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

1.

INTRODUCTION

2.

INDIA’S CRITICAL NEED

2.1

3.

Page No.

:

1

FOR POWER

:

3

WATER POWER

:

3

BASIC PRINCIPLE AND METHODS OF ELECTRIC GENERATION

:

4

3.1

BASIC PRINCIPLE

:

4

3.2

TYPICAL HYDRO POWER :

5

:

6

:

7

:

7

STATION 3.3

4.

OUTPUT SYSTEM

GENERAL DESCRIPTION 4.1

FUNCTION OF RPS HPS

4.2

COST AND OPERARATIONAL STATISTICS OF RPS HPS

:

8

:

8

RPS HPS

:

9

SELECTION OF SITE

:

10

:

11

:

11

4.3

FUNCTIONAL IMPORTANCE

4.4

PARAMETRS RELATED TO

4.5

MAJOR ELEMENTS

5. 5.1

STORAGE RESERVOIR

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

:

15

5.2 TURBINE CLASSIFICATION 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

:

21

6.

POWER TRANSFORMER 6.1

TRANSFORMER RATING

:

21

6.2

GOVERNING SYSTEM

:

21

6.3

ELECTRICAL EQUIPMENT

:

22

:

22

:

24

:

25

6.3.1

MAIN COMPONENTS OF GENERATOR

ELECTRICITY GENERATION

7. 7.1

HYDRAULIC POWER

7.2

INDUSTRIAL HYDROELECTRIC :

28

PLANTS

:

28

7.4

ADVANTAGES

:

29

7.5

ECONOMICS

:

29

7.6

GREEN HOUSE GAS EMISSIONS

:

29

7.7

RELATED ACTIVITIES

:

30

PLANTS 7.3

SMALL SCALE HYDROELECTRIC

7.8

DISADVANTAGES

7.9

HYDROELECTRIC POWER STATIONS AND ENVIRONMENT

:

30

:

30

7.10 COPARISONS WITH OTHER METHODS OF POWER GENERATION

8.

ELECTRICAL SYSTEM 8.1

:

33

:

33

8.1.1

ALTERNATOR

:

33

8.1.2

ALTERNATOR RATING

:

33

:

34

:

35

:

36

CURRENT TRANSFORMER 8.2.1

CURRENT TRANSFORMER RATING

8.3

POTENTIAL TRANSFORMER

8.4

CIRCUIT BREAKER

9.

31

MAJOR ELECTRICAL EQUIPMENTS WITH THEIR SPECIFICATION

8.2

:

:

36

8.4.1 THE TYPES OF CIRCUIT BREAKER

:

36

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

FIREPROTECTION SYSTEM

:

44

:

44

10. 10.1

FIRE PROTECTION SYSTEM

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

:

35

(Victrans Engineers) 8.3 Current Transformer Rating (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 demandsGeneration

Demands

Hydel 32%

Agriculture 40%

Thermal 55%

Industrial 38%

Gas 10%

Domestic 22%

Nuclear 3% 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 areUnit

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

24°-53° North

-Longitude

75°-35°East

-Altitude

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 SPECIFICATIONSFRANCIS HYDRAULIC TURBINE KW Net head RPM No. of blades Designed by Built by Installed

52.00 49.7M 125 16 KMW and Johnson & co. ltd Marine industries ltd. Sorei, que 1969 Table 5.1

5.2.4 Design and manufacture of turbines Kaplan

 Head :1.80/25m  Runner blades :4/5/6  Runner diameter: 700mm to 4000mm Arrangements  Vertical simple or Double regulated  Horizontal simple or Double regulated  Inclined simple regulated  Siphon intake  Power: 100kw to 7mw

Francis

Pelton

 Head:15m/200m  Head:100m/1000m  Runner  Diameter of the diameter:250m wheel till 1800mm m/ 3500mm  Specific speed from 90 to 425 Arrangements Arrangements  Vertical 3 jets/4 jets  Vertical shaft  Horizontal  Horizontal shaft 1jet/2jets  Semi spiral  Double (horizontal casing or full 4 jets) spiral casing  Power:100kw to  Double francis 10mw (2 runners)  Power:500kw to 15kw

Table 5.2

5.2.5 Level of Equipment

Floor Dam road

Level (feet) 1172

Switch yard

1084

Top of EOT crane Workshop

1052 1040

Control room

1025

Machine hall

1006

Turbine pit Dt manhole Dt gallery Bottom of craft tube Bottom of sump

985.5 969 957.5 939

Equipments  60 ton EOT crane  Entrance to penstock gate gallery  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  125 ton EOT crane  Machine shop  Oil handing tanks  3.3/0.4 kv transformer of diesel  250KVA,400V diesel generator  Control room  Transformer yard  High head discharge pumps for rainy season  Dewatering pumps  Station auxiliary transformer  Air conditioning system Service boy and divisional store  11kv switch gear system  440V breaker and lighting system  PLCC room  Cable room  Exciter and PMG of generator Sump pump for dewater the sump tank

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 isP =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/