4. COMBINATION OF TWO CYCLES
GAS CYCLE
STEAM CYCLE
TWO GAS TURBINES
ONE STEAM TURBINE
TWO HRSG SYSTEMS
MORE EFFICIENT
ECO FRIENDLY
NO WASTAGE
5. PRINCIPLE:
In a combined cycle power plant, a gas turbine generator generates
electricity and the heat in the gas turbine’s exhaust gases is used to generate
steam in a Heat Recovery Steam Generator that in turns used to generate
electricity with steam turbine generator which enhances the efficiency in
power generation.
6. PRINCIPLE
DOMINANT ROLE
CONSISTS OF STATOR AND ROTOR
NEED OF PROTECTION
GAS TURBINE GENERATOR(GTG)
STEAM TURBINE GENERATOR(STG)
RATINGS
GTG STG
RATED VOLTAGE 15.75 KV 11KV
RATED CURRENT 7698 A 12543 A
POWERFACTOR 0.8 0.8
COOLING TYPE WATER WATER
7. ROTOR:
ROTATORY PART IN THE MACHINERY
SPECIFIED DETAILS OF ROTOR
Diameter of body 1050 mm
No. Of wound slots per half pole 8
Conductor material CuAg
STATOR :
Supports armature core with laminations.
SPECIFIED DETAILS OF STATOR:
Core length 4620mm
Inside diameter of core 1150mm
No. of slots 60
9. During fault and abnormal conditions
Generator Differential Protection.
Loss of excitation
Overvoltage Protection
Earth fault protection
Negative Sequence Protection
Over current/Under voltage Protection.
95% Stator Earth Fault protection
Reverse Power protection
Cooling system:
CACW means circulating air circulating water.
For circulation of the air two fans are mounted on both ends of
the generator rotor.
10. PRINCIPLE -ELECTROMAGNETIC INDUCTION
MAGNETICAL COUPLING
DESIRED VOLTAGE LEVELS FOR MACHINERY
11. Description units
No. of phases 3
Rated power 210MVA
No. of windings per phase 2
Rated Voltage(no load) on
H.V side 400KV
Rated Voltage(no load) on
L.V side 15.75Kv
Rated Current on H.V side 303.7A
Rated Current on L.V side 7707.1A
Rated frequency 50Hz
12. TYPES OF TRANSFORMERS
step-up transformer
step-down transformer
current transformer
potential transformer
ideal transformer
Cooling system
Oil Forced Air Forced unit
Five units coolers each having 25% cooling capacity
4 working and 1 standby with selective switching
Protection system
Differential Protection Buchhlolz Relay
Over current Earth Fault Protection
13. Mv system:
Bus-duct of GT generator via station service
transformer with 6.6kv
low resistance earthed system
Vaccum circuit breaker(VCB)
Microprocessor based protection system
Lv system :
Rating up to maximum 250 KW, including the UPS system,
chargers & batteries.
Automatic dead-bus changeover
motors rated 160-250 KW CB are provided motors rated < 160
KW, contactor-controlled feeders
14. ONE AND HALF BREAKER SWITCHING SCHEME
400 KV SWITCHYARD
STARTUP POWER SUPPLY FOR BACK CHARGING
15. INTERCONNECTION PURPOSE
Loads and source of electrical power systems
Generators and main transformer
Types of bus bars according to voltages
Voltage levels Bus bars
Low Rigid
Medium Rigid, insulated phase,sf6
High Rigid,strain,sf6
16.
17. CIRCUIT BREAKERS
SF6 CIRCUIT BREAKER
Rated voltage 420v
Normal current 2000A
ISOLATORS
EARTH SWITCH
Operating Mechanism Manual
Control 220V DC
SURGING ARRESTORS
LIGHTNING ARRESTORS
18. BREAKER CONTROL
Line bay breaker
Steam Turbine Generator Transformer Bay
Gas Turbine Generator Transformer Bay
Local Control
Remote Terminal Unit
A RTU has been envisaged for facilitating the data transmission
such as MW, MVAr, MWH and MVArH of each line to the Remote
Load Dispatch Center through the Microwave Links, as planned and
will be supplied by AP Transco.
In addition, the RTU will be able to collect and communicate the
switchyard status and data to SCADA system which will be supplied
by APTransco. The RTU will be located in the switchyard control
room.
19. 1 Line bays protection
Main I protection
Main II protection
Generator Transformer bays
Common Protections:
For all the bays, following additional protections and relays will be
provided.
◦ Local breaker backup protection (LBB)
◦ Trip Circuit Supervision for each trip coil
◦ DC supply supervision
◦ Pole discrepancy protection
◦ Anti pumping device for breaker closing
◦ All auxiliary relay as per system requirement
20. STANDBY DIESEL GENERATOR
The standby diesel generator is connected to the LV switchgear. The diesel generator is a
rated 625 KVA in order to feed the essential auxiliaries for the safe shut down of the plant
in the event of loss of normal AC power. This is used to charge the station batteries. The
standby diesel generator set is automatically started upon detection of loss of normal AC
power
21. PARTS OF DIESEL GENERATOR
Generator Controller
Fuel Tank
Automatic Voltage Regulator
TYPES OF DIESEL GENERATORS
The TS25 Baldor Standby Generator
The 10,000 Watt Aurora Standby Generator
22. DC&UPS SYSTEM
220V DC SYSTEMS:-
Each DC system consists of battery and battery charger, and associated D.C. distribution
boards. The whole battery system is sized for one (1) hour ST shut down operation. The safe
shutdown is carried out bye the DC system in conjunction with the standby diesel generator
set. For meeting this 2*50% battery banks of lead acid tubular type are provided .
23. UPS:-
240V AC uninterruptible power supply is provided bye two inverters with automatic static
changeover switches. During normal operation the UPS is supplied through the inverters
and the chargers which are connected to the respective low voltage switchgear.
24. Here overall view of the combined cycle power plant suggests
the best generation of power and gives better efficiency by
using the gas and steam cycles
Electrical equipments such as gengrators,transformers,circuit
breakers, isolators and most of the equipments been observed
and their workings has been observed. Finally there is a far
distance between the practical scenario and the bookish
knowledge and we linked between the both conditions.
