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1
Dr. S. VIJAYA BHASKAR
Professor in Mechanical
EngineeringSreenidhi Inst. of Science & Tech.,
Hydereabad
HYDRO ELECTRIC POWER PLANT:
Water power
Hydrological cycle / flow measurement
Drainage area characteristics
Hydrographs
St...
The energy of water utilized for generation of
power using KE and PE of water by motion
and position respectively
3
• Hydro power is considered as one of the most
economic and non polluting sources of
energy.
• Power generated from water ...
5
 Potential Energy is the stored energy in an object or
system because of its position or configuration.
 Kinetic energ...
6
 If water source is in abundance then the water power
is very cheap.
 Though initial investment is high the operating co...
8
How it Works
• On September 30, 1882, the world's first
hydroelectric power plant began operation on
the Fox River in Appleton, Wiscons...
10
11
12
• The study of water, including rain, snow,
water on earth’s surface, covering its
properties, distribution and utilizatio...
14
15
Before the Construction
of the Dam
After construction of
the Dam 

16
17
18
1) Precipitation: it is same as condensation i.e. converting
natural water vapour into water.
• Basically precipitation is...
• It is a cyclic movement
of water from the sea
to the atmosphere of
evaporation and then
back to the earth
surface (sea, ...
• The quantity of water flowing in a river would be
varying and may not be constant for a period of
time.
• Therefore the ...
23
24
• A hydrograph is a discharge vs. time curve of the water flow.
• It shows the variation of river flow with time.
• It may...
• Hydrograph gives
discharge available at
different time ( day, week,
month or year ).
• Maximum and minimum
runoff can al...
• In drainage area characteristics generally used to study the
hydro-graphs: flow duration curve, mass curve for estimatio...
STEADY FLOW RIVERS
• If the variation of discharge is less for a considerable time
such streams are termed as steady strea...
29
• Hydrologic data generally consist of a sequence of observations of
some phase of the hydrologic cycle made at a parti...
30
 Flow duration curve is a plot of discharge versus percentage of time
for which the discharge is available. It is obta...
• It is a plot of cumulative volume of water that can be stored
from a stream flow versus time in days, weeks or months.
•...
Storage:
• The collection of water in a reservoir upstream of the plant
and increasing the capacity of stream for a long p...
Pondage:
• For a short period of time the pondage increases the stream
capacity behind a dam near the plant.
• Pond permit...
The following factors should be given careful consideration
while selecting a site for a hydro-electric power plant:
1. Wa...
 2. Water-Storage:
• The output of a hydropower plant is not uniform due to wide
variations of rain fall. To have a unifo...
36
Before the Construction
of the Dam
After construction of
the Dam 

 5. Access to Site :
• It is always a desirable factor to have a good access to the
site of the plant.
• This factor is v...
38
• Hydroelectric power plants use the potential energy of water
stored in a reservoir to operate turbines. The turbines ...
39
The essential features of a water
power plant are as below:
1. Catchment area.
2. Reservoir.
3. Dam.
4. Inlet water way...
40
F Flow Sheet of Hydro Electric Power Plant
Catchment AreaReservoir
Dam
Sluice Gate or Valve
Penstock
3-Phase output
Inl...
41
1. Catchment Area:
• The catchment area of a hydro plant is the whole area behind the
dam, draining into a stream or ri...
42
2. Reservoir:
• Whole of the water available from the catchment area is collected
in a reservoir behind the dam.
• The ...
4. Spill Ways:
• When the water enters the reservoir basin the level of
water rises.
• To relieve of this excess water a s...
5. Conduits:
• A headrace is a channel which leads water to a turbine and
a tailrace is a channel which conducts water fro...
 7. Prime Movers:
• The prime mover converts the energy of water into
mechanical energy and further into electrical energ...
46
• 1) masonry dams
• 2) fill dams.
Masonry Dams FILL DAMS
i. Gravity dams
ii. Buttress dams
iii. Arch dams
i) EARTH FILL...
• Dam is a concrete or stone masonry barrier to raise water for
storage and also hydraulic head.
• The Dam must fulfil two...
1) solid gravity dam
• This dam is constructed using masonry concrete.
• It is bulky and massive than other types.
• Sound...
 2) Arch dams:
• Arch dams are curved in plane.
• Structure is curved upstream.
• This type of dams are more economical a...
50
 3) Buttress Dam:
• They are also known as hollow gravity dams inclined
upstream face so that the pressure of water creat...
52
 1) EARTH FILL DAMS:
• It is generally used for small capacity power plants.
 ADVANTAGES:
• Cheaper than masonry dams.
•...
 DIS ADVANTAGES:
◦ 1) requires more maintenance.
◦ 2) supplementary spill way is required.
◦ 3) fails suddenly with out a...
 2) Rock Fill dam:
• These dams are eventually constructed in mountaneous
regions where rock is rather than earth is avai...
• The part of the dam which discharges the flood flow to the
down stream side is called as spillway.
• Spillways act as a ...
57
OVERALL SPILLWAYS
• This is the simplest , low in cost and suitable for concrete dams.
• When dam reaches full reservoi...
 Chute Spillway:
– This spillway is a channel made of reinforced concrete
slap.
– The water is discharged into steep slop...
 Side channel spillway:
– These are employed at narrow gorges or canyons.
– When scope for overflow on chute spillways is...
60
Spillways .
• Way for juvenile
fish to bypass
down
• Decreases O2
levels in water
• Increase CO2
levels in water
• A simple surge tank is a vertical stand pipe connected to the
penstock.
• Surge tanks are built high so that water can n...
• When a surge tank is
inclined to the horizontal its
effective water surface
increases and therefore ,
lesser height surg...
• This type of surge tank has
an expansion tank at the
top and expansion gallery
at the bottom, these
expansions limit the...
• The main function of this
surge tank is to create an
appreciable friction loss when
the water is flowing to or from
the ...
• A differential surge tank
has a riser with a small
hole at its lower end
through which water
enters in it.
• The functio...
• This is known as tapered draft
tube and used in all reaction
turbines where conditions
permit. It is preferred for low
s...
• The elbow type draft tube is often preferred in most of the
power plants, where the setting of vertical draft tube does ...
68
Hydro electric plants are classified according
1)Based on available head
 a) High head plants
 b) Medium head plants
 c...
• The water from the reservoir can be taken to a smaller
storage known as a forebay, by mans of tunnels.
• From the foreba...
• The turbines will thus be fed with under a constant static
head.
• Thus, the forebays help to regulate the demand for wa...
• It is used If the head of water available is more than 50 m.,
then the water from the forebay is conveyed to the
turbine...
• A dam is built on the river and the water is diverted into a canal
which conveys the water into a forebay from where the...
• Plants supplying base load which is generally
constant and runs without stop are known as
base load plants.
• These are ...
• These plants supply power at the peak load
time.
• When load is more than the average load.
• Run off river plants with ...
• Pondage refers to the collection of water
behind the dam and increases the steam
capacity for short periods.
• This plan...
• These plants would have reservoirs of large
size to facilitate the storage of water and
thus it is independent of season...
78
• Like peaking, pumped storage is a method of keeping water in
reserve for peak period power demands.
• Pumped storage ...
• The reservoir acts much like a battery, storing power in the
form of water when demands are low and producing
maximum po...
80
Types of Micro-Hydroelectric
Systems
There are many
different types of Micro-
Hydroelectric systems
Here are 3 Micro-...
81
How Micro-Hydro Systems Work
• Micro-Hydroelectric systems take water
from a stream and channel it into a pipeline
that...
Unit_IV-HYDRO ELECTRIC POWER PLANTS
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Unit_IV-HYDRO ELECTRIC POWER PLANTS

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Unit_IV-HYDRO ELECTRIC POWER PLANTS

  1. 1. 1 Dr. S. VIJAYA BHASKAR Professor in Mechanical EngineeringSreenidhi Inst. of Science & Tech., Hydereabad
  2. 2. HYDRO ELECTRIC POWER PLANT: Water power Hydrological cycle / flow measurement Drainage area characteristics Hydrographs Storage and Pondage Classification of dams and spill ways. HYDRO PROJECTS AND PLANT: Classification – Typical layouts – plant auxiliaries – plant operation pumped storage plants. 2
  3. 3. The energy of water utilized for generation of power using KE and PE of water by motion and position respectively 3
  4. 4. • Hydro power is considered as one of the most economic and non polluting sources of energy. • Power generated from water is termed as Hydroelectricity. • Hydro electricity means electricity generated by hydropower or from the use of the gravitational force of falling or flowing water. 4
  5. 5. 5  Potential Energy is the stored energy in an object or system because of its position or configuration.  Kinetic energy of an object is relative to other moving and stationary objects in its immediate environment.
  6. 6. 6
  7. 7.  If water source is in abundance then the water power is very cheap.  Though initial investment is high the operating costs are quite low when compared to other power plants. 7
  8. 8. 8 How it Works
  9. 9. • On September 30, 1882, the world's first hydroelectric power plant began operation on the Fox River in Appleton, Wisconsin, USA 9
  10. 10. 10
  11. 11. 11
  12. 12. 12
  13. 13. • The study of water, including rain, snow, water on earth’s surface, covering its properties, distribution and utilization is called hydrology. • The science which deals with rainfall and run-off is also called hydrology. • The evaporation of water from the surface of river and oceans and its precipitation on the earth is known as the hydrological cycle. 13
  14. 14. 14
  15. 15. 15 Before the Construction of the Dam After construction of the Dam  
  16. 16. 16
  17. 17. 17
  18. 18. 18
  19. 19. 1) Precipitation: it is same as condensation i.e. converting natural water vapour into water. • Basically precipitation is of two types a) liquid precipitation (rainfall). b) solid precipitation (snow). 2) Run-off: it is the portion of precipitation which reaches the streams again . • Run off occurs only if the rate of precipitation exceeds the rate of which water infiltrates into the soil. 3) Evaporation: • it takes place from the surface of oceans, rivers, lakes etc. • The stored water is used for irrigation, water supply, energy production etc. 20 Hydrology Terminology
  20. 20. • It is a cyclic movement of water from the sea to the atmosphere of evaporation and then back to the earth surface (sea, ocean) by precipitation. • The hydrological equation is Precipitation= run off + evaporation. 21
  21. 21. • The quantity of water flowing in a river would be varying and may not be constant for a period of time. • Therefore the flow measurement is very important. • Using a channel of fixed cross section and measuring the water velocity using current meters at maximum points of the cross section at different water levels at regular intervals the flow volume may be measured. • And by integrating the velocities over the cross section total flow can be calculated. • A curve can be plotted between gauge height and discharge. 22
  22. 22. 23
  23. 23. 24
  24. 24. • A hydrograph is a discharge vs. time curve of the water flow. • It shows the variation of river flow with time. • It may be plotted based on data, of weeks, months and even years. • Discharge on y-axis and time on x-axis. 25
  25. 25. • Hydrograph gives discharge available at different time ( day, week, month or year ). • Maximum and minimum runoff can also be studied. • It gives mean run off. • It helps in studying the effects of storage on flow. 26 • The area under the hydrograph gives total volume of water for given durations.
  26. 26. • In drainage area characteristics generally used to study the hydro-graphs: flow duration curve, mass curve for estimation of storage capacity of a reservoir. • There are three types of streams based on nature of flow. 1) steady flow rivers. 2) flashy flow rivers. 3) Perennial flow. 27
  27. 27. STEADY FLOW RIVERS • If the variation of discharge is less for a considerable time such streams are termed as steady streams. FLASHY FLOW • In certain areas where soil surfaces are impervious (solid), irregular distribution and slope. PERENNIAL STREAMS • The streams in the geographical areas of monsoon lands generally river flow levels are low in summer and high during monsoon time. Such streams are called as perennial stream. 28
  28. 28. 29 • Hydrologic data generally consist of a sequence of observations of some phase of the hydrologic cycle made at a particular site. • The data may be a record of the discharge of a stream at a particular place, or it may be a record of the amount of rainfall caught in a particular rain gauge. Phases of Hydrologic Cycle • Although for most hydrologic purposes a long record is preferred to a short one, the user should recognize that the longer the record the greater the chance that there has been a change in the physical conditions of the basin.
  29. 29. 30  Flow duration curve is a plot of discharge versus percentage of time for which the discharge is available. It is obtained from hydrograph data.  The flow or discharge can be expressed as cubic meters per second, per week or other unit of time.  This flow duration curve is also known as power duration curve. Flow Duration Curve
  30. 30. • It is a plot of cumulative volume of water that can be stored from a stream flow versus time in days, weeks or months. • It shows a mass curve, Maximum intercept between line AB and mass curve is known as reservoir capacity • Slope of the mass curve at a point gives the rate of inflow at that instant. 31
  31. 31. Storage: • The collection of water in a reservoir upstream of the plant and increasing the capacity of stream for a long period of time a called storage. • Storage plants work as base load stations. • Base load plants are of high capacity and takes the load on the base portion of the load curved. • Peak load plants are designed for taking care of peak loads. 32
  32. 32. Pondage: • For a short period of time the pondage increases the stream capacity behind a dam near the plant. • Pond permits to store water during off peak hours and this could be used during peak hours of the same day. • If there is a considerable distance between plant and the reservoir, pond is needed at the plant to regulate the flow. 33
  33. 33. The following factors should be given careful consideration while selecting a site for a hydro-electric power plant: 1. Water Available: • The estimates of the average quantity of water available should be prepared on the basis of actual measurements of stream or river flow. • The river flow data should be based on daily, weekly, monthly and yearly flow ever a number of years. • The plant capacity and the estimated output as well as the need for storage will be governed by the average flow. • The primary or dependable power which is available at all times when energy is needed will depend upon the minimum flow. • The maximum of flood flow governs the size of the headwords and dam to be built with adequate spillway. 34
  34. 34.  2. Water-Storage: • The output of a hydropower plant is not uniform due to wide variations of rain fall. To have a uniform power output, a water storage is needed so that excess flow at certain times may be stored to make it available at the times of low flow. • To select the site of the dam ; careful study should be made of the geology and topography of the catchment area to see if the natural foundations could be found and put to the best use.  3. Head of Water: • The level of water in the reservoir for a proposed plant should always be within limits throughout the year.  4. Distance from Load Center: • Most of the time the electric power generated in a hydro- electric power plant has to be used some considerable distance from the site of plant. • To be economical on transmission of electric power, the routes and the distances should be carefully considered since the cost of erection of transmission lines and their maintenance will depend upon the route selected. 35
  35. 35. 36 Before the Construction of the Dam After construction of the Dam  
  36. 36.  5. Access to Site : • It is always a desirable factor to have a good access to the site of the plant. • This factor is very important if the electric power generated is to be utilized at or near the plant site. • The transport facilities must also be given due consideration.  6. Type of the Land of Site: • The land to be selected should be cheap and rocky. • The land should have largest catchment area to store water at high head and will be economical in construction. • The rock should be strong to withstand the stresses transmitted from the dam structure as well as the thrust of the water when the reservoir is full. • The rock should remain stable in all conditions. 37
  37. 37. 38 • Hydroelectric power plants use the potential energy of water stored in a reservoir to operate turbines. The turbines are connected to large generators, and can operate on varying volumes of water to adapt to changing demand for electricity. • Hydroelectric power plant capacity is related to the height and capacity of a reservoir and require certain conditions in local geography in addition to a water source. • Hydro is a renewable energy source and more cost-effective than many other renewable sources of energy such as photovoltaic. • Hydropower currently provides about 25% of the world’s electricity and is very flexible in scale. Commercial installations range from 1 MW up to the largest installation to date of 18,400 Megawatts (China). HYDRO-ELECTRIC POWER PLANT
  38. 38. 39 The essential features of a water power plant are as below: 1. Catchment area. 2. Reservoir. 3. Dam. 4. Inlet water way or spillways 5. Conduits 6. Surge Tank 7. Prime Movers 8. Tail race or outlet water way 9. Power house. 1. Catchment Area: • The catchment area of a hydro plant is the whole area behind the dam, draining into a stream or river across which the dam has been built at a suitable place. ESSENTIAL FEATURES OF A WATER-POWER PLANT
  39. 39. 40 F Flow Sheet of Hydro Electric Power Plant Catchment AreaReservoir Dam Sluice Gate or Valve Penstock 3-Phase output Inlet valve Turbine Draft Tube Alternator Tail Race
  40. 40. 41 1. Catchment Area: • The catchment area of a hydro plant is the whole area behind the dam, draining into a stream or river across which the dam has been built at a suitable place. ESSENTIAL FEATURES OF A WATER-POWER PLANT
  41. 41. 42 2. Reservoir: • Whole of the water available from the catchment area is collected in a reservoir behind the dam. • The purpose of the storing of water in the reservoir is to get a uniform power output throughout the year. • A reservoir can be either natural or artificial. • A natural reservoir is a lake in high mountains and an artificial reservoir is made by constructing a dam across the river. 3. Dam: • A dam is built across a river for two functions: to impound the river water for storage and to create the head of water. • Dams may be classified according to their structural materials such as: Timber, steel, earth, rock filled and masonry. Timber and steel are used for dams of height 6 m to 12 m only. Earth dams are built for larger heights, up to about 100 m.
  42. 42. 4. Spill Ways: • When the water enters the reservoir basin the level of water rises. • To relieve of this excess water a structure is provided in the body of dam or near the dam or on the periphery of the dam. • The safeguarding structure is called spill ways. 43
  43. 43. 5. Conduits: • A headrace is a channel which leads water to a turbine and a tailrace is a channel which conducts water from the wheels. • The conduits may be open or close • Open conduit ---- Canals and flumes • Closed conduit --- Tunnels, pipelines 6. Surge Tanks: • It is a small reservoir or tank in which the water level rises or falls to reduce the pressure swings so that they are not transmitted in full to a closed circuit. 44
  44. 44.  7. Prime Movers: • The prime mover converts the energy of water into mechanical energy and further into electrical energy. • They are classified into impulse and reaction turbines.  8. Draft Tubes: • The draft tube serves two purposes. • It allows the turbine to be set above tail water level, without loss of head. • It regains, by diffuser action, the majority of KE delivered to it from the runner.  9. Power House: • The power house is a building in which • the turbines, alternators and the • auxiliary plant are housed. 45
  45. 45. 46 • 1) masonry dams • 2) fill dams. Masonry Dams FILL DAMS i. Gravity dams ii. Buttress dams iii. Arch dams i) EARTH FILL DAM ii) ROCK FILL DAM
  46. 46. • Dam is a concrete or stone masonry barrier to raise water for storage and also hydraulic head. • The Dam must fulfil two fundamental functions. ◦ 1) it develops a reservoir which has a capacity to store water. ◦ 2) It builds up head and thus potential for the river i.e. water head.  Different types of dams:  1) Masonry dams ◦ 2) Fill dams. ◦ 3) Timer dams Masonry dams are classified into three categories. a) Gravity dams b) Buttress dams c) Arch dams Fill dams are classified into two categories. a) Earth Dams b) Rock fill dams 47
  47. 47. 1) solid gravity dam • This dam is constructed using masonry concrete. • It is bulky and massive than other types. • Sound rock foundation is required. • The height of the dam is limited by the strength of the base. • The design is simple but it consume heavy materials. • This type of dams are more economical at small river valleys. • These dams provides safe and economical spillway facilities. 48
  48. 48.  2) Arch dams: • Arch dams are curved in plane. • Structure is curved upstream. • This type of dams are more economical and stronger than gravity dams. • This type of dams are only suitable for narrow valleys with steep slopes of solid rock to support the outward thrust of the structure. • The water thrust is compression. 49
  49. 49. 50
  50. 50.  3) Buttress Dam: • They are also known as hollow gravity dams inclined upstream face so that the pressure of water create large downward force which provides stability of sliding and overturning. • The force is transmitted to a row of buttress. • They are also safe against earthquakes. • Hence countries like Japan and Italy are going for these dams. • It requires 1/3 rd of material required for solid gravity dam. • These dams are generally triangular in shape. 51
  51. 51. 52
  52. 52.  1) EARTH FILL DAMS: • It is generally used for small capacity power plants.  ADVANTAGES: • Cheaper than masonry dams. • Can be built at any locations. • Suitable for relatively pervious foundation. • Gets stronger with age. • Can be erected quickly. 53
  53. 53.  DIS ADVANTAGES: ◦ 1) requires more maintenance. ◦ 2) supplementary spill way is required. ◦ 3) fails suddenly with out any warning. ◦ 4) it is subjected to erosion and flood damage. ◦ 5) limited in height. 54
  54. 54.  2) Rock Fill dam: • These dams are eventually constructed in mountaneous regions where rock is rather than earth is available. • Rock fill dam consists of ◦ a) lose rock fill. ◦ b) an upstream dry rubble cushion of laid up stone bonding into the dumped rock. ◦ c) an upstream impervious membrane on dry rubble cushion. 55
  55. 55. • The part of the dam which discharges the flood flow to the down stream side is called as spillway. • Spillways act as a safety valve for a dam. • They are provided on dams to avoid damage to dams. • They keep the reservoir level below the predetermined maximum level. • The down stream must always be provided a safe passage. 56 Types of spill ways 1) overflow spillways. 2) chute spillways. 3) shaft spillways. 4) side channel spillways. 5) siphon spillways.
  56. 56. 57 OVERALL SPILLWAYS • This is the simplest , low in cost and suitable for concrete dams. • When dam reaches full reservoir level stream overflows from the top. • There may be gate control at the top of the dam • Counter weight is provided to lift the gate. • This is widely used on gravity arch and buttress dams.
  57. 57.  Chute Spillway: – This spillway is a channel made of reinforced concrete slap. – The water is discharged into steep sloped open channel called chute. – This type of spillways are adopted to earth or rock fill dams. – This is simple in design and suitable for all foundations.  Shaft Spillways: – In this spillways water drops through vertical shaft and passes though a conduit horizontally and sends the water down stream. – When there is very limited space for spillways this type is adopted – Main draw back is the hazard of clogging with debris. – So we need to prevent debris from entering into shaft spillway. 58
  58. 58.  Side channel spillway: – These are employed at narrow gorges or canyons. – When scope for overflow on chute spillways is very less this type is employed.  Siphon spillway: – The stream is discharged by siphonic action. – When all the air is removed in siphon the space gets filled with water, siphon action starts and water starts flowing over the crest. – This will continue until the reservoir level becomes down below the inlet or mouth level. 59
  59. 59. 60 Spillways . • Way for juvenile fish to bypass down • Decreases O2 levels in water • Increase CO2 levels in water
  60. 60. • A simple surge tank is a vertical stand pipe connected to the penstock. • Surge tanks are built high so that water can not overflow even with a full load change on the turbine. • The surge tank always placed on ground surface, above penstock line, at the point where the latter drops rapidly to the power house. • The height of the tank should be increased with the help of support. 61
  61. 61. • When a surge tank is inclined to the horizontal its effective water surface increases and therefore , lesser height surge tank is required of the same diameter if it is inclined or lesser diameter tank is required for the same height. • This type of surge tank is more costlier than ordinary type as construction is difficult and is rarely used unless the topographical condition are in favour. 62
  62. 62. • This type of surge tank has an expansion tank at the top and expansion gallery at the bottom, these expansions limit the extreme surges. • The upper expansion chamber must be above the maximum reservoir level and the bottom gallery must be below the lowest steady running level in the surge tank. • Besides this the intermediate shaft should have a stable minimum diameter. 63
  63. 63. • The main function of this surge tank is to create an appreciable friction loss when the water is flowing to or from the tank thorough this restricted orifice or throttle area. • When the load on the turbine is reduced the surplus water passes through the throttle and retarded head equal to the loss due to throttle is built up in the conduit. • The size of the throttle adopted is usually such as the initial retarding head is equal to the rise of water surface in the tank when the full load is rejected by the turbine. • This type is rarely used. 64 Advantage is storage function of the tank can be separated from accelerating and retarding functions. Disadvantage is water hammer pressure is transmitted directly into the low pressure conduit.
  64. 64. • A differential surge tank has a riser with a small hole at its lower end through which water enters in it. • The function of the surge tank depends upon the area of hole. 65
  65. 65. • This is known as tapered draft tube and used in all reaction turbines where conditions permit. It is preferred for low specific speed and large high head units, vertical shaft Francis turbine. • The maximum cone angle of this draft tube is limited to 8° (a = 4°) for the cause mentioned earlier. • The hydraulic efficiency of such type of draft tube is 90%. • In any event, the draft tube should be made as to secure a gradual reduction of velocity (uniform decease towards the exit of draft tube) from the runner to the mouth. • A form that is theoretically good is “Trumpet Shaped”. 66
  66. 66. • 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. • This offers an advantage in the cost of excavation ; specially in the rock. • If the tube is large in diameter ; it may be necessary to make the horizontal portion of some other section than circular in order that the vertical dimension may not be too great. • A common form of section used is oval or rectangle. 67
  67. 67. 68
  68. 68. Hydro electric plants are classified according 1)Based on available head  a) High head plants  b) Medium head plants  c) Low head plants 2) Based on nature of load  a) Base load plants  b) Peak load plants 3) Based on quantity of water available  a) Run-off river plants (with and without pond age).  b) Storage plants.  c) Pumped storage plants.  d) Mini and Micro hydel plants 69
  69. 69. • The water from the reservoir can be taken to a smaller storage known as a forebay, by mans of tunnels. • From the forebay, the water is then distributed to the penstocks. • The function of the forebay is to distribute the water to penstocks leading to turbines. • The inflow to the forebay is so regulated that the level in the forebay remains nearly constant. 70
  70. 70. • The turbines will thus be fed with under a constant static head. • Thus, the forebays help to regulate the demand for water according to the load on the turbines. • In the valve house, the butterfly valves or the sluice type valves control the water flow in the penstocks and these valves are electrically driven. • Gate valves are also there in the power house to control the water flow through the turbines. after flowing through tile turbines . The water is discharged to the tail race. 71
  71. 71. • It is used If the head of water available is more than 50 m., then the water from the forebay is conveyed to the turbines through pen-stocks. • In these plants, the river water is usually tapped off to a forebay on one bank of the river as in the case of a low head plant. • From the forebay, the water is then led to the turbines through penstocks. 72
  72. 72. • A dam is built on the river and the water is diverted into a canal which conveys the water into a forebay from where the water is allowed to flow through turbines. • After this, the water is again discharged into the river through a tail race. At the mouth of the canal, head gates are fitted to control the flow in the canal. Before the water enters the turbines from the forebay. • It is made to flow through screens or trash-racks so that no suspended matter goes into the turbines. If there is any excess water due to increased flow in the river or due to decrease of load on the plant, it will flow over the top of the dam or a waste weir can be constructed along the forebay so that the excess water flows over it into the river. • For periodic cleaning and repair of the canal and the forebay, a drain gate is provide on the side of the waste weir. The head gate is closed and the drain gate is opened so that whole of the water is drawn from the forebay and the canal for their cleaning and repair. 73
  73. 73. • Plants supplying base load which is generally constant and runs without stop are known as base load plants. • These are of greater capacity. • The run off river and storage type power plants are used as base load plants. 74
  74. 74. • These plants supply power at the peak load time. • When load is more than the average load. • Run off river plants with pond age and pumped storage plants are used as peak load plants. • They store water during off peak time and supply for peak hours. • The load factor is low compared to base load plants. 75
  75. 75. • Pondage refers to the collection of water behind the dam and increases the steam capacity for short periods. • This plant has a flexibility to meet the hourly demand. • Hence the discharge is more than the normal, may be 3 to 8 times more. • Pondage increases the stream capacity for short time periods. • These plants can meet peak load demand and also used as base load plants. 76
  76. 76. • These plants would have reservoirs of large size to facilitate the storage of water and thus it is independent of seasonal streams. • The stream flows are considerably higher than natural flow. • There fore this plant can be used as base load as well as peak load alternative. • The majority of the hydro plants in world are this type. 77
  77. 77. 78 • Like peaking, pumped storage is a method of keeping water in reserve for peak period power demands. • Pumped storage is water pumped to a storage pool above the power plant at a time when customer demand for energy is low, such as during the middle of the night. • The water is then allowed to flow back through the turbine- generators at times when demand is high and a heavy load is place on the system. Pumped Storage Plants
  78. 78. • The reservoir acts much like a battery, storing power in the form of water when demands are low and producing maximum power during daily and seasonal peak periods. • An advantage of pumped storage is that hydroelectric generating units are able to start up quickly and make rapid adjustments in output. • They operate efficiently when used for one hour or several hours. • Because pumped storage reservoirs are relatively small, construction costs are generally low compared with conventional hydropower facilities. 79
  79. 79. 80 Types of Micro-Hydroelectric Systems There are many different types of Micro- Hydroelectric systems Here are 3 Micro- Hydro systems from Energy Systems and Design
  80. 80. 81 How Micro-Hydro Systems Work • Micro-Hydroelectric systems take water from a stream and channel it into a pipeline that creates a vertical drop in order for the water to turn turbines that powers the system END

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