Operational Security

Operational security is the transmission system's capability to retain a normal state or to return to a normal state as soon as possible, and which is characterised by operational security limits (Article 3(1) of the Network Code on System Operation). 

Where the level of reactive power ancillary services is not sufficient for maintaining operational security, Transmission System Operators (TSOs) prepare and activate remedial actions (Article 109(3) of the Network Code on System Operation). In such a case the TSO informs the neighbouring TSOs.

According to the Network Code on Network Operation each TSO is required to publish the levels of reserve capacity necessary to maintain operational security. For each operational planning timeframe, each TSO is also required to assess, against their forecasts, whether its available reactive power ancillary services are sufficient to maintain the operational security of the transmission system.

On 17 November 2023, the European Network of Transmission System Operators for Electricity (ENTSO-E), on behalf of  TSOs, submitted to the ACER an amendment proposal to the methodology for coordinating operational security analysis (CSAM). Following the receipt of the TSOs’ proposal, ACER has initiated a procedure to decide on these amendments.

CSAM supports the EU’s operational security by outlining the 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 proposed 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) as recommended in the Incident Classification Expert Panel’s final report on Continental Europe Synchronous Area Separation on 8 January 2021.

The amendment proposal aims at:

• Aligning the reassessment period for the observability area with the one for 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 over accurately across all timeframes.
• Including busbar couplers in the contingency lists and in the TSOs’ Individual Grid Models (IGMs). This update ensures that the power flows are kept within the operational security limits after a contingency has occurred.

The public notice initiating the procedure is available here.

   Regulatory chronicle

24 November 2023

ACER to decide on amending the methodology for coordinating operational security analysis in the electricity systems

14 June 2021

ACER Decision No 07/2021 of 14 June 2021 on the Amendment of the Methodology for Coordinating Operational Security Analysis

Annex I Amendment of the Methodology for Coordinating Operational Security Analysis in accordance with Article 75 of the Commission Regulation (EU) 2017/1485 of 2 August 2017 establishing a guideline on electricity transmission system operation

Annex Ia

4 September 2020

ACER consults to decide on coordination of operational security in power systems of 13 Member States

    Documentation

Network Code on System Operation, Articles 3(1), 108, 109

ACER Decision No 08/2019 of 19 June 2019 on the all TSO’s proposal for the methodology for assessing the relevance of assets for outage coordination

ACER Decision No 07/2019 of 10 June 2019 on the all TSO’s proposal for coordinating operational security analysis

ACER Public Consultation on the proposals of the Electricity Transmission System Operators for the methodologies for Coordinating Operational Security Analysis and Relevant Asset Outage Coordination as mandated by the EU Regulation establishing a guideline on electricity transmission system operation, 25 January 2019

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