“STUDY OF ELECTRICAL DESIGN OF 220KV SUBSTATION”

PROJECT WORK

UNDER THE ESTEEMED GUIDANCE OF

Mr. Arun Kumar

Astt. Manager (Tech.) 220KV P.P.K –II

Submitted by –

Akshya

ROLL NO. - 05313304912

BATCH – 2012-2016

H.M.R. INSTITUTE OF TECHNOLOGY & MANAGEMENT

ACKNOWLEDGEMENT

“Gratitude is not a thing of expression; it is more a matter of feeling.”

I would like to express my deep gratitude to Mr. Arun Kumar , Assistant Manager (Tech.), Mr. Tushar Patil ,J.E. (E) and Mr. Anil Kumar, Foreman and special thanks to all staff working at DTL 220KV P.P.K.II SUBSTATION” for their active support and continuous guidance without it would have been difficult for me to complete this project. They were generous enough to take time out of their regular work to lend a helping hand whenever I needed one hand enabling me to compete this project.

I also like to thank the entire staff of “DTL 220 KV P.P.K.II SUBSTATION” for making my brief stay in substation a memorable one.

Akshya (05313304912)

DEPARTMENT OF ELETRICAL AND ELECTRONICS ENGINEERING

H.M.R. INSTITITUTE OF TECHNOLOGY & MANAGEMENT, DELHI

Practical Industrial Training mainly aims at making one aware of industrial

environment; which means that one gets to know the limitation, constraint and

ABSTRACTABSTRACT

freedom under which an engineer works. One also gets an opportunity to watch

from close quarter that indicates manager relation. This training mainly involves

industrial and complete knowledge about designing, assembling and process of

various equipments industry.

During this six weeks period, as a student, there is a great opportunity of

understanding Industrial practices. Most of the theoretical knowledge that has

been gained during our course is useful only if it can be applied to production

and services in the industry. The learnt is applied, tested, verified and rectified.

Apart from this the student gets an opportunity to learn latest technology and is

upgraded of the new trends immersing in the industry of interest.

I had the opportunity to utilize my six weeks summer training in DELHI

TRANSCO LIMITED, 220KV SUB STATION, PPK-2, DWARKA, SEC-16B,

DELHI.

I was a part of the company’s new venture which provided me a great deal

of learning. My sphere of knowledge was expanded both at technical and

personal level. I not only got chance to work on Live Project but also witnessed

the related industrial processes and got acquainted to many of the prevalent

technologies.

INTRODUCTION

SINGLE LINE DIAGRAM OF PPK-II

VISUAL INSPECTION

INDEXINDEX

220KV SUB-STATION PPK-II

ELECTRICAL COMPONENTS

SYMBOLS TABLE

LIGHTINING ARESSTER

CAPICATOR VOLTAGE TRANSFORMER

EARTH ISOLATORS

LINE ISOLATORS

CURRENT TRANSFORMER

POTENTIAL TRANSFORMER

CIRCUIT BREAKER

BUSES

BUS COUPLER

POWER TRANSFORMER

POWER BANK

BATTERY CHARGER

BATTERY BANK

CONTROL ROOM

MISLLENOUS EQUIPMENTS AND MATERIALS

GENERATOR

POWER TRANSFORMER

EARTHING CLAMP

BUSHING

CABLES

INSULATOR

INSULATION MATERIALS

POLES

SINGLE LINE DIAGRAM

INTRODUCTION

Delhi Transco Limited is the State Transmission Utility for the National Capital

Territory of Delhi. It is responsible for the transmission of power at 220 kV and

400 kV level and for upgrading, operating and maintaining the high voltage

network. A transmission substation increase the voltage of electricity coming in

to allow it for long distance transmission

Delhi Transco Limited

Delhi Transco Limited, a successor company of erstwhile Delhi Vidyut board,

came into existence on 1st July 2002, as a State Transmission Utility of the

National Capital. After unbundling of DVB the distribution sector has been

handed over to private companies while the generation and transmission are still

with the government. Over the years, DTL has evolved as a most dynamic

performer, keeping pace with the manifold challenges that confront the ever

increasing demand-supply power situation and achieving functional superiority

on all fronts.

Being the capital of India and the hub of commercial activities in the Northern

Region, coupled with the prosperity of population, the load requirement of Delhi

has been growing at a much faster pace. Added to that, being the focus of socio-

economic and political life of India, Delhi is assuming increasing eminence

among the great cities of the world. Plus the vgision-2021, aiming to make

Delhi global Metro politic and world class city demand greater infrastructure to

enrich many services of infrastructure development. DTL has been responsibly

playing its role in establishing. Upgrading, operating and maintaining the EHV

(Extra High Voltage) network. DTL has also been assigned the responsibility of

running the State load Dispatch Centre (SLDC) which is an apex body to ensure

integrated operations of power system in Delhi. Delhi Transco is also committed

to promote energy conservation not only in its own establishments but also in

the entire Delhi. The company has done a lot to educate and sensitize the

general public about the need of energy conservation. Transmission loss level

has been reduced from 3.84 per cent in 200-203 to 1.38 per cent in 2009-10,

which is one of the lowest transmission loss levels in the country. To ensure

adequate and efficient power supply. DTL has been continuously upgrading its

biggest achievement has been its ability to handle the highest ever peak demand

of 4720 MW in July 2010. The total availability of its transmission system stood

98.78%. The modern technologies are being implemented in DTL by way of

constructing GIS sub stations and laying XLPE 220 KV cable by employing

cable link techniques and would be the largest network of its kind in India.

VISUAL INSPECTION OF 220KV SUB-STATION PPK-II

INPUT CIRCUIT PPK-II

The PPK-II Sub-Station has two circuits. One is Bamnauli CKT-I and another is

Bamnauli CKT-II. In Bamnauli village, the DTL 400Kv Sub-Station is

established. The Bamnauli 400KV step-down into 220KV. The Input comes

through overhead transmission line. The Bamnauli CKT-I & II have common

overhead transmission tower. These circuits contain 220KV ckt-1 & ckt-2.

220KV PPK-II Sub-Station has two yards known as:-

220KV Yard

66KV Yard

220KV

In 220KV sections, we analyses the 220KV supply. The installments and

arrangements of equipments are:-

LIGHTING ARESSTER

CAPACITOR VOLTAGE TANSFOMER

EARTH ISOLATOR

LINE ISOLATORS

CUREENT TRANSFORMER

SF6 CICRUIT BREAKER

BUS-I

BUS-II

BUS COUPLER FOR PARALLEL THIS BUS-1 & BUS-2

BUS-1

OR

BUS-2

CIRCUIT BREAKER (SF6)

CUREENT TRANSFORMER

LINE ISOLATOR

EARTH ISOLATOR

LIGHTING ERRETER

STEP-DOWN POWER TRANSFORMER 220KV – 66KV

66KV

In 66KV sections, we analyses the 66KV supply. The installments and

arrangements of equipments are:-

66KV SUPPLY CAME FROM POWER TRANSFORMER 220KV/66KV

TO POTENTIAL TRANSFORMER

EARTH ISOLATORS

LINE ISOLATOR

66KV CURRENT TRANSFORMER

66KV SF6 CIRCUIT BREAKER

66KV BUS-I

BUS-II

66KV BUS COUPLER FOR PARALLEL THIS BUS-1 & BUS-2

66KV SUPPLY TO OUTGOING 66KV FEEDER THROUGH

66KV BUS-1

OR 66KV BUS-2

66KV SF6 CICRUIT BREAKER

66KV CUREENT TRANSFORMER

66KV LINE ISOLATOR

EARTH ISOLATORS

66KV CAPACITOR VOLTAGE TANSFOMER

66KV LIGHTING ARESSTER

66KV OUTGOING THROUGH CABLE OR OVERHEAD MEDIUM.

SR.

NO.

ELECTRICAL

COMPONENTS

SYMBOLS

1 Bus Bar

2 Power transformer -Three

Winding

3 Current Transformer (CT)

4 Circuit Breaker (CB)

5 CVT Capacitor Voltage

Transformer

Potential Transformer

6 Line Isolator

7 Lighting Arrestor (LA)

8 Earth Isolator

9 Wave or Line trap

SUBSTATION EQUIPMENTS SEEN IN 220KV AND 66KA YARD

1. LIGHTINING ARESSTER

SURGE LIGHTINING ARESSTER AND WORKING DIAGRAM

Lightning arresters (LA): Lightning arresters are the protective devices used for

Protection of equipment from lightning strokes. They are located at the starting

of the Sub-station and also provided near the transformer terminals.

RATED VOLATGE 220KV/66KV

ARESSTER RATED

VOLTAGE

198KV/60KV

OPERATION

VOLTAGE

160KV/55KV

2. CAPACITOR VOLTAGE TANSFOMER

CVT 220KV

ONE LINE DIAGARM OF CVT 220KV

DIAGRAM OF CVT 220KV WITH INNER PART

SPECIFICATIONS:-

PRIMARY VOLTAGE 220/√3kV

SECONDARY VOLTAGE 110/√3V

OIL TYPE YES

INSULATION PROCLEIAN

TYPE SINGLE PHASE

FREQUENCY 50Hz

3. CVT 66KV

PICTURE OF 66KV CVT

PRIMARY VOLTAGE 66/√3kV

OUTPUT VOLTAGE 110/√3V

TYPE SINGLE PHASE

INSULTION Porcelain

FREQUENCY 50 Hz

OIL TYPE YES

The lines in substations operate at high voltages. The measuring instruments are

designed for low value of voltages. Capacitor Voltage Transformers are

connected in lines to supply measuring instruments and protective relays. These

transformers make the low voltage instruments suitable for measurement of high

voltages. For example a 220kV/66KV/110V CVT is connected to a power line

and the line voltage is 220KV/66KV then the secondary voltage will be 110V.

4. EARTH ISOLATOR

5. LINE ISOLATOR

PICTURE LINE ISOLATORS

Isolators are employed in substations to isolate a part of the system for general

maintenance. Isolator switches are operated only under no load condition. They

are provided on each side of every circuit breaker.

6. CURRENT TRANSFORMER

Current transformers (CT): The lines in substations carry currents in the

order of thousands of amperes. The measuring instruments are designed for low

value of currents. Current transformers are connected in lines to supply

measuring instruments and protective relays. For example a 100/1A CT is

connected in a line carrying 100A, and then the secondary current of CT is 1A.

PICTURE AND CIRCUIT DIAGRAM OF CURRENT TRANSFORMER

Voltage class 220KV 66KV

CT Ratio Amp. 1 / 1 A 1 / 1 A

Rated Burden (VA) Core

- 1

Core - 2

30

30

15

15

Type of connection Single Primary Single Primary

Earthing Effective Effective

Type of insulation Class – A Class – A

System Frequency (Hz) 50 z 51 z

7 POTENTIAL TRANSFORMER

Potential transformers (PT): The lines in substations operate at high voltages.

The measuring instruments are designed for low value of voltages. Potential

transformers are connected in lines to supply measuring instruments and

protective relays. These

Transformers make the low voltage instruments suitable for measurement of

high voltages. For example an 11kV/110V PT is connected to a power line and

the line voltages 11kV then the secondary voltage will be 110v.

PRIMARY VOLTAGE 66/√3kV

OUTPUT VOLTAGE 110/√3V

TYPE SINGLE PHASE

INSULTION Porcelain

FREQUENCY 50 Hz

OIL TYPE YES

8. SF6 CIRCUIT BREAKER

OPERATION DIAGRAM OF GAS CIRCUIT BREAKER

Circuit breakers are used for opening or closing a circuit under normal as well as

abnormal (faulty) conditions. Different types of CBs which are generally used

are oil circuit breaker, air-blast circuit breaker and vacuum circuit breaker and

SF6 circuit breaker.

Sulphur hexafluoride to other medium such as oil or air for the use in circuit

breakers for the following reasons:

(1) Being an Inert gas, it is non-reactive to the other components of

circuit breakers.

(2) Sulphur hexafluoride has high dielectric strength (about 24 times that of air

and it is comparable to that of oil)

(3) When extinction of arc is concerned it is about 100 times more effective than

air.

(4) Its heat transfer property is about 16times that of air because of its high

density.

Applications:-

(1) The circuit breakers are designed for voltages 115kV to 230kV, power rating

of 10MVA to 20MVA and interrupting times less than 3cycles.

(2) A typical sulphur hexafluoride circuit breaker consist of interrupter units,

each capable of dealing with currents up to 60000A and voltage in the range of

50 to 80kV.A number of units are connected in series according to the voltage

of the system.

Rated voltage kV (rms) 220 66

Rated frequency (Hz) 50 50

No. of Poles 3 3

Design ambient temperature

(°C)

50 50

Type 3 phase 3 phase

Insulation porcelain porcelain

9. 220KV BUS-I & BUS-II AND 66KV BUS-I & II 66KV BUS-II

This arrangement is also known as duplicate bus-bar system. It consists of two

bus-bars ‘main’ and ‘spare’ of same capacity. Incoming line and outgoing lines

can be connected to either bus by means of bus coupler breaker and isolators.

Continuity of supply to the circuit can be maintained during maintenance of

main bus-bar or fault occurring on it. Three incoming lines and three outgoing

lines are connected to either bus by a bus coupler.

DIAGRAM OF THE BUS BAR

10. BUS COUPLER

SINGLE LINE DIAGRAM OF BUS COUPLER

Bus coupler is used in sub-station for changing the source of supply without

interrupting the transmission. Let we have two source feeders A1 (220KV) &

A2 (220KV). And initially A1 is connected via transfer bus, main bus, and bus

coupler 1 to transformer. Now we want to change source feeder A1 with A2, the

Bus coupler comes into play. 1st we connect all three phases of feeder A2 to

Transfer bus which in turn connected to main bus in parallel to transfer bus of

feeder A1.Since both are in parallel so there neither be any damage nor any

interruption in supply takes place. Thus we have same value (132KV) supply

from combined sources in our main bus. Now we connect the bus coupler of A2

and disconnect bus coupler of A1. Next, we remove the transfer bus connection

of A1 from main bus followed by disconnecting all three phases.

Now our supply is completely through feeder A2 and bus coupler 2.

11. POWER TRANSFORMER

CIRCUIT DIAGRAM

12. POWER BANK

In a Sub-Station, the power bank is play most important role and power bank is

heart of the sub-station. The power bank contains two most important parts are:-

BATTERY CHARGER

BATTERY BANK

BATTERY CHARGER:-

DC systems are installed in substations to supply power for control, protection,

alarms, communications, and other critical auxiliary circuits where maximum

reliability of supply is essential.

The battery charger is device which converts AC into DC supply.

The battery charger charges the battery in the battery bank. Battery

charger/Battery Bank providing the DC supply power to the control emergency

lighting, protection relays, alarms, communications and other equipment.

BATTERY BANK

Battery Bank has many batteries. These batteries are connecting in series one by

one. The battery bank is connected with battery charger. In PPK-II Sub-Station

has approx one hundred ten batteries. These batteries have 2v cells which

provide the 110V/220V. These batteries have storing in open type room which

have many windows, adjustable fans.

13. CONTROL ROOM

Control Room is remote control system in sub-station. It also has two parts one

is 220 KV and 66KV. In control room, we install the measuring meters,

indicator, sensing device and protection system. In control room, we use

Voltmeter, Energy meter, wattmeter, ohm meter, ammeter etc. in sensing

system, we use relays like mechanical, differential, electronic etc. and we also

install protection system like relays sensing the faults, over voltage, over

earthing, high and low temperature in equipments etc.

These relays are two type one mechanical and electronics. In control room, we

install the indicating system like alarms, indicating display, indicating circuits

like breaker circuits, isolators etc.

MISLLENOUS EQUIPMENT

GENERATOR

EARTHING CLAMP

BUSHING

TEST LAMP

CABLES

INSLUTION MATERIAL

INSULATOR

POLE

GENERATOR

Generator is used in Sub-Station to provide backup AC supply for substation

needs, when the AC supply from local transformer is failure. The Generator

gives the AC supply to battery charger and other appliances and substation

needs.

EARTHING ROD:

Earth Rod is type of protection accessory which use for proper Earthing.

Earthing rod is use during maintenance under shut-down of feeder in sub-

station. Earthing Rod have a wire, clamp, insulated rod and hook.

CONDUCTOR,

ALUMINIUM CONDUCTOR STEEL RAINFORCED (A.C.S.R)

Aluminium has low tensile strength, as a result produce greater sag which

prohibits their use for longer spans and makes them unsuitable for long distance

transmissions. So in order to increase the tensile strength of the aluminium

conductor, it is used with a core of galvanized steel wires. The combinational

conductor thus obtained is called as A.C.S.R. (Aluminium Conductor Steel

Reinforced). A.S.C.R conductor

The above figure shows, one steel core conductor wire surrounded by 18 wires

of aluminium. The aluminium carries bulk of current while the steel core takes a

greater percentage of mechanical stress.

Produces small lag and therefore can be used for longer spans.

A.C.S.R. Conductor gets deteriorated in service due to atmospheric

corrosion.

BUSHING

The inside of the bushing may contain paper insulation and the bushing is often

filled with oil to provide additional insulation. Bushings for medium-voltage

and low-voltage apparatus may be made of resins reinforced with paper. The use

of polymer bushings for high voltage applications is becoming more common A

bushing is a hollow insulating liner through which a conductor may pass.

Bushings appear on switchgear, transformers, circuit breakers and other high

voltage equipment. The bushing is a hollow insulator, allowing a conductor to

pass along its centre and connect at both ends to other equipment. Bushings are

often made of wet-process fired porcelain, and may be coated with a semi-

conducting glaze to assist in equalizing the electrical stress along the length of

the bushing.

INSULATOR

Pin type insulators.

Suspension type insulators.

Strain type insulators.

Shackle insulators.

Pin type insulators

A pin type insulator is designed to be mounted on a pin, which in turn is

installed on cross-arm of the pole. The insulator on the pin and electrical

conductor is placed in the groove at the top of the insulator and soft aluminium

binding wire according to the material of the conductor.

Pin type insulators made of glass are generally used for low voltages.

Pin type insulators made of porcelain can be used up to 90kV but are

rarely used on lines above 60kV.

Suspension type insulators

In a pin type insulator its cost is increased rapidly as the working voltage

is increased. Therefore pin type insulator is not economical beyond 33kV.

So it is as usual practice to use suspension type insulators for voltage

higher than 33kV.

A pin type insulator sits on top of the cross arm, whereas a suspension

insulator hangs from the cross arm. The line conductor is attached to its

lower end.

Strain insulators

Strain insulators can be of pin type insulator or suspension type insulator. Strain

insulators are made use when making very long spans or corners of transmission

lines.

Shackle insulators

Shackle insulators can be fixed to a pole directly with a bolt or to the cross arm.

The line conductor is fixed in the groove with a soft binding wire. Before,

shackle insulators were used as strain insulator, but these days they are used for

low voltage distribution lines.

POLES

Steel towers

Wooden poles, steel poles, R.C.C. poles are used for distribution purpose

at low voltage (say 11kV), but steel towers are invariably employed for

long distance transmission at higher voltage.

Troubles regarding lightning are minimised as each tower acts as a

lightning conductor.

Steel tower has greater mechanical strength.

Longer life span.

Steel towers can withstand most severe climate conditions.

Steel towers are suitable for longer spans.

INSULATION MATERIAL

Porcelain

Most commonly used material for insulator in overhead lines.

Porcelain is usually weak in tension and does not withstand tensile

strength more than 50MN/m2

A good porcelain insulator has compressive strength of about 7000N/m2

and dielectric strength of 60kV/cm of its thickness.

Porcelain is mechanically stronger than glass.

Glass

Mainly used for E.H.V, AC and DC systems.

Glass insulator is cheaper than porcelain when simple shapes are

considered.

Under ordinary atmospheric conditions the glass insulator can be used up

to 25kV and in dry atmosphere, it can be used up to 50kV.

In H.V lines having voltage above 100kV, toughened glass is employed

for insulation.

Steatite

It is produced by mixing hydrated magnesium silicate with small portion

of clay and feldspar.

It has high insulation resistance.

Steatite has much greater tensile and bending stress than porcelain. Thus

can be used at tension towers or when the transmission lines take a sharp

turn.

Synthetic resin

Synthetic resin is an insulator which is made up materials like rubber,

silicon, resin etc.

Synthetic resin insulator has high strength and lower weight.

Leakage current is higher and longevity is low.

Comparatively cheaper.

Used in various indoor application.

Synthetic resin insulators are extensively used for bushings.

END OF

TRAINING REPORT ON

220KV SUB-STATION PPK-II,

SEC-16B DWARKA,

NEW DELHI