Gunibskaya HPP

The Gunibskaya HPP is located on the Karakoisu River (Kara-Koisu), a tributary of the Avar Koysu River , above the Gergebilskaya HPP that was started up in 1937 . The average annual consumption of Karakois at the Gunibskaya HPP site is 19.2 m³ / s, the maximum consumption is 510 m³ / s. From April to October, about 90% of the annual flow passes along the river. The water of the river is distinguished by a large turbidity (the average for the year is 4.36 kg / m³, the maximum is up to 25 kg / m³), ​​for a year the river carries 1.86 million tons of sediment mainly during the flood period. The climate around the Gunibskaya HPP is continental with a short mild winter and hot summer, with an average annual air temperature of + 9 ° C. The maximum recorded temperature is + 42 ° С (August), the minimum is −30 ° С (January). The average annual rainfall is 500 mm, most of which falls from May to September. Continuous ice cover on the river is not installed, there are zberegi , sludge and zazhora ^[2] .

The reservoir of the Gunibskaya HPP is located 22 km above the Karakois confluence into the Avar Koysu in the narrowing of the river valley (the gorge of the Red Bridge). At the site of the main hydroelectric power station construction there are common hard rocks - limestone , siltstones , argillites , sandstones are also found. In some places, rocks are blocked on the slopes by lumpy - rubble deposits up to 10 m thick, and in the riverbed by alluvial boulder – pebble deposits with sandy aggregate up to 20-25 m. Seismicity of the HPP location zone is 9 points on the MSK-64 scale ^[2] .

The Gunibskaya HPP is a mid-pressure hydroelectric dam with an arched dam and a shore-type hydroelectric power station (located separately from the dam on the right bank of the river). The capacity of hydroelectric power plants is 15 MW, the average annual output is 57.6 million kWh ^[3] .

The Gunibskaya hydroelectric dam is a concrete arched with a plug (the Gunibskaya hydroelectric power station is one of the three hydroelectric power plants in Russia with arched dams (along with Chirkei and Miatlinskaya ). The full height of the dam is 73 m, of which the arched part accounts for 33 m, and the cork is 40 m, The dam crest has a mark of 863.5 m. The length of the dam along the ridge is 58.7 m. The thickness of the arched part is 4 m in the upper part and 6 m at the contact with the plug, the thickness of the cork is 20 m. On the ridge the dam expands to 6.5 m in order to provide the necessary dimensions for organizing the passage of motor transport (along the dam There is a car passage 4.5 meters wide with two pedestrian pavements .) In a traffic jam at 822.0 m there is a deep spillway with a section of 4.3 × 4.5 m, having a capacity of 448 m³ / s. The main main gates of the spillway are located on the side downstream, flat emergency repair gates on the upstream side, emergency repair gates maneuvering mechanisms located on the crest of the dam. There are two galleries in the body of the dam, which serve to accommodate the control and measuring equipment ithout water dam body. To prevent filtration, cementing curtains are arranged at the base and sides of the dam ^{[3] [4]} .

The water intake , which serves to draw water into the supply diversion tunnel , is located near the right bank abutment of the dam, is a reinforced concrete structure embedded in a rocky massif 20 m long and 9 m wide. The inlet of the water receiver has dimensions of 5 × 8 m, it is equipped with a trash screen and a flat emergency repair gate, which is maneuvered by a gantry crane with a lifting capacity of 40 tons. The threshold of the intake is at 847.5 m ^[3] .

Behind the water intake there is a weakly inclined shaft 40 m deep, circular in cross section (3.1 m in diameter) with reinforced concrete lining. The mine goes over slightly inclined (0,015 slope) diversion tunnel, which is part of the former box-section building tunnel with a height of 7.5 m and a width of 7 m (including the lining thickness — 0.5 m), the tunnel is 92 m long. At the end, the tunnel is sealed with a concrete plug 10 m thick, through which a metal pipeline with a diameter of 3.1 m (wall thickness of 12 mm) is laid. The pipeline ends with a metal fork separating the incoming water between the three hydraulic units ^[3] .

The shore-type hydropower building, located 70 m from the dam, consists of three aggregate blocks and an installation site. The machine hall has a length of 40 m, a width of 14 m, the distance between the axes of hydraulic units is 7.5 m. The building of the hydroelectric power station has 3 vertical hydraulic units with radial-axial turbines RO-75-B-75 (power 5.2 MW, impeller diameter 1.4 m, design head 48.5 m, rotational speed 375 rpm, water flow through the turbine 11.8 m³ / s). If necessary, the flow of water to the turbines is blocked by using ZDb160-115 disc pre-turbine valves with a diameter of 1.6 m. Turbines drive the CB 325 / 50-16 hydrogenerators with a capacity of 5 MW each, which produce electricity at a voltage of 6.3 kV. Turbines produced by Kharkov plant " Turboatom ", generators - Yekaterinburg " Uralelectrotyazhmash ." The hydraulic units of the Gunibskaya HPP are identical to those that were previously used in the reconstruction of the Gergebilskaya HPP. To move the elements of hydraulic units in the engine room there is a bridge crane with a lifting capacity of 32 tons ^{[3] [4] [5]} .

• Facilities Gunibskaya HPP
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  View from the dam to the downstream

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  Deep spillway in the work

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  Engine room

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  Open switchgear

Electricity is supplied to the power system from an open switchgear (ORU) with a voltage of 110 kV, the dimensions of the switchyard are 35 × 50 m. There are two TDN 16000/110 step-up transformers with a capacity of 16,000 kVA each placed on the switchyard. Three 110 kV transmission lines depart from the station: Gunib , Khunzakh and Gergebil . Also, a three-storey production and technical building is located on the site of the hydroelectric station, in which a generator switchgear with a voltage of 6 kV and other production facilities is located ^[4] .

The dam of the Gunibskaya HPP has created a small reservoir with the following parameters: the maximum length is 3.8 km, the maximum width is 350 m, the maximum depth is 53 m, the total volume of the reservoir is 10.58 million m³, its useful volume is 0.87 million m³, The reservoir mirror area at a normal level is 0.6 km². The reservoir flooded only 55 hectares of low-value land, including pastures - 6.39 hectares, gardens - 3.94 hectares, bushes - 7 hectares, forest - 0.6 hectares, and other lands - 27.77 hectares ^[4] . In addition to energy goals, the reservoir is used for water supply and irrigation , a trout farm is also organized at the Gunibskaya HPP ^[6] . Due to the fact that the Karakoisu River carries a large amount of sediment, which leads to the gradual silting of the reservoir, it is washed annually ^[7] .

Designing

For the first time, the possibility of hydropower utilization of the Karakoisu river above the Gergebil hydroelectric station was considered in the “Water-Energy Scheme of the North Caucasus” developed by the Rostov branch of the Hydroenergoproekt Institute in 1935 . According to this scheme, it was planned to construct three diversion hydropower plants with a total capacity of 58 MW and an average annual output of 0.3 billion kWh. In 1966, the Institute " Hydroproject " issued "Technical Directions for the Use of Caucasus Resources", in which the use of Karakois above the Gergebil HPP was planned to be carried out in two stages. In 1970, the Institute " Lengidroproekt " was compiled "Scheme of use pp. Andean and Avar Koisu ”, which examined in detail the scheme of use of Karakois, which included three hydroelectric power plants - Magarskaya, Botsadakhskaya and Gunibskaya with a total capacity of 120 MW and an average annual output of 0.5 billion kWh. In 1988, the same institute in the work “Refinement of the scheme of use of the watercourse p. Kara-Kois ”were considered in detail the sections and parameters planned for the construction of the Magarsky, Botsadakhsky, Gunibsky and Kurminsky waterworks ^[2] .

The technical and economic calculation of the construction of the Gunibsky hydroelectric complex was developed in 1987 by the Institute “Lengidroproekt” and approved by order No. 97 of October 16, 1990 by the territorial energy association Yuzhenergo. The working project of the Gunibskaya HPP was developed by Lengidroproekt from 1991 to 1996 , the chief engineer of the project was V. A. Minin ^[2] . During the design, two versions of the dam (arched with cork and deep spillway and without cork with surface spillway) and water supply path (with separate or combined with a construction tunnel arrangement of the water conduit) were considered ^[3] .

Construction

Construction of the Gunibskaya HPP was started in August 1995 with the preparation of the construction base, roads and engineering communications, ChirkeyGESstroy OJSC was the general contractor of the construction (since 1998, Energostroy LTD has become the general contractor). In 1996, work began on the main structures of the hydroelectric complex - the construction tunnel and the building of hydroelectric power plants. In 1999, work began on the construction of a water intake, in 2001 the construction of a construction tunnel was completed. At the first stage of construction (1995–2001), construction was financed in a small amount and irregularly, which led to a considerable delay in construction time ^[8] .

• Construction of the Gunibskaya HPP
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  Concrete dam

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  View of the dam before filling the reservoir

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  Concreting downhole spillway

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  Construction of a production and technical complex

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  Installation of equipment at 110 kV outdoor switchgear

Since 2002, funding has been significantly increased, which made it possible to complete the construction of the station within three years. On November 28, 2002, the Karakoisu River was blocked by a bulkhead, the river flow was redirected to the construction tunnel. Under the protection of the lintel began the development of the ditch pit. In 2003, the main construction work on the water intake, hydroelectric station building, open switchgear, production and technological building was completed, the installation of hydropower and electrical equipment began ^[8] .

Concrete construction work on the dam began in late March 2004 . By September of the same year, the dam reached the level of 825.0 m, after which the construction tunnel was blocked and the first stage of filling the reservoir began. From now on, water is passed through the operational spillway in the dam body. Concrete traffic jams were arranged in the entrance and exit parts of the construction tunnel, the tunnel was connected to the intake shaft and became part of the water supply system. On December 21, 2004, the launch of the hydro-units of the Gunibskaya HPP took place in commercial operation ^[8] . All construction work was completed in 2005, on May 6, 2005 the Gunibskaya HPP was accepted by the State Commission for commissioning. The construction of the Gunibskaya HPP cost OAO Dagenergo about 600 million rubles (in 2005 prices) ^[9] .

Operation

Even during construction, on June 1, 2004, the Gunibskaya HPP was named after the national poet of Dagestan Rasul Gamzatov ^[10] . After the construction was completed, the Gunibskaya HPP was on the balance sheet of the specially created Prometey OJSC (a subsidiary of Dagenergo OJSC). By November 19, 2006, the station produced 100 million kWh. electricity ^[11] . During the reform of RAO UES of Russia, JSC HydroOGK became the owner of JSC Prometey (later renamed JSC JSC RusHydro. In 2009, the decision was made to liquidate JSC Prometey, Gunibskaya HPP was transferred to the jurisdiction of the Dagestan branch JSC RusHydro " ^[12] .

From July 27, 2009, abundant rains began in the Karakoisu basin, which formed a powerful flood and caused a sharp increase in inflow into the reservoir of the Gunibskaya HPP. The maximum inflow of water was recorded on July 29 and amounted to more than 200 m³ / s. The reservoir delayed part of the runoff, reducing the level of the flood in the downstream, however, the water level in the reservoir rose to the level of the dam crest, resulting in July 29 it began to overflow through the ridge, which ended the next day, July 30 ^[13] . The HPP facilities were not affected, but some damage was caused to the station equipment, which amounted to 13.7 million rubles and was reimbursed by the insurance company ^[14] . Taking into account the experience of passing through an extreme flood, in 2010 the spillway valves were refined, which allowed them to be controlled remotely, and the aeration pipes were reconstructed in order to prevent water from entering the gate mechanisms. Also, a retaining wall was built to protect the switchgear from flooding from the downstream ^[15] .

• Abigasanov M. The Glow of the Black River. - Makhachkala: Publishing House "Epoch", 2005. - 331 p. - ISBN 5-98390-006-4 .
• Minin V.A. Design and construction of the Gunibskaya HPP on the river Kara-Koisu in Dagestan // Hydraulic Engineering. - 2006. - № 7 . - S. 2-11 .

• Description of Gunibskaya HPP on the site of the Dagestan branch of JSC RusHydro (Neopr.) . RusHydro. The appeal date was July 8, 2011. Archived January 25, 2012.
• Description Gunib HPS on the website of the Institute "Lengidroproekt" (Neopr.) . Lengidroproekt. The appeal date was July 8, 2011. Archived January 25, 2012.