500 kV HV Electric Transmission Line “Kavkasioni”
500 kV electric transmission line “Kavkasioni” is unique engineering construction, that has significant meaning for Georgia’s power supply system and country’s security. The “Kavkasioni” line intersects rivers’s: Enguri, Nakra, Kodori, Klichi & Yubani valleys and through Khida and Nakhari passes, stretched on the territory of Karachay-cherkessia & Republic of Adygea connects the substation “Centralnaya” in the Krasnodar Region.
The total length of the line is 405Km and includes 991 towers, however on the Georgian soil (from Engurhesi to Nakhari pass) it is only 105Km with 236 towers in it. The transmission line was put in operation in 1984. It should be mentioned that due to the difficult relief the exploitation and maintenance of the line is extremely problematic, especially during the winter season. Emergency shut-down of the line usually causes deterioration of the stability of the Georgian power system and the quality of electricity. So far, 500 kV “Kavkasioni” is the only alternative power line that can transmit excess electricity generated at Georgian hydroelectric power plants to Russia in the summer and fill the deficit from Russia in the winter. The line is also used to transmit electricity to other Georgia’s neighbor countries.
Maintaining the “Kavkasioni” line is one of the company’s priorities. With the transmission line, it is possible to work in parallel with Russian power supply system and exchange 700 MW of electricity. Because of tough relief and extreme climate on the main ridge on Caucasus mountain power towers are seriously damaged by the avalanches and freezing that causes serious problems for the whole energy system. There was a case when power towers were damaged several times during the year however, finding safer place for placement of towers was almost impossible. Based on the above, a decision was made to hang electric wires in the avalanche-prone areas instead of towers and stretch them between the mountain ranges. Due to the difficulty, extreme conditions and 2500m heights in the mountain range this operation had no analogue in Georgian reality. This operation became possible only by the noble work and dedication of our specialists: Shota Maisuradze, Iuri Nadiradze and others, who made almost impossible and solved the problem of avalanches. 500 kV Electric Transmission Line Kavkasioni wire-hanging
As already mentioned above, electric transmission line “Kavkasioni” is stretched through extremely tough relief & climate zone, the emergency shut-downs of the line is usually caused by the Atmospheric discharges, in addition, transmission line is not equipped with modern high-speed protection, single-phase and three-phase automatic reconnection devices that usually complicates the situation. The statistics of emergency shut-downs of the line shows that 90% of breakdowns are caused by the absence of protections system. In order to resolve this problem JSC Sakrusenergo received an instruction from the Ministry of Economy and Sustainable Development of Georgia to equip the transmission line with the “General Electricity” Protection System and to ensure this goal the agreement was signed with Russian Scientific Research Institute of Relay Construction OAO “VNIIR”.
“VNIIR” conducted a research & report and based on them “General Electric” protections systems will be installed on substations “Jvari-500” as well as “Centralnaya”.
Electric transmission line “Kavkasioni” is maintained (on Georgian soil) by the JSC “Sakrusenergo”. It should be mentioned that alongside with other Meteorological conditions, glazing is one of the reasons for emergency breakdowns of the line. During the winter season the thickness and weight of the ice exceeds the mass of the line several times that causes shut-downs. Glazing is mainly a challenge in Kodori region and the territory of Russia, where previously ice-melting equipment was implemented, however over the time they went out of order. 500 kV Electric Transmission Line “Kavkasioni” ice-melting equiment
Although Georgia is not an intensive ice zone, unit cases are recorded at 500 kV “Imereti” & “Kartli-1” transmission lines followed by emergency interruptions.