Georgia’s nationwide blackout on July 24 followed the loss of its electricity interconnection with Azerbaijan, according to preliminary findings from a GNERC working group.
Before the incident, Georgia’s power system was operating in parallel with Azerbaijan through a 330 kV transmission line.
However, at approximately 00:10:49, the Georgian grid disconnected from the neighbouring system. Georgia then began operating as an isolated electricity system.
According to the working group, frequency and voltage fell sharply after the separation. Both indicators reached critical levels.
As a result, generating units and electricity consumers disconnected in succession. The cascading outages eventually caused a system-wide blackout.
Geguti line identified as a contributing factor
GNERC said information supplied by Georgian State Electrosystem identified the 110 kV Geguti transmission line as one contributing factor.
The line originates from the Kutaisi 220 kV substation and belongs to Energo-Pro Georgia.
However, the preliminary findings do not identify the Geguti line as the sole or final cause of the blackout.
The regulator’s working group said investigators must examine the incident through two separate questions.
First, they need to establish why Georgia lost its interconnection with Azerbaijan. Second, they must assess whether the Georgian grid could continue operating safely after becoming isolated.
Working group questions GSE’s preventive measures
The working group also criticised Georgian State Electrosystem’s approach to system protection.
According to GNERC, GSE should not have waited for the installation of new high-speed protection systems on transmission lines.
Instead, the transmission operator should have recalculated the settings of existing relay protection and automation systems. The working group said this could have reduced the risk of activating the automation that separated Georgia from Azerbaijan.
GNERC framed this as a measure necessary to protect the reliability and resilience of the Georgian electricity system.
The findings remain preliminary. Therefore, they do not yet represent a final technical determination of the blackout’s causes or responsibility.
Island operation becomes a central question
The incident raises a wider question about Georgia’s ability to maintain electricity supply when cross-border connections are lost.
An interconnected grid can receive support from neighbouring systems when generation and demand become unbalanced. Once isolated, however, the national system must control its own frequency and voltage without external assistance.
This requires adequate reserves, correctly configured protection systems and effective emergency automation.
The final investigation will therefore need to examine both the original disturbance and the system’s response after the separation.
Further investigation continues
A nationwide power outage occurred on July 24. Another large-scale disruption followed on July 25.
GNERC has so far presented preliminary findings only for the first event. The regulator has not yet published a final report.
The State Security Service has also opened a separate investigation under the criminal-law provision concerning sabotage. The opening of that investigation does not establish that sabotage occurred or determine the technical cause of either outage.
At the time of drafting, no response from GSE to the working group’s criticism was included in the available source material.
The July incidents have increased attention on grid reliability, emergency protection and Georgia’s ability to operate independently during regional disturbances.
These issues will also affect the country’s plans to integrate additional hydropower, wind and solar capacity. A larger and more diverse generation system will require reliable protection, balancing resources and effective system control.
Source: Preliminary findings presented by Tornike Apriashvili on behalf of GNERC’s July 24 blackout working group at a Commission meeting, as reported by GPB First Channel and Interpressnews.