HYDROELECTRIC POWERPLANTS : Major hydroelectric plants operational in India

HYDROELECTRIC POWERPLANTS:
Major hydroelectric plants operational in the
country
Group No: 6
Members: Arsh Srivastava (17-12-093)
Sama Yashwanth Reddy (17-12-094)
Mayurjyoti Neog (17-12-095)
Shivam Raj (17-12-096)
Pradeep Kumar Singh (17-12-097)
Ankit Kumar (17-12-098)

Introduction
 Hydro or water power is important only next to thermal power.
 Nearly 20 percent of the total power of the world is met by hydropower stations. There
are some countries like Norway and Switzerland where the hydropower forms almost the
total installed capacity.
 Hydroelectric power utilizes the energy of water to drive the turbine which, in turn, runs
the generator to produce electricity.
 Hydroelectric power was initiated in India in 1897 with a run-of-river unit near
Darjeeling. However, the first major plant was the Sivasamudram Scheme in Mysore of
4.5 MW capacity commissioned in 1902.

Objectives
 To understand what Hydroelectric plant is and how does it work.
 To understand the benefits and limitations of Hydroelectric powerplant.
 To learn about various parts of a hydroelectric plant.
 To learn about various types of hydroelectric plants in India.

Advantages
 Water source is perennially available.
 The running costs of hydropower installations are very low as compared to thermal or
nuclear power stations.
 The problem of emission of polluting gases and particulates to the atmosphere also does
not exist.
 The hydraulic turbine can be switched on and off in a very short time.
 System reliability is much greater than that of other power plants.
 Hydro-plants provide ancillary benefits like irrigation, flood control, afforestation,
navigation and aqua-culture.

Limitations
 Hydro-power projects are capital-intensive with a low rate of return.
 The gap between the foundation and completion of a project may extend from ten to
fifteen years.
 . Power generation is dependent on the quantity of water available, which may vary from
season to season and year to year.
 Plants are often far away from the load centre and require long transmission lines to
deliver power.
 Large hydro-plants disturb the ecology of the area.

Selection of site for a hydroelectric plant
 Availability of water: The design and capacity of the hydro-plant greatly depends on the
amount of water available at the site.
 Water storage capacity: Since there is a wide variation in rainfall all around the year, it is
always necessary.
 Available water head: In order to generate the desired quantity of power, it is necessary that
a large quantity of water at a sufficient head should be available.
 Distance from the load centre: If the site is close to the load centre, the cost of transmission
lines and the transmission losses will be reduced.
 Accessibility of the site: The site should be easily accessible by rail and road.
 Type of land of site: The land of the site should be cheap and rocky.

Essential elements of a hydroelectric powerplant
1.Catchment Area: The whole area behind the dam draining
into a stream or river across which the dam has been
constructed is called the catchment area.
2.Reservoir: A reservoir may be natural, like a lake on a mountain
or artificially built by erecting a dam across a river. Water held in upstream
reservoir is called storage, whereas water behind the dam
at the plant is called pondage. It is used for storage during
times of plenty for subsequent use in times of scarcity.

3. Dam: Dam develops a reservoir of the desired capacity to store water and builds up a head for
power generation.
4. Spillways: When the water level in the reservoir basin rises, the stability of the dam structure is
endangered. To relieve the reservoir of this excess water, a structure is provided in the body of a
dam or close to it, called a spillway.

5. Conduits: Conduits are channels for conveying water in hydraulic powerplant. Canals and flumes
are open conduit, while tunnels, pipelines and penstocks are closed conduit.
6. Surge Tanks: A surge tank is a small reservoir in which the water level rises or falls to reduce the
pressure swings so that they are not transmitted to the closed conduit.

7. Draft Tubes: The draft tube allows the turbine to be set above the tailrace to facilitate inspection
and maintenance and by diffuser action regains the major portion of the kinetic energy or velocity
head at runner outlet, which would otherwise go waste.
8. Powerhouse: The equipment provided in the powerhouse includes the following. Hydraulic
turbines, Electric generators, Governors, Gate valves, Relief valves, Water circulation pumps, Air duct,
Switch board and instruments, Storage batteries etc.

Classification of hydroelectric powerplant
According to the availability of head
(i) High head power plants: These plants work under a head of 100 m and above. Water is stored in
lakes or high mountains during rainy season or when snow melts. Surplus water is discharged by a
spillway. Pelton wheel is the common prime mover.

(ii) Medium head power plants: These plants operate under heads varying from 30 m to 100 m.
Francis turbine is the common prime mover. Forebay before the penstock acts as the water
reservoir and also as a surge tank.

(iii) Low head power plants: A dam is constructed across a river and a sideway stream diverges from
the river at the dam. Francis turbine or Kaplan tur bine is used for power generation.

According to the nature of load
(i) Base load plants: These plants are required to supply constant power to the grid. They run
continuously without any interruption and are mostly remote controlled.
(ii) Peak load plants: They only work during certain hours of a day when the load is more than the
average.

According to the quantity of water available
(i) Run-of-river plant with or without pondage: Such a plant works daily according to the nature
and limit to the flow in the river. Power generated depends on the quantity of flow.

(ii) Hydroelectric Plants with Storage Reservoir: These plants are most common in India. During the
rainy season water is stored in reservoirs so that it can be utilized during other seasons to
supplement the flow of the river whenever the flow in the river falls below a specified minimum.
(iii) Pumped Storage Plants: Water after working in turbines is stored in the tailrace reservoir.
During low load, the water is pumped back from the tail to the head reservoir drawing excess
electricity from the grid or from the nearby steam plant. During peak load, this water is used to
work on turbines to produce electricity.

(iv) Mini and micro hydroelectric plants: More emphasis is now being given on such plants. The
natural water source in hilly terrain can be utilized for power generation with low-head standardized
turbogenerator units. Its ad verse effect on ecology is negligible.

HYDRAULIC TURBINES
• Hydraulic turbines convert the potential energy of water into shaft
work, which in turn rotates the electric generator coupled to it
producing electric work

WORKING PRINCIPLE
• When the fluid strikes the blades of the turbine, the blades are displaced, which
produces rotational energy.
• When the turbine shaft is directly coupled to an electric generator , mechanical
energy is converted into electrical energy.
• This energy obtained is known as hydro -electric power, which is one of the
cheapest forms of energy generation .

Classification of hydraulic turbines
Turbines are classified according to the
1. Head and quantity of water available
2. Nature of working on blades
3. Direction of flow of water
4. Axis of turbine shaft
5. Specific speed

1.According to the head and quantity of water
• The difference in elevation of water surface between upstream and down stream of turbine is
the head under which the turbine acts.
• The classification of turbine based on head as follows
Low head 2m -15m e.g. Kaplan and Propeller turbine
Medium head 16m-70m e.g. Francis turbine
High heads 71m-500m e.g. Francis turbine or Pelton turbine
very high heads above 500m e.g. Pelton turbine
• Turbines are also classified as low discharge , medium discharge and high discharge turbines
depending on the flow available.
Low discharge - Pelton turbine
medium discharge - Francis turbine
High discharge - Kaplan turbine

2.According to the nature of working on the blades
• Turbines are classified as impulse and reaction turbines depending on the mode of energy
conservation of potential energy of water into shaft work.
Impulse turbine – all head available is converted into kinetic energy in nozzle.
e.g. Pelton turbines
Reaction turbine – only a part of potential energy is converted into kinetic energy and
remaining into potential energy e.g. Francis , Propeller turbines.
3. According to the direction of flow of water
Axial flow – inlet and outlet flow are parallel to axis of shaft e.g. Propeller and Kaplan turbine.
Tangential flow - flow is tangential to the circumference of impeller e.g. Pelton turbine.
Mixed flow – flow direction changes in between inlet and outlet e.g. Francis turbine.
Radial flow – flow is along the radius of the shaft e.g. Francis turbine.
Diagonal flow – flow is angular with respect to axis of shaft e.g. Deriaz turbine.

4.According to the axis of turbine shaft
Horizontal shaft turbine – Shaft of the turbine is horizontal e.g. Pelton turbine.
Vertical shaft turbine – shaft of the turbine is vertical e.g . Francis turbine.
5.According to the specific speed
• The total range of specific speed for the hydraulic turbine is from 4 to 1100.
• The lower specific speed machines are denoted as slow runners while high specific speed
machines are known as fast runners.
Runner Specific Speed
slow Medium High
Pelton 5-15 16-30 31-70
Francis 60-150 151-250 251-400
Kaplan 300-450 451-700 701-1100

Pelton Wheel Turbine
• It is an impulse turbine extensively used for high head installations.
• The runner consists of a large circular disc on the periphery of which a number of two lobe
ellipsoidal buckets are evenly mounted.
• Each bucket has a ridge or splitter in the middle which
divides the jet into two equal streams.
• The symmetry ensures that there is no momentum in
axial direction and hence there is no axial force on shaft
bearings.
• Nozzle directs the flow on the wheel.
• Nozzle also governs the quantity of flow with the help of spear
valve controlled by governor action.

• The jet moves in tangential plane before and after striking the wheel and the bucket moves at a
speed given by
r & D=bucket circle radius and diameter
• With nozzle diameter D/d is a size Parameter for the turbine . This is known as jet ratio m having a
value in the range of 10 to 24
• The velocity of the jet issuing from the nozzle is as follows
H=net head available at the nozzle
=coefficient of velocity(0.97-0.99)
gH
C
V v 2
1 
v
C
60
2
1
DN
V
V b
b




• Total energy transferred to the wheel is given by euler’s equation
Where 1,2 represents the condition at inlet and outlet of bucket
• Now from the exit velocity diagram we get
Now k is the blade friction coefficient
   
2
1
2
2
1
(
1
W
W
b
b
W
b
W
V
V
g
V
g
V
V
V
V
E 



   

 cos
180
cos 2
2
2 r
b
r
b
W V
V
V
V
V 




 
b
r
r V
V
k
kV
V 

 1
1
2

cos
)
( 1
2 b
b
W V
V
k
V
V 



Substituting the above parameters in the energy equation we get
at
kinetic energy of the input jet=
Therefore the hydraulic efficiency of the wheel is given by
Where =velocity ratio
)
(
cos
1 2
1 b
b V
V
V
g
k
E 



4
cos
1
2
1
max
V
g
k
E


 2
1
V
Vb 
g
V
2
2
1
)
)(
cos
1
(
2
2
2
2
1


 


 q
k
g
V
E
D
1
V
Vb



when there is no energy loss due to friction
Degree of reaction(R)=(energy transfer due to pressure drop)/(total energy transfer)
2
cos
1
max




2
cos
1
)
( max


k
work
D


1
1
2
1
2
2
2
1
b
W V
V
V
V
R




Francis turbine
• It is a reaction turbine . During energy transfer from water to the runner there is a drop in static
pressure as well as drop in velocity head.
• It is a mixed flow turbine with radial inlet and axial outlet.
• Water from the penstock enters a spiral or
scroll casing which surrounds the runner.
• The cross section of the spiral diminishes uniformly.
along the surface to keep the water velocity
constant along the path.

• The water then enters the guide vanes or wicket gates which are provided which can be turned
suitably to regulate flow and output.
• The guide vanes impart a tangential velocity or angular momentum
to the water before entering the runner.
• The runner has a number of curved blades welded to the shrouds.
• The velocity of water gradually changes from radial to axial
after flowing past the runner the water leaves
through draft tube.
• Draft tube increases the pressure reducing
velocity before entering tail race.

We assume that the flow velocity remains constant so and since the discharge is axial
with
Therefore work done per second per unit mass is
where =exit angle of guide vanes
=inlet blade angle
2
1 f
f V
V 
0
2

W
V 90
2 

1
1 w
b V
V
E 
)
cot
(cot 1
1
1
1

 
 f
b V
V
1
cot
1
1

f
W V
V 
)
cot
(cot
cot 1
1
1
2
1


 
 f
V
E
1

1


Loss in kinetic energy
Blading or diagram efficiency
2
2
1
2
2
2
1
r
r V
V
E 

1
1
1
E
E
E
E
E
E
D






 
1
1
1 cot
cot
cot
2
1
1
1


 




Degree of reaction ,
Hydraulic efficiency,
Overall efficiency,
Where P is the total power output.
E
V
R
f 1
2
2
cot
1 1



gH
V
V
H
E b
W
h
1
1



QgH
P
o

 

Propeller Turbine
• The propeller turbine is a reaction turbine used for low heads and high specific speeds.
• It is an axial flow device providing a large flow area utilizing a large volume flow of water with low
velocity.
• It consists of an axial flow runner usually with four to
six blades of air foil shapes.
• The spiral casing and guide vanes are similar
to that in Francis turbine.
• The runner blades are fixed and non adjustable
as in Francis turbine.

Kaplan Turbine
• Kaplan turbine is a special type of propeller turbine in which the individual runner blades are
pivoted on the hub.
• Their inclination may be adjusted during operation responding to changes in load
• The blades are adjusted automatically rotating about pivots with
the help of governor servo mechanism.
• The efficiency of the reaction turbine depends on
inlet blade angle.
• In Kaplan turbine because of arrangement for
automatic variation of inlet blade angle with
variation in load ,the turbine can
be run at maximum efficiency at all loads.

Kaplan Turbine and Propeller turbine velocity diagram

Deriaz Turbine
• It is also known as the diagonal turbine. The flow over the runner is at an angle of 45 degrees
to the axis.
• It has the adjustable blades like Kaplan turbines.
• It can be described as a cross between Kaplan and Francis turbine.
• The guide vanes and stay vanes are also inclined.
• It is particularly suited for reversible flow conditions when
the turbine also has to work as a pump as in pumped
storage power plant.

Bulb Turbine
• Tubular or Bulb turbines are small fixed axial flow propeller turbines operating under low
heads.
• The turbo generator is housed in an enclosed bulb shaped casing which is installed right in
the middle of flow passage.
• The bulb and the propeller form an integral unit followed by a straight conical flaring draft
tube.
• Bulb turbines are suitable for tidal power plants.

India’s major hydroplants
1. Tehri Hydropower Complex
• Having a height of 855ft and length of 1886ft, it is the India’s tallest dam on the
Bhagirathi River near Tehri in Uttarakhand.
• It is also the eighth-tallest dam in the world and the second-tallest in Asia.
• Maximum planned capacity 2,400MW.
• Owned and operated by Tehri Hydro Development Corporation (THDC).
• Francis turbine is used in this powerplant.
2. Koyna Hydroelectric Project
• This power plant is Located near Patan, in Maharashtra’s Satara district, close to the
Koyna River.
• Maximum planned capacity 1,960MW.
• Owned and operated by MAHAGENCO and Maharashtra State Power Generation.
• Pelton wheel turbine is being used in this hydroelectric project.

3. Srisailam Dam
• Srisailam Dam is located on the Krishna River in the Nallamala Hills near
Srisailam temple in Andhra Pradesh.
• Owned by the Government of Andhra Pradesh via operator APGENCO.
• Maximum capacity 1,670MW.
• It is considered to be India’s third-largest working hydroelectric power project
• Francis turbine is used in this hydroelectric plant.
4. Nathpa Jhakri Dam
This power plant is Located in Himachal Pradesh.
• Maximum capacity 1,530MW.
• Owned and operated by Satluj Jal Vidyut Nigam (SJVN).
• The dam is powered by six 250MW Francis-type turbines.
• Francis turbine is used in this powerplant.

5. Sardar Sarovar Dam
• This concrete gravity dam is located on the Narmada river, near Navagam in the
state of Gujarat.
• Capacity of 1,450MW.
• Operated by the Sardar Sarovar Narmada Nigam.
• Sardar Sarovar Dam supplies water and electricity to four Indian states—
Gujarat, Maharashtra, Rajasthan and Madhya Pradesh.
• This dam counts as the world’s second largest concrete dam—after Grand
Coulee which sits across River Columbia in the US—in terms of the volume of
concrete used in its construction.
• Francis turbine is used in this turbine.

Some Indian Hydroelectric plants where Francis turbine is used:
S.No. Scheme/Project Location (State) Source of water
1 Bhakhra dam project Bhakra (Punjab) Sutlej river
2 Cauvery hydroelectric scheme Siva Samudram (Karnataka) Cauvery river
3 Chambal hydroelectric scheme Gandhi sagar (Rajasthan) Chambal river
4 Hirakud dam project Hirakud (Orissa) Hirakud river
5 Rihand dam project Rihand (Uttar Pradesh) Rihand river

Some Indian Hydroelectric plants where Pelton turbine used:
1 Mahatma Gandhi hydroelectric works Sharavathi (Karnataka) Sharavathi river
2 Mandi hydroelectric scheme Joginder Nagar
(Himachal Pradesh)
Uhl river
3 Pallivasal power station Pallivasal (Kerala) Mudirapuzle river
4 Pykara hydroelectric scheme Pykara (Tamil Nadu) Pykara river.

Some Indian Hydroelectric plants where Kaplan turbine used:
1 Bhakra-Nangal Project Gangwal & Kota
(Punjab)
Nangal hydel
2 Nizam Sagar Project Nizam Sagar (Andhra
Pradesh)
Nanjira river
3 Radhanagri Hydroelectric Scheme Kolhapur (Maharashtra) Bhagvati river
4 Tungbhadra Hydroelectric Scheme Tungbadhra (Karnataka) Tungbadhra river

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