11
Presentation on
SUB STATION BASIC : PART – I Single Line Diagram
Bus Bar Arrangement
Sub Station Layout
22
Introduction
The economics of generation of electrical energy and the huge demands for power in the modern times requires creation of bigger POWER STATIONS.
The power stations may be far from the load centre / consumers and so long high voltage transmission lines are necessary for transfer of bulk power from power station to different load centres.
In between power station and ultimate consumers a number of transformation and switching stations are to be created. Such stations are known as Sub Station.
33
Concept of Power System
44
What is Sub Station ?
A SUBSTATION is a subsidiary station of an electricity Generation, Transmission and Distribution system where voltage is transformed from high to low or vise versa using transformers. Electric power may flow through several substations between generating plant and consumer, and may be changed in voltage in several steps. A Step-up transformer increases the voltage and proportionally decreases the current, while a step-down transformer decreases the voltage and proportionally increases the current for domestic and commercial distribution.
55
House Electrification
DISTRIBUTION BOARD
3- & 1- MCBsBUS BAR STRIPS
SOURCE CABLE (Incoming)
3- LOAD CABLE (Outgoing)
1- LOAD CABLE (Outgoing)
1- LOAD CABLE (Outgoing)
1- LOAD CABLE (Outgoing)
66
General Arrangement
LIGHTNING ARRESTOR
POTENTIAL TRANSFORMER
TR. LINE (INCOMER / OUTGOING)
TR. LINE (INCOMER)
CURRENT TRANSFORMER
WAVE TRAP
EARTH SWITCH
ISOLATOR
CIRCUIT BREAKER
ISOLATOR
CAP. VOLTAGE TRANSFORMER POWER TRANSFORMER
SUB STATION
BUS BAR
77
Single Bus Bar Scheme
BUS BAR
SUB STATION POWER STATION LOAD CENTRE
Faulty
Faulty
88
Advantage & Disadvantage
SINGLE BUS BAR (UPTO 33kV SS)
Advantages
Lowest cost
Small land area required
Easily expandable
Simple in concept and operation
Disadvantages
Lowest reliability
Failure of a circuit breaker causes loss of the feeder
Bus fault causes loss of the entire substation
99
Improvement
Main Disadvantage ?
Loss of the entire Sub Station in case of Bus fault.
Requirement ?
Avoid loss of entire bus i.e., entire Sub Station in Bus fault.
How to Achieve ?
By Sectionalizing the Single Bus Bar.
Arrangement ?
Sectionalisation of Single Bus Bar Arrangement.
1010
Sectionalization of Single Bus Bar Scheme
BUS SECTION - I BUS SECTION - II
SUB STATION POWER STATION LOAD CENTRE
Faulty
Faulty
SECTIONALIZING CB
1111
Advantage & Disadvantage
SECTIONALIZATION BUS BAR (33kV & 66kV SS)
Advantages
Flexible operation
Higher reliability than single bus scheme
Isolation of bus sections for maintenance
Loss of only part of the substation for a bus fault
Disadvantages
Loss of circuit for breaker failure
A sectionalized bus arrangement has a higher cost than a single bus scheme as additional circuit breaker and isolators are required for sectionalizing
1212
Improvement
Main Disadvantage ?
Circuit Breaker failures are more than Bus fault. Thus, we loose important feeder in case of Circuit Breaker outage.
Requirement ?
Avoid loss of important circuit in case of Circuit Breaker outage.
How to Achieve ?
By by-passing the faulty circuit breaker.
Arrangement ?
Main and Transfer Bus Bar Arrangement.
1313
Main and Transfer Bus Bar Scheme
MAIN BUS I
SUB STATION POWER STATION
TRANSFER BUS
LOAD CENTRE
Faulty
Faulty
TRANSFER BUS COUPLER (TBC)
1414
Advantage & Disadvantage
MAIN & TRANSFER BUS BAR (132kV SS)
Advantages
Circuit breaker outage / maintenance does not disrupt the service of feeder / circuit
Reasonable in cost
Fairly small land area
Easily expandable
Disadvantages
Bus Fault causes disruption of service of entire sub station
An additional circuit breaker is required for bus tie
1515
Improvement Main Disadvantage ?
Bus fault in a sub station having more nos. of circuits causes greater interruption of power. In Main and Transfer Bus Bar arrangement bus fault results loss of entire sub station i.e., all circuits.
Requirement ?
Avoid loss of too many circuits in case of bus fault.
How to Achieve ?
By providing another Main Bus for connection of circuits.
Arrangement ?
Double Main Bus Bar Arrangement.
1616
Double Main Bus Bar Scheme
MAIN BUS I
MAIN BUS II
SUB STATION POWER STATION LOAD CENTRE
Faulty
Faulty
BUS COUPLER (BC)INTERRUPTION
Single Bus Scheme Mode
1717
Advantage & Disadvantage
DOUBLE MAIN BUS BAR (220kV SS)
Advantages
Bus Bar outage / maintenance does not disrupt the service of any feeder / circuit
Reasonable in cost
Fairly small land area
Easily expandable
Disadvantages
Circuit Breaker outage causes disruption of service of that feeder
1818
Improvement Main Disadvantage ?
Double Main Bus arrangement is an alternative to Main & Transfer Bus scheme. In both cases, the investment is same. The only difference is that in Double Main Bus the outage of Bus Bar and in Main & Transfer Bus the outage of Breaker is prioritized.
Interruption of Power during Isolator operation.
Requirement ?
Both Bus fault and Circuit Breaker outage are to be taken care off.
How to Achieve ?
By using one of the Main Buses as “Main Cum Transfer Bus”.
Arrangement ?
Double Main Cum Transfer Bus Bar Arrangement.
1919
Double Main Cum Transfer Bus Bar Scheme
BUS I CUM TRANSFER
BUS II
SUB STATION POWER STATION LOAD CENTRE
Faulty
Faulty
BC
INTERRUPTION
Single Bus Scheme Mode
Main and Transfer Bus Scheme Mode
2020
Advantage & Disadvantage DOUBLE MAIN CUM TRANSFER BUS BAR (220kV
SS)
Advantages
Bus Bar outage / maintenance does not disrupt the service of any feeder / circuit
Circuit Breaker outage does not cause disruption of service of that feeder
Reasonable in cost
Fairly small land area
Easily expandable
Disadvantages
Additional Isolator in each circuit increases the cost
2121
Improvement
Main Disadvantage ? Double Main Cum Transfer Bus Bar
arrangement outage of Circuit Breaker and Bus together causes loss of faulty Circuit Breaker feeder.
Interruption of Power during Isolator Operation.
Requirement ? Avoid loss of feeder in case of simultaneous
outage of Circuit Breaker and a Main Bus.
How to Achieve ? By providing separate transfer Bus along with
Double Main Buses.
Arrangement ? Double Main and Transfer Bus Bar
Arrangement.
2222
Double Main and Transfer Bus Bar Scheme
SUB STATION POWER STATION LOAD CENTRE
BUS I
BUS II
TRANSFER BUS
Faulty
Faulty
BC
TBC
INTERRUPTION
Single Bus Scheme Mode
Main and Transfer Scheme Mode
2323
Advantage & Disadvantage
DOUBLE MAIN AND TRANSFER BUS BAR (220kV SS)
Advantages
Bus Bar outage / maintenance does not disrupt the service of any feeder / circuit
Circuit Breaker outage does not cause disruption of service of that feeder
Maintenance of Bus and CB does not interrupt supply
Disadvantages
Additional Isolator and Circuit Breaker required for transfer Bus tie.
2424
Improvement Main Disadvantage ?
Interruption of Power during Isolator operation.
Interruption of Power is likely to cause major disturbance if the feeders are important and heavily loaded.
Requirement ?
Avoid interruption of important and heavily loaded feeders during bus fault or outage of Circuit Breaker.
How to Achieve ?
By connection of circuits for double feed through Circuit Breakers and avoid Isolator switching.
Arrangement ?
One and a Half Breaker Bus Bar Arrangement.
2525
One and a Half Breaker Bus Bar Scheme
BUS I BUS II
MAIN CB MAIN CBTIE CB
MAIN CB MAIN CBTIE CB
SUB STATION
POWER STATION
LOAD CENTRE
Faulty
Faulty
Faulty
Faulty
2626
Advantage & Disadvantage ONE & HALF BREAKER BUS BAR (400kV SS)Advantages Flexible operation High reliability Can isolate either main bus for maintenance
without disrupting service Can isolate any circuit breaker for
maintenance without disrupting service Double feed to each circuit Bus fault does not interrupt service to any
circuits All switching done with circuit breakersDisadvantages One-and-a-half breakers are required per
circuit
2727
Improvement Important
In transmission system the highest reliable Bus Bar Arrangement adopted by POWERGRID is One and a Half Bus Bar Scheme. However, where bulk power evacuation without alternative path is concerned, further reliable arrangement may be adopted.
What Arrangement ?
Connection of circuits in Double Bus Bar Arrangement where each circuit will have a spare Circuit Breaker in service.
Where can be used ?
In large Generating Plants where implication of generation outage is much higher than the cost of Circuit Breakers.
2828
Double Breaker Bus Bar SchemeBUS I BUS II
SUB STATION
POWER STATION
LOAD CENTRE
Faulty
Faulty
2929
Advantage & Disadvantage DOUBLE BREAKER BUS BAR (Mega Generating
Units)Advantages Flexible operation Very high reliability Isolation of either main bus for maintenance
without disrupting service Isolation of any circuit breaker for
maintenance without disrupting service Double feed to each circuit No interruption of service to any circuits from
bus fault Loss of only one circuit for breaker failure All switching with circuit breakersDisadvantages This configuration carries a high cost Two circuit breakers are required for each
circuit.
3030
PHOTOGRAPHS
3131
Photographs
BUS BAR
3232
CIRCUIT BREAKER ISOLATOR AND EARTH SWITCH
Photographs
3333
CURRENT TRANSFORMER POTENTIAL TRANSFORMER
Photographs
3434
LIGHTNING ARRESTERCAPACITOR VOLTAGE
TRANSFORMER
Photographs
3535
WAVE TRAP TRANSMISSION LINE
Photographs
3636
TRANSFORMER
Photographs
3737
REACTOR
Photographs
3838
Photographs
SUB STATION
3939
LAYOUT & SECTION
4040
DRAWING – EXAMPLE : 1
CL-CT
CL-WT
CL-CVTCL-LA
A
A
B
B
CL-ISO
CL-CB
CL-ISO
SINGLE LINE DIAGRAM
CL-LA
CL-TFR.
SLIDE : 1 of 3
LAYOUT DRAWING
4141
Ground LevelLA CVT WT CT ISO & ES CB ISO
SECTION - AA
DRAWING – EXAMPLE : 1
SLIDE : 2 of 3
Earth Wire
Gantry
4242
Ground LevelLA CT ISO CB ISO
SECTION - BB
DRAWING – EXAMPLE : 1
SLIDE : 3 of 3
Transformer
4343
DRAWING – EXAMPLE : 2
SLIDE : 1 of 3
CL-CTCL-WTCL-CVTCL-LA
A
A
B
B
CL-ISO
CL-CB
CL-ISO
CL-LA
CL-TFR.
CL-ISO
SINGLE LINE DIAGRAM
LAYOUT DRAWING
4444
SECTION - AA
DRAWING – EXAMPLE : 2
SLIDE : 2 of 3
Ground LevelLA CVT WT CT ISO & ES CB ISO ISO
Gantry
Earth Wire
4545
SECTION - BB
DRAWING – EXAMPLE : 2
SLIDE : 3 of 3
Ground LevelCT ISO & ES CB ISO ISO
Gantry
LATransformer
Earth Wire
4646
4747
QUESTION
What are the different parts of Power System ?
What is Sub Station ?
What is Single Line Diagram ?
Explain BUS BAR ?
What do you understand by Bus Bar Arrangement ?
What are the limitations of Single Bus Bar Scheme ?
What is the advantage of Sectionalisation of Single Bus Bar over Single Bus Arrangement ?
Bus Bar Arrangement for 132kV Sub Station is .
4848
QUESTION
What are the limitations of Main & Transfer Bus Bar Scheme ?
How does Double Main Bus Scheme differ from Main & Transfer Bus Arrangement ?
What is the difference between Double Main Bus and Double Main Cum Transfer Bus Arrangement ?
What is the Bus Bar Arrangement for Sub Station having voltage class 400kV & above ?
What is the advantages of One and a half Breaker Bus Bar Scheme ?
What is the advantage & Disadvantage of Two Breaker Bus Bar Scheme and where the same is used ?
4949
QUESTION
Explain the purpose of using
(a) Circuit Breaker
(b) Isolator
(c) Earth Switch
(d) Lightning Arrestor
(e) Current Transformer
(f) Potential Transformer
(g) Capacitor Voltage Transformer
(h) Wave Trap
(i) Power Transformer
5050
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