BRUSSELS, 24 FEBRUARY 2025 – The final report on the grid incident of 21 June 2024 in the Western Balkan-Region highlights the value of international cooperation by the TSOs and RCCs It presents the gathered facts and the analysis of the causes of the incident in the Balkan region. The report also includes recommendations to improve system security in the future.

On Friday, 21 June 2024, a significant incident occurred in South-East Europe (SEE), leading to a major disruption in the Continental Europe (CE) power system. The incident resulted in a substantial loss of load and generation, affecting multiple countries including Albania (OST), Bosnia and Herzegovina (NOSBiH), Montenegro (CGES), and Croatia (HOPS). The event was characterised by series of outages occurring in the trans­mission network, which ultimately led to a (partial) blackout in these four countries. Normal operations were restored by the TSOs in the region immediately after the incident.

The final report identifies the following root causes of the incident:

  1. The two initial short circuits were caused by vegetation that had grown too close to the power lines
  2. The resulting outages on the grid affected more than one TSO, without the operators concerned having an overall view of the grid in the region.
  3. When the voltage in the system decreased, the available measures were not sufficient to avoid a voltage collapse which ultimately led to the partial black-out in the region.

 

An Expert Panel was set up on 15 July 2024 to carry out an investigation. The Expert Panel composed of ENTSO-E and the relevant Transmission System Operators (TSOs) as well as ACER,  relevant National Regulatory Authority (NRA) representatives and the RCC Investigation Subgroup. Their findings include recommendations for the TSOs which are detailed in the report. They include:

  • Ensuring adequate vegetation trimming is crucial for preventing short circuits and maintaining a secure and reliable power network. The report recommends a check on procedure for vegetation growth control.
  • The TSOs should extend their observability area in the neighbouring grids so they are informed on technical data in real time and have a more complete view of the grid in their region. This will allow them to assess the consequences of possible overload situations affecting powerlines in neighbouring grids that might impact their real-time operations.

TSOs should develop and implement shared standards in the light of these findings and reassess the procedures for handling voltage stability and overloads on powerlines.

“The report shows that cooperation of TSOs is crucial to the safe operation of the interconnected European electricity system. Thanks to the fast and coordinated action after the event, power could be restored to the region affected in short order. As always, any system failure teaches us how to proceed in future and here the report shows that cooperation is key. By working together while having clear responsibilities we are continually improving”, says Sonya Twohig, Secretary-General of ENTSO-E.

Read the full report here.

About ENTSO-E

ENTSO-E, the European Network of Transmission System Operators for Electricity, is the association for the cooperation of the European transmission system operators (TSOs). The 40 member TSOs, representing 36 countries, are responsible for the secure and coordinated operation of Europe’s electricity system, the largest interconnected electrical grid in the world. In addition to its core, historical role in technical cooperation, ENTSO-E is also the common voice of TSOs.

Contact: media@entsoe.eu