Hydroelectric principle of operation scheme equipment power. Hydroelectric power plant, principle of operation, design and components. What can these facilities be used for?

A hydraulic power plant (HPP) is a power plant that uses the energy of a water stream as an energy source. Hydroelectric power plants are usually built on rivers by constructing dams and reservoirs.

For the efficient production of electricity at hydroelectric power plants, two main factors are necessary: a guaranteed supply of water all year round and the possible large slopes of the river, favoring hydro construction canyon-like topography.

HPP Features

· The cost of electricity at Russian HPPs is more than two times lower than at thermal power plants.

HPP generators can be turned on and off quickly enough depending on energy consumption

Renewable energy source

Significantly less impact on the air environment than other types of power plants

HPP construction is usually more capital intensive

Often efficient HPPs are more remote from consumers

· Reservoirs often occupy large areas, but, approximately, since 1963, protective structures (Kyiv HPP) began to be used, which limited the area of the reservoir, and, as a result, limited the area of the flooded surface (fields, meadows, villages).

· Dams often change the nature of the fish economy, as they block the path to spawning grounds for migratory fish, but often favor the increase in fish stocks in the reservoir itself and the implementation of fish farming.

Principle of operation

The principle of operation of a hydroelectric power station is quite simple. A chain of hydraulic structures provides the necessary pressure of water flowing to the blades of a hydraulic turbine, which drives generators that generate electricity.

The necessary pressure of water is formed through the construction of a dam, and as a result of the concentration of the river in a certain place, or by derivation - the natural flow of water. In some cases, both a dam and a derivation are used together to obtain the necessary water pressure.

All power equipment is located directly in the building of the hydroelectric power station. Depending on the purpose, it has its own specific division. In the engine room there are hydraulic units that directly convert the energy of the water current into electrical energy. There are also all kinds of additional equipment, control and monitoring devices for the operation of the hydroelectric power station, a transformer station, switchgear and much more.

Hydroelectric stations are divided depending on the generated power:

· powerful - produce from 25 MW to 250 MW and more;

medium - up to 25 MW;

· small hydroelectric power plants - up to 5 MW.

The power of a hydroelectric power station directly depends on the pressure of the water, as well as on the efficiency of the generator used. Due to the fact that, according to natural laws, the water level is constantly changing, depending on the season, and also for a number of reasons, it is customary to take cyclic power as an expression for the power of a hydroelectric station. For example, there are annual, monthly, weekly or daily cycles of operation of a hydroelectric power station.

A small hydropower plant typical of the mountainous regions of China (Houzibao HPP, Xingshan County, Yichang District, Hubei Province). Water comes from the mountain through a black pipeline.

Hydroelectric power plants are also divided according to the maximum use of water pressure:

high-pressure - more than 60 m;

medium-pressure - from 25 m;

low-pressure - from 3 to 25 m.

Depending on the water pressure, different types of turbines are used in hydroelectric power plants. For high-pressure - bucket and radial-axial turbines with metal spiral chambers. At medium-pressure HPPs, rotary-blade and radial-axial turbines are installed, at low-pressure ones, rotary-blade turbines in reinforced concrete chambers are installed.

The principle of operation of all types of turbines is similar - water under pressure (water pressure) enters the turbine blades, which begin to rotate. The mechanical energy is thus transferred to the hydroelectric generator, which generates electricity. Turbines differ in some technical characteristics, as well as chambers - iron or reinforced concrete, and are designed for different water pressures.

Hydroelectric stations are also divided depending on the principle of using natural resources, and, accordingly, the resulting water concentration. Here are the following HPPs:

· Run-of-river and near-dam HPPs.

These are the most common types of hydroelectric power stations. The pressure of water in them is created by installing a dam that completely blocks the river, or raises the water level in it to the required level. Such hydroelectric power plants are built on high-water lowland rivers, as well as on mountain rivers, in places where the riverbed is narrower, compressed.

· Dam HPPs.

Built with higher water pressure. In this case, the river is completely blocked by the dam, and the building of the hydroelectric power station itself is located behind the dam, in its lower part. Water, in this case, is supplied to the turbines through special pressure tunnels, and not directly, as in run-of-river hydroelectric power plants.

· HYDROPOWER PLANTS.

Such power plants are built in places where the slope of the river is large. The necessary concentration of water in this type of HPP is created by derivation. Water is diverted from the river bed through special drainage systems. The latter are straightened, and their slope is much smaller than the average slope of the river. As a result, water is supplied directly to the power plant building. Derivative HPPs can be of different types - non-pressure or with pressure derivation. In the case of pressure diversion, the conduit is laid with a large longitudinal slope. In another case, at the beginning of the derivation, a higher dam is created on the river and a reservoir is created - this scheme is also called mixed derivation, since both methods are used to create the necessary concentration of water.

· HYDRO-STORAGE POWER PLANTS.

Such pumped storage power plants are capable of accumulating the generated electricity and putting it into operation at times of peak loads. The principle of operation of such power plants is as follows: at certain moments (times of non-peak load), the pumped storage units operate as pumps and pump water into specially equipped upper pools. When the need arises, water from them enters the pressure pipeline and, accordingly, drives additional turbines.

Hydroelectric stations, depending on their purpose, may also include additional structures, such as locks or ship lifts that facilitate navigation through the reservoir, fish passages, water intake structures used for irrigation, and much more.

The value of a hydroelectric station lies in the fact that they use renewable natural resources to produce electricity. Due to the fact that there is no need for additional fuel for hydroelectric power plants, the final cost of the generated electricity is much lower than when using other types of power plants.

LET'S CONSIDER IN MORE DETAILS THE WORK OF THE HPP.

The most efficient use of the watercourse is possible with the concentration of water level differences in a relatively short area. In the presence of a natural waterfall, the solution to this problem is simplified, but such conditions are extremely rare. To use the drop in the level of rivers, distributed over a considerable length of the watercourse, they resort to artificial concentration of the drop, which can be done in different ways.

DAM SCHEME. Dams are built on flat rivers with a high water flow and a small slope, which provides support and can be used as a control tank, which allows periodically accumulating water reserves and more fully using the energy of the watercourse. At the same time, two schemes for the location of the HPP building are distinguished: channel and dam proper.

Run-of-river hydroelectric power station. Its building is part of the water-pressure structures and perceives water pressure from the upstream side.

The structure of the building in this case must meet all the stability and strength requirements for dams. Hydroelectric power plants with a run-of-river building are built at relatively low pressures - up to 40 m. A classic example of such a plant is the Volzhskaya HPP.

Dam hydroelectric power station. Its building is located behind the dam and does not perceive water pressure. At large modern hydroelectric power plants of this type, the pressure reaches 300 m. For example, at the Sayano-Shushenskaya HPP - 242 m.

Figure 1 - Dam HPP

DERIVATION SCHEME. A concentrated water drop is obtained by diverting water from a natural channel through an artificial conduit, which has a smaller longitudinal slope. Due to this, the water level at the end of the conduit is higher than in the river. This level difference is the head of the HPP. There are stations with non-pressure and pressure derivation.

With non-pressure diversion, water is diverted from the river through an open channel or through a tunnel. To take water into the diversion canal, a low dam is being built in the riverbed, which creates a reservoir. Water enters the channel without pressure, and the channel itself ends with a pressure basin, from which water is supplied through pipes to the turbines. Waste water is diverted back to the riverbed.

In upland diversion, pressure pipelines are used, where water is supplied by pumps. From pipelines, water flows to turbines and then returns to the river downstream.

The construction of diversion HPPs is expedient in mountainous conditions with large slopes of rivers and relatively low water flow rates. In this case, you can get a head of up to 1000 m and, accordingly, more power.

Figure 2 - Derivative scheme

Hydroelectric power plants are part of the hydroelectric complex. A hydroelectric complex is a complex of hydraulic structures that ensure the use of water resources for generating electricity, water supply, irrigation, as well as flood protection, improving the conditions for navigation, fish farming, recreation, etc.

Composition and purpose of HPP structures. If the main task of creating a hydroelectric complex is to generate electricity, then it is usually called a hydroelectric power station or a hydropower facility. In the complex of structures of the hydroelectric complex, the main and auxiliary structures are distinguished. To ensure the production of construction and installation works during the construction period, temporary structures are erected.

The main structures, depending on the functions performed, are divided into:

water and drainage structures, designed, depending on the scheme of the hydroelectric power station, to create a reservoir, all or part of the head of the hydroelectric power station, pass operating costs to the downstream, including floods (including dams and spillways of various types), as well as for discharging ice, slush, washing sediments (including for these purposes in some cases special devices). On high-water rivers, the maximum flood discharges can reach 100 thousand m3 / s or more. So, at the world's largest hydroelectric power station "Three Gorges" on the river. The Yangtze (China) hydroelectric facilities are designed to allow the maximum design flood of 102.5 thousand m3 / s at the FPU, at the Cheboksarskaya HPP on the Volga the maximum design flow with a security of 0.01% is 48 thousand m3 / s, at Dneproges - 25.9 thousand m3 /s.

Power facilities designed to generate electricity and issue it to the power system and include water intakes; conduits supplying water from the upstream to the hydro turbines in the HPP building and diverting water from the HPP building to the downstream; HPP buildings with power equipment (hydro turbines, hydro generators, transformers, etc.), mechanical, handling, auxiliary equipment, control system; open (ORU) or closed (ZRU) distribution devices for receiving and distributing electricity to the power system, as well as emergency shutdown of power lines.

Shipping and timber-rafting facilities designed to pass ships, rafts through the hydroelectric complex and include locks, ship lifts with inlet and outlet channels, boats, etc.

Water intakes for irrigation, water supply, providing the necessary water supply and including water intakes, pumping stations, etc.

Fish-passing and fish-protecting structures designed to pass passage fish species to spawning grounds in the upstream and in the opposite direction, and including fish passages and fish elevators.

Transport facilities designed to connect the structures of the hydroelectric complex with each other, as well as to pass roads and railways through them, and including bridges, highways and railways, etc.

Depending on the natural conditions of the location of the hydroelectric complex (hydrological, topographic, geological, climatic), the scheme for creating pressure, the type of hydroelectric power station, some of the main structures of the hydroelectric complex can be combined with each other (for example, spillway buildings of a hydroelectric power station, where the hydroelectric power station building is combined with a spillway).

Auxiliary facilities are designed to provide the necessary conditions for the normal operation of the hydroelectric complex and the work of maintenance personnel and include administrative buildings, water supply systems, sewerage systems, etc.

Temporary structures necessary for the production of construction and installation works can be divided into two groups.

The first group includes structures that ensure the flow of the river during construction, bypassing the pits and structures under construction and protecting them from flooding and including construction channels, conduits, tunnels, dams, dewatering systems, etc.

The second group includes auxiliary production enterprises, including concrete plants with warehouses of cement, aggregates for concrete, reinforcing, woodworking and mechanical shops, mechanization and motor transport bases, warehouses, temporary roads, temporary power supply systems, communications, water supply, etc.

In many cases, part of the temporary structures after construction is completed is used during the operation of the HPP. So, from the structures of the first group, construction channels and tunnels can be partly or completely part of the spillways or water conduits of a hydroelectric power station, and lintels can be part of dams.

The structures of the second group can be fully or partially used as the initial infrastructure of territorial production complexes based on hydroelectric power plants.

To ensure reliable and durable operation of HPPs under operating conditions, taking into account integrated use, to achieve the maximum economic effect by reducing costs, reducing construction time and accelerating the commissioning of hydroelectric units, it is important to choose a rational layout and types of structures, based on natural conditions, reservoir parameters and hydroelectric power stations, operating modes.

Taking into account the long construction periods of large HPPs, reaching 5–10 years, it is usually envisaged to erect structures and put hydroelectric units into operation in stages with unfinished structures, low pressures, which increases economic efficiency.

HPPs and PSPPs are divided into:

According to the method of creating pressure, based on the principal diagrams of the use of hydraulic energy at HPPs, the placement of the HPP building as part of the structures: HPP with run-of-river buildings; HPP with dam buildings; diversion HPPs.

In terms of installed capacity (for HPS in terms of power in generator mode) for: powerful - more than 1000 MW, medium power from 30 to 1000 MW, low power - less than 30 MW.

By head (maximum): high-pressure - more than 300 m, medium-pressure - from 30-50 to 300 m, low-pressure - less than 30-50 m.

Hydroelectric power stations with channel buildings are usually used on flat rivers on soft and rocky foundations with heads up to 50 m and are characterized by the fact that the hydroelectric power station buildings are part of the pressure front and perceive water pressure from the upstream side. The complex of HPP structures usually includes concrete structures, including the HPP building, weir dam and shipping lock, and earthen dams, which form most of the pressure front. In many cases, the run-of-river buildings of HPPs are combined with spillways. The use of combined run-of-river buildings at Kievskaya, Kanevskaya, Dniester (Ukraine), Plyavinskaya (Latvia), Saratovskaya (Russia) HPPs and a number of others made it possible to abandon spillway concrete dams, reduce the front of concrete structures and obtain significant savings. The choice of the general layout of HPP structures with run-of-river buildings used on high-water rivers, where the estimated flood discharges during the construction period can reach 10–20 thousand m3 / s, is significantly influenced by the scheme for skipping river discharges during the construction period.

Depending on the location of the concrete structures of the HPP, the following layouts are distinguished (Fig. 4.1):

Coastal and floodplain layout.

Such layouts are distinguished by the fact that the main concrete structures (hydroelectric power station building, spillway dam, etc.) are located outside the riverbed, their excavation is protected by cofferdams, and during their construction, construction costs, including floods, are passed along the riverbed. When concrete structures are erected, the channel is blocked by a blind dam, most often earthen, and the river flows are passed through concrete structures. With a coastal layout, the height of the lintels is less, and when the pit is located within the coast area that is not flooded by floods during the construction period, there is no need to install lintels at all. A significant disadvantage of the coastal layout is the need to perform large volumes of earthworks for excavation in the pit, inlet and outlet channels. With a floodplain layout, the pit of concrete structures is located in the floodplain closer to the channel, which leads, on the one hand, to an increase in the height of the lintels that enclose the pit, and, on the other, to a decrease in the amount of excavation work.

Channel arrangement. With this arrangement, concrete structures are placed in the riverbed. In this case, the following schemes for their construction are used:

In one pit, fenced with cofferdams, with the passage of construction costs through a channel made in the shore.

In two (rarely in three) stages, when part of the channel is fenced off with jumpers and concrete structures of the 1st stage are erected in it, and construction costs are passed through the other part of the channel. When the structures of the 1st stage are erected, the flow of the river is passed through them, and the other part of the channel is protected by jumpers and concrete structures of the 2nd stage are erected.

Mixed layout. With this arrangement, concrete structures are placed partly in the channel and on the shore (in the floodplain) or in the channel over its entire width and partly on the shore (in the floodplain).

The choice of the HPP layout option in each specific case is determined by the natural conditions of the site where the HPP is located, the provision of favorable operating conditions, the reduction of construction time, the cost of the hydroelectric complex, and is made on the basis of a technical and economic comparison of options.

As an example, in fig. 4.2 shows the layout of the Kyiv HPP. The structure of concrete structures located on the right bank includes: a run-of-river HPP building with 20 horizontal capsular hydroelectric units with a total installed capacity of 360 MW with an average annual output of 0.64 billion kWh per year, combined with surface spillways, a single-chamber lock. The earthen dam blocking the channel and the left-bank dam have a total length of about 54 km. The maximum head of the HPP is 11.8 m, the design head is 7.6 m. The estimated maximum flood flow through the HPP facilities is 14.8 thousand m3/s, and the maximum specific flow rate at the water break is 90 m3/s. In the conditions of a sandy base, to ensure reliable operation of the run-of-river building of the hydroelectric power station, anti-filtration measures are provided, including clay ponur, a sheet pile curtain under the foundation slab of the power plant building, behind which a drainage is arranged, connected to the downstream. To prevent dangerous erosion of the bottom during the operation of the hydroelectric power station and the passage of floods in the downstream, a fastening was made, including a water break and an apron made of reinforced concrete slabs with a thickness of 2.5 to 1.5 m and a bucket filled with rock riprap, which, if an erosion funnel is formed, will prevent further erosion.

The complex of facilities includes the Kyiv PSP, located on the banks of the Kyiv reservoir, 3.5 km from the HPP.

HPPs with dam buildings are built on flat and mountain rivers, mainly on rocky foundations with heads from 30 to 300 m and are characterized by the fact that the HPP building is located behind the dam.

The length of pressure conduits and the layout of the HPP building depend on the type, height and other parameters of the dam, the natural conditions of the site.

In the conditions of lowland rivers, the layout of HPPs with dam buildings is similar to the layouts with run-of-river buildings and differs from them in that there is a concrete dam with a water intake and penstocks (station dam) in front of the building, separated from the HPP building by an expansion joint. An interesting example of such a layout is the Dneproges (Fig. 4.3).

After the construction of the Kremenchug hydroelectric power station with a reservoir with a useful capacity of 9 km3, which provides seasonal regulation of the Dnieper flow, the estimated maximum flood flow of the Dneproges in the conditions of regulated flow decreased from 40 to 25.9 thousand m3 / s, due to which part of the spillways (spans) of the dam was released, which made it possible to use them as water inlets of the second HPP building with a total capacity of 888 MW and increase the total capacity of the Dneproges to 1595 MW. Water is supplied to each turbine from two spans (water inlet openings) through two reinforced concrete pressure pipelines, supported by a dam and separated by an expansion joint from the HPP building.

b in

Rice. 4.3. Dneproges: a - plan; b, c – turbine hall of HPP-1 and HPP-2, respectively; 1 - HPP-1 building; 2 - gravity dam; 3 - HPP-2 building; 4 - gateway

At higher heads, usually in the conditions of mountain rivers, the layout of hydroelectric power plants with concrete dams and dams made of soil materials has features.

Layouts with concrete dams, as a rule, are carried out as channel or mixed with the placement of the HPP building behind a gravity, buttress or arch dam and are characterized by the location of pressure conduits in the body of the dam, on its upstream or downstream sides (Fig. 4.4). The structure of the hydroelectric complex includes a station dam with a dam building of a hydroelectric power station, a spillway dam and blind dams, which can be concrete and made of soil materials.

In narrow sections, there are difficulties with the placement of the building of the hydroelectric power station and the spillway. In these cases, the spillway can be made separately on the shore (for example, the Chirkeyskaya HPP) or in the form of a surface spillway located on the floor of the hydroelectric power plant near the dam building (for example, the Toktogulskaya HPP). It is extremely rare that the turbine hall of a hydroelectric power station is located in the body of a dam (for example, the Monteinar hydroelectric power station in France, where the turbine hall with four hydraulic units with a total capacity of 320 MW is located in a cavity inside an arch-gravity dam 153 m high and 210 m long along the crest, and the surface spillway is on the downstream side dams). Such built-in buildings, placed in a cavity inside a concrete dam (see Fig. 4.4, d), constitute a separate group and conventionally belong to the dam buildings.

a b

in
G

Rice. 4.4. HPP layouts with dam buildings and concrete dams: a - channel layout - HPP "Three Gorges": 1 - spillway dam; 2 - left-bank and right-bank station dams and HPP buildings; 3 - ship lift; 4 - two-line gateway; b - mixed layout - HPP Itaipu: 1 - left-bank dam made of soil materials; 2 - channel for skipping construction costs; 3 - temporary spillway; 4 - bottom jumper; 5 - HPP building; 6 - top jumper; 7 and 8 - concrete dam; 9 - spillway; 10 - right-bank dam made of soil materials; c - options for the location of pressure conduits of HPP with a dam building; d - option with built-in building

Rice. 4.5. Krasnoyarsk HPP: a - plan; b - cross-section of the station dam and the HPP building; 1 - HPP building; 2 – station dam; 3 - spillway dam; 4–7 – blind dams; 8 - mounting platform; 9 and 10 - upstream and downstream shipping routes; 11 - rotary device; 12 - ship's camera; 13 - wave protection wall

In relatively wide sections, construction is usually carried out in two phases with the construction of a concrete spillway dam (or part of the dam) in the first place and the passage of construction costs through the cramped riverbed, and after its blocking, in the second turn - through the spillway openings in the constructed spillway dam and the completion of construction hydroelectric facilities.

In narrow sections, to pass construction costs, a construction tunnel is being built, which, under operating conditions, can be used to construct a flood spillway.

a
b

Rice. 4.6. Chirkeyskaya HPP: a – cross section; b - plan; 1 - dam; 2 - water intake; 3 - pressure conduits; 4 - HPP building; 5 - access tunnel; 6 - operational spillway, combined with a construction tunnel

Examples of HPPs with a dam building in a relatively wide alignment are the world's largest HPP "Three Gorges" with a capacity of 18.2 million kW (see Fig. 4.4, a), the Itaipu HPP with a capacity of 12.6 million kWh, (see Fig. 4.4, b), Sayano-Shushenskaya HPP with a capacity of 6.4 million kW, Krasnoyarsk HPP with a capacity of 6 million kW with an average annual output of 20.4 billion kWh. The structures of the Krasnoyarsk HPP include a gravity dam with a length of 1065 m and a maximum height of 125 m (Fig. 4.5), consisting of a station and blind dams, a spillway dam, which ensures the passage of a flood flow of 14.6 thousand m3 / s (taking into account the transformation of the flood into reservoir when the level is forced), as well as a ship lift.

An example of a HPP with a dam building in a narrow alignment is the Chirkey HPP with a capacity of 1.0 million kW with an arched dam with a crest length of 333 m and a maximum height of 233 m and with a two-row arrangement of hydraulic units in the building (Fig. 4.6). On the left bank, a tunnel operational spillway was made, designed to pass a flood flow of 3.5 thousand m3 / s.

At the Toktogul HPP with a capacity of 1.2 million kW with a dam building in a narrow alignment with a two-row arrangement of hydraulic units in the HPP building and a gravity dam with a maximum height of 216 m, HPP pressure conduits and a deep spillway are located in the body of the dam, and a surface spillway is located on the lower face of the dam (Fig. 4.7).

In narrow sections with concrete dams and from soil materials, layouts with a coastal and underground HPP building can be used.

The main layouts of HPPs with dams made of soil materials are shown in fig. 4.8. In this case, the HPP building can be located directly behind the dam (a) or the most commonly used layouts with the onshore (b) and underground (c) HPP building are used.

For layouts of HPPs with dams made of soil materials, the coastal placement of operational spillways to pass flood flows is typical: in the form of a coastal surface spillway with a fast flow or a tunnel spillway. Construction tunnels are commonly used to skip construction costs.

A complex of hydropower facilities, including a water intake, conduits, a hydroelectric power station building, made outside the dam, is called the pressure-station unit (NSU) of the hydroelectric power station.

An example of a high-pressure HPP with a dam building and a dam made of earth materials is the Nurek HPP with a capacity of 2.7 million kW with an average annual output of 11.2 billion kWh per year (Fig. 4.9). Water is supplied to the turbines from tower-type water inlets by pressure tunnels. To speed up the commissioning of the HPP, the first three hydroelectric units were operated at reduced pressure, when the dam was built only to a height of 143 m (with a design height of 300 m), for which a temporary water intake and a tunnel were made. During the construction period, the flow of the river was passed through three tiers of construction tunnels located on the left bank. Flood discharges during the operational period (maximum discharge 5.4 thousand m3/with a probability of 0.01%) are passed through a tunnel spillway connected to the end section of the construction tunnel of the third tier.

Diversion HPPs are used with a wide range of heads, ranging from a few meters at small hydroelectric power plants to 2000 m (the Reisseck hydroelectric power station in Austria has a head of 1767 m), and are usually built in foothill and mountainous areas.

Hydroelectric power station with gravity diversion can be used with minor fluctuations in the water level in the reservoir. At such HPPs, water is supplied from a water intake to a diversion channel running along the coast (under appropriate topographical and geological conditions) or to a non-pressure diversion tunnel.

Hydroelectric power station with pressure diversion is used for both large and minor fluctuations in the water level in the reservoir. At such HPPs, water is supplied from a water intake to a pressure diversion pipeline located on the surface, or to a pressure diversion tunnel (Fig. 4.10). Structures of a diversion HPP, as well as a hydroelectric power plant with a dam-derivation (combined) scheme, in which the pressure is created by a dam and a diversion (see 2.4), include:

The head unit, which is designed to create backwater in the river and direct the flow to the derivation, as well as to clean water from sediment, litter, in some cases from ice, sludge, consists of a dam, a spillway, a water intake, a sump, washing and ice-discharge facilities.

Head nodes with low-pressure dams, usually built on mountain rivers, have reservoirs with a limited volume, and therefore measures are taken to prevent their filling with sediments. To do this, as part of the hydroelectric complex, a spillway concrete dam equipped with gates is made with a low threshold and a sufficient width of the spillway front, which ensures washing of sediments when flood flows are missed. With a large amount of suspended sediments in the water, which can lead to rapid abrasion of the flow part of hydraulic turbines, settling tanks are arranged in the form of a chamber in which, with a decrease in the flow rate, suspended particles settle to the bottom and then are removed.

The blind part of the dam can be made of concrete or earth materials. The water intake can be combined with a dam or made on the shore.

Reservoirs usually carry out daily regulation and are characterized by a small drawdown depth, which makes it possible to perform both free-flow and pressure derivation.

The head units with medium and high pressure dams are characterized by a large volume of the reservoir (with the possibility of sediment settling within the dead volume) and a significant drawdown of the reservoir during seasonal or long-term regulation of the flow. In this regard, the water intakes are deep, and the derivation is pressure.

Dams can be made of concrete (gravitational, buttress, arched) with a spillway and, in many cases, a water intake of a hydroelectric power station, as well as from local materials with a spillway and a water intake located outside the dam body.

Derivative conduits and structures on their route (derivation), which supply water to the station node, are divided into pressure (tunnels, pipelines) and non-pressure (channels, tunnels), along the route of which spillways, siphons and other structures can be arranged.

The station node includes, in case of non-pressure diversion, a pressure basin with a fore-chamber, a water intake, an emergency spillway and, regardless of the type of derivation, common structures: turbine pressure conduits, if necessary with a surge tank, a power plant building, diverting conduits in the form of a channel or tunnel (pressure or non-pressure), distribution device.

As part of the station node, the HPP buildings are open-shore, underground, and less often semi-underground.

A typical example of a dam-diversion HPP is the Inguri HPP (Georgia) with a capacity of 1.3 million kW (Fig. 4.11), the head unit of which includes an arch dam 271 m high with a flood spillway designed for a flow rate of 1900 m3 / s. The reservoir has a useful volume of 0.68 km3 with a drawdown depth of 70 m. From a deep water intake, designed for a flow rate of 450 m3 / s, a diversion pressure tunnel begins with a diameter of 9.5 m and a length of 15.3 km. The HPP station unit includes a shaft-type surge tank, a butterfly valve room, tunnel turbine conduits, an underground HPP building, a discharge free-flow tunnel and a channel with a total length of 3.2 km.

The total static head of the Inguri HPP, equal to 409.5 m, is formed from the pressure created by the dam (226 m) and the derivation (183.5 m). The design head is 325 m, and the average annual output is 5.4 billion kWh per year.

Types of HPP buildings and their main elements. The HPP building is a hydraulic structure in which, with the help of hydropower, electrical, hydromechanical, auxiliary equipment, control systems, the mechanical energy of water is converted into electricity transmitted to the power system to consumers. At the same time, reliable operation, strength and stability of the HPP building under the action of external loads (hydrostatic and hydrodynamic pressure, filtration pressure, temperature, seismic effects, etc.), as well as loads from the operation of process equipment, must be ensured.

The type and design solutions of HPP buildings are determined by the general layout of HPP structures and the main power equipment. Depending on the pressure and working conditions, rotary-blade, axial, radial-axial, diagonal and bucket turbines are installed in the HPP buildings.

The lower part of the building, where the flow path is located, including the spiral chamber, the suction pipe, turbine equipment and a number of technological systems, is called the aggregate part, and the upper part of the building with the upper structure, where the machine room with hydro generators and crane equipment, as well as power transformers, is located. crane equipment of the water intake (in run-of-river buildings), repair gates of suction pipes and other technological equipment - the supra-aggregate part.

The design and dimensions of the HPP building in plan and height, penetration into the base are significantly affected by the dimensions of the hydraulic unit, the spiral (turbine) chamber and the suction pipe, the penetration of the axis of the hydraulic turbine impeller under the tailwater level, and the number of hydraulic units. As a rule, two or more hydroelectric units are installed in the building of the HPP (for example, in the building of the Saratovskaya HPP - 23 hydroelectric units, Kanevskaya HPP - 24 hydroelectric units), rarely - one hydroelectric unit, since when it is repaired, the HPP completely stops working.

The structure of the HPP building includes an installation site, where the installation of hydroelectric units and their repair during operation are carried out. The assembly site also houses part of the auxiliary systems.

Multi-unit buildings of hydroelectric power stations, having a considerable length, are divided into separate sections by expansion joints: temperature-sedimentary with a soft base, temperature with a rocky base. Thus, the building of the Volzhskaya HPP with a capacity of 2530 MW with 22 hydroelectric units is divided into sections 60 m long, each of which houses two aggregate blocks with rotary-blade turbines with an impeller diameter of 9.3 m (with a design head of 19 m and a power of 115 MW). ).

The block of the mounting platform is usually also separated from the building by a seam.

The aggregate part of the HPP building is characterized by considerable massiveness. It perceives hydrostatic and hydrodynamic pressure in the flow path, loads from equipment and higher structures of the building and transfers them to the base. Geological conditions have a significant impact on the design of the aggregate part of the building. So, with a rocky base, it is greatly facilitated. In the aggregate part of the building there are systems of technical water supply, drainage of the flowing part, drainage of the building, etc.

The design of the aggregate part depends on the type of HPP building.

In accordance with the types of hydroelectric power plants, there are:

Run-of-river buildings of hydroelectric power stations, which are part of the pressure front and perceive pressure from the upstream side. In run-of-river buildings with a head of up to 50 m, rotary-blade turbines can be used, and with a head of more than 30 m, also radial-axial ones.

Dam buildings located behind the dam, which receives pressure from the upstream side. Water supply to them is carried out by turbine conduits. In dam buildings with a head of 30 to 300 m, mainly radial-axis turbines are used, as well as, under certain conditions, high-pressure rotary-blade turbines (for example, at the Orlik HPP with a head range of 45–71 m and a unit power of 90 MW) and diagonal ones (for example, the Zeya HPP with head range 78.5–97 m and unit power 215 MW).

Shore buildings used in dam and diversion schemes of HPPs practically do not differ from dam buildings.

Underground buildings, which are also used in dam and diversion schemes of HPPs, have discharge tunnels (pressure or non-pressure). In the buildings of diversion HPPs with high heads, radial-axial turbines up to a head of 600 m and bucket turbines are used starting from a head of 500 m and above. All the above types of buildings are used both in the schemes of hydroelectric power plants and pumped storage power plants.

The main diagrams of the aggregate part of HPP buildings (except for underground HPP buildings) are shown in fig. 4.12. Schemes I and II show the aggregate parts of a low-pressure run-of-river HPP building with vertical hydraulic units and bent suction pipes of an uncombined and combined type, respectively, with deep spillway conduits, and diagrams IV and V show horizontal and inclined hydraulic units of a combined type with a surface spillway.

Scheme III shows the aggregate part of the dam or diversion building of the HPP with a metal turbine (spiral) chamber of circular cross section.

Scheme VII shows the aggregate part of a diversion HPP with low-capacity hydraulic units using vertical conical and socket suction pipes. At the same time, a rectangular cross-section discharge channel is made to drain water.

Scheme VI shows the aggregate part of a diversion HPP with bucket (active) hydraulic turbines, which is distinguished by the absence of conventional turbine chambers and suction pipes, due to which the aggregate part is greatly simplified.

The parameters of the supra-aggregate part of the HPP building depend on the design and dimensions of the upper structure.

With a closed-type top structure with a high machine room within the HPP building and the installation site, the most favorable conditions for the operation, installation and repair of the main equipment are provided under various climatic conditions. At the same time, the height and width of the turbine hall are determined both by the conditions for placing the equipment in it and for its delivery by cranes of the turbine hall to the aggregate block or to the installation site during the installation or repair of the main equipment.

The superstructure usually consists of a supporting frame in the form of a system of columns on which crane beams and floor trusses, walls, slabs and floor roofs are supported.

Most HPP buildings are made with a high turbine hall (Fig. 4.13 - 4.15).

With a semi-open topside structure with a reduced machine room within the HPP building and the installation site, the main equipment is located in the machine room, except for the main heavy-duty crane, which is placed outside it. During installation and repair, the assembly and disassembly of hydraulic units is carried out through a removable ceiling above each hydraulic unit (in the form of removable covers) using an external gantry crane. At large hydroelectric power plants, in most cases, a reduced-capacity crane is installed in a lower turbine hall, with the help of which installation and repair work is carried out that do not require the use of the main crane (Fig. 4.16 - 4.18).

With an open-type top structure without a machine room, the hydroelectric generator is located under a removable cover, and the rest of the equipment is in the process rooms of the power plant building aggregate part and the installation site. Installation and repair work is carried out using an external crane. Given the complication of operating conditions, installation and repair of hydraulic units, this type of superstructure is used extremely rarely.

Run-of-river HPP buildings(Fig. 4.19). The run-of-river buildings of HPPs are subject to the same loads as concrete dams, and they are subject to the same requirements for strength, stability, filtration conditions in the base, which are ensured with the appropriate dimensions of the building, anti-filtration and drainage devices in the base. Channel buildings are divided into non-combined and combined with a spillway.

Due to the fact that the flow entering the outlet channel from an uncombined and especially a combined building has excess kinetic energy to prevent erosion, fastening is performed in the outlet channel (see Fig. 4.2).

Rice. 4.17. Run-of-river spillway building with horizontal capsular hydraulic units of the Kyiv HPP: a - cross section; b - machine room; 1 - gantry crane; 2 - capsular hydraulic unit; 3 - groove of the trash grate

The connection of the HPP building with the earthen dam adjacent to it or with the shore is carried out with the help of interface abutments in the form of retaining walls (gravitational, corner, buttress, cellular and other types).

In run-of-river buildings of an uncombined type with vertical hydraulic units, the flow part includes a water intake, a spiral chamber, mainly of a T-section, and a suction pipe, the dimensions of which determine the dimensions of the aggregate block. In this case, the width of the block with a Kaplan turbine can be 2.6–3.2 of the diameter of the turbine impeller (D1). The dimensions of the water intake are determined by the required deepening under the ULV, the provision of favorable hydraulic conditions at the inlet and when paired with a spiral chamber, the allowable flow velocities on the grates (usually 0.8–1.2 m/s), the placement of the grate, emergency repair and repair gates , the grooves of which can be combined with the grooves of the lattice. At the inlet section of the water intake, as a rule, a socket with a visor wall is made, which ensures a smooth supply of water.

The deepening of the HPP building under the tailwater level depends on the required deepening of the impeller axis under the tailwater level (suction height) and the dimensions of the suction pipe, as well as the engineering and geological conditions of the foundation.

The main step-up transformers are installed on the floor above the technological premises from the downstream side.

Run-of-river buildings of the combined type, in which, in addition to turbine conduits, spillways are also located, can be made: with bottom spillways located below the spiral chamber above the suction pipes - Volgograd, Novosibirsk, Kakhovskaya hydroelectric power plants (Fig. 4.19, b);

with bottom spillways and a high intake of turbine conduits - Cheboksarskaya, Golovnaya HPP (see Fig. 4.13);
with deep spillways located above the spiral chamber (between it and the generator) - Irkutsk, Saratov, Dubossary HPPs (see Fig. 4.16);
spillway with vertical hydraulic units - Pavlovskaya, Plyavinskaya (see Fig. 4.14), Dniester HPP;
weirs with horizontal hydraulic units - Kyiv, Kanevskaya HPPs (see Fig. 4.17);
gobies with the placement of hydroelectric units in the gobies of the spillway dam - Ortochalskaya (Georgia), Wells (USA).

Buildings of the combined type can significantly reduce the length of spillway dams or even abandon them, which is especially important when building HPPs on soft foundations, reducing construction costs. So, at the Novosibirsk hydroelectric power station, the length of the spillway dam was reduced by 50%. At the Irkutsk, Pavlovskaya, Plyavinskaya, Dniester HPPs, the throughput capacity of the spillways of the HPP building ensures the passage of the estimated flood flow without spillway dams. In the combined buildings of the HPP, the water intake includes a turbine water intake and a water intake part of spillways.

The disadvantages of such buildings include the complexity of the design, significant additional hydrodynamic loads during the operation of spillways, and the complication of operating conditions.

In buildings of combined type with horizontal capsule units, used at low pressures (up to 25 m), due to the absence of a spiral chamber and the use of a straight-axis conical suction pipe, a significant reduction in the width of the aggregate block and an increase in the foundation of the building foot are achieved. In addition, improving the geometry and hydraulic conditions of the flow path, including the inlet part without a spiral chamber of complex configuration and replacing the bent suction pipe with a straight-axial conical one with higher energy performance, makes it possible to reduce pressure losses, increase the throughput of a horizontal unit by 20–30% and, accordingly, at the same power, reduce the diameter of the impeller. In general, the use of horizontal capsule units compared with vertical ones reduces the width of the aggregate block by up to 35%, increases efficiency. by 2–4%.

Rice. 4.19. Rustic buildings. Cross sections and views from the downstream: a - Kremenchugskaya and b - Kakhovskaya HPP: 1 - foundation slab; 2 - metal sheet pile; 3 - bottom spillway

The surface spillway provides favorable conditions for the passage of floods, and in many cases makes it possible to abandon the installation of a spillway dam. In such buildings, a metal capsule with a hydrogenerator enclosed in it is placed in the flowing part of the building from the upstream side. Access to the capsule is through special cavities in the vertical bull. The installation and dismantling of the hydraulic unit is carried out using an overhead crane, which is located in the engine room under the spillway, and an external gantry crane through hatches with removable covers in the spillway threshold (see Fig. 4.17).

At a number of small hydroelectric power plants, the generator is located openly in the turbine hall, the axis of the hydraulic unit is inclined, and water is supplied to the turbine through a conduit passing under the generator (see Fig. 4.12, scheme V)

Run-of-river buildings of the goby type are used extremely rarely, mainly on rivers that carry a large amount of sediment, providing favorable conditions for the passage of ice, sediment and flood flows through the spillway spans. At the Wells bull-type HPP (USA) with a capacity of 870 MW and a head of 30 m, 10 hydroelectric units are installed in the gobies of the dam, the estimated flood flow is 33.4 thousand m3 / s. The disadvantages of such HPPs include the lack of a common machine room, the lengthening of technological communications and, in general, the complication of operating conditions.

Dam buildings of the hydroelectric power station. In the dam buildings of the HPP, water is supplied to the turbines through turbine conduits (metal or steel-reinforced concrete), passing mainly in the body or on the bottom face of concrete dams, with the placement of the water intake on the upper face of the dams, the HPP building directly adjacent to the dam, and a separate seam (see Fig. 4.3, 4.5–4.7). With dams that are rectilinear in plan, the HPP building is also rectilinear; when it is located behind arched or arch-gravity dams, the HPP building can have a rectilinear or curvilinear outline along an arc corresponding to the outline of the lower face of the dam.

To ensure a smooth supply of water from the turbine conduit to the spiral chamber, a horizontal section of the conduit with a length of (4–6) D 1 is usually made in front of it, within which technological rooms are arranged with step-up transformers placed on the upper floor.

With dams made of local materials, water is supplied to the turbines through turbine conduits passing through the body of the dam or bypassing it in the form of tunnels or open conduits, with a separate water intake in the upstream and with the location of the power plant building at some distance from the dam.

Unlike run-of-river dam buildings, they do not perceive the pressure of the upstream, and the pressure transmitted to them through turbine conduits is small, which makes it possible to facilitate the construction of the building.

Spiral chambers of such buildings have a circular cross section and are made of metal or steel-reinforced concrete with metal cladding.

The width of the aggregate block with vertical radial-axial (or diagonal) hydraulic turbines is determined by the dimensions of the turbine (volute) chamber and is at least 4D 1 (impeller diameter).

A typical example of a dam building is the building of the Krasnoyarsk HPP with a total length together with an installation site of 428.5 m, where 12 hydroelectric units with a total capacity of 6 million kW are installed (see Fig. 4.5). The stationary dam has a water intake with 24 intake openings. Water is supplied to the unit through two steel-reinforced concrete conduits with a diameter of 7.5 m.

At the Chirkeyskaya HPP with an arch dam built in a narrow gorge, a reduction in the length of the dam building is achieved by a two-row arrangement of hydraulic units (see Fig. 4.6). Both turbine halls are served by one overhead crane, which is transferred from one turbine hall to another along the crane runways in the installation site. The placement of suction pipes in two tiers leads to an additional deepening of the HPP building.

When placing hydroelectric power plants in a narrow gorge, where it is difficult to carry out coastal spillways, spillways pass in the body of the dam, on its downstream side and on the floor of the building. Such an arrangement was made at the Toktogul HPP with a two-row arrangement of units in the HPP building (see Fig. 4.7). In this case, step-up transformers are placed indoors. With such an arrangement, the flow, passing through the spillway, is thrown from the HPP building by a toe-springboard to a considerable distance, and the energy is extinguished mainly due to the aeration of the flow.

A typical example of a dam building located behind a dam made of local materials with water supply through tunnels is the building of the Nurek HPP (see Fig. 4.9, 4.18). The HPP building has 9 units with a capacity of 300 MW each with a maximum head of 275 m. Water is supplied through three tunnels with a diameter of 9 m, each divided into 3 turbine conduits. The building is made with a lowered turbine hall with removable covers in the ceiling above the hydraulic units and the installation site. Overhead cranes are installed in the turbine hall and in the valve room for maintenance and repair of equipment, and a gantry crane is used for the installation and complete dismantling of the hydraulic unit and ball valve.

Buildings of diversion HPPs with radial-axial turbines practically do not differ from dam buildings. When installing bucket turbines, the design of the aggregate part of the HPP building changes. Instead of a turbine chamber, a pressure distribution pipeline is made in the form of a metal casing, on which turbine nozzles with flow control mechanisms are mounted, and water is discharged from the turbine through a non-pressure tray. Depending on the power of the hydraulic turbine and the number of nozzles, the axis of the hydraulic unit can be located vertically or horizontally. Due to the fact that the impeller of bucket turbines is located above the maximum level of the tailwater, when they are installed, the depth of the building is significantly reduced.

In the buildings of high-pressure diversion HPPs, with a large length or branching of pressure conduits, disk or ball valves are installed in front of the turbines, depending on the pressure and diameter (at pressures of more than 600 m, only ball valves), which allow shutting off the pipelines and stopping the hydraulic unit in an emergency in the event of a guide vane failure, as well as during normal operation and repair work.

Recently, instead of pre-turbine gates, built-in annular gates are used, which are placed between the stator columns and guide vanes, which makes it possible to reduce the dimensions of the building, the weight and cost of equipment.

Underground HPP buildings. In recent decades, the construction of underground hydroelectric power plants has been widely developed. Of these, the largest were built in Canada: Churchill Falls with a capacity of 5225 MW with a head of 320 m, Mika - 2610 MW with a head of 183 m. Ust-Khantayskaya - 441 MW in Russia, etc. In underground buildings, construction work does not depend on climatic conditions, which is important when building in northern regions with harsh winters or in the tropics with a long rainy season. Underground buildings are also used in cases where, due to unfavorable natural conditions in the gorge (steep landslide-prone slopes, high water level when a flood is passed), as well as a large deepening of the turbine wheel axis below the tailwater level, the construction of open buildings can lead to a violation of stability coastal slopes, to a sharp increase in the volume of work.

The disadvantages of underground buildings include: in the case of unfavorable engineering and geological conditions, a significant complication of underground work; complication of operating conditions due to the lengthening of technological communications, more complex schemes for power output; an increase in the cost of electricity for own needs, which is caused by the need for constant ventilation of the premises, their lighting, etc.

The dimensions and layout of underground HPP buildings depend primarily on the parameters and placement of hydropower, electrical and hydromechanical equipment. At large hydroelectric power plants, where the dimensions of the workings of the turbine halls reach large sizes (span up to 30 m or more), the main hydraulic power equipment is usually placed in the turbine hall, which is serviced by overhead cranes, and the pre-turbine gates are made in a separate room located at some distance from the turbine hall. With long discharge tunnels, the downstream repair gates and the mechanisms serving them for shutting off the exhaust pipes are also located in a separate room. With a large number of units, several discharge tunnels are arranged, most often non-pressure or pressure (with large fluctuations in the levels of the downstream) with a surge tank. For short tunnels that discharge water separately from each unit, downstream gates are installed in the exit portals of the tunnels.

One of the important factors determining the layout of buildings of underground hydroelectric power plants is the choice of the layout of the main step-up transformers: in a separate underground room (HPP Kariba in Zimbabwe, HPP Yali in Vietnam), in an expanded underground turbine hall (HPP Timet I and II in Australia), open on the surface of the earth at outdoor switchgear sites (Borisoglebskaya, Ingurskaya).

The open location of transformers is mainly used for shallow underground building (at a depth of up to 200–300 m) and favorable topographic and geological conditions of the site. At the same time, conductors from generators to transformers, which are of considerable length, are laid in special galleries and shafts with the implementation of special measures for heat removal due to the large heat dissipation by current conductors.

The transmission of electricity to the outdoor switchgear and indoor switchgear from the main transformers with their underground location is carried out at a voltage of 110-500 kV by oil-filled cables with special measures for heat removal, and more recently also by gas-insulated busbars.

In underground buildings, installation sites are provided, which in most cases are a continuation of the turbine hall, usually located at its end and connected to the ground using transport tunnels and cargo shafts.

Fans and air conditioners are installed to remove heat and ventilate the underground spaces of the HPP building.

Turbine hall lining designs depend on engineering and geological conditions. In most turbine halls, a bearing vault of a circular shape is made with an increase in the thickness of the reinforced concrete lining at the heels. In sufficiently strong rocks, the walls are fastened with sprayed concrete, and in less strong ones, a continuous concrete or reinforced concrete cladding up to 0.5 m thick or more with reinforcement with anchors is arranged, in areas of weakened rocks - with strengthening cementation, and in some cases drainage measures are provided.

In the underground building of the Inguri hydroelectric power station with a length of 145.5 m, a span of 21.2 m and a cut height of 53.7 m, 5 hydraulic units were installed. Water is supplied to the units by turbine conduits located in plan at an angle to the longitudinal axis of the units, which made it possible to place pre-turbine gates within the turbine hall, practically without increasing its span (see Fig. 4.20). The water is diverted by a pressure tunnel.

Semi-underground HPP buildings. Under favorable engineering-geological and topographic conditions and large fluctuations in the level of the tailwater, semi-underground buildings can be built located in trench workings, and the top structures of the turbine halls can be arranged on the surface of the earth. Solutions for semi-underground buildings are possible with the placement of one or more units in separate shafts, above which the upper structure of the turbine hall is erected on the surface of the earth, as at the Dniester PSP.

The semi-underground building of the Vilyui hydroelectric power station with a capacity of 648 MW, made in a trench working 60 m deep, is completely located under the earth's surface (Fig. 4.21).

Buildings of small hydroelectric power stations. Small HPPs usually include hydroelectric power plants with a capacity of up to 10–30 MW. Along with the use of hydropower resources of large rivers at medium and large hydroelectric power stations, which in most cases require the creation of large reservoirs and operate in unified energy systems, small hydroelectric power stations have received wide development in the world. Such HPPs use the hydropower potential of small rivers, tributaries, waste channels and have an extremely limited impact on the environment. They can supply electricity to the power grid or work for a specific consumer, which is especially important for remote areas where there is no developed power transmission network.

Small HPPs, like large ones, are divided into HPPs with run-of-river and dam buildings and diversion HPPs.

At small HPPs, to simplify the structures in buildings with the installation of vertical hydraulic units, straight-axis conical suction pipes can be used, horizontal units, including capsule ones, as well as those with an inclined arrangement of the unit axis (see Fig. 4.12, diagrams IV, V, VII) are widely used.

On page 283 (photo) and in fig. 4.22 shows diversion HPPs - Tereblya-Rikskaya with a capacity of 27 MW with a head of 215 m and Egorlykskaya with a capacity of 30 MW with a head of 32 m.

Hydroelectric power plant (HPP)- a complex of structures and equipment, through which the energy of the water flow is converted into electrical energy. Hydroelectric power plants are usually built on rivers by constructing dams and reservoirs. Two main factors are necessary for the efficient production of electricity from hydroelectric power stations: a guaranteed supply of water all year round and the possible large slopes of the river. Canyon-like relief types are favorable for hydraulic construction.

The structure of a hydroelectric complex on a flat river includes: a dam, a power plant building, spillways, navigation passes (locks), fish passages, etc.

Principle of operation. The principle of operation of a hydroelectric power station is quite simple (Fig. D.1). A chain of hydraulic structures provides the necessary water pressure, and power equipment converts the energy of water moving under pressure into mechanical energy of the turbine, which drives generators that generate electricity.

Figure D.1 - Scheme of a hydroelectric power plant

The power of a hydroelectric power station is determined by the flow and pressure of water. At hydroelectric power plants, as a rule, the pressure of water is formed through the construction of a dam or by diversion - the natural flow of water. In some cases, both a dam and a derivation are used together to obtain the necessary water pressure. The water area in front of the dam is called the upstream, and below the dam - the downstream. The difference between the levels of the upstream (UVB) and downstream (UNB) determines the pressure H. The upstream forms a reservoir in which water accumulates, which is used as needed to generate electricity.

HPP classification . Hydroelectric stations are divided depending on:

1) generated power:

powerful - produce from 25 MW and above;

medium - up to 25 MW;

small hydroelectric power plants - up to 5 MW.

2) maximum use of water pressure:

high-pressure - more than 60 m;

medium pressure - from 25 m;

low-pressure - from 3 to 25 m.

3) the principle of using natural resources, and, accordingly, the resulting water concentration:

Run-of-river and dam hydroelectric power stations. These are the most common types of hydroelectric power stations. The pressure of water in them is created by installing a dam that completely blocks the river, or raises the water level in it to the required level. At the same time, some flooding of the river valley is inevitable. Such hydroelectric power plants are built on high-water lowland rivers, as well as on mountain rivers, in places where the riverbed is narrower, compressed.

Dam HPPs. Built with higher water pressure. In this case, the river is completely blocked by the dam, and the building of the hydroelectric power station itself is located behind the dam, in its lower part. Water, in this case, is supplied to the turbines through special pressure tunnels, and not directly, as in run-of-river hydroelectric power plants.

Derivative hydroelectric power plants. Such power plants are built in places where the slope of the river is large. The necessary concentration of water in this type of HPP is created by derivation. Water is diverted from the river bed through special drainage systems. The latter are straightened, and their slope is much smaller than the average slope of the river. As a result, water is supplied directly to the power plant building. Derivative HPPs can be of different types - non-pressure or with pressure derivation. In the case of pressure diversion, the conduit is laid with a large longitudinal slope. In another case, at the beginning of the derivation, a higher dam is created on the river, and a reservoir is created - this scheme is also called mixed derivation, since both methods of creating the necessary water concentration are used.

Hydro storage power plants. Such pumped storage power plants are capable of accumulating the generated electricity and putting it into operation at times of peak loads. The principle of operation of such power plants is as follows: during certain periods (not peak load), pumped storage units operate as pumps from external energy sources and pump water into specially equipped upper pools. When the need arises, water from them enters the pressure pipeline and drives the turbines.

Turbine. Depending on the water pressure, different types of turbines are used in hydroelectric power plants. For high-pressure - bucket and radial-axial turbines with metal spiral chambers. At medium-pressure HPPs, rotary-blade and radial-axial turbines are installed, at low-pressure HPPs - rotary-blade turbines in reinforced concrete chambers. The principle of operation of all types of turbines is similar - water under pressure (water pressure) enters the turbine blades, which begin to rotate. The mechanical energy is thus transferred to the hydroelectric generator, which generates electricity. Turbines differ in some technical characteristics, as well as chambers - steel or reinforced concrete, and are designed for different water pressures.

The power developed by the hydraulic unit is proportional to the pressure H and the water flow Q:

Turbines and generators can be installed directly in the dam or near it. In some cases, a pipeline is used, through which water under pressure is brought below the level of the dam or to the water intake of the hydroelectric power plant.

Dam . A dam is a hydraulic structure that blocks a stream or reservoir to raise the water level. It also serves to concentrate pressure at the location of the structure and create a reservoir.

Dams can differ depending on the design and are divided into gravity, arch, etc. Gravity dams look like stone or concrete barriers. Structures of this type prevent the flow of water with their weight. Arched ones perform their duties due to a special design. The successful functioning of dams depends on three indicators: the resistance of the vertical elements of the structure, the mass and features of the arch structure, which is based on the bank abutments. When constructing a dam, it is necessary to take into account the impact of some external factors. These are the so-called shear forces, the appearance of which is due to the influence of water, wind, wave impacts, and temperature changes. Neglect of builders to the above factors can lead to the destruction of the dam. Therefore, certain calculations are made to prevent the negative action of shear forces.

Waste . The sources of waste generation are the buildings and structures of the HPP, the activities of the station's divisions, as well as related activities aimed at ensuring other economic activities. On the territory of the stations, as a rule, there are also subsidiaries that carry out repair and auxiliary work.

The main wastes (hazard classes 4–5) are waste (sludge) generated during mechanical and biological wastewater treatment, textiles, construction and other waste, miscellaneous waste of paper and cardboard, glass, asphalt concrete or asphalt concrete mixture, reinforced concrete, as well as scrap of building bricks and reinforced concrete products, sawdust and cuttings of wood, garbage from the protective gratings of power plants, etc. The main way to handle waste of these classes is to transfer it to other organizations for recycling.

Waste of the 1st and 2nd hazard classes (mercury lamps, fluorescent mercury-containing tubes that have expired and are replaced with energy-saving ones) are transferred for recycling to specialized organizations.

At first glance, a hydroelectric power plant is a rather simple thing - water flows, a generator spins, electricity is generated. In fact, a modern hydroelectric power station is a system with very complex equipment and thousands of sensors, controlled by computers.

Today I will talk about what few ordinary people know about hydroelectric power stations.

Now I am at the construction site of the Ust-Srednekanskaya HPP, which is located 400 kilometers from Magadan. I will tell you more about the hydroelectric power station and construction, but today I will tell you a few interesting facts.

1. Hydroelectric power station is probably the only major engineering facility that begins to operate long before the completion of construction. At the Ust-Srednekanskaya hydroelectric power station, the dam has not yet been fully erected, the turbine hall has not been fully built, and the first two of the four hydroelectric units are already generating electricity.

2. While the hydroelectric power station is being built, temporary impellers are working in its hydroelectric units, designed for low water pressure. When the dam is completed, the water head will increase and the temporary wheels will be replaced by permanent high-head wheels with a different blade shape.

3. Despite the fact that the construction of hydroelectric power plants is very expensive, many hydroelectric power plants pay off even before they are completed. By the way, the Ust-Srednekanskaya HPP sells electricity at 1.10 rubles per kWh.

4. Before getting to the HPP turbine, the water is swirled with the help of a huge steel snail - a spiral chamber. Now at the Ust-Srednekanskaya HPP, the installation of the spiral chamber of the third power unit is just being completed, and I managed to see and photograph it. When the power unit is completed, the giant snail will be in the thickness of the concrete.

To understand the dimensions of the structure, pay attention to the workers involved in the installation of the volute chamber.

5. The impeller of the hydraulic unit always rotates at the same speed, providing a stable frequency of 50 hertz. It has always been a mystery to me how a stable rotational speed is maintained. It turned out just by changing the flow of water. The computer-controlled paddles are constantly in motion, decreasing and increasing the flow of water. The task of the system is to achieve an accurate rotation speed, regardless of the effort with which the generator shaft is spinning (and it depends on the generated power).

6. The voltage output by the generator is adjusted by changing the excitation voltage. This is a constant voltage that is applied to the rotor electromagnet. In this case, the voltage that is generated by the stator winding depends on the strength of the magnetic field. In the photo, a multi-ton rotor rotates above my head.

7. The hydroelectric generator generates a voltage of 15.75 kV. Generators with a rated power of 142.5 MW (142,500,000 W) are installed at the Ust-Srednekanskaya HPP, and the current in the wires diverting the generated electricity from the generator can reach 6150 A. Therefore, these wires, or rather tires, have a huge cross section and are enclosed in such pipes .

Any switching at such currents turns into a big problem. This is what a simple switch looks like. Of course, at a current of six thousand amperes and a voltage of fifteen thousand volts, it becomes quite difficult.

8. Step-up transformers are usually located on the street behind the machine room of the hydroelectric power station (for transmission to consumers, the voltage received from the generators is most often increased to 220 kV).

9. Not only electricity at a frequency of 50 Hz is transmitted through the wires of power lines, but also information signals at a high frequency. With the help of them, for example, it is possible to determine the location of an accident on a power line with high accuracy. At power plants and substations, special high-frequency signal filters are installed. Surely you have seen such things, but you hardly knew what they were for.

10. All high voltage switching takes place in SF6 (sulfur fluoride, which has a very low electrical conductivity), so the wires look like pipes and the electrics are more like plumbing. :)

p.s. Thanks to the employees of the Ust-Srednekanskaya HPP Ilya Gorbunov and Vyacheslav Sladkevich (he is in the photo) for detailed answers to my many questions, as well as to RusHydro for the opportunity to see with my own eyes the construction and operation of such a grand structure.

2016, Alexey Nadezhin

The main topic of my blog is technology in human life. I write reviews, share experiences, talk about all sorts of interesting things. I also make reports from interesting places and talk about interesting events.
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Small hydro turbines are very specific in principle of their operation, in contrast to the turbines of conventional hydroelectric power plants. The process of operation of a micro hydroturbine is interesting in that the properties of its structure can provide for a specific object the volume of water masses that will flow to parts of the hydroturbine (blades), bring the generator into working condition (the generator plays the role of generating electricity).

The process of increasing the pressure of water is ensured by the formation of a “derivation” - free flow of water (provided that this micro hydroelectric power station is of a diversion type) or a dam (the condition is a mini thermal power plant similar to a dam).

Mini HPP power

The power level of a mini hydroelectric power station directly depends on the conditions in which its hydraulic properties are located:

Water flow is the volume of water masses (l) that passes through the turbine in a certain period of time. It is customary to take 1-2 seconds for this interval.
Water pressure - the distance between two opposite points of the water mass (one is located at the top, the other at the bottom). The head has a number of characteristic features, on which the types of micro hydroelectric power plants also depend (high head, medium head, low head)

The peculiarity of the operation of a micro hydroelectric power station is assessed from the point of view of its territorial location. For example, a pressurized micro hydroelectric power station performs work by diverting water flows through a special channel made of wood, located at a certain angle of inclination, which allows water to flow faster. The water pressure in such a hydroelectric power station depends on how long this channel is. Further, the water flows into the pressure pipeline, after which it enters the hydraulic unit, which is located in the lower part. Then the recycled water is sent back to the source by squeezing.

Location of mini hydroelectric power station

It is important to note that the position of the hydraulic turbine, depending on the type of construction, may be different:

Horizontal position. This position of the hydro turbine leads to a natural increase in the size of the mini hydroelectric power station itself (with the help of a turbine shaft, which also increases the size of the energy system during rotation, as well as a change in the scale of the turbine hall). However, it is worth noting that the construction of such hydraulic turbines is not more complicated than the others, but on the contrary, it simplifies it.
Vertical arrangement. This type of arrangement helps to reduce the size of the HPP, improves the balance of center lines, and its compactness. This arrangement is more difficult to build, since it creates the need for a detailed balance of the axis in the rotational element. Also in such a situation, it is important to be more careful about the mandatory position of the working floor, when it is in one horizontal line and its strength characteristics, so that they are able to withstand the weight of the entire structure. The vertical arrangement increases the pressure on the axis of the structure.

The use of mini hydroelectric power plants

In general, installations of small hydroelectric power plants are used mainly for their use in remote areas of residential facilities. They cannot be serious competitors to large power plants, but rather serve to provide energy savings. Recently, the number of people using both hydroelectric power plants, solar-type batteries and various wind control installations. The turbines described in this article may soon become one with these innovative energy sources, which will eventually lead to the creation of new electrical circuits and models.

What can these structures be used for?

to provide electricity to private property;
for remote industrial areas;
for electric charging stations;
for temporary use.

Advantages of a mini hydroelectric power station

Small hydropower plants have a number of special advantages:

they are available in two versions: fixed at the bottom of the reservoir, as well as with special hooks that allow you to work on the surface
the unit can reach a power equal to 5 kW, in order to increase the power and efficiency of the hydroelectric power plant, the turbines are installed as modules
HPPs do not negatively affect the environment in any way during the construction process, because to create it, natural water is used, which is directed into a certain stream and sets the blades in motion.

Turbines for mini hydroelectric power plants

Now let's talk directly about hydro turbines for mini hydroelectric power stations and what we need for its construction. Characteristics and features of the operation of the hydraulic turbine:

The temperature of the water supplied to the turbine must exceed +4 °C.
The temperature that should be in the block module is +15 °С and higher.
Sound pressure, the source of which is located 1 m from the turbine, is 80 dB or less.
The outer surface of the hydroturbine must be heated to a temperature not exceeding +45°C, provided that the air temperature is around +25°C.

Let's consider an example of a well-balanced and working hydroturbine under ideal conditions.

Let's assume that we have a flow turbine, radial, high-pressure with an average head, which provides a tangential water supply to the blades, the shaft is horizontal. Such types of pipes are classified as "quiet". They have the peculiarity of adapting to the environment, the place of installation and various differences in altitude pressures. If the water flow changes dramatically, then the design of a two-chamber bag is used in the turbine, which makes the operation of the device better.

The body of any hydraulic turbine is made of structural steel, it is durable and reliable. The cost of materials, construction is significantly reduced compared to hydro turbines for conventional hydroelectric power plants. The most common material used to build a hydro turbine will withstand drops of 90 to 120 meters, some parts are made of stainless steel (housing, piping).

In the new generation of hydro turbines, it is possible to replace the generator and the impeller without severe deformation and sorting. It should be noted that the impeller has the property of self-cleaning due to water flows that pass through the area of the impeller in the course of their work. During the design of the generator and the hydro turbine itself, a number of measures are taken to reduce the cavitation level. Current hydro turbines are 100 percent free from this problem.

The main part of the hydraulic turbine is the impeller. The material for the manufacture of blades is often profile type steel. The blades, due to their properties, can create an axial level force, facilitating the work of the bearings, and the impellers themselves are in constant balance. The duration of the operation of the impeller axis is determined by its position; for longer operation, it is installed on the bearing level.

Features of hydro turbines for mini hydroelectric power plants

Can be used in purification systems to obtain high-quality drinking water.
It is possible to connect an industrial generator.
Increased requirements for the reliability of the generator.

Some characteristics of the technical plan:

Height difference: 3 - 200 m
Water consumption: 0.03 - 13 cubic meters per second
Power: 5 - 3,000 kW
Number of blades located on the axial sector: 37
Efficiency: 84% - 87%

Of course, mini HPPs are unlikely to become the main source of energy, but their use is quite reasonable as a means of reducing the load on the main supply grid, especially during periods of peak consumption.

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