ACER’s updated methodology improves the operational security analysis in electricity systems

Electricity pylons

ACER’s updated methodology improves the operational security analysis in electricity systems

What is it about?

On 13 May 2024, with its Decision No 07/2024, ACER amended the methodology for Coordinating Operational Security Analysis (CSAM).

The amendment proposal was submitted to ACER in November 2023 by the European Network of Transmission System Operators for Electricity (ENTSO-E), on behalf of Transmission System Operators (TSOs).

What is the role of the methodology?

CSAM supports the EU’s operational security by outlining the TSOs' requirements to ensure:

  • the electricity transmission system is operated in a coordinated manner;
  • an effective system operational planning;
  • transparency and reliability of information on transmission system operation.

The methodology was first approved by ACER in 2019 under the Guideline on Electricity Transmission System Operation (SOGL) and amended in 2021.

What are the main improvements in the methodology?

The amendments relate to the implementation of the observability area (i.e., where TSOs implement real-time monitoring and modelling of their systems to maintain operational security), following the recommendations of the Incident Classification Expert Panel’s final report on Continental Europe Synchronous Area Separation on 8 January 2021.

The main changes include:

  • Aligning the observability area reassessment period with that of the external contingency list (i.e., the list of contingencies to be simulated to test the compliance with the operational security limits). This alignment is important to ensure that the operational security analysis is carried out accurately across all timeframes.
  • The inclusion of busbar couplers in the contingency lists and in the TSOs’ Individual Grid Models (IGMs), along with a defined timeline for implementation by the TSOs. This update ensures that the power flows are kept within the operational security limits after a contingency has occurred.

What are the next steps?

Within a year after the adoption of the new CSAM (by 13 May 2025), TSOs are required to update their ordinary contingency lists. These updates must specifically include the loss of a single busbar coupler, whether protected by an overcurrent protection device or by an over-/under-voltage protection device.