Hydro Power Plant

15EE42 : “POWER GENERATION & ECONOMICS”
Prepared by
Vineeth Kumar P. K.
Assistant Professor
Department of Electrical & Electronics Engineering
SDM Institute of Technology, Ujire, D. K, Karnataka, India
vineethkumarpk@gmail.com
vineethkumarpk@sdmit.in
9746738675 (Kerala) and 9741346475 (Karnataka)
Academic year 2016-17 Even semester
7/21/2017 1Dept. of EEE, SDMIT, Ujire, Karnataka, India

Module 1
Hydro Electric Power Plants
2Dept. of EEE, SDMIT, Ujire, Karnataka, India7/21/2017

Syllabus
• Hydrology, Run off & stream flow, hydrograph,
flow duration curve, Mass curve, reservoir
capacity, dam storage.
• Hydrological cycle, merits and demerits of
hydroelectric power plants, selection site.
• General arrangement of hydel plant, element
of the plant, classification of the plants based
on water flow regulation, water head and type
of load the plant has to supply.

• Water turbines- Pelton wheel, Francis, Kaplan
and propeller turbines.
• Characteristics of water turbines, governing of
turbines, selection of water turbines.
• Underground, small hydro and pumped
storage plants.
• Choice of size and number of units, plant
layout & auxiliaries.
Syllabus
Total allotted time= 10 hours

Hydrology
What is hydrology?
• Hydrography or hydrology deals with the
occurrence and distribution of water over and
under the earth surface.
• Hydrology is the study of hydrological cycle, in
which the water rises by evaporation from
sea, is carried over the land, where it falls as
precipitation & rises again by evaporation or
transpiration or flow back to ocean.
7/21/2017 Dept. of EEE, SDMIT, Ujire, Karnataka, India 5

Segments of hydrology
• Hydrology consists of i) Precipitation ii)Evaporation and
iii)Run-off
• i) Precipitation: Precipitation or rain fall may be defined
as the total condensation of moisture that reach the
earth in any form. It includes rain, ice, hail & frost.
• ii) Evaporation: Evaporation includes all the rain fall
that is returned to the atmosphere from the land &
water surfaces.
• iii)Run-off: It can be defined as the part of the
precipitation which is available as a stream flow.
Run-off = Total precipitation – total evaporation.
Hydrology

Hydrograph
What do u mean my ‘Hydrograph’?
• It is a graphical representation between discharge or
flow with time.
• It is plotted with flow as ordinates and the time intervals
as abscissas.
• Ordinates may be plotted in terms of the gauge height,
power in kW that can be developed.
• Abscissas may be taken in terms of hours, days, weeks
or months.
• It also indicates the power available from the stream at
different times of a day or year.
• Similar to load curve.

Hydrograph provides the following information:
• The discharge at any time during the period
under consideration.
• The maximum and minimum run off during
the period.
• The average run off during the period.
• Total discharge up to any time, given by the
area under the curve up to that time.
Hydrograph

Hydrograph

Flow duration curve
• It is a convenient form of hydrograph for
determine the available power at site.
• It gives the relation between flows and lengths of
time during which they are available.
• The flows are plotted as the ordinates and the
length of time as abscissas.
• The flow duration curve is a rearrangement of all
the stream flow elements of a hydrograph in a
descending order and is similar to load duration
curve.

• A flow duration curve may be used for determination
of minimum and maximum conditions of flow.
• The area under a flow duration curve represents the
total quantity of run off during the period.
Flow duration curve

Flow duration curve

Mass curve
• It is a curve which indicates the total volume of
run off in m^3 up to a certain time.
• The abscissa may be a day, month or year.
• This curve is obtained from records of average of
monthly flows.
• The slope of this curve at any points give the rate
of flow at that time.
• If rain fall is uniform throughout the year the mass
curve would be straight line having uniform slope.
• These curves are used in determination of the
capacity of storage reservoir in hydro project.

Mass curve

Hydrological or Rain Evaporation Cycle
• It is a process by which moisture from the surface
of water bodies covering the earth’s surface
transferred to the land & back to the water
bodies again.
• Input to this cycle is the solar energy.
• Due to this water from the water bodies
evaporates & on cooling these water vapors form
clouds.
• Further cooling makes the clouds to fall down in
the form of rain, snow, hail etc known as
precipitation.

• Precipitation includes all water that falls from
atmosphere to the earth’s surface in any forms.
• 2/3 rd of this precipitation, which reaches to the
land surface is returned to the atmosphere by
evaporation from water surface, soil & vegetation.
• The remaining precipitation returns ultimately to
the sea or ocean through surface or underground
channel.
• The amount of rainfall which runs off the earth
land surface to the form stream’s or river is useful
for generation of electric power generation.

Hydroelectric Power Station

Introduction to Hydroelectric power station
• Hydro electric power plant is the power plant is
the power plant utilizing the potential energy of
water at a high level for the generation of
electrical energy.
• Water head is created by constructing a dam
across a river or lake.
• The pressure head of water or kinetic energy of
water is utilized to drive the water turbine
coupled to alternators & therefore generation of
electric power.

Expression for hydro power
• Electrical power developed in Hydro electric
power station is given as
P = w x Q x H x η x 9.81 x 10^ -3 kW.
w – Specific weight of water in kg/m^3
Q – rate of flow of water in m^3/s
H – Height of fall or head in meters
η – Overall efficiency of operation.

What is hydroelectricity………………..?
• Hydroelectric power plant use the potential
energy of water stored in a reservoir to operate
the turbine & operate the generator & produce
electricity.
• Potential Energy (Reservoir) Mechanical
Energy (Turbine ) (Generator) Electrical
Energy.
Dept. of EEE, SDMIT, Ujire, Karnataka, India 217/21/2017

Factors affecting hydro power station…….?
• Size & height of reservoir
• Depends upon local geography
• Water availability
Features of hydropower…….?
• Resources are widely spread
• Well & proven advanced technology
• Lowest operating cost
• Longest plant life
• Water is renewable
Dept. of EEE, SDMIT, Ujire, Karnataka, India 22
7/21/2017

Hydropower Generation
Selection of site
• Preliminary investigation like catchment area,
rainfall, ground gradient, geology of foundation,
availability of raw material for construction.
• Location of the dam – large storage capacity, neck
formation etc.
• Choice of dam depends safety & economic factors
• Dam close to the turbine
• Accessibility of the site hilly area
• Availability of land

Selection of site
• Availability of water.
• Distance from the load centre – Distance should
be as small as possible & reduction in
transmission line losses.
• Availability of construction materials
• Water head
• Storage of water
• Cost & type of land
• Transportation facilities

Block diagram of hydro power station ( General arrangement)

Block diagram of hydro power station( General arrangement)
Draw the same diagram for VTU exam

Components of hydro electric power station
(Construction)
Primary Elements
•Catchmements area
•Reservoir, forebay & Intake
•Dam, Penstock & Tail race
•Prime movers
•Draft tube
•Power house & equipments
Safety Elements
•Spill ways
•Surge tank
•Trash rack

(Construction)
1. Catchment area
• The whole area behind the dam training into a
stream as a river across the dam has been built
at suitable place is called catchment area.
• Create a path for the water movement to dam
from river or lake.
• The whole area which supports the water
movement to dam is called as catchment area.

(Construction)
2. Reservoir
• A reservoir is employed to store water which
is further utilize to generate power by running
the hydroelectric turbine.

(Construction)
3. Dam
• Dam is a barrier confines or raise the water for storage
or diversion to create a hydraulic head.
4. Turbine- Generator set
• Heart of hydro electric power station
• Turbine is made up large number of turbine blades
• Generator will produce continuous electricity

5. Draft tube
• Usually found bottom side of turbine
• Empty tubes
• Which supports maintenance of the turbine
• Increases output & efficiency of turbine
• Helps for pumped storage unit.

6. Penstock
• Connecting pipe between dam & turbine
• Helps to increase the kinetic energy of the water.
• It is made up of strong materials like stainless
steel & concrete.
7. Power house & equipments
• Turbine-Generator set , valves, pump &
protective device

8. Spill ways
• Beside of the dam
• Control the water level
• Prevent the excess of water flow or flood
• Protect turbine generator set
9. Surge tank
• Pressure control valve
• Connected with penstock

10.Forebay
• Forebay serves as a regulating reservoir storing
water temporarily during light load period &
providing the same for initial increase on account
of increasing load during which water in the canal
is being accelerated.
• In short a forebay may be considered as an
enlarged body of water just above the intake to
store the water temporarily to meet the hourly
load fluctuations.

11. Intake
• Divert water towards turbine
• Prevent the entries of external bodies
12. Trash Racks
• To prevent the floating & other material to the
turbine.

Storage
Why storage is needed in hydro power plants?
• In most of the streams, the flow in excess
during one season and deficient during
another and for its regulation artificial storage
is needed.
• The storage capacity should be determined
with the help of the mass curve.

Pondage
• In case power plant is away from the storage
reservoir, a small pond is required near the
power plant in order to meet the hourly
changes in the power demand.
• The capacity of the pond should be sufficient
to cope with hourly changes for 24 hours.

Classification of hydro power plant.
Based on the following criteria
(a)Classification based on capacity
(b)Classification based on construction
(c) Classification based on operation
(d)Classification based on head

(a)Classification based on capacity
1. Micro hydal power plant- Less than 5MW
capacity
2. Medium capacity power plant- (5-100)MW
3. High capacity power plant- (101 – 1000)MW
4. Super capacity power plant- Above 1000MW

(b) Classification based on construction
1. Run off river without pondage
2. Run off water with pondage
3. Valley dam plant
4. Diversion canal plant
5. High head diversion plant

1. Run off river without pondage
- Water is taken from the river directly
- No pondage or any storage
- Small head
- Special rack made of steel
- Rack is keep out foregin particle without disturbing the
turbine
- Its should clear periodically
- Low capacity power plant
- Not suitable for operating at all the time.
- Low capacity power plants

2. Run off water with pondage
- pondage increases usefulness of the plant
- Flood doesn’t disturb the tail race
- Storage water with pondage supports the hour to
hour fluctuating load throughout a weaker or
longer period.
- Capacity is a bit large

3. Valley dam plant
-Storage reservoir supports necessary head
requirements.
-These are medium to high head plants.
-Plant can be efficiently use through out the
year.

4. Diversion canal plant
- Low & medium head plant
- No storage device
- Water of the river diverted away from the
diversion canal

5. High head diversion plant
- High head resulting from diversion of water

Classification based on operation
1. Base load power plant
2. Peak load plant
3. Pumped storage power plant

1. Base load power plant
- Suitable for the load operates through out the
year
-Large capacity
-High load factor
- Satisfies bottom portion of load curve

2. Peak load plant
-Short term operation
-Load factor is low
-These plant supply power to the system
corresponding to load at top portion of the load
curve.
-Run off river plants with pondage can be used for
this purpose

3.Pumped storage power plant
-Special kind of power plant
-Which works ordinary hydro power plant at part
time (During peak hours)
-They can use for pumping section
- During off peak hours pump the water from tail
race to head
- During peak hours it works as a normal hydro
power plant

3.Pumped storage power plant

Classification based on head
1. Low head plant- Less than 70m head
2. Medium head plants- 70m- 300m
3. High head plant- Above 300m

Control block diagram

Advantages
• No fuel charge
• Less supervising charge is required
• Plant is highly reliable
• Maintenance charge is less
• Low running cost
• Plant efficiency doesn’t change with age
• No fuel transportation is required
• No ash or flue gas problem
• Flood control
• Irrigation

Advantages continued
• Long life ( more than 50 years)compared to
thermal & nuclear power plant.
• The load can vary quickly & rapidly changing
load demand can meet without any difficulty.
• There are no stand by losses.
• Cost per unit is less

Disadvantages
• High initial cost of plant
• Take a long time for construction
• Large area is required
• It affects aquatic organism
• Relocation
• Plant is located at hilly area & its far away from load
centre, reason for transmission line losses.
• Hydro power station depends on rain & its difficult
operate the hydro power station during summer.

Small Hydro Power Plant
Introduction
• Generation of electricity based on the movement
of water from the natural water resource.
• Small hydro power plant has a generating
capacity of 10MW.
• Eco friendly
• Small hydro power plant can be sub divided into
two.
(1) Mini hydro power plant- 500kW to 2mW
(2) Micro hydro power plant- 50kW to 200kW

What is mini hydro power plant….?
• Use run of water
• With Weir or without Weir
• Small hydro is in most cases “run-of-river”; in
other words any dam or barrage is quite small,
usually just a weir, and little or no water is stored.
• No adverse effect on the environment because
no big construction of dam.
• High efficient

What is mini hydro power plant….?

What is micro hydro power station……?
• Suitable for power generation for small
communities , isolated home etc.
• Micro hydro plant is site specific
• It doesn’t have a dam or reservoir
• Mainly using in developing countries
• Pelton turbine is suitable for micro hydro power
station.
• Penstock or pipe carries water which is going to
operates turbine/generator & produce electricity.
• Completely eco friendly

• Power from micro hydro system is given by
P = Q x H
K
Where Q= Flow rate in gallon per minute
H= Height of Head
K = Constant

What is micro hydro power station…?

Advantages of small hydro power station
• Renewable energy source
• No pollution
• No fuel cost
• Less operating & maintenance cost
• Long life
• 90% of efficiency

Drawbacks of small hydro power station
• Site specific
• Site selection is difficult

Water turbines
Classification of turbine
Impulse turbine
Example- Pelton turbine
& Turgo turbine
Reaction turbine
Francis turbine,
Kaplan turbine etc

Impulse turbine:
• An impulse turbine is a horizontal or vertical
wheel that uses the kinetic energy of water
striking its buckets or blades to cause rotation.
• In an impulse turbine, water is forced to hit
the turbine at high speed.
• That means a fast-moving fluid (water) is fired
through a narrow nozzle at the turbine blades
to make them spin (rotation) around.
Water turbines

Impulse turbine
• The blades of an impulse turbine are usually
bucket-shaped.
• so they catch the fluid (water) and direct it off
at an angle .
• The wheel is covered by a housing and the
buckets or blades are shaped so they turn the
flow of water about 170 degrees inside the
housing.
Water turbines

• Impulse turbine
Water turbines
An impulse turbine is one in which the driving energy is
supplied by the water in kinetic form & produce mechanical
energy

Example of Impulse turbine- “ Pelton Wheel”
What is Pelton wheel or Pelton turbine….?
• The Pelton turbine is a tangential flow impulse
turbine.
• The Pelton wheel is most efficient in high head
applications.
• Power plants with net heads ranging from 200
to 1,500 m.
Water turbines

• Pelton turbines are best suited for high head and low
flow sites.
Water turbines
Or Bucket

Water turbines

• The main components of Pelton turbines are Nozzle,
eliptical shaped bucket.
• Rotor (Runner) is equiped (bolted) with eliptical bucket.
• Water strikes on bucket through jet. Where water jet is
a part of nozzle.
• After doing the useful work water discharges into tail
race.
• Speed deflectors & Spear are used to control the water
flow.
• Rotor of the runner is made up of stainless steel.
• Runner not submerged in the water.
Water turbines

What do you mean by Reaction turbine....?
• A reaction turbine is a type of turbine that
develops torque by reacting to the pressure or
weight of a fluid.
• Reaction Turbines are commonly used in
situations where the water level is low but has a
high flow rate.
• These turbines operate under Hydraulic energy,
Pressure energy and a part of Kinetic Energy too.
• Examples: Francis turbine, kaplan turbine etc
Water turbines

What is Francis turbine.....?
• Mixed flow type reaction turbine.
• Radial entry and axial exit of water.
• Suitable for medium head and medium flow power
plants ( Head 45 to 400m & 10 to 700 m^3/s).
• Francis turbine works based on velocity of water &
difference in pressure acting on the front and back of the
runner bucket.
• Lift force & Impulse force responsible for the movement
of runner.
• During energy transfer from water to the runner there is
a drop in static pressure & drop in velocity.
Water turbines

Shape of the runner
Water in
Water out
Water turbines

Water turbines

Water turbines
Suitable diagram for VTU exam

• Water from the penstock enters a spiral or scroll
casing which surrounds the runner.
• Water enters guide vanes.
• Guide vane impart tangential velocity or angular
momentum to the water before entering to the
turbine.
• Guide vane is suitable for flow rate control & flow
angle.
• Velocity of water changes from radial to axial.
Water turbines

What is Kaplan turbines?
• Kaplan turbine (Propeller turbine) is a reaction turbine
used for low heads (4m to 80m) & high specific speed
(300 m/s to 1000 m/s).
• Axial flow device.
• It consists of the axial flow runner usually with 4-6
blades of airfoil shape.
• Decreasing area of casing reason for water enters
centre portion with uniform velocity.
• Important components are Runner, Guide vanes( flow
control), Draft tube etc
Water turbines

Water turbines

• Individual runner blades are pivoted on the
hub so that their inclination may be adjusted
during operation responding to changes in the
load.
• Kaplan turbine can be run at maximum
efficiency at all load because of arrangement
for automatic variation of inlet blade angle
with variation in load.
Water turbines

Characteristics of water turbine
Water turbines
•Overall efficiency increases
With discharge.

Water turbines

Selection of water turbine
• Depends on working head (Operating head) Eg. Kaplan
turbine- up to 80m, Francis turbine –up to 400m &
Pelton turbine- above 400m .
• The effective head under which the turbine is to operate
gives the first guide to the selection of turbine. Eg.
Pelton turbine is suitable for very heavy head
application.
• Based on performance characteristics.
• Available discharge.
• Speed and output .
• Nature of the load.
• Size of the turbine
Water turbines

Underground Hydro-Power Plant
• Underground hydro-power plant is one which
whole of the generating equipment is placed in
an underground chamber.
• An underground layout of hydro power plant may
be favored due to technical and economical
consideration.
• It has great security in war time, lower
maintenance cost, minimum problem of land
acquisition, easier design of tail race, no risk of
avalanche, free from fire hazard & protection to
the staff against severe winter climate.

• Increased cost of construction, excessive cost
of lighting, special ventilation and air
conditioning is needed, additional cost of
under ground location of transformer & switch
gears & costly tail race tunnels.
• Examples of underground hydro power
stations: 860 MW Koyana underground power
plant Maharastra & Salal semi underground
hydro power plant.

Choice of size & number of generating units
• In order to maintain reliability & continuity of power
supply at all times, another unit of equal capacity is
required.
• Instead of selecting a single large unit of generator,
select small number of units up to a limit.
• Selection should be made such that it must fit with the
load curve.
• The aim should be have a small number of units & fit
them as well as possible on the load curve.
• Neither we should go for a single generating unit of
larger capacity for a large number of generating units
of small size.

Plan layout of Hydro-Power Plant
• The general layout of the hydro power plant is
determined by its type.
Typical plan layout of Hydro power plant with vertical reaction turbine

Numerical Problems

Assignment
• List the hydro electric power stations in the
world.
• Find out the large hydro electric power plants
in the world.
• List the hydro electric power plants in India.
• Find out the large hydro electric power plant
in India.
• List out the hydro electric power plants in
Karnataka.

Hydro Power Plant

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