Improper frequency and voltage regulation by the units of Enguri HPP, a key facility in Georgia’s power system, may have been one of the main causes behind the large-scale outages in July, according to GNERC Electricity Department Director Tornike Apriashvili.
Speaking after a working group meeting, Apriashvili said the review of Enguri HPP’s hydro unit oscillograms revealed issues with the automatic voltage regulation system. Voltage deviations were recorded at the high-voltage busbar of the Enguri substation on July 24 and 25.
According to data provided by Georgian State Electrosystem (GSE), during an isolated operation of the power system on July 4, Enguri HPP’s units showed conflicting behavior: units No. 2 and No. 5 regulated voltage in one direction, while units No. 1, No. 3, and No. 4 acted in the opposite direction. GNERC said it remains unclear what measures were taken after this issue was identified.
The regulator also questioned GSE’s previous assessment of Enguri HPP’s equipment, noting that the methodology used to verify automatic voltage regulation has not been provided. GNERC said GSE, as the system operator, had grounds to request immediate testing of Enguri HPP’s units.
GSE and Enguri HPP are expected to jointly conduct on-site testing of the voltage regulation systems in the coming days. Meanwhile, GNERC continues analyzing data from Enguri HPP and other power plants, stressing that the findings are preliminary and a final conclusion will be published after the full investigation is completed.
