Zaramag HPPs: the need for construction

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Zaramagskiye HPPs are the youngest cascade of stations in South Ossetia. They are built in the upper reaches of the Ardon mountain river in the Kassar Gorge. The stations were named so because they are located in the immediate vicinity of the village of Nizhny Zaramag. The construction of this complex was recognized as expedient primarily because South Ossetia is currently experiencing an acute shortage of electricity.

A bit of history

The construction of the Zaramag HPPs began in 1976. However, the head station of the cascade was put into operation only in 2009. The second facility, Zaramagskaya HPP-1, is currently under construction. The construction of a cascade of stations on the Ardon River, like many other similar facilities, was frozen in the 90s of the last century. The main reason was the lack of funding.

Feasibility of construction

The organizer of the construction of these stations is Zaramagskiye HPP JSC, a subsidiary of RusHydro. The decision to unfreeze this facility was made by the management of the corporation at the beginning of 2015. According to South Ossetia, afterits construction, the shortage of electricity in the republic will be reduced from 80 to 30%.

Significant changes were made to the design of the station with the new project. In particular, the engineers decided to significantly reduce the height of the dam and the volume of the reservoir. Initially, huge areas of farmland were supposed to fall into the flood zone. In addition, a lot of people would have to be relocated from villages and even several small towns. After the implementation of this project, according to which the maximum depth of the reservoir was only 30 m, no settlements were flooded.

Feasibility study

The uniqueness of the HPP cascade near the village of Nizhny Zaramag lies primarily in the fact that in this place the Ardon River creates a slope of as much as 700 meters for 16 km. Such conditions can be called truly ideal for creating a complex of hydroelectric power plants according to the diversion scheme. Upon completion of construction of HPP-1, the total capacity of the cascade will be 352 MW. Thus, the complex will become the largest in South Ossetia.

The Zaramag HPPs are being built in the most difficult natural conditions. The design of these stations includes many extraordinary and complex technical solutions. After commissioning, the complex, for example, will have the largest head in the Russian Federation. In addition, it is planned to supply the most powerful bucket hydro turbines in the country (at HPP-1). Also, the longest diversion tunnel will be dug at the station, bringing water from the head station to HPP-1.

Zaramag HPPs Company

This is a small JSC,which is the customer for the construction of the cascade, was formed on May 10, 2000. Its head office is located at: Moscow, Stroitelny proezd, 7A, bldg. 5. Also, there is a branch of the company, of course, in North Ossetia itself - Alania. The address of the second office of the Zaramagskiye HPPs: Vladikavkaz, st. Pervomaiskaya, 34. The main activity of the company is to carry out technical supervision during the construction of the cascade. The CEO of this company is Vitaly Totrov.

What is a derivational scheme

Stations of this type are built in those places where the river bed has a significant slope, and consequently, the construction of the dam does not allow to accumulate a large amount of water. In order to remedy the situation, a special construction scheme is used. In this case, a dam is first built on the river and a reservoir is arranged. Water conduits run from it to the building of the hydroelectric power station. The latter are equipped with a slight slope (much more flatter than the natural channel). As a result, water is supplied to the HPP building under very high pressure from a considerable height, which makes it possible to increase the station's capacity by an order of magnitude.

Environmental Issues

It is assumed that the Zaramag hydroelectric power stations, the need for the construction of which, according to the administration of the republic, is obvious, will not have any impact on the nature of the Kassar Gorge. Too large territories that are important for the economy of the republic, after the construction of the dam, as alreadymentioned, it was not flooded. The amount of agricultural land in the area of its construction has practically not decreased.

At the time when the construction of a cascade of hydroelectric power stations was still supposed to begin near Nizhny Zaramag, the project had many opponents. In particular, the well-known ecologist B. Beroev strongly disapproved of the construction of the station. But after making changes to the project, this scientist radically changed his opinion regarding the construction of the hydroelectric power station. According to B. Beroev, lowering the height of the dam from 79 to 39 m, and the depth of the reservoir from 70 to 30 m reduced the unpleasant environmental consequences of the HPP to a reasonable minimum.

Some scientists expressed concern that after the construction of the stations, the Tibskoye mineral water deposit and the sources of the Nar group and Kudzakhta might suffer. However, the inspections carried out showed that the construction of the HPP will not have any negative impact on these valuable natural objects.

Criticism of the station

Despite the fact that the environmentalists, in fact, gave the go-ahead for the construction of this important facility for the economy of the republic, he still had a lot of opponents. Basically, criticism of the station comes down to the fact that it is being built in a seismically dangerous zone - at the junction of three tectonic faults. The concern of a number of public organizations is easily explained. In their opinion, the object is quite dangerous (Zaramag hydroelectric power stations). An accident, in particular a dam break during an earthquake, will lead to such terrible consequences as the destruction of the cities of Ardon and Alagir, as well as all the small settlements located between them. As a result, more75 thousand people. Also, in the event of a breakthrough, water will cause irreparable damage to the Ossetian Military Highway passing through the Kassan Gorge and several important historical and archaeological monuments.

However, the design engineers of the station do not share the fears of public organizations. According to them, the project of the cascade has been developed in such a way that its structures can easily withstand an earthquake of up to 11 points. The parameters of the dam and other HPP structures even exceed the design standards somewhat. The public's fears about microcracks already present in the embankment, which appeared during several earthquakes that occurred during the freezing of the station, the design engineers are also trying to dispel. In their opinion, the hydroelectric dam is in satisfactory condition.

Expertise

The project of the Zaramagsky cascade, the customer of which is JSC Zaramagsky HPPs, before it was put into practice, of course, passed all the necessary checks. Permission to build the station was obtained from:

• Ministries of Fuel and Energy of the Russian Federation;
• Gosgortechnadzor RF;
• Glavgosexpertiza;
• Ministry of Emergency Situations of Ossetia;
• EMERCOM of Russia.

Moreover, the results of all examinations were verified during public hearings in the Committee for Fuel, Housing and Energy of North Ossetia-Alania with the participation of representatives of the Public Chamber.

Headend: Statistics

After completion of workThe Zaramag hydroelectric power station will become the most powerful in the republic. The depth of the Kassar Gorge in the station construction area is 1000 m. The river has a very large fall in this place. At the site of the main HPP, its catchment area is 552 km2. The speed of the river in this area reaches 2.5-3.5 m/s.

The dam of the station has a maximum height of 39 m. Its length is 300 m, and its width at the base is 330 m. Its maximum depth is 30.6 m. The station's flood tunnel is located on the left bank of the river. Ardon. It is designed to discharge 938 m³/from the water.

A four-bladed rotary hydraulic turbine with a butterfly valve is installed in the building of the hydroelectric power station, located on the right bank. The diameter of its impeller is 3.5 m, and its weight is 30 tons. The generator of the SV 565/139-30 UHL4 station, driven by a turbine, produces a voltage of 15 MW. Electricity is transferred from the hydraulic unit to a 110 kV switchgear. From here, the current flows through two power lines to the Zaramag and Nuzal substations. Pressure tunnel No. 1 of the HPP has a cross section of 7.3 x 7 m and a length of 674.29 m.

Statistics on HPP-1

The construction of the second object of the cascade as of 2016 is already coming to an end. Soon the list of the most important industrial facilities in South Ossetia will be supplemented by the existing Zaramag hydroelectric power plants. Zaramagskaya HPP-1 is the main node of this complex and, upon completion of construction, will generate the main part of electricity. This building is locatedmostly underground.

Water from the head station to the HPP-1 building will be supplied through a non-pressure diversion tunnel. First, it is supposed to be drained into a special pool of daily regulation. According to many in South Ossetia, the Zaramagsky HPP project is truly grandiose. The BSR of the station, for example, will have a volume of 270 thousand m³. The design length of the most non-pressure diversion tunnel will be 14,226 m.

The building of HPP-1 is supposed to be equipped with two hydraulic units operating at a head of 619 m. The diameter of the wheels of their turbines will be 3.345 m. Also, two generators SV 685/243-20 with a capacity of 173 MW will be installed in the building. Energy with a voltage of 15.75 kV will go to transformers (230 MVA), and then to a switchgear (330 kV). Its issuance will be carried out through two power lines to the Alagir collection point. The capacity of the hydroelectric unit of the head station after the construction of the Zaramagskaya HPP-1 will be reduced to 10 MW.

Conclusion

Thus, the Zaramag hydroelectric power plants are indeed a very important object for the economy of South Ossetia. They can significantly reduce the shortage of electricity. And given that the original project was finalized in such a way as to minimize the negative impact on the region's ecology, its construction can be considered quite expedient and justified.