Synchronisation in wartime: lessons from Ukraine

On 24 February 2022, hours before the start of large-scale Russian military action in Ukraine, the country's transmission system operator launched a test of isolated operation of the electricity system - the final and crucial step in the process of disconnecting from the Russian grid and synchronising with continental Europe. Ukraine's energy sector has shown exceptional professionalism, dedication and courage: even in wartime conditions, when power plants and grids were under constant shelling and bombardment, they managed to keep the power system stable, to supply power to as many people as possible and to achieve synchronisation.

In an interview with Maria Tsaturian, Head of Communications and International Cooperation Department at Ukrainian Transmission System Operator NPC UKRENERGO , we talk about energy security, preparing for synchronisation, international cooperation and the vital importance of adapting in times of war.

Could you tell us a little bit about the background - when and why Ukraine decided to connect to continental European grid?

Interconnection of the integrated power system of Ukraine with the power system of Continental Europe ENTSO-E has been one of the strategic goals for NPC Ukrenergo. Moreover, the interconnection of the two power grids is included in major state documents such as the Association Agreement between Ukraine and the European Union and the Energy Strategy of Ukraine.

For Ukraine, this is a critical component of the country’s energy security as the synchronous operation with ENTSO-E increases reliability and stability of operation of the national power system, expands opportunities for electricity exchanges with neighbouring countries, enhances competition in the internal market, as well as creates pre-conditions for full-fledged operation on the European electricity market.

It is worth noting that since 2002, a part of Ukraine’s power system had already been operating synchronously with the European Continental grid. A so-called “Burshtyn Island”, which accounted for around 4% of total electricity generation and consumption, was physically disconnected from the main part of Ukraine’s power system and operated in a parallel mode with the European grid, exporting electricity to Slovakia, Hungary and Romania.

On 28 June 2017, after several years of preliminary studies on feasibility and expediency of the interconnection, the representatives of ENTSO-E and NPC Ukrenergo signed the Agreement on the conditions for the future interconnection of the power system of Ukraine with the power system of Continental Europe. The implementation of this Connection Agreement was regarded as a final step towards the completion of the transfer of the integrated power system of Ukraine to the permanent parallel operation with the Continental Europe’s power system, initially scheduled for 2023. However, the full-scale war made its adjustments.?

What was the preparation process for synchronisation like? What changes to the software and hardware were needed before it?

The Connection Agreement signed in 2017 consisted of three main parts: the Catalogues of Measures, the Roadmap of integration, and the list of required additional studies. Each component of these documents had specific conditions and timeframes for implementation.

Since 2017, NPC Ukrenergo has been consistently and timely implementing all necessary measures to prepare for the interconnection. In particular, we are talking about modernisation and construction of new grid infrastructure, improvement of IT and cybersecurity, conclusion of relevant agreements with transmission system operators of neighbouring countries, harmonisation of the regulatory framework with European legislation, as well as the improvement of dispatching control procedures.

For example, in 2020, NPC Ukrenergo in cooperation with Siemens started a joint project on the modernisation of the SCADA dispatch control system. Modernisation of SCADA is a particularly important process in the conditions of the rapid growth of the RES share in generation, as well as considering the synchronous operation with ENTSO-E.

NPC Ukrenergo also installed the state-of-the-art WAMS devices at its substations to monitor the dynamic stability of the power system’s operation.

?How long did these projects and changes take to complete?

In accordance with the Connection Agreement, NPC Ukrenergo had approximately six years to implement the measures required for the approval of a final decision on synchronisation. In Q1-Q2 2019, NPC Ukrenergo arranged and carried out the technical tests of units at Ukraine’s thermal, combined heat and power and hydropower plants. In Q4 2020, similar tests were carried out at nuclear power plants. The received information was then used for the development of a mathematical model of the Ukrainian power system. This model was used for the Additional studies on the possibility of the interconnection.

Then, during Q2-Q4 2021, additional studies on the steady-state and dynamic stability were conducted to assess the stability of the interconnected power system in case of the integration of Ukraine. Based on the results of these studies, in terms of enhancing the synchronous operation stability, ENTSO-E recommended several additional measures related to the installation of network compensation devices and re-tuning of the equipment at power units to ensure the security level within ENTSO-E is maintained at its highest level. While it was expected that the implementation of these measures might take less than a year, the process was interrupted by the full-scale russian invasion.

How did the cooperation with international partners such as ENTSO-E, Moldovan, Polish, Slovakian, Hungarian, Romanian transmission operators proceed??

Back in 2006, the Romanian transmission system operator submitted an application for the expansion of ENTSO-E Continental European Network by means of connecting the power system of Ukraine to it. Later, after considering different options of implementation of the synchronisation project, it was decided that Ukraine and Moldova would establish a load-frequency control block, which would then be interconnected with ENTSO-E as a single unit.

Besides, Ukraine had extensive experience of cooperation with Slovakia, Hungary and Romania when the Burshtyn Island operated in a parallel mode with these countries. Ukraine also operated a tie-line with Poland in an antenna mode. Moreover, even in the conditions of the full-scale war, Ukraine and Poland managed to restore and put into operation a powerful interconnector, which significantly increased the capacity for electricity exchange between the power systems and thus strengthened the resilience and stability of operation of both power systems.

Speaking about cooperation with ENTSO-E, it is worth noting that it is a technical rather than political organisation. The association serves as a joint platform for the European transmission system operators to discuss and improve the policies and standards in the European electricity sector. When approving its decisions, ENTSO-E is guided predominantly by technical calculations and data-based opinions, leaving any political biases outside the organisation’s operation. Therefore, NPC Ukrenergo is proud that ENTSO-E highly assessed our efforts and approved the emergency synchronisation and then the transition to permanent synchronous operation. Additionally, after a unanimous decision at the ENTSO-E Assembly in December 2023, NPC Ukrenergo became the 40th full-fledged member of the association.

We highly value the extensive assistance of ENTSO-E members during the preparation for the finalisation of the synchronisation project, as well as all the support and facilitation from our fellow neighbouring system operators. NPC Ukrenergo is making every effort to make our cooperation both at the bilateral level and within ENTSO-E productive and mutually beneficial.

russia launched its invasion of Ukraine precisely during the testing of the isolated electricity system. What factors were most important in keeping the system stable during the war and emergency synchronisation?

In the morning of 23 February 2022, Ukrenergo started the process of disconnecting the power system of Ukraine from the power systems of russia and belarus. It was a scheduled procedure, agreed both with Europeans and russians, aimed to conduct the isolated mode system tests on the next day, on 24 February. We gradually disconnected the lines, one by one, and eventually it took almost the whole day until the last line connecting the Ukrainian and russian grids was switched off. Just two-three hours after the Ukrainian power system was fully disconnected from the russian and belarusian grids to run these scheduled system tests in isolation, the full-scale military invasion began.

We understood the risks and took necessary measures to protect our facilities. In anticipation of the critical situation, we established back-up centres for managing the power system in the relatively safer locations in Ukraine and relocated our key personnel there. We also prepared a stock of equipment, spare parts and special equipment, as well as ensured the availability of in-house repair teams (around 70 repair teams comprised of 1500 Ukrenergo’s employees) to enable quick arrangement of restoration works 24/7.

We also considered and defined possible back-up and reserve schemes of power supply to consumers, defined key power facilities in these back-up schemes, and prepared in advance all types of possible power outage schedules. It’s necessary to understand and eliminate the bottlenecks within power system to prevent negative consequences. To implement all these measures as effectively as possible, we established close cooperation with distribution system operators.

We tried to ensure the maximum possible active and passive protection of critical high-voltage equipment at power facilities. Active protection means air defence, and we are working very closely with the General Staff on this issue to ensure anti-missile and anti-drone protection of at least our key facilities. It is good news that as of now, we have a much stronger defence of our infrastructure from the sky if to compare it with October 2022, when massive attacks against energy infrastructure started. Passive protection includes two levels (gabions with sand, concrete/reinforced metal structures), which are primarily aimed at protecting the equipment from missile debris and even direct hits of kamikaze drones.

NPC Ukrenergo also significantly strengthened the reliability of its cybersecurity. Over the past years, we invested millions of dollars in this sphere. And such investments were expedient and well-grounded as the number of cyberattacks against the company’s resources increased threefold if to compare with the pre-war period. However, since the outbreak of hostilities, the enemy has never managed to cross the perimeter of our cyber protection.

Finally, we would like to express gratitude to our international partners and colleagues, especially from ENTSO-E. Thanks to their facilitation and support, Ukraine’s power system was synchronised in March 2022 and significantly added to its resilience and stability. Also, we received access to the possibility of electricity exchanges with the EU countries and electricity emergency assistance as well. Thus, we obtained another additional source of resilience and flexibility for the power system operating in the wartime conditions.

What were the biggest challenges in trying to secure the electricity supply under attack while working towards full synchronisation??

From October 2022 to March 2023, Ukraine suffered from 15 massive missile and 18 drone attacks. The targeted acts of terror committed by the enemy caused appalling consequences as 43% of Ukrenergo’s assets were severely damaged or destroyed. Moreover, all thermal and hydroelectric power plants in the country were damaged to a certain degree. Ukraine’s power system temporarily lost almost 10 GW of installed capacity due to the russian occupation.

This forced Ukrenergo’s dispatch centre to restrict consumption for businesses and households. From the end of October 2022 to February 2023, up to 12 million Ukrainians did not have access to electricity every hour due to the consequences of russian attacks. According to the World Bank and UNDP, the country’s energy sector suffered losses of more than USD 11 billion.

It took decades to build the Ukrainian power system. Obviously, it is impossible to fully restore all damaged facilities in several months, but we at least managed to restore their functionality. ?

In these conditions, one of the biggest challenges is the time it takes to manufacture new equipment. In 2022/2023 winter, our employees gained unique experience of working in emergency conditions. We learned how to replace damaged equipment 2-3 times faster than in peacetime. However, some types of equipment require a fairly long manufacturing period. For example, autotransformers. This is very technologically complex equipment, and there are not many countries in the world that know how to manufacture the autotransformers that would be suitable for our power system. It takes ten months to produce each such autotransformer, while additional three or four months are needed to deliver it to Ukraine.

Another important challenge relates to the construction of engineering protection structures at our facilities. There were simply no such solutions in the world to protect energy facilities from missiles and drones, so they had to be invented by us, here in Ukraine. Not because we are very smart, but because we must protect our infrastructure from the aggressor. Now, the construction of appropriate engineering structures is underway. You have to understand that the development of these levels of protection also takes time: at least 1-1.5 months for the gabions with sand and 4-5 months for anti-drone concrete and metal constructions. However, Ukrenergo’s substations will become the world’s first facilities where such advanced anti-missile and anti-drone protection solutions are implemented.