina Bašta substations, increasing the voltage level at Bajina Bašta to 400 kV, and equipping the 400 kV field at the 400/220 kV Obrenovac substation) should be completed by the end of 2025, while Section 4 (a double-circuit 400 kV overhead line from the Bajina Bašta substation to the borders with Montenegro and Bosnia and Herzegovina) is planned to be put in operation in 2026.