As per the New Syllabus of GTU

1. HYDRO-ELECTRIC POWER PLANT
Kiranmoy Samanta

2. Contents
 Introduction
 Classification of hydro power plants.
 Factors affecting site selection for hydro-power project.
 Major components of hydroelectric plant
 Power generation
 Advantages and disadvantages of hydroelectric power.

3. Introduction
 Hydroelectric Power refers to energy or electricity generated by the
energy of falling or flowing water, the potential energy of water due
to its high location is converted into electrical energy.
 Hydroelectric Power obtained from the generators coupled to water
turbines which converts the hydraulic or fluid energy Electrical
energy.
 The total power generation capacity of the hydroelectric power
plants depends on the head of water and volume of water flowing
towards the water turbine.

4. • 25% of electricity generation capacity in world is provided by hydel
power plant.
• 4% of the total hydel energy potential in world is in India.
• In India 25.32% of total electricity generation capacity is produced by
hydel power.

5. Classification Of Hydro Power
Plants
 Hydropower Plants may be classified according to different
considerations as follows:
 Based on storage characteristics
 Based on head
 Based on plant capacity
 Based on nature of project

6. Based on Storage
Characteristics
 Run-off river plants
 Storage Plants
 Pumped storage Plants
 Tidal Plants

7. Run-off River Plants
 Run-off plants are those in which any storage
facilities is not provided and which utilize the
river flow to generate electricity.
 Generally such type of hydro plants is set up
where adequate discharge is available
throughout the year
 A weir or barrage is constructed across the
river close to the power plant to maintain a
given water level.

8. Storage Plants
 Storage plants are plants where necessarily
storage provision is required, so a dam is
constructed across the river.
 Storage is done during the wet season when
flow is in excess of demand to maintain
continuous power generation.
 The demand should fulfill from storage
during low supply period.

9. Pumped Storage Plants
 Pumped Storage plants generates power as usual but during the off
peak hours, water is pumped back from tail water pool to the head.
 As during off peak hours the power itself from that power plant
utilized in pumping to head so additional cost can be saved.
 So no water is wasted in such power plants and provision such as
reversible pump turbines which can function both as turbine + pump.

11. Tidal Plant
 Tidal plants are the recent innovation in the field of hydropower
generation.
 Tidal plants are designed to make use of high tides occurring in the
sea.
 Water at the time of high tides stored in a basin which can be
utilized during the low tides.

13. Based on Head
 Operating Head is the difference of the water level in the fore bay
and that in the tail race.
 Based on Operating Head Classification can be done as follows:
 Low Head Plants
 Medium Head Plants
 High Head Plants

14. Low- Head Plants
 Low Head Plants applications use river current or tidal flows of 30
meters (approximately 100 feet) or less to produce energy.
 These power plants do not need to dam or retain water to create
Hydraulic head it uses the current of river or the naturally occurring
tidal flow to create electricity.
 As Low Head Power Plants generates electricity from river currents
it is renewable energy and it affect less to environment.

16. Medium Head Plants
 If the operating head is between 30 m and 250 m, it is usually
classified as a medium-head plant.
 In Medium Head Plant construction of high dam across the river is
necessary to create required head by storing sufficient water for
power generation.
 It is the most common hydro power plant used in India.

18. High Head Plants
 If the operating head on the plant is greater than 250m, it is usually
classified as High Head Plants.
 A dam of sufficient height is, therefore required to be constructed,
so as to store water on the upstream side to utilize that water for
electricity generation.
 The common example is Bhakra dam in Punjab, Rihand dam in U.P.

20. Based on Plant Capacity
 Based on hydro plant capacity another classification of power plant
is done.
 Micro-hydel Plants
 Medium Capacity Plants
 High Capacity Plants
 Super Hydro Plants

21. Cont..
 Micro-Hydel Plants:
 A micro hydel plant is the one which has a capacity less than 5
MW.
 Medium Capacity Plants:
 A medium capacity plant is the one which has a capacity in the
range of 5 to 100 MW. Most of the hydropower plants in India are
medium capacity plants.
 High Capacity Plants:
 A high capacity plant is one which has a capacity in the range of
101 to 1000 MW.
 Super Hydro Plants:
 A super hydro plant has a capacity greater than 1000 MW.

22. Based On Nature of Project
 On the basis of nature of project hydro-power plant is classified as
 Power Project: In mountainous regions, hydro electric stations
are constructed only for power generation.
 Multi-Purpose Project: in multipurpose project, power is
generated besides other functions such as irrigation, water
supply, flood control etc.

23. Factors affecting site
selection
 General available topography of the area.
 Available head
 Available flow
 Political influences of the area
 Location of power house
 Economy

24. Components Of Hydro-electric
Plant
 The principle components of a hydro-electric power plant are as
described
 Dam Or Weir
 Reservoir
 Fore bay
 Intake Structure
 Penstocks
 SurgeTank
 Turbines
 Power House
 DraftTube
 Tail Race

26. Fore-Bay
 Fore-Bay is generally provided in case of run-off river plants & where
Power Plant is located far from Dam-Reservoir and through channel
water is stored here.
 It’s main Function is to temporarily store water which is rejected by
plant due to reduced load during off peak hours, and also to meet
instantaneous demand when the load is suddenly increased.
 It is provided just front of the penstocks.
 If power house is located nearby then requirement of fore-bay is not
necessary.

27. Intake Structure
 The water is conveyed from the fore-bay to the penstocks through
the intake structure.
 The main components of Intake structure are trash racks and gates.
 The trash rack is provided to prevent the entry of debris into the
water passage.

28. Pen-stocks
 Pen-stocks are the pipes of huge diameter usually made of steel,
reinforced concrete which carry water from storage to turbines.
 As penstocks are directly subjected to water hammer pressure it is
provided with surge tank to absorb water hammer pressure.
 Penstocks are provide with head gates which dominates the water
flow.

30. Surge tanks
 SurgeTank is a cylindrical storage tank which is connected to
penstocks at a suitable point.
 It is provided near downstream end of the long penstocks to relieve
excess pressure caused by sudden closure of valve.
 Basically the surge tank is provided to reduce the water hammer
pressure.

32. Turbines
 HydraulicTurbines convert hydraulic energy into mechanical energy.
 And the Mechanical energy developed by turbine is used in running
an electric generator which is coupled to shaft of the turbine.
 The water flows through the turbine consist of a wheel with
designed blades and makes it rotate.
 This rotation of turbine wheel is coupled with generator and it
generates electricity which is known as hydro electricity.
 HydraulicTurbines may be classified under 2 Heads
 ImpulseTurbines
 ReactionTurbines

34. Power House
 A power house is a building consisting of a
substructure to support the hydraulic and electrical
equipments and a superstructure to house and protect
there equipments.
 The sub-structure of the power house mainly consist of
foundation block of concrete extending from the
foundation to the generator floor with waterways
formed within it.
 Superstructure is the main building of the power house
which is constructed above the generator floor.
 Superstructure mainly contains transformers,
switching devices and control units.

35. Draft Tube
 DraftTube is a pipe or passage of gradually increasing c/s which
connects the runner exit to the tail race.
 It reduces the high velocity of the water discharged by the turbine by
enlarging the c/s and thus converts the Kinetic energy of water into
mechanical energy.

36. Tail Race
 Tail race is the channel into which the water is discharge after
passing through the turbines.
 When river is far off from the power house, one may have to
construct a channel of considerable length between the power
house and the river which is known as tail race.

37. Power generation

38. Advantages of hydro electric
plant
• Water is a renewable energy source.
• Maintenance and operation charges are very low.
• The efficiency of the plant does not change with age.
• In addition to power generation, hydro-electric power plants are also
useful for flood control, irrigation purposes, fishery and recreation.
• Have a longer life(100 to 125 years) as they operate at atmospheric
temperature.
• Water stored in the hydro-electric power plants can also be used for
domestic water supply.

39. Disadvantages
• The initial cost of the plant is very high.
• Since they are located far away from the load centre, cost of
transmission lines and transmission losses will be more.
• During drought season the power production may be reduced or even
stopped due to insufficient water in the reservoir.
• Water in the reservoir is lost by evaporation.