Date: 24. Jun. 2024. - Notices
Information on the Power System Disturbance in Bosnia and Herzegovina on 21st June 2024
On 21st June 2024, at 12:24, the power systems of Albania, Montenegro, Bosnia and Herzegovina, and part of Croatia experienced a widespread system separation. According to the initial preliminary analyses and information presented during the ENTSO-E teleconference held on 21st June 2024 at 16:30, the disturbance originated at 12:20 in the Albanian transmission network with the outage of the 400 kV Zemlak (Albania) – Kardia (Greece) interconnection transmission line.
Although this event was preceded by the outage of the 400 kV Podgorica 2 – Ribarevina transmission line in Montenegro, the Montenegrin transmission network and the neighbouring power systems had been operating within normal operating parameters up to that point. Following the outage of the Zemlak – Kardia transmission line, a series of cascading outages of 400 kV, 220 kV and 110 kV transmission lines occurred in Albania. The disturbance then rapidly propagated to the power system of Montenegro, causing the outage of the 220 kV Mojkovac – Podgorica 1 transmission line. As a result, the Montenegrin transmission system remained connected only to the power system of Bosnia and Herzegovina while simultaneously exporting approximately 400 MW through the HVDC submarine cable to Italy.
Due to excessive power flows from the north-eastern part of Bosnia and Herzegovina towards the south, a voltage collapse occurred, followed by the cascading outage of all interconnection transmission lines between Bosnia and Herzegovina and Montenegro at 12:22. This subsequently led to the complete collapse of the power system of Bosnia and Herzegovina and the coastal part of Croatia within the following 60 to 90 seconds. As the power system of Bosnia and Herzegovina forms an integral part of the interconnected Continental European transmission system, this sequence of events in Bosnia and Herzegovina and part of Croatia was unavoidable. Considering the amount of electrical power being transmitted through Bosnia and Herzegovina at that moment and the speed at which the cascading outages propagated across the region, it was not possible to prevent the escalation of the disturbance.
For a better understanding of the situation, it should be noted that the transmission capacity of a 400 kV transmission line is approximately 1,300 MW, while at the time of the disturbance the SCADA/EMS system in the NOSBiH National Dispatch Centre recorded power flows of up to 2,250 MW on certain 400 kV transmission lines.
Unlike the event of 20th June 2024, when a similar situation occurred with significantly lower transit power flows through Bosnia and Herzegovina and the timely actions of the operational personnel at the NOSBiH National Dispatch Centre successfully prevented the collapse of the power system, the event of 21st June 2024, due to its intensity and the speed of escalation, was entirely beyond the operational control of the NOSBiH National Dispatch Centre and could not have been prevented.
By applying the standard dispatching procedures used for restoring the system from a blackout condition, the operational personnel of the NOSBiH National Dispatch Centre stabilised the power system of Bosnia and Herzegovina in the shortest possible time. In accordance with the prescribed operating procedures and Transmission System Operation Rules, voltage was first restored to the most important load centres and generating units in order to enable system resynchronisation and secure the electricity required to meet consumption. With the exception of the temporary generation deficit caused by the outage of thermal power plants, which could not be returned to service immediately due to technological constraints, the resynchronisation of the power system of Bosnia and Herzegovina and the restoration of normal operating conditions were completed in a record time of only two hours.
In accordance with established ENTSO-E practice, a detailed analysis of the event will be carried out over the coming weeks, and the public will be informed of its findings in due course. At this stage, it can be stated with certainty that the events affecting the power system of Bosnia and Herzegovina were the consequence of regional power system disturbances.
In order to minimise the risk of similar events in the future, it is essential to strengthen the power system of Bosnia and Herzegovina through much-needed investments in the transmission network. Due to the ageing of the existing infrastructure and the changing operating patterns of modern power systems, particularly the increasing integration of renewable energy sources, the current transmission network is no longer able to respond adequately to all operational challenges.