Zaramagskie HPPs are the youngest cascade of stations in South Ossetia. They are being built in the upper reaches of the mountain river Ardon in the Kassar Gorge. The stations were named so because they are in the immediate vicinity of the village of Nizhny Zaramag. It was recognized that the construction of this complex was expedient primarily because South Ossetia is currently experiencing an acute shortage of electricity.
A bit of history
The Zaramagsky hydroelectric power plants began to be built in 1976. However, the head station of the cascade was not commissioned until 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.
Expediency of construction
The organizer of the construction of these stations is Zaramagskiye HPPs JSC, a subsidiary of RusHydro. The decision to defrost this facility was made by the corporation’s management at the beginning of 2015. According to South Ossetia, after its construction, the shortage of electricity in the republic will decrease from 80 to 30%.
Significant changes were made to the design of the station with a 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, many people would have to be resettled 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 hydroelectric power station 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 stations according to the derivational scheme. Upon completion of the construction of HPS-1, the total capacity of the cascade will be 352 MW. Thus, the complex will become the largest in South Ossetia.
Zaramagsky hydroelectric power plants 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 pressure in the Russian Federation. In addition, it is planned to supply the most powerful bucket hydraulic turbines in the country (at HPP-1). Also, the longest derivation tunnel supplying water from the head station to HPP-1 will be dug at the station.
Society “Zaramagskie HPPs”
This small OJSC, which is the customer of the construction of the cascade, was established on May 10, 2000. Its head office is located at: Moscow, Stroitelny proezd, 7A, building. 5. There is also a company branch, of course, in North Ossetia-Alania itself. Address of the second office of Zaramagskiye HPPs: Vladikavkaz, ul. Pervomaiskaya, 34. The main activity of the company is the implementation of technical supervision during the construction of the cascade. The general director of this company is Vitaly Totrov.
What is a derivation scheme?
Stations of this type are built in those places where the riverbed has a significant slope, and consequently, the construction of the dam does not allow the accumulation of a large amount of water. In order to rectify the situation, a special construction scheme is used. In this case, a dam is first built on the river and a reservoir is built. Water conduits run from it to the hydroelectric power station building. The latter are equipped with a slight bias (much more polite than the natural channel). As a result, water is supplied to the building of the hydroelectric power station under very high pressure from a considerable height, which allows increasing the power of the station by an order of magnitude.
Ecological problems
It is assumed that the Zaramagsky hydroelectric power stations, the need for construction of which, according to the administration of the republic, is obvious, will not have any effect 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 already mentioned, were not flooded. The number of agricultural land in the area of its construction has not practically decreased.
At that time, when Nizhny Zaramag began to build the cascade of hydroelectric power stations just was supposed, the project had many opponents. In particular, the renowned ecologist B. Beroev did not approve of the construction of the station. But after making changes to the draft, this scientist changed his opinion regarding the construction of hydroelectric power stations radically. 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 hydropower plant 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 Nara group and Kudzakhta could be affected. However, the tests showed that the construction of hydroelectric power stations will not have any negative impact on these valuable natural objects.
Criticism of the station
Despite the fact that environmentalists, in fact, gave the go-ahead for the construction of this important for the republic’s economy, many opponents remained. Basically, the 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 simply explained. In their opinion, the facility is quite dangerous (Zaramagsky hydroelectric power stations). The accident, in particular the breakthrough of the dam 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 towns located between them. As a result, more than 75 thousand people will suffer. Also, in the event of a breakthrough, water will cause irreparable harm to the Military Ossetian road passing along the Kassan Gorge and several important historical and archaeological sites.
However, the design engineers of the station do not share the fears of public organizations. According to them, a cascade project has been developed in such a way that its structures are able to easily withstand an earthquake of up to 11 points. The parameters of the dam and other hydroelectric structures are even slightly higher than the design standards. Public concerns about the already existing microcracks in the mound, which appeared during several earthquakes that occurred during the station’s freezing, are also being addressed by design engineers. In their opinion, the dam is in satisfactory condition.
Expertise
The project of the Zaramagsk cascade, whose customer is Zaramagskiye HPPs OJSC, before it began to be implemented, of course, passed all the necessary checks. Permission for the construction of the station was obtained from:
Ministry of Fuel and Energy of the Russian Federation;
Gosgortekhnadzor of the Russian Federation;
Glavgosekspertizy;
Ministry of Emergencies of Ossetia;
Russian Emergency Situations Ministry.
Moreover, the results of all examinations were checked during public hearings at the Committee for Fuel, Housing and Public Utilities and Energy of North Ossetia-Alania with the participation of representatives of the Public Chamber.
Head station: statistics
At the end of the work, the Zaramagskaya hydroelectric 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. In the site of the head hydroelectric station, its catchment area is 552 km 2 . The river flow 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 the width at the bottom is 330 m. The useful volume of the hydroelectric reservoir is 0.5 million m 3 . Its maximum depth is 30.6 m. The flood tunnel of the station is located on the left bank of the river. Ardon. It is designed for discharge of 938 m 3 / s of water.
In the building of the hydroelectric power station, located on the right bank, a four-blade rotary hydraulic turbine with a disk shutter is installed. The diameter of its impeller is 3.5 m, and its weight is 30 tons. The generator of the station CB 565 / 139-30 UHL4, 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 goes through two power lines at the Zaramag and Nuzal substations. Pressure tunnel No. 1 of the hydroelectric station has a cross section of 7.3 x 7 m and a length of 674.29 m.
Statistics on HPS-1
The construction of the second cascade facility 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 Zaramagsky hydroelectric power stations. Zaramagskaya HPP-1 is the main unit of this complex and upon completion of construction will generate the bulk of the electricity. This building is located mostly underground.
Water from the headend to the HPP-1 building will be supplied through a pressureless derivational tunnel. First, it is supposed to be drained into a special pool of daily regulation. According to many in South Ossetia, the Zaramagskiye HPPs project is truly grandiose. BSR station, for example, will have a volume of 270 thousand m³. The design length of the most pressure-free derivational tunnel will be 14,226 m.
The building of HPP-1 is supposed to be equipped with two hydraulic units operating at a pressure 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 delivery will be carried out on two power lines to the reception center "Alagir". After the construction of the Zaramagskaya HPP-1, the power of the hydraulic unit of the head station will drop to 10 MW.
Conclusion
Thus, Zaramagsky hydroelectric power stations are indeed a very important object for the economy of South Ossetia. Electricity shortages can be reduced significantly. And if we take into account the fact that the initial project was finalized in such a way as to minimize the negative impact on the ecology of the region, its construction can be considered quite expedient and justified.