Miatlinskaya HPP: description, history and interesting facts

Miatlinskaya HPP belongs to the Sulansky cascade of hydroelectric power stations. The station is located on the Sulak River in Dagestan, near the village of Miatli. It performs three main functions - generating electricity, is the Chirkei HPP (located upstream of the river), supplies water from the reservoir to the city of Makhachkala (the capital of Dagestan). The station, in comparison with many objects of this type, is small in size but unique in structure and complexity of construction. Within the framework of the program of modernization of the entire energy complex of Russia, the station is undergoing a reconstruction.

Beginning of work

During the construction of the Chirkey HPP, it was found out that the amount of discharged water needed to be adjusted, so in 1973 it was decided to start the construction of another station. All works were conducted in difficult conditions of mountains. The first head of the project was the best specialist in arched dams. Shandalov, who left the country soon after work began, never seeing how Miatlinskaya HPP would be launched.

The history of the construction of the station was quite complicated. In 1976, the road was paved, which led to a slope shift and a landslide on the right bank of the river, where several objects of the future station were already standing. Specialists made an attempt to remedy the situation with the help of engineering facilities, but the risk of collapse continued.

Transfer of construction

To ensure security, the future facility was found two kilometers below the dam. These changes entailed the complication of the entire system, the construction of an equal-tank mine (diameter 25 meters, depth-76 meters), a diversion pipeline (1,700 meters), an auto tunnel tunnel (1,500 meters) on the left bank was required.

The overlap of the Sulak River ridge occurred in 1980, which redirected the flow of water along the dugout derivational tunnel. To the credit of the builders is the fact of erecting the most complicated structure of the arch dam in just one season. At the same time, a new tiered technology of concrete works was mastered, the first pouring took place in 1983, during the same period, a breakdown of the auto tunnel took place. Automobile traffic along the highway and the bridge was opened in 1984.

First starts

In 1985, the installation of the first unit was started, at the end of the year there was a planned flooding of the reservoir. Miatlinskaya HPP launched the first hydroelectric unit in December 1985, in January 1986 it gave industrial current, in summer the second hydroelectric unit was launched at the station, which was the start of the full station loading.

The reservoir of the hydroelectric power station was filled up to the planned mark of 154 kilometers in 1987. The comparative tank of Miatlinskaya HPP has a length of about 15 kilometers at a width of 300 meters, the depth reaches 60 meters. The catchment in the estuary occupies a volume of 13.3 km. Cube, and in the range about 14 m ³ , the total useful capacity of the catchment area is from 16.2 to 32.7 km. Cu. Discharge of water through the facilities is 3000 m ³ / s at maximum load. 151 hectares of agricultural land fell through the construction of the reservoir for flooding.

Miatlin HPP: Overview

Description of the station facilities:

• Arch dam. The design implemented at the station is one of the unique and complex. Arched dams built only three in the USSR - Meatlino HPP, Chirkey HPP, Gunibskaya HPP. The height of the dam is 86.5 meters, the length of 179 meters.
• Building tunnel.
• The building of the hydroelectric power station on the bank of the Sulak River.
• Equalizing reservoir.
• Turbine water lines.
• The deriving tunnel from the dam.

Miatlin HPP is a relatively small station with a capacity of 220 MW, generating nearly 700 million kWh per year. Two hydraulic turbines are installed at the hydroelectric power station, each with a capacity of 110 MW, with a head of water of 46 meters per second. The Lenghydroproject Institute was engaged in designing the station.

Problems of hydro turbines

Miatlinskaya HPP on the Sulak River has been under reconstruction since 2014. From the beginning of operation it was found out that cracks appear quickly on the turbine blades, which necessitated constant repairs. The installed turbines did not differ in quality from the others working at other stations, but the conditions in which they were located were extreme, the speed of water movement was 46 meters per second, which made the blades quickly deteriorate.

In addition, due to the increased demand for electricity, there was a need to increase the supply of electricity. As part of the comprehensive modernization program, RusHydro has entered into an agreement with the Austrian manufacturer Voith Hydro to supply and replace the impellers of both hydroelectric units.

Reconstruction

In 2015, the first hydro turbine was reconstructed, where, as planned, the impeller was replaced. It is equipped with seven blades with increased strength (2 tons more on each blade), the total weight of the wheel reaches 128 tons. To ensure uninterrupted operation, the oil pressure in the regulating system was increased to 63 atmospheres (40 atm.), This step allowed to reduce the amount of consumed oil and improve environmental performance. The measures taken provided an increase in capacity, and in the future promises to increase capacity.

In addition to the hydro turbine wheel, there was a replacement of the control system, electrical protection of the generator and the cover of the hydroturbine. The turbine's power has increased to 113 MW. The second hydroturbine was supposed to pass through the same stage of reconstruction, but the work was postponed.

Planned works

The place where the Miatlinskaya HPP is located belongs to the rocky terrain, and the Sulak River is often "capricious," so it is vital to ensure the operation of the hydroelectric power station by conducting routine inspection, repair and cleaning of the derivation channel. Preventive work is carried out once in thirty years, which happened in October 2016.

Since the launch of the station, the derivation tunnel has never dried, its height is 12 meters, and the width is about 15 meters, the length is 1.7 kilometers. To drain the waterway it was required to descend under the water and prepare for lifting the gates and containment systems, after which the sections were closed and the water conduit drained. The gates are lifted by means of cranes, they are multi-toned structures, which can only be driven by machinery.

Inspection of the tunnel was carried out with the help of laser scanning and in the traditional way - personal inspection. Global problems (cracks, voids) were not revealed, the thickness and solidity of concrete casting were not violated in any place. Minor repairs are still required. The filling of the water conduit happened in a planned order - the gate gates open only 15 centimeters, but that's enough to get tons of water to enter the system. Today Miatlinskaya HPP is operating in its regular mode.