substation

1. Sharavathi Receiving Station
Hootagalli Substation , Mysuru
NIE INSTITUTE OF TECHNOLOGY
To
Assistant Executive Engineer
KPTCL,SRS Hootagalli Substation, Mysuru
BY
H . C . Naveen . Kumar (4NN14EE013)
D . V . Manjunath (4NN14EE012)

2. CONTENT
• Introduction
• About Hootagalli SRS Substation
• Single Line Diagram of SRS
• List of component in Substation
• Description of the yard
• Control Room
• Battery Room

3. INTRODUCTIOIN
Sharavati Hydroelectric project
Originating at a height of 730 m near Ambuthirtha, in Shimoga district,
the Sharavathi river flows in a north-west direction.
 In its long, 132-km journey, it is joined by several tributaries after a stretch of 80 km along its course,
the river drops down a steep mountain face of 293m – spectacle known as the Jog Falls.
The Sharavati Hydroelectric project was started to tap the electricity generating potential of the river,
three power generating stations in this project
 The Sharavati Generating Station with 10 Units and an installed capacity of 1035 MW
 The Linganamakki Dam Powerhouse with 2 units and an installed capacity of 55 MW
The Gerusoppa Dam Project with 4 units totalling to 240 MW.
The KPCL blueprint identifies Sharavathi as its “Master Station” – a headpoint that will control all
peripheral stations through a nodal monitoring system. The prime objective here is to optimize power
generation through a systematic integration of several reservoirs and water conductor systems.

4. About Hootagalli SRS Station
A substation is an assembly of apparatus, which transform’s the characteristics of electrical
energy from one form to another , from one voltage level to another level. Hence a substation is
an intermediate link between the generating station and the load units.
There are total three, 220KV incoming feeders in SRS receiving station
 Kadakola Line
 Basthipura no 1 line
 Basthipura no 2 line
The incoming feeders are connected to bus-bar through lightning arresters , line isolator, circuit
breakers , current-transformers etc. .The bus-bars are to have an arrangement of auxiliary bus.
The incoming 220KV supply is stepped down to 66KV using 100MVA transformer. The 220KV
SRS station consist of 3 nos. of 100MVA transformer, with there voltage ratio respectively are
220/66/11kv.
 The incoming 220kv line also forwarded to other region, there is one 220KV outgoing line to
Vijaymangala.

5. SINGLE LINE DIAGRAM OF 220 KV SRS HOOTAGALLY,MYSORE

6. Components in the Power station
 Power transformer: 100MVA &12.5MVA
 Circuit breakers:220KV,110KV,66KV,11KV
 66KV capacitor banks
 Potential transformer:220KV bus PT,66KV bus PT
 Current transformer:220KV,66KV,11KV
 Capacitor voltage transformers: 220KV ,66KV
 Isolator: 220KV,66KV,11KV
 Lightning arrestor:220Kv,66KV
 Auxiliary transformer
 Battery and battery charger
 Relays
 Centralized air compressor

7. Power Transformer
A static electrical machine used for transforming power from one circuit to
another circuit without changing frequency is termed as power transformer.
 The transformers are generally used to step down or step up the voltage level
of a system for transmission and generation purpose.
Description of the yard

8. Circuit Breaker
Operation
 A circuit breaker can make or breaker circuit either manually or automatically under all condition as no load , full
load and short circuit condition.
 Circuit breaker essentially consists of fixed and moving contacts. These contacts can be opened manually or by
remote control whenever desired. When a fault occurs on any part of the system, the trip coils of breaker get
energized and the moving contacts are pulled apart by some mechanism, thus opening the circuit.
 When contacts of a circuit breaker are separated, an arc is struck; the current is thus able to continue. The
production of arcs are not only delays the current interruption, but is also generates the heat. Therefore, the main
problem is to distinguish the arc within the shortest possible time so that it may not reach a dangerous value
 SF6 circuit breaker: Current interruption in a high-voltage circuit breaker is
obtained by separating two contacts in a medium, such as sulfur hexafluoride
(SF6), having excellent dielectric and arc-quenching properties. After contact
separation, current is carried through an arc and is interrupted when this arc
is cooled by a gas blast of sufficient intensity.
Types of Circuit breaker
1.Oil Circuit Breaker
2.Air -Blast Circuit Breaker
3.Sulphur Hexafluoride Circuit Breaker (Sf6)

9. CAPACITOR BANK
Capacitor bank accomplishes following operations
1. Supply reactive power
2. Increases terminal voltage
3. Improve power factor
 The load on the power system is varying being high during morning and evening
which increases the magnetization current. This result in the decreased power factor.
The low power factor is mainly due to the fact most of the power loads are inductive
and therefore take lagging currents. The low power factor is highly undesirable as it
causes rise in current, resulting in additional losses.
In order to improve the power factor come device taking leading power should be
connected in parallel with the load. One of the such device can be capacitor bank. The
capacitor draws a leading current and partly or completely neutralize the lagging reactive
component of load current.

10. CURRENT TRANSFORMER
Current transformer is used for measurement of
the altering current by taking samples of high
current of the system.
These reduced samples are in accurate
proportions with actual high current of system.
These are used for installation and maintenance
of current relay in substation for protection
purpose which are normally have low-current
for their operation

11. POTENTIAL TRANSFORMER
Potential transformer is quite similar to the current transformer, but it is
used for taking samples of high voltages of a system for providing low-
voltage to the relays of protection system and also to the low-rating meter
for voltage measurement.
From this low-voltage measurement, actual system’s high voltage can be
calculated without measuring high voltage directly to avoid the cost of the
measuring system.

12. BUS BAR
When numbers of generators or feeders operating at the
same voltage have to be directly connected electrically,
bus bar is used as the common electrical component. Bus
bars are made up of copper rods operate at constant
voltage.
The following are the important bus bars arrangements
used at substations:
1. Single bus bar system.
2.Duplicate bus bar system.
.
 In substations, it is often desired to disconnect a part of the system for general maintenance
and repairs. Isolator operates under no load condition.
 While opening a circuit, the circuit breaker is opened first then isolator while closing a
circuit the isolator is closed first, then circuit breakers. Isolators are necessary on supply
side of circuit breakers, in order to ensure isolation of the circuit breaker from live parts for
the purpose of maintenance.

13. Lightening Arrester
The substation equipment's such as conductor,
transformer etc., are always erected outdoor.
Whenever light surges occur then, a high-voltage
pass through these electrical components causing
damage to them.
Therefore to avoid this difficulty, lightening
arrester are placed to pass entire lightening
surge to earth.

14. Relay
Relays are used for disconnected the circuit by manual or automatic
operation.
Relay consists of coil which is excited or energized and such that the
making the contacts of relay closed ,activates the relay to break or make
the connection.
There are different types of relay such as current relay, microprocessor
relay, mho relay, Buchholz relay etc., . The SR substation uses Buchholz
relay and many other types of relays.
Isolator
 Isolator is a manually operated mechanical switch that isolates a part of a
circuit of substation meant for repair from a healthy section in order to
avoid occurrence of more fault. Hence it is also called as disconnecter.
There are different types of isolators such as single-break isolator, double-
break isolator, bus isolator, line isolator etc.

15. Insulator
The substance which does not allow free movement of electron is
called as insulator. There are different types of insulators such as
suspension type, strain type, pin type so on.
 Insulator are used or insulation purpose while erecting electric
poles with conductors to avoid short circuit and for other purpose.
 It is used to trap the high frequency communication
signals sent on the line from the remote substation
and diverting them to the telecom/tele-protection
panel in the substation control room. Line trap also is
known as Wave trap.
Wave Trap

16.  Bus voltages and frequencies, line loading, transformer loading, power
factor, temperature, etc. are the basic variables related with substation
control and instrumentation.
 The various supervision, control and protection function are preformed
in substation control room. The relays, protection and control panels
are installed in the controlled room. These panels along with PC aids in
automatic operation of various circuit breakers tap changers, auto-
recloses, sectionalizing switches and other devices during faults and
abnormal conditions.
Control room
 When the oil expands or contacts by the change in the temperature, the oil
level goes either up or down in main tank. A conservator is used to
maintain the oil level up to predetermined value in the transformer main
tank by placing it above the level of the top of the tank.
 Breather is connected to conservator tank for the purpose of extracting
moisture as it spoils the insulating properties of the oil. During the
contraction and expansion of oil air is drawn in or out through breather
silica gel crystals impregnated with cobalt chloride. Silica gel is checked
regularly and dried and replaced when necessary.
Conservator and Breather

17. BATTERY ROOM
There is a battery room which has 110 batteries of 2 volt each for 220KV section. Therefore D.C. power available is
for functioning of the control panels. A battery charger to charge the battery.
1.Various parts of lead acid batteries
2.Plates
3.Separators
4.Electrolyte
5.Container
6.Terminal port
7.Vent plugs
CHARGING OF BATTERIES
Initial charging
It is the first charging given to batteries by which the positive plates are converted to “lead peroxide", where
as the –ve plates will converted to spongy lead. Also in a fully charged battery the electrolyte specific gravity
will be at its highest venue or 1.2 and its terminal voltage will be 24 volts.
DISCHARGING
When a fully charged battery delivers its energy out by meeting a load the lead peroxide of the +ve plates slowly gets
converted to lead sulphate and the spongy lead of the –ve plates also gets converted into lead sulphate during this time the
specific gravity of the electrolyte also decreases the value around 1.00 and the terminal voltage also decreases from its initial
to a lower value which may be around 1.85 or 1.8.