Critical Grid Situation (CGS) represents one of the additional RSC services, which was introduced after the cold spell in January 2017. Synchronous effect of cold spell and outages of particular generation units during the January 2017 led to critical network situation in Western and South-East Europe countries. After this experience, the need for a better coordination between TSOs, RSCs and ENTSO-E, in the case of potential critical grid situations, was recognized. ENTSO-E formed dedicated team in order to analyse operation of transmission system and electricity market during the mentioned critical situation, to define and introduce the term CGS and to adopt regional procedures that would be applied during CGS. As the input for regional procedures preparation, ENTSO-E group gave general coordination process for CGS including: 

• Possible ways for detection of a CGS;
• The communication process to be followed during a CGS;,
• Roles and mandates in order to ensure the execution and real-time application of the actions before, during and after a critical grid situation.

Following mentioned ENTSO-E team’s request, engineers of SCC and Serbian TSO EMS AD proposed Procedure for Critical Grid Situations in SEE region. It is foreseen that this Procedure applies to all TSOs of SEE region as well as to neighbouring TSOs and RSCs. This Procedure is approved in September 2017. Procedure defines business process, the ways for potential CGS detection in SEE region and coordination process. After triggering, the sequence of coordination activities between TSOs and RSCs follows and SCC has the role of coordinator during CGS procedure.

CGS process is officially active but on standby until triggering by TSO or RSC. Since CGSs are not frequent in SEE region, from 2017 SCC performs tests of CGS protocol once a year, in order to maintain the Procedure alive and active. All SEE TSOs (which approved this Procedure) including neighbouring TSOs and RSCs are part of these tests. For the time being, there was no Procedure activation in real life.