Current situation with operation of Baltic States in synchronous mode with IPS/UPS power system

The power system of the Baltic States which includes Estonia, Latvia, Lithuania (Baltic Integrated Power System) currently is operating in parallel with the Integrated/Unified Power System (IPS/UPS) of Russia and Belarus. The Russian power system ensures primary power reserves for the frequency regulation and the secure system operation within BRELL (Belarus, Russia, Estonia, Latvia and Lithuania) ring.

At present the power system of the Baltic States is participating in frequency regulation with its own demand and generation regulation. The power system of the Baltic States is tightly connected to the Russian and Belarus power systems with alternating current (AC) 330 kV interconnectors. The tight connection of the Baltic States with Russia and Belarus provides reliable, flexible and secure system operation within the Baltic States and the whole BRELL ring.

Besides the interconnections with Russia and Belarus, the Baltic States have interconnectors with the Nordic countries via Finland (Estlink 1 and Estlink 2) and Sweden (NordBalt), and an interconnector to Poland towards Continental Europe. A common goal for the Baltic States is greater energy supply independence through the diversification of primary energy sources. Furthermore the integration of Latvia, Lithuania and Estonia within common EU energy market has been identified as a strategic priority for Baltic States in the previous Pan-European TYNDPs 2012 and 2014 and it is a strategic priority for all three countries.

Based on geographical location and different kind of feasibility studies done before, the Baltic States are focussing on three main synchronising/desynchronising scenarios which are described in this report:

• Baltic States synchronous operation with continental Europe (HVAC Lithuania-Poland interconnector), including soft coupling supported by existing HVDC links;

• Baltic States synchronous operation with Nordic countries (HVAC Estonia-Finland), including soft coupling supported by existing HVDC links;

• Baltic States isolated island operation, including soft coupling supported by existing HVDC links.

What are the main reasons to shift from IPS/UPS power system to continental Europe?

The aim is to remove the energy isolation of the Baltic States from the rest of the EU and connect their power systems with systems using the same technical standards and developing in the same European legal framework. This strategic goal has been set by the Prime Ministers of the Baltic States in 2007.

The Baltic States and the European Commission, the Kingdom of Denmark, the Federal Republic of Germany, the Republic of Poland, the Republic of Finland, the Kingdom of Sweden has established the Memorandum of Understanding on the reinforced Baltic Energy Market Interconnection Plan “BEMIP”.

A Declaration on energy Security of Supply was signed on 14 January 2015 by the energy Ministers of the Baltic States. The Declaration calls for: “developing liberal, transparent, competitive and fully functioning regional gas and electricity markets; full implementation of the third energy package; market integration; construction of necessary infrastructure; synchronisation of the Baltic States with the continental European network, and implementation of the European Energy Security Strategy.”

The synchronisation of the Baltic States with the Nordic or continental European networks implies an elimination of the Baltic States isolated island operation scenario.

Which studies regarding desynchronization from IPS/UPS are already available?

Since the early 2000s, several studies on the synchronization of the Baltic power system with continental Europe have been carried out.

BALTSO coordinated the following studies related to desynchronization:

• 2007 – The Baltic states completed a Baltics transmission system development plan “Baltic Grid 2025”.

• 2007 – In cooperation between BALTSO and the Polish TSO a study “Baltic and Polish TSOs on synchronous operation of Baltic power systems with UCTE” was performed.

• 2008 – A pre-feasibility study covering a state load-flow study on synchronous operation of Baltic power systems with the UCTE was carried out.

Executive summaries of the mentioned studies can be found here: https://www.entsoe.eu/news-events/former-associations/baltso/system-studies/Pages/default.aspx

During 2012-2013, the Baltic TSOs carried out a Feasibility study to evaluate the possible technical and economic consequences and benefits of synchronising power systems of the Baltics within the synchronous area of Continental Europe. One of the main objectives and outputs of the feasibility study was an identification of the most feasible interconnection variant and scenario with detailed analysis of the process and steps needed for the Baltic States power system in order for full synchronous interconnection with Continental Europe.

The feasibility study has been carried out using network models for load flow calculations, regional and wide area stability analysis, and also market models for socio-economic analysis and cost/benefit evaluation. The legal and regulatory issues have been analysed based on European legal acts, operational standards of ENTSO-E and existing operational standards within IPS/UPS. The study identified necessary grid reinforcements and associated costs.

The study identified necessary grid reinforcements and associated costs. The feasibility study concluded that the cost/benefits analysis of the synchronization would be negative for the project and has not identified traditional technical or economic reasons that can justify a change of synchronization from the present IPS/UPS system to the CE system.

However, reinforcements are needed in the present power system of the Baltic States, Poland, and third countries to ensure safe systems operation. Power plants in Baltic States providing control and reserves have to be up-graded, and a number of back-to-back converters towards Russia and Belarus could be installed in order to maintain power exchange possibilities with the third countries.

In the second half of 2014 PSE and Litgrid performed pre-feasibility studies for the second Polish – Lithuanian interconnection between Intersection of overhead line “Kaunas-Sovieck” through Mariampolė substation (LT) to Olsztyn Mątki (PL), i.e. a key infrastructural element for implementation of the scenario analysed in Gothia Power feasibility study and chosen by the Baltic TSOs in the “Synchronization roadmap”.

The outcomes of the pre-feasibility study identified several risks in North-Eastern part of Poland, which doesn’t allow effective implementation of the second double circuit 400 kV line, linking the Polish and Lithuanian power systems. It is also concluded, that the routing in Lithuania is mapped out, but the exact placing and possibility of construction can only be identified after environmental impact assessment, public consultations and territorial planning is completed.

The prepared alternative does not conflict with any protected areas. Therefore, the main potential problems would be related to territorial planning and land use only.

In the beginning of 2015, notwithstanding the earlier pre-feasibility study results, the three Baltic TSOs developed an action plan towards synchronous operation with the network of Continental Europe, with the target to establish synchronous operation by 2025. Baltic synchronous operation with the network of Continental Europe will eliminate dependence on the Russian system, the Belarus power systems uncoordinated behaviour and development, as well as their market actions governed by different legislation comparing to the EU rules.

The possible integration of a large scale generating unit into the Lithuanian power transmission system might influence the operation of the Estonian, Latvian and other neighboring power transmission systems.

Litgrid has during 2015 developed the Study “Identification of Technical Requirements and Costs for Integration of Large Scale Generating Unit Into the Baltic States’ Power System Operating Synchronously with the Continental Europe Networks” investigating what are the additional measures and cost for integration of a large unit into the Lithuanian power transmission system without endangering security of supply.

No major legal or regulatory obstacle against integration of a large scale generation unit has been identified in the feasibility study, but a number of issues have to be negotiated and resolved. The investment costs and annual costs are high in comparison to the Baltic States TSOs’ normal investments and to the technical and economic outcome.

The “BEMIP Synchronisation working group” has been established by the European Commission in 2015 for evaluation of possible Baltic States synchronisation variants. On 17 December 2015 a study of integration of the Baltic States into EU electricity system was launched. The study is led by DG ENER/JRC, and all related TSOs are involved in the study. The aim of the study is to assess all possible variants and benefits of integration of the Baltic States electricity network into the EU electricity market.

The study is ongoing and the first outcomes of the study are the cross-border transmission corridors inside the Baltic States are sufficient to sustain the electricity consumption patterns assumed in the scenarios. Additional reinforcements are needed in the northern part of Estonia and south-west of Riga (Latvia). The current status of the study provides insight in the ability of the Baltic States to operate their electricity system independently and self-sufficiently. More detailed studies are still required.

What are the options currently on the table?

In order to evaluate how the synchronous or asynchronous interconnection of the power systems in the Baltic States affects the power systems in Continental Europe or Nordic countries, a more detailed analysis should be done as well as to determine the number of interconnections and the maximum power exchange for the three main and optional synchronization cases.

1. Baltic States synchronous operation with continental European Network through Lithuania-Poland interconnection and also soft coupling supported by existing HVDC links.

Two subcases have to be evaluated when the Kaliningrad region is operating in synchronous mode with Baltic States and EU or in asynchronous mode. The expected results of such operation are stable system operation with increased vulnerability, due to considerably weaker AC interconnection of the Baltic Countries power systems to the CE power grids.

Loop flows from/to IPS/UPS can be controlled/eliminated due to DC interconnections replacing the AC ones. In the case of positive developments in the field of soft-coupling and synthetic-inertia synchronization schemes, using HVDC technologies, operational stability of Baltic Country power systems can reach unprecedented levels of security.

Current AC loop flow patterns through the bulk power networks of Baltic Countries will be replaced by more radial flows in North-South orientation. If possible, development of AC or modern HVDC interconnection development between Kaliningrad region (Russia) and Poland (CE) is to be investigated as well. From technical and geography point of view such interconnections are highly likely and could improve the performance of Baltic Country power system operation as well.

2. Baltic States is synchronised with the Nordic countries through soft coupling supported by existing HVDC and new HVAC connections.

Two subcases have to be evaluated when Kaliningrad region is operating in synchronous mode with Baltic States and Nordic countries or in asynchronous mode. With currently available technologies AC interconnection for this scenario is the most challenging one to implement. In case of R&D breakthrough in the field of soft-coupling and synthetic-inertia synchronization schemes this scenario will show similar benefits and challenges to the previous scenario.

Current AC loop flow pattern through the bulk power networks of Baltic Countries will be replaced by more radial flows in North-South orientation. If possible, development of AC or modern HVDC interconnection development between Kaliningrad region (Russia) and Poland (CE) must be investigated as opposed to majority of previous studies in this field. From technical and geography point of view such interconnections are highly likely and could improve the performance of Baltic Country power system operation as well.

3. The Baltic States technical capability to operate in the self-standing mode (asynchronous operation) with soft coupling supported by existing HVDC links.

Isolated operation is an extremely important scenario for the study. Only in the case of successful results on Baltic Country power system island operation scenarios should one go further towards various synchronisation scenarios. The scenario will pinpoint the majority of weaknesses and challenges in the existing network schemes, automation architectures and generation/load adequacies. The most expensive system operation and most stressed network operation modes are expected.

This scenario will benefit greatly from any developments in the field of soft-coupling and synthetic-inertia synchronization schemes. A bottleneck on the Estonia-Latvia interconnection is expected. Also deep frequency variations due to currently existing large generation unit (up to 400 MW) trips are expected. Frequency regulation (generation reserves, automation, settings) development is critically important to study in more detail.

What are the next steps?

The future steps on synchronization are as follows:

• June-November 2016: discussions on the results and conclusions of the BEMIP study;

• End of 2016: BEMIP High-Level Group meeting on the decision of one of the options for synchronisation, discussions with Russia, elaboration of a synchronisation programme;

• End of 2016 – beginning of 2017: additional study on an alternative track for a second interconnection Poland – Lithuania.

Additional challenges for the Baltic power system

Litgrid, the Lithuanian TSO, has studied in 2015 the impact on the Estonian, Latvian and other neighbouring power systems of the possible integration of a large scale generating unit into the Lithuanian power transmission system. The study shows that there is no major legal or regulatory obstacle but that a number of issues have still to be resolved. The investment and annual costs of the project seem relatively high compared to the normal investment costs of Baltic TSOs and with regard to the technical and economic outcome expected of the project.