Training at Rana Pratap Sagar Hydro Power Station
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Transcript of Training at Rana Pratap Sagar Hydro Power Station
ACKNOWLEDGEMENT
Any project of work cannot be accomplished to one’s satisfaction with proper
guidance and total co-operation of all these involved in this project. I convey
my deep regards to all of them.
I express my sincere thanks to my trainer Mr. Batra for guiding me right from
the inception till the successful completion of my training. I sincerely
acknowledge him for extending their valuable guidance, support for literature,
critical reviews of training and the report and above all the moral support that
had provided to me with all stages of this training.
I would also like to thanks the supporting staff of the HYDRO POWER
STATION for their help throughout the training.
PAGE INDEX
Topic Page No.
1. INTRODUCTION : 1
2. INDIA’S CRITICAL NEED
FOR POWER : 3
2.1 WATER POWER : 3
3. BASIC PRINCIPLE AND
METHODS OF ELECTRIC
GENERATION : 4
3.1 BASIC PRINCIPLE : 4
3.2 TYPICAL HYDRO POWER
STATION : 5
3.3 OUTPUT SYSTEM : 6
4. GENERAL DESCRIPTION : 7
4.1 FUNCTION OF RPS HPS : 7
4.2 COST AND OPERARATIONAL
STATISTICS OF RPS HPS : 8
4.3 FUNCTIONAL IMPORTANCE : 8
4.4 PARAMETRS RELATED TO
RPS HPS : 9
4.5 SELECTION OF SITE : 10
5. MAJOR ELEMENTS : 11
5.1 STORAGE RESERVOIR : 11
5.1.1 DAM : 12
5.1.2 FOREBAY : 12
5.1.3 TRASHBACK : 12
5.1.4 SPILWAY : 12
5.1.5 PENSTOCK : 12
5.1.6 TAIL RACE : 13
5.1.7 DRAFT TUBES : 13
5.1.8 HYDRAULIC TURBINES : 13
5.2 TURBINE CLASSIFICATION : 15
5.2.1 IMPULSE TURBINE : 15
5.2.2 REACTION TURBINE : 15
5.2.3 TURBINE SPECIFICATIONS : 17
5.2.4 DESIGN AND MANUFACTURE OF TURBINE : 18
5.2.5 LEVEL OF EQUIPMENTS : 19
5.2.6 MOUNTED ON UNIT CONTROL BOARD : 20
6. POWER TRANSFORMER : 21
6.1 TRANSFORMER RATING : 21
6.2 GOVERNING SYSTEM : 21
6.3 ELECTRICAL EQUIPMENT : 22
6.3.1 MAIN COMPONENTS OF GENERATOR : 22
7. ELECTRICITY GENERATION : 24
7.1 HYDRAULIC POWER : 25
7.2 INDUSTRIAL HYDROELECTRIC
PLANTS : 28
7.3 SMALL SCALE HYDROELECTRIC
PLANTS : 28
7.4 ADVANTAGES : 29
7.5 ECONOMICS : 29
7.6 GREEN HOUSE GAS EMISSIONS : 29
7.7 RELATED ACTIVITIES : 30
7.8 DISADVANTAGES : 30
7.9 HYDROELECTRIC POWER STATIONS
AND ENVIRONMENT : 30
7.10 COPARISONS WITH OTHER METHODS
OF POWER GENERATION : 31
8. ELECTRICAL SYSTEM : 33
8.1 MAJOR ELECTRICAL EQUIPMENTS
WITH THEIR SPECIFICATION : 33
8.1.1 ALTERNATOR : 33
8.1.2 ALTERNATOR RATING : 33
8.2 CURRENT TRANSFORMER : 34
8.2.1 CURRENT TRANSFORMER RATING : 35
8.3 POTENTIAL TRANSFORMER : 36
8.4 CIRCUIT BREAKER : 36
8.4.1 THE TYPES OF CIRCUIT BREAKER : 36
9. SF6 GAS CIRCUIT BREAKER : 38
9.1 GENERAL INFORMATION : 38
9.2 OPERATION OF CIRCUIT BREAKER : 40
9.3 AUXILIARY SWITCH : 40
9.4 RAPID AUTOMATIC RECLOSING : 41
9.5 COMMISSIONING : 41
10. FIREPROTECTION SYSTEM : 44
10.1 FIRE PROTECTION SYSTEM : 44
10.1.1 SMOKE DETECTION SYSTEM : 44
10.1.2 MULTIFIRE SYSTEM : 44
10.2 ISOLATOR : 45
10.3 EARTHING SWITCH : 45
TABLE INDEX
Table Page No.
4.1 Parameters related to RPS HPS : 9
5.1 Francis hydraulic turbine : 17
5.2 Design and manufacture of turbines : 18
5.3 Level of equipment : 19
6.1 Transformer rating : 21
8.1 Alternator Rating : 33
8.2 Current Transformer Rating : 35
(Victrans Engineers)
8.3 Current Transformer Rating : 35
(General electric)
FIGURE INDEX
Figure Page no.
3.1 Hydroelectric dam : 5
5.1 Inside a hydroelectric plant : 11
5.2 Impulse turbine v/s Reaction turbine : 16
5.3 Francis turbine : 17
7.1 Hydroelectric power : 24
7.2 Generator : 25
9.1 SF6 circuit breaker : 39
9.2 Cross section of SF6 circuit breaker : 42
ABSTRACT
Practical knowledge is very important in every field one must be familiar with
the problem related to that field, so that he may solve them and become a
successful person.
After the successful completion of study an engineer has to serve a industry,
may be public or sector or self owned.
To be a good engineer, one must be aware of industrial environment, working
in industry, labor problem etc. so as to tackle technical problems successfully.
To bridge the gap between theory and practice, our engineering curriculum
provides training course of 45 days.
I have undergone my 45 days training at Rana Pratap Sagar Hydro Power
Station, Rawatbhata. This report has been prepared on the basis of
knowledge acquired by me during the period at the power station.
CHAPTER 1
INTRODUCTION
In the second stage CHAMBAL RIVER VALLEY DEVELOPMENT
PROJECT a masonry dam at RAWATBHATA “RANA PRATAP SAGAR
DAM” in district Chittorgarh. The dam and Hydro Power Plant constructed
in the second stage of the Chambal project and was named “RANA
PRATAP SAGAR DAM and Hydro Power Plant” in the memory and
honor of the great warrior of Mewar, the legendary Maharana Pratap.
The Rana Pratap Sagar Dam is the part of “Chambal Project”. There are
three hydroelectric power stations: First at Gandhi Sagar , Second at
Rawatbhata Rana Pratap Sagar and third at Jawahar Sagar.
RPS is balancing reservoir between G.S. upstream and J.S. downstream.
This is followed by the Kota Barrage and water diverted from it is
extensively used for irrigation purpose in parts of Rajasthan and Madhya
Pradesh.
The RPS dam was constructed between 1965 to 1968 and dedicated to the
nation by former Prime Minister Late Smt. Indira Gandhi .
There are four dams in cascade on Chambal River in the stretch of 70 kms
as riverbed drops by about 120 meters between Gandhi Sagar and Kota.
Kotan Thermal Power Station of 1060MW(e) is located at upsteam of Kota
barrage.
This dam is used for both irrigation and generation of electricity. The total
dam length is about 1km and 25 feet wide.
RPS hydro power plant consists of four units of each 43 MW. This plant
serves electricity to Kota, Bhilwara and Gandhi Sagar. The generated
voltages are 11KV and transmission voltage is 132 KV. AT the discharge
water side a tunnel is constructed for raising the effective head of water.
RPS consists of four vertical type generator build specification no.
GS/2/1962 CANADIAN GENERAL ELECTRIC EN1607080 parts list
117L456. The direct connected exciters are build by CANADIAN
GENERAL ELECTRIC EN101213. These machines are designed in
accordance with ASA standard British Standard.
CHAPTER 2
INDIA’S CRITICAL NEED FOR POWER
Severe power shortage is one of the greatest obstacles to India’s
development. Over 40 percent of the country’s people –most living in the
rural areas—do not have access to electricity and one third of Indian
business constraints.
India’s energy shortfall of 10 percent (rising to 13.5 percent at peak
demand) also works to keep the poor entrenched in poverty. Power
shortages and disruptions prevent framers from improving their agricultural
incomes, deprive children of opportunities to study and adversely affect the
health of families in India’s tropical climate.
Poor electricity supply thus stifles economic growth by increasing the costs
of doing business in India, reducing productivity and hammering the
development of industry and commerce which are the major creators of
employment in the country.
2.1 WATER POWER
Water is the cheapest source of power. It served as the source of power to
of power to our civilizations in its earlier days in the form of water wheels.
Faraday’s discovery of electricity has proved to be very useful to use water
for producing electric power. A hydroelectric power plant is aimed at
harnessing power water flowing under pressure.
CHAPTER 3
BASIC PRINCIPLE AND METHODS OF
ELECTRIC GENERATION
3.1 BASIC PRINCIPLE
When a closed coil is rotated rapidly in a strong magnetic field, the number
of magnetic flux lines passing the coil changes continuously. Hence an
EMF is induced in the coil and the current flows in it. In fact the
mechanical energy expended in rotating the coil appears as electrical
energy ( current) in the coil.
There are different types of methods or systems by which electricity is
produced such as:
Hydel electric power station- water turbine
Thermal power station-steam turbine
Nuclear power station-steam turbine
Gas power station-gas turbine
Neptha of lignite base power station
Solar power station
Wind power station
Fig-3.1 Hydroelectric dam
3.2 TYPICAL HYDRO POWER INSTALLATION
As shown schematically in fig 3.1, the hydraulic components of a
hydropower installation consist of an intake, penstock, guide vanes or
distributor, turbine and draft tube. Trash racks are commonly provided to
prevent ingestion of debris into the turbine. Intake usually required some
type of shape transition to match the passage way to the turbine and also
incorporate a gate or some other means of stopping the flow in case of an
emergency or for turbine maintenance. Some types of turbines are set in an
open flume; others are attached to a close conduit penstock.
3.3 OUTPUT SYSTEM
Electricity is distributed in our country by a big and vast grid system. The
total grid of India is divided in to the five regions and distributing the
power through different load dispatch centers.
Following are the regional grids-
Northern regional grid
Western regional grid
Southern regional grid
Eastern regional grid
North-East regional grid
Rajasthan is connected to the Northern regional grid where as Madhya
Pradesh is connected to the western regional grid.
Northern region is the largest region among the five regions of the country
in terms of geographical area as well as the number of consumption.
Following is the balance sheet of generation and load with their sources and
demands-
Generation Demands
Hydel 32%
Thermal 55%
Gas 10%
Nuclear 3%
Agriculture 40%
Industrial 38%
Domestic 22%
Table 3.1
CHAPTER 4
GENERAL DESCRIPTION
At RPS HEPS, vertical turbine rotates at 125 rpm by the water velocity.
Generator is directly coupled with the turbine, giving output of 43MW(e) at
11KV voltage 50 Hz frequency. Output voltage is step up to 132 KV by the
transformer and transmitting to the Northern grid through several transmission
lines which are going to Bhilwara (2 No), Jawahar sagar (1No) and Gandhi
sagar (2No).
The plant is operated and controlled from a centralized control room which is
having all the information and parameters regarding different system of the
plant and its equipments.
Alarm systems are provide in C/R to take appropriate actions in case of any
abnormal operation and taking the action accordingly.
A small diesel generator set of 300KW capacity providing the emergency
power supply to their plant equipments and being used for starting the units.
The water after doing its work on the turbine, discharged in a fore bay form
where it goes to the downstream of Chambal River through a big tunnel.
4.1 FUNCTION OF RANA PRATAPSAGAR HYDRO
ELECTRIC POWER STATION
To produce electricity as an active power of 4*43 MW(e) and
supplying it to Rajasthan through 7 lines of 132 kv.
Operates synchronous condenser for better voltage regulations of the
grids as and when required.
To provide dedicated power supply to the nearest Nuclear power
station on priority basis whenever there is a problem in Northern grid
for starting of the plant and for maintaining auxiliary power supply of
their plant in order to meet the safety norms of Nuclear Stations
To supply first power to the grid by the self-start in case of total
collapsing of northern grid.
4.2 COST AND OPERATIONAL STATISTICS OF RPS HEPS
The total cost of RPS dam and power station was Rs 40.65crores out of
which Rs 14.74crores was spent for power station. All the equipments of
power station were imported from Canada under Colombo Yojana.
There are four units of 43 MW(e) each. First starting date of these units are-
Unit Capacity Date of generation
First 43MW 03.02.1968
Second 43MW 26.06.1968
Third 43MW 28.12.1969
Fourth 43MW 24.05.1969
4.3 FUNCTIONAL IMPORTANCE
This plant plays a most crucial role when there is a disturbance in the Northern
grid. When the grid fails this power station provides the startup power for
restoring the Northern grid. It also plays a major role in the routine times by
providing stability to the machines of Rawatbhata Atomic Power Plant
contributing to the stability of the grid.
4.4 PARAMETERS RELATED TO RPS HPS, RAWATBHATA
S.no. PARTICULARS
1 Location:
-Attitude
-Longitude
-Altitude
24°-53° North
75°-35°East
354 meter above MSL
2 Water Storage Capacity 9600Sq.Mile
3 Catchment Area 76.55Sq.Mile
4 Reservoir Capacity 76.55Lakh acr. Ft
5 Max. reservoir level 1162Ft.
6 Min. Draw down level 1128.5Ft
7 Full reservoir level 1157.5Ft
8 Generating capacity 4X43 MW
9 Diameter of Penstock 20Ft.
10 Maximum Head 189Ft.
11 Minimum Head 152Ft.
12 Crest Gate 17;60X28 Ft.
13 Sluce Gate 4;9X11 Ft.
14 Length of tunnel 4840 Ft.
15 Diameter of tunnel 40 Ft.
16 Maximum Discharge 14000cusecs
17 Length of Top Portion Of Dam 3750 Ft.
18 Maximum Height Of Dam 177 Ft.
19 Generator output 11KV
20 Output Lines Voltage 132KV
21 Submerged Area 198 Esq.
Table 4.1
4.5 SELECTION OF SITE
Selection of suitable site for hydroelectric plant. If a good system of natural
storage lakes at high altitudes and with catchment can be located.
The following factors should be considered.
Such power stations are build where there is adequate water be build at
good head i.e. huge quality of water is following across a given point.
Since storage of water in a suitable reservoir at 5 a height or building of
Dam across the river is essential in order to have continuous & terminal
supply during the dry season. Therefore, convenient accommodation for
erection of a Dam or reservoir must be available.
The reservoir must have a large catchment area.
The land should be cheap in cost & rocky in order to withstand the
weight of large building & heavy machinery.
Adequate transportation facilities must be available or there should be
possibility the same .So that the necessary equipment & machinery
could be easily transported.
There should be possibility of stream diversion, during period of
construction.
CHAPTER 5
MAJOR ELEMENTS
FIG:5.1: INSIDE A HYDRO-ELECTRIC PLANT
5.1 STORAGE RESERVOIR
Its purpose is to store water during excess flow periods and supply the same
during lean flow periods. Thus it helps in supplying water to the turbines
according to load of power plant. Live storage i.e. 1.27 MAFT, the full
reservoir levels is 1162 feet.
5.1.1 DAM
The function of dam is not only to raise the water surface of the stream but
also to create an artificial head and to provide the poundage, storage or the
facility of diversion into conduits. A dam is the most expensive & important
part of a hydro-project . this dam’s total length is about 1 Km 25 feet wide and
total height of dam is 177 feet.
5.1.2 FOREBAY
A for bay may be considered as an enlarged body of water just above the
intake to store water temporarily to meet the hourly load fluctuations.
5.1.3 TRASHRACK
It is provided for preventing the debris form getting entry into the intakes from
the fore bay. Manual cleaning or mechanical cleaning is used to remove the
debris from trash rack. Trash rack is made up of steel bars and it is placed
across the intake to prevent the debris form going into the intake.
5.1.4 SPILWAY
This is constructed to act as safety valve. It discharges the overflow water to
the down streamside when the reservoir is full. A condition mainly arises
during floods periods. These are generally constructed of concrete and
provided with water discharge opening shut off by gates. There are 17 gates
used for discharge the overflow water. The size of each gate is 60X28 Feet.
5.1.5 PENSTOCK
It is closed conduct, which connected the fore bay or surge tank to the scroll
case of turbine. In case of medium heads power plants(like R.P.S)such unit is
usually provided with its own penstock with its own penstock. Penstock is
build of steel. The typical diameter of penstock is 20 feet.
5.1.6 TAIL RACE
The water after having done its useful worked in the turbine is discharged to
the tailrace, which may lead it to the same stream or to another one. The water
is discharge through a tunnel. The tunnel is raised the effective head of water
level. The tunnel length is 4810 feet and average discharge through tunnel is
14000 cufeet/sec.
5.1.7 DRAFT TUBES
An airtight diverging with cross-sectional area increasing along its length. It is
an integral part of turbine. The inlet of draft tube is connected to the turbine
and outlet is submerged deep into tailrace. The draft tube makes the turbine
capable of utilizing kinetic energy of the exit water. It also decreases the
pressure at the runner exit to a value less than atmospheric pressure hence the
working head gets increased.
5.1.8 HYDRAULIC TURBINE
A hydraulic turbine is a mechanical device that converts the potential energy
associated with a difference in water elevation head into useful work. Modern
hydraulic turbines are the result of many years of gradual development.
Economic incentives has resulted in the development of very large units
(exceeding 800 MW in capacity) with efficiencies that are sometimes in excess
of 95%.
The emphasis on the design and manufacture of very large turbines is shifting
to the production of smaller units, especially in developed nations, where
much of the potential for developing large-base load plants has been realized.
At the same time, the escalation in the cost of energy has made many smaller.
Sites economically feasible and has greatly expanded the market for smaller
turbines. The increased value of energy also justifies the cost of refurbishment
and increasing the capacity of older facilities.
Thus, a new market area is developing for updating older turbines turbines
with modern replacement runners having higher efficiency and greater
capacity.
In the hydro electric power plants water turbine are used as prime movers and
their functions is to convert the kinetic energy of water into mechanical
energy, which is further utilized to drive the alternators generate electrical
energy.
The RPS hydroelectric power plant is low head plant so “ FRANCIS
TURBINE”
is used. It is a reactor turbine and is suitable for low and medium head power
plant. Such turbines develop power partly due to velocity of water and partly
due to difference in pressure acting on the front and back of the runner
buckets.
Such a turbine essentially consists of “guide apparatus”. Consisting of an outer
ring of stationary blades are fixed to the casing of the turbine and an inner ring
consisting of rotating blades forming a runner. Number of blunders in a glide
over the blades with a small and fairly constant velocity and exerts a pressure,
varying form maximum at the top to a small value at the bottom. The water
flows radically inwards and changes to a downward direction while passing
through the runner.
As the water passes over the rotating blades of the runner, both pressure as a
velocity of water are reduced causing a reaction force during the turbine. After
doing work, water is discharged to the tailrace through a closed tube of
increasing cross section called the draft tube.
The guide blades of the turbine are adjustable about the hinged point with the
help of governing mechanism but don’t rotate with the runner. The guide
blades arranged in the casing around the runner, which give proper direction to
water jets in such a way that the jet don’t strike the runner vanes in opposite
direction.
5.2 TURBINE CLASSIFICATION
There are two types of turbines, denoted as impulse and reaction. In an
impulse turbine, the available head is converted to kinetic energy before
entering the runner, the power available is extracted from the flow at
approximately atmospheric pressure. In a reaction turbine, the runner is
completely submerged head in the inlet to the turbine runner is typically less
than 50% of the total head available.
5.2.1 IMPULSE TURBINES
Modern impulse units are generally of the pelton type and are restricted to
relatively high head applications. One or more jets of water impinge on a
wheel containing many curved brackets.
5.2.2 REACTION TURBINES
Reaction turbines are classified according to the variation in the flow direction
through the runner. In radial and mixed flow runners, the flow exists at a
radius different than from the radius at the inlet. If the flow enters the runner
with only radial and tangential components, it is a radial flow machine. The
flow enters a mixed flow runner with both radial and axial components.
Francis turbines are of radial and mixed flow types, depending on the design
specific speed. A Francis turbine is illustrated in fig. The efficiency of francis
turbine varies from 80% to 85%.
FIG.5.2 Impulse turbine vs Reaction turbine
FIG 5.3 FRANCIS TURBINE
5.2.3TURBINE SPECIFICATIONS-
FRANCIS HYDRAULIC TURBINE
KW 52.00Net head 49.7MRPM 125No. of blades 16Designed by KMW and Johnson & co. ltdBuilt by Marine industries ltd. Sorei, queInstalled 1969
Table 5.1
5.2.4 Design and manufacture of turbines
Kaplan Francis Pelton
Head :1.80/25m Runner
blades :4/5/6 Runner diameter:
700mm to 4000mm
Arrangements Vertical simple or
Double regulated Horizontal simple
orDouble regulated
Inclined simple regulated
Siphon intake Power: 100kw to
7mw
Head:15m/200m Runner
diameter:250mm/ 3500mm
Specific speed from 90 to 425
Arrangements Vertical shaft Horizontal shaft Semi spiral
casing or full spiral casing
Double francis (2 runners)
Power:500kw to 15kw
Head:100m/1000m Diameter of the
wheel till 1800mm
Arrangements Vertical 3 jets/4 jets Horizontal
1jet/2jets Double (horizontal
4 jets) Power:100kw to
10mw
Table 5.2
5.2.5 Level of Equipment
Floor Level (feet) Equipments Dam road 1172 60 ton EOT crane
Entrance to penstock gate gallery Switch yard 1084 102kv switch yard including 9
circuit breakers, 3 SF6 breaker & associated equipments
33/11kv-1MVA transformer Entrance to bypass valve High head discharge pump house for
emulsifier tank Top of EOT crane 1052 125 ton EOT craneWorkshop 1040 Machine shop
Oil handing tanks 3.3/0.4 kv transformer of diesel 250KVA,400V diesel generator
Control room 1025 Control room Transformer yard High head discharge pumps for
rainy season Dewatering pumps Station auxiliary transformer Air conditioning system
Service boy and divisional storeMachine hall 1006 11kv switch gear system
440V breaker and lighting system PLCC room Cable room Exciter and PMG of generator
Turbine pit 985.5 Sump pump for dewater the sump tankDt manhole 969Dt gallery 957.5Bottom of craft tube
939
Bottom of sump 939.5 Table 5.3
5.2.6 Mounted on unit control board
Temperature indicator with 14 position transfer switch 4-point generator, stator 4-point cooler air outlet 2-point test 4-points spare 4- temperature indicators, foxbaro rotax vapour pressure, dial type with
alarm contacts 1-generator thrust bearing 1-generator guide bearing 1-oil reservoir 1-turbine bearing Rotor temperature indicator with 2 alarm contacts
CHAPTER 6
POWER TRANSFORMER
Power transformer is used for stepping up the voltage for transmission.
Generally Δ-Y connected power transformers are used. They are oil-immersed
transformer. The transformer connection is generally shown by vector group.
The vector groups of power transformers of RPS power plant are Yd11.
6.1 TRANFORMER RATING
KVA 55000
Phase 3
Cycle 50Hz
Input 11KV(delta)
Output 132KV(star)
Cooling OFW-55°C
Table 6.1
Cooling water
Cooler -55000 KVA 109 GPM
Cooler-60000 KVA 150 GPM
6.2 GOVERNING SYSTEM
In order to have electrical output if constant frequency it is necessary to
maintain speed of the alternation driver with the turbine constant. An operation
of speed regulation is called the governing. It is attained automatically by
means of a governor. The principle elements of the governor are-
The speed responsive elements usually fly ball mechanism or speed
governor
Control value or rally value to the either side of servomotor piston
Servomotor along with fluid pressure operates piston to activate the
turbine control mechanism
The restoring mechanism or follow up linkage to hold servomotor in the
required fixed position. When the input and output are equalized
The fluid pressure supply require for the action of servomotor.
6.3 ELECTRICAL EQUIPMENT
Generator
The generators used in hydro power plant are usually three phase
synchronous machines. The generators have the speed range of 70-1000
RPM. Generators have either a vertical shaft arrangement or horizontal
shaft arrangement. But the vertical shaft arrangement is preferred. The
generator cooling can be achieved by air circulation through the stator
ducts
6.3.1 Main components of generator
Stator
The 396 slot stator is wound with diamond type coils containing four
windings and connects 6 circuit wires with 6 main and 3 neutral leads
brought out. Resistance between lines at 25 centigrade is 0.01348 ohms.
Stator winding insulation is class b, the ground installation segment of
which is asphalt-mica.
Rotor
The field coils are lubricated strip wound, 27 turns per pole in class B
installation. Resistance of the 48 posts field windings 0.196 ohms at 25
centigrade.
Main bracket
All rotating parts in addition to hydraulic thrust are supported through
the thrust bearing by the main bracket has 4 arms resting on the edge of
the turbine pit. At the end of each bracket arms are mounted two units of
counted brackets and jacks.
Housing and cooler
Totally enclosed in an octagonal steel housing 38’-1’ across flats, with
top flush with upper bracket arms. Approx. 120000CFM of ventilating
air passes through the rim and between passes through the stator and
finally through the air coolers before recycling. Air coolers are 8 inch
mounted symmetrical around the machine.
Maximum tested pressure is 10kg/cm square.
CHAPTER 7
ELECTRICITY GENERATION
FIG7.1HYDROELECTRIC POWER
7.1 HYDROELECTRIC POWER: HOW IT WORKS
So just how do we get electricity from water? Actually, hydroelectric and coal
fired power plants produce electricity in a similar way. In both cases a power
source is used to turn a propeller-like piece called a turbine, which then turns a
metal shaft in an electric generator, which is the motor that produces
electricity. A coal-fired power plant uses steam to turn the turbine blades,
where as a hydroelectric plant uses falling water to turn the turbine. The result
is the same.
FIG7.2 GENERATOR
The theory is to build a dam on a large river that has a large drop in elevation.
The dam stores lots of water behind it in the reservoir. Near the bottom of the
dam wall there is the water intake. Gravity causes it to fall through the
penstock inside the dam. At the end of the penstock there is a turbine propeller,
which is turned by the moving water. The shaft from the turbine goes up into
the generator, which produces the power. Power lines are connected to the
generator that carry electricity to your home and mines. The water continues
past the propeller through the tailrace into the river past the dam. By the way,
it is not a good idea to be playing in the water right below a dam when water is
released.
“A hydraulic turbine converts the energy of flowing water into mechanical
energy. A hydro electric generator converts this mechanical energy into
electricity.
The operation of a generator is based on the principle discovered by Faraday.
He found that when a magnet is moved past a conductor, it causes electricity to
flow. In a large generator, electromagnets are made by circulating direct
current through loops of wire wound around stacks of magnetic steel
laminations. These are called field poles and it is mounted on the perimeter of
the rotor. The ro is attached to the turbine shafts and rotates at a fixed speed.
When the rotor turns, it causes the field poles (the electromagnets) to move
past the conductors mounted in the stator. This in turn causes the electricity to
flow and a voltage to develop at the generator output terminals”.
Most hydroelectric power comes from the potential energy of dammed water
driving a water turbine and generator. In this case the energy extracted from
the water depends on the volume and on the difference in height between the
source and the water’s outflow. This height difference is called the head. The
amount of potential energy in water is proportional to the head. To obtain very
high head, water for a hydraulic turbine may be run through a large pipe called
a penstock.
Pumped storage hydroelectricity produces electricity to supply high peak
demands by moving water between reservoirs at different elevations. At the
times of low electrical demand, excess generation capacity is used to pump
water in to the higher reservoir. When there is higher demand, water is
released back into the lower reservoir through the turbine. Pumped storage
schemes currently provide the only commercially important means of large
scale grid energy storage and improve the daily load factor of the generation
system. Hydroelectric plants with no reservoir capacity are called run of the
river plant, since it is not possible to store the water. A tidal power plant makes
use of the daily rise and fall of water due to tides, such sources are highly
predictable and if conditions permit construction of reservoirs can also be
dispatch able to generate power during high demand periods.
Less common types of hydro schemes use water’s kinetic energy or
undammed sources such as undershot waterwheels.
A simple formula for approximately electric power production at a
hydroelectric plant is-
P =hrgk,
Where,
P is power in kilowatts
h is height in meters
r is flow rate in cubic meters per second
g is acceleration due to gravity
k is a coefficient of efficiency ranging from 0 to 1
Efficiency is often higher with larger and more modern turbines.
Annual electric energy production depends on the available water supply. In
some installations the water flow rate can vary by a factor of 10:1 over the
course of a year.
7.2 INDUSTRIAL HYDROELECTRIC PLANTS
While many hydroelectric projects supply public electricity networks, some
are created to serve specific industrial enterprises. Dedicated hydroelectric
projects are often built to provide the substantial amounts of electricity needed
for aluminum electrolytic plants.
7.3 SMALL SCALE HYDRO ELECTRIC PLANTS
Although large hydroelectric installations generate most of the worlds
hydroelectricity , some situations require small hydro plants. These are defined
as plants producing up to 10 megawatts or projects up to 30 megawatts in
north America. A small hydro power plant may be connected to a distribution
grid or may provide power to a isolated community or a single home. Small
hydro projects generally do not require the protracted economic, engineering
and environmental studies associated with large projects and often may be
completed much more quickly. A small hydro development may be installed
along with a project with flood control, irrigation or other purposes providing
extra revenue for project costs. In areas that formerly used waterwheels for
milling and other purposes often the site can be redeveloped for electric power
production, possibly eliminating the new environmental impact of any
demolition operation. Small hydro can be further divided into mini hydro units
around 1MW in size and micro hydro with units as large as 100KW down to
couple of KW rating.
Small hydro schemes are particularly popular in china, which has over 50% of
world small hydro capacity. Small hydro units in the range of 1MW to about
30MW are often available from multiple manufacturers using standardized
“water to wire” packages, a single contractor can provide all the major
mechanical and electrical equipment (turbine, generator, controls, switchgear),
selecting from several standard designs to fit the site conditions. Micro hydro
projects use a diverse range of equipments, in the smaller sizes industrial
centrifugal pumps can be used as turbines with comparatively low purchases
cost compared to purpose built turbines.
7.4 ADVANTAGES
The upper reservoir and dam of the festiniog pumped storage scheme. 360
MW of electricity can be generated within 60 seconds of the need arising.
7.5 ECONOMICS
The major advantage of hydro electric is elimination of the cost of fuel. The
cost of operating a hydroelectric plant is nearly immune to increase in the cost
of fossil fuels such as oil, natural gas or coal and no imports are needed.
Hydroelectric plants also tend to have longer economic lives than fuel fired
generation, with some plants now in service which were built 50 to 100 years
ago.
Operating labor cost is also usually low, as plants are automated and have few
personnel on site during normal operation.
When a dam serves multiple purposes, a hydro electric plant may be added
with relatively low construction cost, providing a useful revenue stream to
offset the costs of dam operation.
7.6 GREEN HOUSE GAS EMMISSIONS
Since hydro electric dams do not burn fossil fuels, they do not directly produce
carbon dioxide. While some carbon dioxide is produced during manufacture
and construction of the project, this is a tiny fraction of the operating emissions
of equivalent fossil fuel electricity generation.
7.7 RELATED ACTIVITIES
Reservoirs created by hydroelectric schemes often provide facilities for water
sports, and become tourist attractions in themselves. In some countries,
aquaculture in reservoir is common. Multi uses dams installed for irrigation
support agriculture with a relatively constant water supply. Large hydro dams
can control floods, which would otherwise affect people living downstream of
the project.
7.8 DISADVANTAGES
The power produced by the plant depends upon the quantity of water
which in turn is dependant upon the rainfall, so if the rainfall is in time
and proper and the required amount of water is collected, the plant will
function satisfactory otherwise not.
Hydro electric plants are generally situated away from the load centers.
They require along transmissions lines to deliver power. Therefore the
cost of transmission lines and losses in them will be more.
Initial cost of plant is high.
It takes fairly long time for the erection of such plants.
7.9 HYDRO ELECTRIC POWER STATIONS AND
ENVIRONMENT
Hydro electric power plants are most efficient electricity generators. They
produce no green house gases and are ideal way to store electricity. However,
building hydro electric plants can have serious consequences for both the
environment and the people. Damming a watercourse normally results in the
flooding of the surrounding area with the consequent loss of flora and fauna.
People living in the area can be displaced for the same reason.
Even though a hydroelectric plant produces no green house gases they can
have a impact on the greenhouse effect. The carbon on the flooded land has to
be considered. It has been proposed that as a size of the lake associated with
the flooding due to a hydroelectric scheme increases, so does the amount of
carbon dioxide equivalent emissions. The amount of the carbon that is
converted to methane increases with the size of the lake. However, this
decreases as the output of the hydro schemes and its lifetime increases. Over a
period of a hundred years, methane has a warning effect twenty one times that
of carbon dioxide. More research into this aspect of hydro electric plants is
required.
7.10 COMPARISON WITH OTHER METHODS OF POWER
GENERATION
Hydro electricity eliminates the flue gases emissions from fossil fuel
combustion, including pollutants such as sulfur dioxide, nitric oxide, carbon
monoxide, dust and mercury in the coal. Hydroelectricity also avoids the
hazards of the coal mining and the indirect health effects of coal emissions.
Compared to nuclear power, hydroelectricity generates no nuclear wastes, has
none of the dangers associated with uranium mining, nor nuclear leaks. Unlike
uranium, hydroelectricity is also a renewable energy source.
Compared to the wind farms, hydroelectricity power plants have a more
predictable load factor. If the project has a storage reservoir , it can be
dispatched to generate power when needed. Hydroelectric plants can be easily
regulated to follow variation in power demand.
Unlike fossil fueled combustion turbines, construction of a hydroelectric plant
requires a long lead time for site studies, hydrological studies, and
environmental impact assessment. Hydrological data up to 50 years or more is
usually required to determine the best sites and operating regimes foe a large
hydroelectric plant. Unlike plants operated by fuels, such as fossil and nuclear
energy, the number of sites that can be economical developed for hydro
electric production is limited in many areas the most cost effective sites have
already been exploited. New hydro site tends to be far from population centers
and require extensive transmission lines. Hydro electric generation depends
upon rainfall in watershed and may be significantly reduced in years of low
rainfall or snowmelt. Long term energy yield may be affected by climate
change. Utilities that primarily use hydro electric power may spend additional
capital to build extra capacity to ensure sufficient power is available in low
water years.
Hydro power is one of the three principle source of energy used to generate
electricity, the other two being fossil fuels and nuclear fuels. Hydro electricity
has certain advantages over these other sources: it is continuously renewable
thanks to the recruiting nature of the water cycle, and causes no pollution. Also
ii is one of the cheapest sources of electrical energy.
The electrical power obtained from conversion of potential and kinetic energy
of water is called hydropower.
PE=WZ
Where
PE is potential energy
W is total weight of water
Z is vertical distance travelled by water
Power is the rate at which energy is produced or utilized
1 horsepower(hp) = 550 ftlb/s
1 KW = 738 ft lb/s
CHAPTER 8
ELECTRICAL SYSTEM
The generation of the electricity is at 11KV and transmitted on 132 KV. There
are four transmission lines from the RPS power plant, two lines to Kota and
other two to Bhilwara, two lines to Gandhi sagar and one industrial line.
8.1 MAJOR ELECTRICAL EQUIPMENT WITH THERE
SPECIFICATIONS
8.1.1 ALTERNATOR:
At the RPS hydel power plant vertical overhung type alternator is used, with
one thrust and one guide bearing both located below the rotor. The alternator
used with Francis turbine of vertical configuration. The vertical generators at
RPS are very low about 125 RPM so no. of poles are 48.
8.1.2 ALTERNATOR RATING
Model 100780
Type ATI
Class 48-47778-125
Cycles 50
Volts 11000
RPM 125
KVA 47778
KW 43000
AMP 2515
Excitation volts 250
Amp. Excitation 854
Max. stator temp. raise 55°C
Table 8.1
Stator temperature raise measured by RTD rotor temperature raise measured
by resistance.
8.2 CURRENT TRANSFORMER
These instrument transformers are connected in ac power circuits for leading
the current coils of indicating and meeting (ammeters, watt meters, watt hour
meters) and protective relays.
Thus the CT broadens the limit of measurements and maintain a watch over
the current flowing in the circuits and over the power load. In high voltage
installations CT in addition to above also isolates the indicating and metering
instruments fron high voltages. The CT basically consists of an iron core on
which few turns of primary is directly installed of the power circuit and to the
secondary winding the indicating or metering instruments or relay is
connected. When the rated current of CT flows through its primary winding a
current of 5 amperes will appears in its secondary winding. The primary
winding is usually single turn and the no. of turns on secondary depends upon
the power circuit current to be measured.
The larger current to be secondary current is known as transformation ration of
CT. The CT are rated for voltage of the installations the rated current of the
primary and secondary winding and the accuracy class. The accuracy class
indicates the limit of the errors in percentage of the rated turn ratio of the given
current transformer is available in the accuracy classes 0.5, 1.3 and 10.
Basically CT is a step up transformer. It is a primary side current is high and
secondary side current is less than 5A, which is used for protection of meeting
purpose. Its primary is always connected in series.
8.2.1 CURRENT TRANSFORMER RATING
VICTRANS ENGINEERS,NAGPUR(INDIA)
High system voltage 145KV
Frequency 50Hz
Insulation level 275/650KV
Type C-1140
Short time thermal current 31.5KV
Ratio 200-400/5-5.5A
TABLE 8.2
GENERAL ELECTRIC,CANADA
Type CTP-15
Ratio 3000-5amps
Cycles 25-60
Max. continuous amp 4500 at 35°C
INS CLASS 0.6Kr
CAT no. 4.0732XX3
TABLE8.3
8.3 POTENTIAL TRANSFORMER
The potential transformers are employed for voltages above 380 volts to feed
the potential coils of indicating and metering instruments (voltmeters, watt
meter, watt hour meter) and relays. These transformers make the ordinary low
voltages instruments suitable for measurement of high voltages and isolate
them from high voltages. The primary winding of the potential transformer is
connected to the main bus-bars of the switch gear installation and the
secondary winding various indicating and metering instruments and relays are
connected when the rated high voltage is applied the primary of PT. The
voltage of 110 volts appears across the secondary winding. The ratio of the
rated primary voltage to rated secondary voltage is known as transformers
ratio.
The potential transformers are rated for primary and secondary rated voltage,
accuracy, class, no. of phases and system of cooling. Basically P.T.’S are step
down transformer. They are only used foe metering purpose. Its secondary
voltage is about of 110 volts and these are connected in parallel with the line.
8.4 CIRCUIT BREAKER
Circuit breakers are mechanical devices designed to close or open contact
members, thus closing or opening an electrical circuit under normal or
abnormal conditions. Circuit breakers are rated in terms of maximum voltage,
no. of poles, frequency, maximum continuous current carrying capacity and
maximum momentary and 4 second current carrying capacity.
The interruption or reparsing capacity of a circuit breaker is the maximum
value of current which can be interrupted by it without any damage.
The circuit breakers are classified on the basis of the medium used for arc
extension.
8.4.1 THE TYPES OF CIRCUIT BREAKERS –
SF6 circuit breaker
Bulk oiled circuit breakers
Air blast circuit breakers
Vacuum circuit breakers
Minimum oil circuit breakers
Air circuit breakers
Miniature circuit breakers
The circuit breakers are automatic switches, which can interrupt fault currents.
The part of the circuit breakers connected in on phase is called the pole. A
circuit
Breakers suitable for three phase is called the pole. A circuit breaker suitable
for three phase system is called a triple pole circuit breaker. Each pole of the
circuit breaker comprises one or more interrupters or arc extinguishing
chambers. The interrupters are mounted on the support insulators. The
interrupter encloses a set of fixed and moving contact. The moving contacts
can be drawn spark by means of the circuit breakers given the necessary
energy for opening and closing of contacts of the circuit breakers.
The arc produced by the separation of current carrying contact is interrupted
by a suitable medium and by adopting suitable techniques for arc extinction
medium.
CHAPTER 9
SF6 GAS CIRCUIT BREAKERS
Sulfur hexafluoride (SF6) is an excellent gaseous dielectric for high voltage
power applications. It has been used extensively in high voltage circuit
breakers and other switchgears employed by the power industry. Applications
for SF6 include gas insulated transmission lines and gas insulated power
distributions. The combined electrical, physical, chemical and thermal
properties offer many advantages when used in power switchgears. Some of
the outstanding properties of SF6 making it desirable to use in power
applications are:
Very high dielectric strength
Very unique arc quenching ability
Excellent thermal stability
Good thermal conductivity
9.1 GENERAL INFORMATION
SF6 circuit breakers are equipped with separated poles each having its own
gas. In all types of the circuit breakers, gas pressure is 2 bars( absolute 3 bars).
Even if the pressure drops to 1 bar, there will be no change in the breaking
properties of the circuit breakers due to the superior features of SF6. During
arcing, the circuit breakers maintains a relatively low pressure ( max 5-6 bars)
inside the chamber and there will be no danger of explosion and s[pilling of
the gas around. Any leakage from the chamber will not create a problem since
SF6 can undergo considerable decomposition, in which some of the toxic
products may stay inside the chamber in the form of the white dust.
Fig 9.1 SF6 circuit breaker
If the poles are dismantled for maintenance, it needs special attention during
removal of the parts of the pole. This type of maintenance should be carried
out only by the experts of the manufacturer.
9.2 OPERATION OF CIRCUIT BREAKER
In general, the circuit breakers consist of two main parts, the poles and the
mechanism. The poles consist of contact and arc-extinguishing devices. the
mechanism is the part to open or close the contacts in the poles at the same
time simultaneously . the closing and opening springs are the first charged. If
“close” button is pressed the opening springs get charged while the contacts
get closed. Thus, circuit breaker will be ready for opening. The mechanical
operating cycle of the circuit breaker is used with re-closing relay. In that
case, after the closing operation , the closing springs are charged by the
driving lever or by driving motor . thus, the circuit breaker will be ready for
opening and re-closing.
Elimsan breaker mechanism can perform 10,000 opening-closing operations
without changing any component. The mechanical life of the circuit breaker is
minimum 10,000 operations. However, it needs a periodical maintenance
depending on its environment. In ideal working condition s, lubrication once a
year or after every 1000 operations is sufficient. In dusty and damp
environment, the mechanism should be lubricated once every 3-6 months or
after every 250-500 operations.
The machine oil and grease with molybdenum must be used for lubricating.
Owning to mechanisms capability of operating between -5C and +40C , it
does not require a heater.
9.3 AUXILARY SWITCH
The auxiliary switch mounted on the circuit breakers has 12 contacts. One of
them is for anti-pumping circuit, four of them are allocated for opening and
closing coils. The remaining 7 contacts are spare. Three of them are normally
opened and four are normally closed. When it is necessary, the no. of the
contacts can be increased.
9.4 RAPID AUTOMATIC RECLOSING
The circuit breaker which opens due to a short circuit failure, can be re closed
automatically after a pre selected time by arc closing relay, assuming the fault
is temporary. Thus, we avoid long time power loss in case of temporary short
circuits. But, if the fault lasts after re-closure, the protection relay will trip to
open the circuit breakers again.
When manual or motor drive is used, the circuit breaker will be ready to close.
The closure can be actuated pressing the closing button located on the circuit
breaker. It is recommended to close it using remote control system for secure
operations. The opening can be performed either by opening button or remote
controlled opening coil. In case of a fault, the relay signal actuates the opening
coil and circuit breaker opens. In addition, there is an anti-pumping relay for
preventing the re-closing and opening of the circuit breaker more than one
cycle(O-C-O) and for preventing possible troubles created by remote closing
button.
9.5 COMMISSIONING
The outer surface of epoxy insulating tubes o the poles are to be wiped out
with a clean and dry cloth. The wiring and connections of the auxiliary circuit
are to be carefully examined. DC voltage should be checked to see whether it
is suitable for coil and motor or not.
Table 9.2 CROSS SECTION OF SF6 CIRCUIT BREAKER
The opening closing coils are to be operated 15-20 times and the accuracy of
relay circuit is to be checked before energizing the circuit breaker. The circuit
breaker is to be mounted with two MI2 bolts through its anchoring shoes. It
should not move during operation. No excessive load should be exerted to the
poles and if possible flexible cables are used. The incoming and outgoing
contacts must have clean surfaces and their contact resistance should be as
low as possible. When connecting the circuit breaker to protection system and
auxiliary supply, the cable cross sections should be according to the table
given. The circuit breaker must be grounded through at least 16mm steel tape.
After all, the following procedure must be performed-
Open the isolator of the circuit breaker
Prepare the circuit breaker for closing operation by driving mechanism
Close the isolator of circuit breaker firmly
Send the closing signal to the circuit breaker
CHAPTER 10
FIRE PROTECTION SYSTEM
10.1 FIRE PROTECTION SYSTEM
10.1.1 SMOKE DETECTOR SYSTEM
Smoke detectors are provided at different areas of the plant, which will operate
and generate an alarm in C/R in case of any fire in that area to take corrective
and timely action.
10.1.2 MULTIFIRE SYSTEM
All big transformers are protected by high velocity “Multi-fire projectors”
erected about and above the equipments are required. The projectors are
coupled together on a pipe work system to an automatic deluge valve assembly
consisting of strainer, isolating valve and a quick opening deluge valve for
control of the water supply.
The automatic deluge valve is operated by means of a separate detector pipe
work system on which quartzoid bulbs are mounted filled with liquid of high
expansion coefficient.
The detector system is charged with compressed air. In the event of a fire, one
or more of these bulbs will burst due to expansion of liquid and allowing
compressed air to escape from the pipe work. When the air pressure has fallen
the deluge valve opens and brings the multi-fire projectors to action and starts
water supply spray on the equipments automatically and protect them from
fire.
Alarming sound will generate the operation of the system to alert to staff to
take further course of action.
10.2 ISOLATOR
Isolator are not equipped with a quenching device and therefore are not used to
open circuits carrying current, as the name implies solatores one portion of the
circuit from another and is not intended to be opened while current is flowing.
Isolators must not be opened until the circuit is interrupted by some other
means. If an isolator is opened carelessly when carrying a heavy current, the
resulting arc could easily cause a flash over the earth. Thus may shatter the
supporting isolators and may even cause a fatal accident to the operator,
particularly in high voltage circuits.
10.3 EARTHING SWITCH
Earthing switch is connected between the line conductor and the earth.
Normally it is open when the line is disconnected, the earthing switch is closed
so as to discharge the voltage trapped on the line capacitance to the earth.
Through the line is disconnected, there is some voltage on the line to switch
the capacitance between line and earth is charged. The voltage is significant in
high voltage system. Before proceeding with the maintenance work the voltage
is discharged to earth by closing the earthing switch. Normally the earthing
switch is mounted on the frame of isolators.
BIBILOGRAPHY
1. http://www.rvunl.com/RPS.php
2. http://www.mannvit.com/HydroelectricPower/HydroelectricPowerPlants/
3. http://services.indiabizclub.com/catalog/635880~gas+refilling+in+sf6+breaker~faridabad
4. http://mygreenchannel.org/