"HPPs ON DRINA RIVER" Višegrad
HYDROELECTRIC POWER PLANT VISEGRAD
Disposition of the plant
Content:
° Construction objects
° Electromechanical equipment
° Hydromechanical equipment
° Technical observation
Head concentration has been obtained by concrete gravitation dam with evacuation part in the right side of the riverbed and machine hall incorporated in the body of the dam near the left part of the riverbed.
The dam consists of 13 concrete blocks which are monolithicised by injecting after finalization.
By the right bank there are 4, and by the left 2 gravitation blocks; in the blocks no. 5 and 6, four bottom outlets are placed. In the blocks no 7 and 8 there are two surface spillways and in the blocks no 9, 10 and 11 turbines are placed.
In the downstream chute of the bottom outlets, surface spillways and flow off, they are separated by dividing walls across which there is a bridge with crane paths and niches for downstream gates. Flow in the downstream parts is regulated by right and left bank wall.
The dam is based on the limestones and dolomites. In order to reduce straining of water from the reservoir, three-line injection curtain 50-130 m deep was designed. It was derivated from injecting gallery and injecting examinating tunnels length of 200 m in the right and 55 m in the left side of the dam. Downstream from injecting curtain, a drainage curtain was designed. The basic profiles of the dam are given in the table below.
| Foundation level | 259,5 mnm/m asl |
| Crest level | 339,0 mnm/m asl |
| Construction height | 79,5 m |
| Foundation width | 30,0 m |
| Crest width | 16,0 m |
| Length of crest | 280,0 m |
| Inclination of upstream face | vertically |
| Inclination of downstream face | 1 : 0,80 |
| Inclination of fundamental surface | 8o upstrean |
Total installed discharge of Qi=800 m3/s is arranged on three units which consist of:
- Three vertical Kaplan turbines with concrete spiral casing with associated turbine regulators. Diameter of the turbine rotor is 6,015 m, and turbine capacity at constructive head of 43 m, unit discharge of 267 m3/sec and efficiency of η=0,94 is 105 MW with nominal speed of n=136 rpm.
- Three three-phase synchronic generators, each capacity of 115 MVA, nominal voltage of 15,75 kV, nominal speed 136 rpm and efficiency of 0,98 with associated excitation and voltage regulation.
- Four monophase energy-transformers (fourth unit as a spare) each capacity of 115 MVA, voltage ratio of 15,75/420 kV, including oil and auxiliary equipment.
- Complete equipment of switchgear 400 kV worked out in SF6 technology, with two powergrid exits including all necessary equipment.
- Equipment with generator voltage (15,75 kV).
- Self-consumption equipment.
- Diesel units.
- Automatic-control, signalization, protection, measurement and data-processing equipment.
- Auxiliary units equipment.
- Transmission lines of 400 kV, length of cca 4,5 km.
- Telecomunications and telemechanics.
- Permanent energy supply of the plant.
- Cable shelves and other equipment.
- Fire protection and protection from third persons.
For installation and maintenance of electromechanical equipment the following cranes are used:
- Portal crane placed on the roof of the machine hall toward left side covers main installation sheltered plateau. Span of the crane is 21 m and maximum capacity 3.500 kN, i.e. capacity of the main hooks is 2x1.750 kN, and auxiliary hooks 250 kN and 50 kN respectively.
- Bridge crane is placed under the roof of the machine hall and it covers auxiliary installation plateau on the level of roof board of generator barrel. Span of the crane is 21,5 m and capacity is 500 kN of the main hook, and 200 kN of the auxiliary one.
Beside the above mentioned, there are also cranes that can provide installation and maintenance of electromechanical equipment:
- The bridge crane capacity of 100 kN for 400 kV switchyard.
- One-bar crane, capacity of 32 kN for generator voltage, equipment maintenance, drainage pumps and other auxiliary equipment in annexes of the machine hall.
Evacuation of flood waters is done through 4 bottom outlets and two spillway openings. Bottom outlets are dimensions of 6x8 m at light openings. Quantity of water evacuated by one outlet at level of 336 m asl is 1.242 m3/sec, i.e. total maximum capacity of all outlets is 4.970 m3/sec. Each of the bottom outlets is equipped with following HM equipment:
- Regulating radial gates 6x8 m with appropriate oil, hydraulic servomotors.
- Safety gates dimensions of light openings 6x11 m. The gates are operated by the oil hydraulic servomotors from the dam crest. They also provide protection and revision of regulating radial gates.
- Steel outlet lining from entrance to downstream trashold of auxiliary gate, length of 55 m. A set of upstream and downstream auxiliary gates is foreseen for revision and maintenance of safety and regulating gates.
- Upstream auxiliary rolled gates are consisting of several parts, dimensions of 6x13,3 m. Raising of the gates is carried out by portal crane from the dam crest by means of automatic pliers.
- Downstream auxiliary gates are flat consisting of more parts, dimensions of 7,2x5,7 m. Their operating is done with portal crane from the bridge on the level 307,50 m asl above downstream separating walls.
Spillways are dimensions of 18x18,9 m. From them it is possible evacuate totally 6.220 m3/s of water with lake level of 336 m asl. Both spillways are supplied with radial gates dimensions of 18x19,6 m. They are also equipped with flapes capacity of 161 m3/s each. The gates are operated by appropriate oil hydraulic servomotors.
Auxiliary rolled flat gates are foreseen for checking up of the radial gates, dimensions of 18x18,9 m, and they are handled by portal crane from the dam crest.
Three identical intake structures are foreseen for water supply to the turbines in the machine hall. Dimensions of each are fitted for flow of 267 m3/s and divided to two entrance openings by separating wall.
Each of turbine tracts is equipped with:
- Entrance trashrack dimensions of 2(8x22m) made of flat steel sticks. Trashrack is cleaned by special device from the dam crest.
- Auxiliary upstream flat gates dimensions of 6,8 x 12,2 m. Revision of the main interturbine gates is carried out under their protection. Their operating is provided with portal crane capacity of 1.200 kN from the dam crest.
- The main safety quick turbine inlet valves which are designed as rolled gates dimensions of 6,8x12,3 m. They are operated by appropriate servomotors.
- Draft tube gates dimensions of 7,52x7,4 m, operated by portal crane capacity of 400 kN, from the bridge above draft tube gates.
Regarding the importance of the object, dimensions of the reservoir and possible influences on the environment, especially in the case of an accident, a great attention is paid to technical observation through a special part of the project. Because of the permanent control of the behavior of the dam, objects and surrounding terrain, appropriate instruments have been installed in order to follow all changes, to process data and make relevant conclusions on stability of the objects and terrain by means of the most modern instrumental and geodesic methods. On these bases, appropriate protection measures are taken.
