At the end of January of the current year, certain problems arose in the operation of the 500kV transmission line KAVKASIONI on the section passing through the Kodori Valley. On April 1, 2024, an aerial inspection of the 500 kV KAVKASIONI transmission line was carried out by helicopter.
The helicopter landed in the Kodori Valley near tower No. 219 of the KAVKASIONI transmission line. From there, personnel proceeded on foot toward tower No. 232 (in the direction of the Nakhari Pass) to locate the damage. The access road from tower No. 219 toward the Nakhari Pass is blocked by a large mass of rock that fell from the mountain.
During the inspection, one damaged conductor of phase “A” was discovered in the span between towers No. 224 and No. 225. The conductor had broken approximately 25 meters from tower No. 225. The other end of the conductor was hanging over the stringing rollers installed instead of tower No. 224 using a temporary rope suspension system.
While moving upward from tower No. 219 in the Kodori Valley, multiple avalanches had occurred along the route, creating a serious hazard for the personnel involved in the inspection.
Due to avalanche risk and for the safety of personnel, it was considered impossible to safely access the damage site and release phase “A” from the broken conductor until the avalanche process had fully subsided.
As soon as meteorological conditions allowed safe access to the damaged section, SAKRUSENERGO personnel were ready to travel to the Kodori Valley to carry out the planned works, which would allow the KAVKASIONI transmission line to resume operation (with a 20% capacity limitation). Specifically, the damaged conductor had to be cut and separated from the other conductors of phase “A.” This required at least two helicopter flights from Sokhumi to the Kodori Valley to transport personnel back and forth.
To eliminate the defect on the KAVKASIONI transmission line, JSC SAKRUSENERGO employees — Iuri Nadiradze, Head of the Design and Construction Service, and Vakhtang Chubinidze, foreman of the Tbilisi Transmission Maintenance Unit — together with five employees of Chernomorenergo, flew from Sikhumi to the Kodori Valley on April 16 and April 19.
The helicopter landed near tower No. 219, and from there personnel had to proceed on foot toward tower No. 225 (toward the Nakhari Pass). Before reaching the site, they had to cross a swollen river several times and transport the materials and equipment necessary for the work.
On April 16, personnel managed only to cut the damaged phase “A” conductor from towers No. 223 and No. 225. On April 19, they accessed the suspension strings and cut the damaged conductor from the stringing rollers.
After completion of these works and the return of personnel from the Kodori Valley to Sokhumi, the transmission line was tested under voltage.
On April 19 at 21:00, the KAVKASIONI transmission line was energized from the Jvari substation up to tower No. 44, located on the territory of the Russian Federation in the Karachay-Cherkess Republic (the distance from Jvari substation to tower No. 44 is 120 km). The transmission line successfully held voltage.
On April 20, loop connections were completed at tower No. 44 and the line was fully integrated up to the Tsentralnaya substation.
On April 20 at 17:47, the KAVKASIONI transmission line was tested from the Tsentralnaya substation. The line failed to hold voltage. The fault locator device indicated a distance of 330.9 km from the Tsentralnaya substation, corresponding to the area near tower No. 156 in the Kodori Valley. This section had been tested on April 19 from the Jvari substation and had successfully held voltage. At that time, a 120 km section up to tower No. 44 — including the Kodori Valley section where the device indicated damage — was energized.
Based on this, a decision was made to re-test the line under voltage from the Jvari substation. On April 21 at 00:03, the KAVKASIONI transmission line was again energized from Jvari, this time up to the Tsentralnaya substation — a total of 400 km. The transmission line held voltage successfully.
To verify voltage symmetry, the line was again energized from Jvari on April 21 at 14:35. Based on the confirmed voltage symmetry, it was requested to energize the KAVKASIONI transmission line from the Tsentralnaya substation, which was carried out on April 21 at 15:08. The transmission line successfully held voltage.
Currently, the transmission line is in operational condition and is under the control of the National Dispatch Center of JSC “Georgian State Electrosystem.”
It should be noted that until the completion of works to replace tower No. 226 with a rope-suspension structure (planned for 2024–2026), operating the line without a 20% load reduction within operational limits will not be permissible.
At present, JSC SAKRUSENERGO has completed the preparation of design and cost-estimation documentation for the access road from tower No. 219 to tower No. 226 of the 500 kV KAVKASIONI transmission line, as well as the design and cost-estimation documentation for replacing tower No. 226 with a rope-suspension structure.
