Gives difference between sub-critical & super-critical plants. Few Examples are discussed.

1. RAGHU ENGINEERING COLLEGE
(AUTONOMOUS)
DEPARTMENT OF EEE
Academic year: 2018-2019
II year II-semester
Power Systems-I Generation and Utilization
CASE STUDY
ON
SUB CRITICAL AND SUPER CRITICAL POWER PLANTS IN INDIA.
BATCH-2
A.Snehitha-18985A0206
A.S.S.R.Murthy-18985A0207
A.Sai Sampath-18985A0208
B.Naga Venkatesh-18985A0209
B.Chaitanya-18985A0210
FACULTY:
V.Pramadha Rani.
Assosiate Professor.

2. What are subcritical and super critical?
Critical pressure of water is 220.64 bar = 3200.11 psi. Below that,
boilers are subcritical and above, supercritical.
Usually, the power rating of a super critical power plant will be more
than 400MW.
Less than that, those can be considered as sub critical and above that
it would be ultra super critical.

3. Comparison.
Sub critical power plant
• System with constant evaporation endpoint
• A typical example of this system is the drum-type
steam generator. Natural circulation is produced by
heating of the risers. The water/steam mixture
leaving the risers is separated into water & steam
in the drum. The steam flows into the super heater
and the water is returned to the evaporator inlet
through down comers.
• If the system is operated only with natural/assisted
circulation, the application range is limited to a
max drum pressure of approx. 190 bar.
• If a circulating pump is used (forced circulation),
this range can be extended somewhat fixing the
endpoint of evaporation in the drum also sets the
size of the heating surface in the evaporator &
superheater.
Super Critical power plant
• System with variable evaporation endpoint
• This type of boiler is drumless steam generator.
Evaporation takes place in a single pass. This
principle used in the BENSON/SULZER boiler, the
world's most frequently constructed steam
generator type. Flow through the evaporator is
induced by the feed pump. The system can
therefore be operated at any desired pressure i.e.
at either subcritical (Close to critical) or
supercritical pressure. The evaporation endpoint
can shift.
• The evaporator & super heater areas thus
automatically adjust to operational requirements.

4. Fig 1: Temperature vs Entropy
graph representing sub critical and
super critical cycles.

5. Vindhyachal Thermal Power Plant.
1. It is located in singrauli, Madhya Pradesh.
2. It is handled by NTPC.
3. Its rating is 4760MW, this is largest power station in India.

6. Mundra Thermal Power Plant.
1. It is of 4600MW capacity.
2. Located in kutch, Gujarat.
3. Handled by adani power ltd.

7. Chandrapur Super Thermal Power Plant
1. It is of capacity 3340MW.
2. It is situated in urjanpur, maharastra.
3. It is operated by Mahagenco(government of maharastra).

8. Sterlite Thermal Power Plant
1. It has a capacity of 2400MW.
2. It is located in jharsuguda, Odisha.
3. It is maintained sterlite energy a subsidiary unit of vadanta
resources.

9. Barh Super Power Plant
1. It is situated in patna, bihar.
2. It has a capacity of 1320MW.
3. It is one of the power plants with least power generating capacity.

10. Advantages of super critical power plants.
1. More thermal efficiency.
2. More flexible.
3. Here, the drum inside acts as a evaporation end point.
4. These automatically adjust to load fluctuations.

11. RAGHU ENGINEERING COLLEGE
(AUTONOMOUS)
DEPARTMENT OF EEE
Academic year: 2018-2019
II year II-semester
Power Systems-I Generation and Utilization
CASE STUDY
ON
VARIOUS BUSBAR ARRANGEMENTS.
BATCH-2
A.Snehitha-18985A0206
A.S.S.R.Murthy-18985A0207
A.Sai Sampath-18985A0208
B.Naga Venkatesh-18985A0209
B.Chaitanya-18985A0210
FACULTY:
V.Pramadha Rani.
Assosiate Professor.
4/19/2019 Power Systems-I 11

12. What is a busbar?
 An electrical bus bar can be defined as a conductor or groups of
conductors which collects electrical power from the incoming feeder
and distributes them to outgoing feeder.
 Busbars distribute electricity with greater ease and flexibility than
some other more permanent forms of installation and distribution.
 They are often metallic strips of copper, brass, or aluminum that
both ground and conduct electricity.
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13. Busbar Arrangements.
 The choice of particular arrangement depends upon viz., system
voltage, position of substation, system flexibility and cost.
 In addition, the following technical considerations must be borne in
the mind while deciding an arrangement:
1) Simplicity is the keynote of a dependable system.
2) Maintenance should be possible without interruption of supply.
3) Alternative arrangements should be available in case of outage of
any apparatus.
4) The installation should be as economical as possible.
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14. Single Busbar
Arrangement.
 The arrangement is the
cheapest possible and simple
in construction.
 But, it suffers from two
major defects,
I. Maintenance without
interruption of supply is
not possible.
II. Extension of substation
without shutdown is not
possible.
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Fig A : Single Busbar Scheme.

15. Single Bus-bar
Arrangement with
Sectionalizer.
 It is used as an alternative for the
single bus-bar arrangement
because any breaker can be
taken for maintenance.
 Though it requires an extra
breaker, and the switching is
more complex.
 A fault in the bus may shut down
the whole system.
 Generally, used for 110kv
substations.
Fig B: Single busbar scheme
with sectionaliser.
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16. Comparison.
Single Bus-bar Scheme.
 It is simplest scheme with artless
protection system.
 Any fault on bus results in
disconnection of power. Any
maintenance on any breaker will lead
to disconnection of relevant breaker,
relevant line or whole system in some
cases.
Single Bus-bar with sectionalizer.
 Single breaker single busbar scheme is
slightly improved by dividing the bus
into two sections.
 This scheme is only effective if there
are two incoming lines and outgoing
lines are distributed evenly in each
section.
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17. Main and Transfer
Bus Scheme.
 It is more flexible because half
number of feeders are connected
on each bus.
 But, it needs an extra breaker
coupler circuit.
 Line breaker fault may result in
taking of all the circuits
connected to out of service and
also failure in the bus-bar results
in shutdown of complete system.
 Mostly used for substations of
66kv, 132kv and up to 220kv.
Fig C: Main and transfer bus-
bar scheme.4/19/2019 Power Systems-I 17

18. Double Bus-bar
Arrangement.
 It is more flexible as we can
connect feeders on either of
buses.
 This scheme is highly reliable as
any breaker can be taken for
maintenance whenever required.
 It is far more expensive when
compared to normal double bus-
bar scheme.
 Generally, used for high voltage
or EHV substations. Fig D: Double bus arrangement.
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19. Comparison.
Double Bus-bar Arrangement.
 In double bus system load can be
connected on either of the bus.
 The infeed and the load circuit can be
separated in two if needed from
operational considerations.
 Either bus can be taken out of
maintenance.
Main and Transfer Bus-bar System.
 This is alternative for double bus
scheme.
 It provides facility for breaker
maintenance but not bud
maintenance.
 Whenever maintenance is required the
circuit can be shifted to another bus
and controlled using bus coupler.
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20. One and Half
Breaker Scheme.
 More flexible in operation as all
the switching is done by
breakers.
 Selective tripping is possible.
 But any breaker can’t be
removed without interruption of
supply.
 Generally, used for substations
for 220kv to 440kv ratings.
Fig E: One and half breaker scheme.
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21. Ring/Mesh
Arrangement.
 Bus-bars gives more operational
flexibility.
 Any fault in the unit separates
the ring into two halves thereby
increasing the complexity of
reclosing and protection.
 Breaker failure during fault on
one circuit causes loss of
additional circuit because of
breaker failure.
 Mostly used for very high power
rating generating stations.
Fig F: Ring Bus-bar Arrangement.
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22. Single Bus-bar Scheme using Simulink.
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23. Double Bus-bar Scheme using Simulink.
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