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Elements of HYDRO ELECTRIC POWER PLANTS

ELEMENTS

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Elements of HYDRO ELECTRIC POWER PLANTS

  1. 1. ELEMENTS OF Hydraulic POWER PLANTS D. KANAKARAJA ASST. PROFESSOR AITS TIRUPATI
  2. 2. Hydraulic Machines
  3. 3. Initially the water of the river is in Catchments Area. From catchments area the water flows to the dam. At the dam the water gets accumulated . Thus the potential energy of the water increases due to the height of the dam . When the gates of the dam are opened then the water moves with high Kinetic Energy into the penstock. Through the penstock water goes to the turbine house. Since the penstock makes water to flow from high altitude to low altitude, Thus the Kinetic Energy of the water is again raised.
  4. 4. In the turbine house the pressure of the water is controlled by the controlling valves as per the requirements. The controlled pressurized water is fed to the turbine. Due to the pressure of the water the light weight turbine rotates. Due to the high speed rotation of the turbine the shaft connected between the turbine and the generator rotates . Due to the rotation of generator the ac current is produced. This current is supplied to the powerhouse . From powerhouse it is supplied for the commercial purposes.
  5. 5. No fuel charges. Less supervising staff is required. Maintenance & operation charges are very low. Running cost of the plant is low. The plant efficiency does not changes with age. It takes few minutes to run & synchronize the plant. No fuel transportation is required. No ash & flue gas problem & does not pollute the atmosphere. These plants are used for flood control & irrigation purpose. Long life in comparison with the Thermal & Nuclear Power Plant.
  6. 6. The initial cost of the power plant is very high. Takes long time for construction of the dam. Generally, Such plant’s are located in hilly area’s far away from load center & thus they require long transmission lines & losses in them will be more. Power generation by hydro power plant is only dependant on natural phenomenon of rain .Therefore at the time of drought or summer session the Hydro Power Plant will not work.
  7. 7. PURPOSES OF MULTIPURPOSE HYDROPROJECT For irrigation of agricultural land. For navigation. For fisheries and tourism. For flood control. For civil water supply. For generation of electricity.
  8. 8. Components of hydel scheme The principal components are: 1. Forebay 2. Intake structure 3. Penstocks 4. Surge tank 5. Turbines 6. Power house 7. Draft tube 8. Tail race
  9. 9. PRIMARY ELEMENT’S CATCHMENTS AREA RESERVOIR DAM PRIME MOVERS DRAFT TUBES POWER HOUSE & EQUIPMENT SAFETY DEVICE’S SPILL WAY’S SURGE TANK TRASH RACK intake house. water way. Tail race or outlet water way.
  10. 10. BASIC ELEMENTS OF HYDEL POWER PLANT • Reservoir • Dam • Trace rack • For bay • Surge tank • Penstock • Spillway • Turbine • Powerhouse
  11. 11. The whole area behind the clam training into a stream as river across which the dam has been built at suitable place is called catchments area
  12. 12. A reservoir is employed to store water which is further utilized to generate power by running the hydroelectric turbines. In a reservoir the water collected from the catchment area is stored behind a dam. Catchment area gets its water from rain and streams. The level of water surface in the reservoir is called Head water level. Note : Continuous availability of water is a basic necessity for a hydro-electric power plant.
  13. 13. A dam is a barrier which confines or raise water for storage or diversion to create a hydraulic head. Dam’s are generally made of concrete, Stone masory, Rockfill or Timber The purpose of the dam is to store the water and to regulate the out going flow of water. The dam helps to store all the incoming water. It also helps to increase the head of the water. In order to generate a required quantity of power it is necessary that a sufficient head is available.
  14. 14. • Dam are classified based on following factors: a) Function b) Shape c) Construction material d) Design a) Based on function the dam may be called as storage dam, diversion dam or detention dam. b) Based on the shape the dam may of trapezoidal section & arch type. c) The materials used for constructing dams are earth, rock pieces, stone masonry. d) According to structural design the dam maybe classified as: i. Gravity dam ii. Arch dam iii. Buttress dam
  15. 15. Types of Dam: 1. Masonry Dams. 2. Earth Dams. The masonry dams are of three major classes: a) Gravity dam. b) Buttress dam. c) Arched dam. d) Gravity dam: Resist the pressure of water by its weight. Construction of material used for his dam, is solid masonry or concrete.
  16. 16. Types of Dam: 1. Masonry Dams. 2. Earth Dams. The masonry dams are of three major classes: a) Gravity dam. b) Buttress dam. c) Arched dam. d) Gravity dam: Resist the pressure of water by its weight. Construction of material used for his dam, is solid masonry or concrete.
  17. 17. b) Arch dam: It resist the pressure of water partly due to its weight and partly due to arch action. c) Buttress dam: • Buttress supporting a flat slab. • When cost of reinforced concrete is high such type of dam is selected.
  18. 18. Arch Dams • Arch shape gives strength • Less material (cheaper) • Narrow sites • Need strong abutments
  19. 19. Arch Dam Monticello Dam impounds Putah Creek west of Sacramento, California. The solid concrete structure stands 93 m (304 ft) tall. The dam’s arched upstream face transfers some of the pressure from its reservoir, Lake Berryessa, onto the walls of the canyon.
  20. 20. Multiple Arch Dam Bartlett Dam impounds the Verde River northeast of Phoenix, Arizona. Like all multiple arch dams, Bartlett Dam makes use of a series of arches supported by buttresses to withstand the pressure of the water in its reservoir, Bartlett Lake. Each of the dam’s 10 concrete arches has a 7-m (24- ft) radius and measures 2 m (7 ft) at the base and just 0.6 m (2 ft) at the crest. The thick base provides additional strength at the bottom of the reservoir, where the water pressure is most intense.
  21. 21. Concrete Gravity Dams • Weight holds dam in place • Lots of concrete (expensive)
  22. 22. Flat Slab Buttress Dam Lake Tahoe Dam impounds the Truckee River in northern California. Like all flat slab buttress dams, it has a flat slab upstream face supported by a series of buttresses on the downstream side. Lake Tahoe Dam measures 5.5 m (18 ft) tall and 33 m (109 ft) long. It was completed in 1913 to raise the water level in Lake Tahoe, a natural lake, to provide additional water for crop irrigation.
  23. 23. Buttress Dams • Face is held up by a series of supports • Flat or curved face
  24. 24. EARTH/ Embankment Dams • Earth or rock • Weight resists flow of water
  25. 25. Intake structure • Water conveyed from forebay to penstocks through intake structures. • Main components are trash rack and gate. • Trash rack prevent entry of debris.
  26. 26. . 1. Water ways are the passages, through which the water is conveyed to the turbines from the dam. These may include tunnels, canals, flumes, forebays and penstocks and also surge tanks. 2. A forebay is an enlarged passage for drawing the water from the reservoir or the river and giving it to the pipe lines or canals. 5 August 2015 30
  27. 27. 5 August 2015 31 Excess accumulation of water endangers the stability of dam construction. Also in order to avoid the over flow of water out of the dam especially during rainy seasons spillways are provided. This prevents the rise of water level in the dam. Spillways are passages which allows the excess water to flow to a storage area away from the dam.
  28. 28.  A gate is used to regulate or control the flow of water from the dam. • Modern dams use (1) vertical lift gates, (2) traitor (radial) • gates, (3) wheeled gates, (a) roller gates, (b) drum or cylindrical • gates and (c) butterfly valves etc.  It is a passage that carries water from the reservoir to the surge tank. 5 August 2015 32 1. Crest control 2. Crest gates 3. Sluice gates and valves.
  29. 29. Surge tank • additional storage for near to turbine, usually provided in high head plants. • located near the beginning of the penstock. • As the load on the turbine decreases or during load rejection by the turbine the surge tank provides space for holding water.
  30. 30. Surge Shaft • Surge shaft is located at the end of tunnel . • It is a well type structure of suitable height and diameter to absorb the upcoming and lowering surges in case of tripping and starting of the machine in the power house. • The surge shaft is provided with gates to stop flow of water to the penstock if repairs are to be carried out in the penstock or inlet valves.
  31. 31. Surge tank:  A Surge tank is a small reservoir or tank in which the water level rises or falls due to sudden changes in pressure. Purpose of surge tank:  To serve as a supply tank to the turbine when the water in the pipe is accelerated during increased load conditions and as a storage tank when the water is decelerating during reduced load conditions.  To reduce the distance between the free water surface in the dam and the turbine, thereby reducing the water-hammer effect on penstock and also protect the upstream tunnel from high pressure rise. Water-hammer effect : o The water hammer is defined as the change in pressure rapidly above or below normal pressure caused by sudden change in the rate of water flow through the pipe, according to the demand of prime mover i.e. turbine 40
  32. 32. • surge tank over comes the abnormal pressure in the conduit when load on the turbine falls and acts as a reservoir during increase of load on the turbine.
  33. 33. Penstock • Penstocks are the water conductor conduit of suitable size connecting the surge shaft to main inlet valve • It allows water to the turbine through main inlet valve. • At the end of the penstock a drainage valve is provided which drains water from penstock to the draft tube. • In case of long penstock and high head, butterfly valve is provided just before the penstock. • It takes off from the surge shaft in addition to spherical valve at the end of the penstock acting as the main inlet valve.
  34. 34. Penstock thickness: • The thickness of penstock depend on water head and hoop stress allowed in the material. t = 𝑝.𝑑 2𝑓𝜂 Where, t= Penstock thickness d= Dia of penstock 𝑓= Permissible stress p= Pressure due to water including water hammer.
  35. 35. Number of penstock A hydro Power Plant uses a number of turbine which are to be supplied water through penstock. • To use a single penstock for the whole a plant. • To use on penstock for each turbine separately. • To provide multiple penstock but each penstock supplying water to at least two turbine. Factors for Selecting number of penstocks: • Economy. • Operational safety. • Transportation facilities.
  36. 36. Penstock Protection Valve The Penstock protection valves are provided after the surge shaft to facilitate maintenance of the penstocks. The valves are of butterfly type. The BF valve are operated hydraulically with provision of pressure accumulators in case of power failure.
  37. 37. Forebay • Enlarged body of water provided in front of penstock. • Provided in case of run off river plants and storage plants. • Main function to store water which is rejected by plant. • Power house located closed to dam penstock directly take water from reservoir, reservoir act as forebay.
  38. 38. Water Intake Structure • It consists of gated structure at the dam/Barrage to control the flow of water and provided with gates along with hoisting arrangement. • Normally these gates remain open and allows water to flow to the tunnel /channel as the case may be until and unless water conductor system is taken under shut down for repair and maintenance.
  39. 39. Pressure Shaft • When the water conduits in the Surge shaft and Main Inlet valve are not exposed to the atmosphere and buried in the ground/concrete due to its high pressure, these are called Pressure shaft.
  40. 40. Main Inlet Valve • Main inlet valve works as the gate valve/isolating valve in the water conductor system. • It is located before turbine and allows water flow from penstock to turbine. • MIV acts as closing valve and cuts the flow of water during an emergency trip. • They are of following type. • Butterfly valve (upto 200 m head) • Spherical valve (more than200m head)
  41. 41. BUTTERFLY VALVE
  42. 42. BUTTERFLY VALVE
  43. 43. SPHERICAL VALVE
  44. 44. Turbines • turbines are used to convert the energy water of falling water into mechanical energy. • water turbine is a rotary engine that takes energy from moving water. • flowing water is directed on to the blades of a turbine runner, creating a force on the blades.
  45. 45. • Since the runner is spinning, the force acts through a distance n this way, energy is transferred from the water flow to the turbine. • The principal types of turbines are: 1) Impulse turbine 2) Reaction Turbine
  46. 46. Kaplan Francis
  47. 47. Draft tube • is a pipe or passage of gradually increasing cross sectional area, which connect to the exit to tail race. • it reduces high velocity of water discharged by the turbine. • draft tube permits turbines to be installed at a higher level than the tail race level, which help the maintaince and repair of turbines.
  48. 48. Draft Tube • Draft tube is located between lower ring of turbine and tail race . It conveys water after discharge from runner to tail race tunnel. • Draft tube (DT) gates are provided for isolating the Power house and tail pool before taking maintenance of the turbine. • The DT gates are provided with hoisting mechanism. • The DT gate may be a single piece or a combination of more than one piece
  49. 49. Draft Tube: Reaction turbines must be completely enclosed because a pressure difference exists between the working fluid (water) in the turbine and atmosphere. Therefore, it is necessary to connect the turbine outlet by means of a pipe known as draft tube upto tailrace level. Types of Draft Tubes (1) Conical Draft Tube. This is known as tapered draft tube and used in all reaction turbines where conditions permit. It is preferred for low specific speed and vertical shaft Francis turbine. The maximum cone angle of this draft tube is limited to 8° (a = 4°). The hydraulic efficiency of such type of draft tube is 90%.
  50. 50. 2- Elbow Type Draft Tube. The elbow type draft tube is often preferred in most of the power plants, where the setting of vertical draft tube does not permit enough room without excessive cost of excavation. 3- Moody Draft Tube. This draft tube has an advantage that its conical portion at the center reduces the whirl action of water moving with high velocity centre reduces.
  51. 51. Spill Way’s is a kind of canal provided besides the dam. Spill Way’s is used to arrange the excess of accumulation of water on the dam because excess accumulation of water may damage the dam structure 1. Over flow spillway 2. Chute or trough spillway 3. Side channel spillway 4. Shaft spillway 5. Siphon spillway'.
  52. 52. The amount of electricity that can be generated by a hydropower plant depends on two factors: • flow rate - the quantity of water flowing in a given time; and • head - the height from which the water falls. The greater the flow and head, the more electricity produced. Flow Rate = the quantity of water flowing Head = the height from which water falls Power generation
  53. 53. Power House. The power house is a building in which the turbines, alternators and the auxiliary plant are housed. Some important items of equipment provided in the power house are as follows: i. Turbines ii. Generators iii. Governors iv. Relief valve for penstock setting v. Gate valve vi. Transformer vii. Switch board equipment and instruments viii. Oil circuit breaker ix. Storage batteries x. Outgoing connections xi. Cranes xii. Shops & offices
  54. 54. The surface power house has been broadly divided into three subdivisions which is separated from the intake as mentioned below : (a) Substructure ; (b) Intermediate structure ; (c) Super-structure.
  55. 55. Tail water level or Tail race: o Tail water level is the water level after the discharge from the turbine. The discharged water is sent to the river, thus the level of the river is the tail water level. Electric generator, Step-up transformer and Pylon :  As the water rushes through the turbine, it spins the turbine shaft, which is coupled to the electric generator. The generator has a rotating electromagnet called a rotor and a stationary part called a stator. The rotor creates a magnetic field that produces an electric charge in the stator. The charge is transmitted as electricity. The step-up transformer increases the voltage of the current coming from the stator. The electricity is distributed through power lines also called as pylon.
  56. 56. GENERATOR • Hydro generator is coupled to the turbine and converts the mechanical energy transmitted by the turbine to electrical energy • Generators can be of: • Suspended type • Umbrella type • Main Generator components include: • Stator • Rotor • Upper Bracket • Lower Bracket • Thrust Bearing & Guide Bearings • Slip Ring & Brush Assembly • Air Coolers • Brakes & Jacks • Stator Heaters
  57. 57. GOVERNOR • Used for controlling the guide vanes by detecting turbine speed & its guide vane opening in order to keep turbine speed stable or to regulate its output. • The performance of the governor dominates the controllability of the power plant and quality of electrical power produced .
  58. 58. AUXILIARIES ATTACHED WITH HYDEL POWER PLANT. (A)Electrical instruments • Generator • Exciter,transformers • Switch gears • Other instruments of control room (B)Mechanical instruments • Shaft coupling,journal bearings,thrust bearings • Lubricating oil system • Cooling system • Brake system for generator-turbine shaft
  59. 59. Because water delivery is the first priority, electricity produced at Arizona Falls is used mainly to supplement high electricity demands in the summer.
  60. 60. Hydropower is an important renewable energy source world wide...
  61. 61. we can experience new, renewable technologies with the power of water! Even here in our desert home,
  62. 62. Advantages of hydropower It is a clean and safe source of energy They are self sustaining They create habitat for more types of fish They can act as a flood controller They are the most efficient energy source running from 90-95% efficiency Other forms of Hydropower Tidal power: electricity generated by turbines moved by the tides. This is still in experimental stages. Ocean thermal power: power generated by the thermal expansion of the ocean. This can only be used in a location like the Gulf stream. Geothermal power: natural steam is used underground to turn turbines. This is limited to location which have these phenomenon. Advantages of hydropower It is a clean and safe source of energy They are self sustaining They create habitat for more types of fish They can act as a flood controller They are the most efficient energy source running from 90-95% efficiency
  63. 63. 1 Itaipu Brazil/ Paraguay 12,600 1984 2 Guri Venezuela 10,300 1968 3 Grand Coulee United States 6,480 1942 4 Sayano- Shushensk Russia 6,400 1980 5 Krasnoyarsk Russia 6,000 1968 6 La Grande 2 Canada 5,328 1982 7 Churchill Falls Canada 5,225 1971 8 Bratsk Russia 4,500 1964 9 Ust-Ilim Russia 4,500 1974 10 Tucurui Brazil 4,245 1984 Rank Name of Dam Location Rated Capacity (Megawatts) Year of Completed World’s Largest Dams By Power Generating Capacity
  64. 64. 1 Owen Falls Uganda 204,800 1954 2 Kariba Zimbabwe /Zambia 180,600 1959 3 Bratsk Russia 169,270 1964 4 Aswan High Egypt 168,900 1970 5 Akosombo Ghana 148,000 1965 6 Daniel Johnson Canada 141,852 1968 7 Guri (RaulLeoni) Venezuela 136,000 1986 8 Krasnoyarsk Russia 73,300 1967 9 W.A.C. Bennett Canada 70,309 1967 10 Zeya Russia 68,400 1978 Rank Name of Dam Country Storage Capacity Cubic Meters Year of Completed World’s Largest Dams By Storage Capacity
  65. 65. 1 Rogun Tajikistan 335 1989 2 Nurek Tajikistan 300 1980 3 Grand Dixence Switzerland 285 1961 4 Inguri Georgia 272 1980 5 Boruca Costa Rica 267 1990 6 Vaiont Italy 262 1961 7 Chicoasen Mexico 261 1980 8 Manuel M. Torres Mexico 261 1981 9 Alvaro Obregon Mexico 260 1946 10 Mauvoisin Switzerland 250 1957 Rank Name of Dam Country Height (m) Year of Completed World’s Largest Dams By Height

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