Download Generator Protection

Bapuji S Palki, INCRC/PowerTechnologies, 15-11-2009
Protection Application – An Overview
© ABB Group
April 30, 2017 | Slide 1
© ABB Group
April 30, 2017 | Slide 3
Electric Power Systems
Generation
Transmission
© ABB Group
April 30, 2017 | Slide 4
Consumption
M
G
Generation
Distribution
Transmission
Distribution
Load
Different fault types in a power system
© ABB Group
April 30, 2017 | Slide 5
The main task for Relay Protection
U
I
C
E
• Protect people and property
around the power system
• Protect equipment, lines etc..
in the power system
• Separate the faulty part from
the rest of the power system
© ABB Group
April 30, 2017 | Slide 8
K
MAIN REQUIREMENTS OF
PROTECTION ARE:
•
•
•
•
•
© ABB Group
April 30, 2017 | Slide 9
SPEED
SENSITIVITY
SELECTIVITY
DEPENDABILITY
SECURITY
Y
Y
Y
A
A
A
A
CT, VT ARRANGEMENTS
© ABB Group
April 30, 2017 | Slide 10
Y
BUS PROTN.
Y
CIRCUIT
PROTN.
Y
F2
Y
F1
Primary and backup protection zones
Remote back-up with time selectivity is most common
at Medium and low voltage functions
© ABB Group
April 30, 2017 | Slide 11
Technology history
Electromechanical 1900 - 1965
- All types of protection
- High impedance busbar
protection
- Very short tripping times
if sufficient torque
- Good reliability in case of
adequate maintenance
Technology history
Solid state 1965 -1980
- No moving parts
- Reduced CT - burden
- Short tripping times
over wide ranges
- More algorithms possible
- Low impedance busbar
protection
- EMC
Technology history
Numerical 1980 - …
- All types of protection
- Optimized numerical algorithms
at increased long time stability
- Multifunctional units with less HW
- New availability concept
using benefit of self monitoring
- Communication / interaction with
Station- & Network control
Adaptive Protection
Technology history
SW Flexibility
Protection Library
CPU Capacity
I>
51
I>>
50
I>U<
51-27
U
60
I
87G
I
87T
I2
46
I TH
49
U>
59
U<
27
F<>
81
U/f
24
Z<
21
X<
40
Ucos
78
P<32
U0>
64S
CTRL
F<>
81
CTRL
0->I
79
I>
51
CTRL
I TH
49
SYNC
25
Logics
e.g. Z<3ph. needs 17%
Timer
Counter
What is Substation Automation ?
A combination of:
© ABB Group
April 30, 2017 | Slide 16

Protection

Monitoring

Control

Communication
What is Substation Automation ?

Substitution for conventional control panels

Substitution for other sub systems

A more efficient way of controlling your substation
© ABB Group
April 30, 2017 | Slide 17
8
Conventional Control & Protection
Fault
Recording
Station Level
ABB
225kV LIGNE ABOBO 1
125VDC Distributuion Battery A
=D04+R01
125VDC Distributuion Battery B
Bay Protection
ABB
225kV LIGNE ABOBO 1
125VDC Distributuion Battery A
Busbar Protection
ABB
=D04+R01
ABB
=D04+R01
225kV LIGNE ABOBO 1
125VDC Distributuion Battery A
125VDC Distributuion Battery B
125VDC Distributuion Battery B
Event
Recording
=D04+R01
ABB
225kV LIGNE ABOBO 1
125VDC Distributuion Battery A
=D04+R01
125VDC Distributuion Battery B
ABB
RTU 200IN 1 IN 2 IN 3 IN 4 IN 5 IN 6 IN 7 IN 8 OUT
1
056 citcadnI
056 citcadnI
056 citcadnI
Network Partner
9114
24351678ABB
10
11
13
15
162REL316*4
=W1
=W2
12345678-Q1
9111
12
13
14
15
160eriosn
V
4.2b
FERMER
cABB
Network Partner
912REL316*4
2435678111
10
13
14
15
16
REB500
ABB
Network Partner
ON/OFF
BAY CONTROL RELAY REC316*4
LOCAL CONTROL
RTU 200IN 1 IN 2 IN 3 IN 4 IN 5 IN 6 IN 7 IN 8 OUT
ON/OFF
38
Indactic650
650
Indactic
METERING
ABB
RTU 200IN 1 IN 2 IN 3 IN 4 IN 5 IN 6 IN 7 IN 8 OUT
ON/OFF
Indactic650
650
Indactic
LINE PROTECTION RELAY REL316*4
ABB
BUSBAR PROTECTION REB500
ABB
225kV LIGNE ABOBO 1
ABB
Bay Level
225kV LIGNE ABOBO 1
125VDC Distributuion Battery A
125VDC Distributuion Battery B
SCADA
RTU
For each function a
dedicated device
and separate Panel
Control
Panel
ABB
=D04+R01
ABB
=W1
=W2
-Q1
SEL
-Q2
SEL
-Q0
SEL
TESTE
LAMPE
Extensive station wide cabling
OUVRIRFERMER
ABB
ESC
EXE
Local
Control
DISTANCE
LOC
Process Level
Marshalling
Extensive bay cabling
GIS or AIS
Switchgear
-Q2
-Q0
-Q1
-Q9
-Q8
System Engineering Tool
The New Way
Station
Monitoring
System
Station HMI
Gateway
Station Clock
Communication only
during engineering
IED Tool
Station bus
Bay
Control
Web Client
Object
Protection
Control &
Protection
Multi Object
Protection
IEDs
Process bus
Merging Unit
© ABB Group
April 30, 2017 | Slide 19
Merging Unit
Multi Bay
Control
Monitoring via IEDs for Protection
Advanced analysis
tools
Alarm Classes
Automatic printing
Summary report
GPS
User friendly
visualization
Universal Time
synchronization
CONCISE / FAST
Distance to Fault
Mo 12. 11. 96
GMT 17:02.43.305
Ayer Rajah & Labrador
Feeder One
Sequence of Events
ABB Network Partner AG
IED Parameter
# Of trips
C
E
ABB Network Partner AG
REL 316*4
ABB Network Partner AG
REL 316*4
ABB Network Partner AG
1
9
1
9
2
10
2
10
1
9
3
11
3
11
2
10
4
12
4
12
3
11
5
13
5
13
4
12
6
14
6
14
5
13
7
15
7
15
6
14
8
16
8
16
7
15
8
16
C
C
E
E
REL 316*4
C
E
The goal of the IEC 61850 standard
Interoperability
The ability for IED’s from one or several manufacturer
to exchange information and use the information for the
their own functions.
Free Configuration The standard shall support different philosophies and
allow a free allocation of functions e.g. it will work
equally well for centralized (RTU like) or decentralized
(SCS like) systems.
Long Term Stability The standard shall be future proof, i.e. it must be able
to follow the progress in communication technology as
well as evolving system requirements.
© ABB Group
April 30, 2017 | Slide 21
© ABB Group
April 30, 2017 | Slide 22
Fault Clearance System
Protection System
Circuit Breaker
CT
VT
Protection
Equipment
TE
DC-System
© ABB Group
April 30, 2017 | Slide 23
Trip
Coil
Circuit
Breaker
Mechanism
Different parts of fault clearance system
© ABB Group
April 30, 2017 | Slide 24
Redundant protection system
Redundant system costs more but can give big savings in the primary
system due to short fault clearance time
© ABB Group
April 30, 2017 | Slide 25
How to enhance dependability of fault
clearance system

The addition of a second main protection
increases the availability and dependability of
fault clearance system

In addition the provision of back-up protection
that operates independently of specified
devices in the main protection system
enhances this further.
© ABB Group
April 30, 2017 | Slide 26
Bapuji S Palki, INCRC/PowerTechnologies, 15-11-2009
Protection of Generators & Generator
Transformers and EHV and UHV
transmission networks
© ABB Group
April 30, 2017 | Slide 27
© ABB Group
April 30, 2017 | Slide 28
Layouts
Typical Parts of a Power Plant
Substation
Busbar in Substation
HV - Breaker
Power plant
Main Transformer
Auxiliary Transformer
Generator Breaker
Excitation Transformer
Excitation System
Turbine valve
Turbine - Generator
Earthing System
G
Field Circuit Breaker
Generator
Protection
Possible Faults

Stator Earth Faults

Rotor Earth Faults

Stator Short Circuits

Stator/Rotor Interturn faults

External faults
Generator
Protection
Abnormal Operating Condition

overcurrent/overload

unbalanced load

overtemperature

over- and undervoltage

over- and underexcitation

over- and underfrequency

over-fluxing

asynchronous running

out of step

generator motoring

failures in the machine control system
(i.e. AVR or governor failure)

failures in the machine cooling system

failures in the primary equipment (i.e.
breaker head flashover)

open phase
• Following are the various protections recommended for the generator
and generator transformer protection:
Type of fault
GENERATOR
STATOR
Short Circuits
Asymmetry
Stator overload
Earth fault stator
© ABB Group
April 30, 2017 | Slide 32
ANSI Device Protection Functions
No.
87G
87GT
21G
51 / 27 G
46G
51G
64G1
64G2
Generator differential
Overall differential
Minimum impedance (or alternatively
Over current / under voltage)
Negative sequence
Overload
95% stator earth fault
100% stator earth fault
Loss of excitation
Out of step
Monitoring
Blade fatigue
Inter turn fault
Mag. Circuits
Higher voltage
Accidental
energisation
Monitoring
© ABB Group
April 30, 2017 | Slide 33
40G
98G
32G / 37G
81G
95G
99G
59G
27 / 50 G
60 G
Loss of excitation
Pole slip
Low forward power / reverse power
(double protection for large generators)
Minimum frequency
Over voltage or over current
Overfluxing volt / Hz
Over voltage
Dead machine
PT fuse failure
GENERATOR
ROTOR
Rotor ground
GENERATOR
TRANSFORMER
Short Circuits
Ground fault
Overhang
UNIT AUXILIARY
TRANSFORMER
Short circuit
Ground fault
© ABB Group
April 30, 2017 | Slide 34
64F
Rotor earth fault
87GT
51GT
87T
51NGT
87NT
87HV
Overall differential
Overcurrent
Transformer differential
Earth fault over-current
Restricted earth fault
HV winding cum overhang differential
87 UAT
51 UAT
51 UAT
64 UAT
Transformer differential
Over-current
Restricted over-current
Restricted earth fault
50/51
Unit aux.
transformer
64F
Field winding
ground-fault
RAGRA
(RXNB4)
1) Instruments
© ABB Group
April 30, 2017 | Slide 35
© ABB Group
April 30, 2017 | Slide 36
Power transformers in a power system
400 kV AC Transmission
130 kV Subtransmission
Generation
MV
Distribution
LV
M
© ABB Group
April 30, 2017 | Slide 37
315MVA Transformer
© ABB Group
April 30, 2017 | Slide 38
Types of Internal Faults
© ABB Group
April 30, 2017 | Slide 39

Earth faults

Short-circuits

Inter turn Faults

Core Faults

Tank Faults

Reduced cooling
Abnormal Conditions
© ABB Group
April 30, 2017 | Slide 40

Overload

Over voltage

Reduced system voltage

Over excitation
Protective Relays Used ( Transformers > 5 MVA)

Gas detector relay ( Buchholz)

Over load protection

Thermal relays

Temperature monitoring relays

Over current protection

Ground fault protection

Differential protection

Interturn faults

Pressure relay for tap changer

Oil level monitor
© ABB Group
April 30, 2017 | Slide 41
Protective Relays Used ( Transformers < 5
MVA)

Gas detector relay

Overload protection

Overcurrent protection

Ground fault protection
© ABB Group
April 30, 2017 | Slide 42
Monitors
Monitors are very important devices which detect
faults and abnormal service conditions which may
develop into fault.
© ABB Group
April 30, 2017 | Slide 43
Transformer Monitors


Mechanical fault detectors

Sudden gas pressure protection

Buchholz protection

Oil level monitoring
Temperature Monitoring
© ABB Group
April 30, 2017 | Slide 44

The oil thermometer

The winding thermometer
• Recommendations for provision of protective and monitoring
equipment for transformers of 400kV and 220kV class are as follows:
(a) Transformer differential protection
(b) Overfluxing protection
(c) Restricted earth-fault protection
(d) Back-up directional O / C + E / F protection on HV side
(e) Back-up directional O / C + E / F protection on LV side
(f) Protection and monitors built in to Transformer (Buchholz relay,
Winding and Oil Temperature Indicators, Oil Level Indicator and
Pressure Relief Device)
(g) Protection for Tertiary winding
2.0 SPECIAL COMMENTS
2.1
• Protection and monitors shall be divided in two groups viz. Gr A and
Gr B at 400kV.
• Given below is the way of grouping these protections:
Group A
Group B
• Transformer biased
differential relay
R.E.F Protection
Buchholz Protection
• Back up Protection(HV)
Back up Protection(MV)
• Overfluxing protection(HV)
Overfluxing protection(MV)
Group A
Group B
• Oil temperature high tripping
Overload protection (Alarm only)
winding, temperature high tripping
• Pressure relief tripping
OLTC Buchholz tripping
• Delta winding protection
Oil level high/low tripping
• Group A and B protections shall be connected to separate DC source/
separately fused supplies.
• DC sources shall be supervised
• Both Gr A and Gr B protections shall give out tripping impulses to HV,
MV AND LV (if applicable), circuit breakers.
© ABB Group
April 30, 2017 | Slide 48
The reactor absorbs the capacitive power
generated in long lines
© ABB Group
April 30, 2017 | Slide 49
Shunt Reactor
© ABB Group
April 30, 2017 | Slide 50
A B C
A B C
L
R
Lp
Lp
Ln
© ABB Group
April 30, 2017 | Slide 51
Lp
General


Shunt reactors are used in EHV systems to limit
the over voltages due to capacitive VAR
generation in Long Transmission Lines
The shunt reactors are normally connected

Through isolators to a line

Through circuit breakers to a busbar

© ABB Group
April 30, 2017 | Slide 52
Through circuit breakers to the tertiary of a
Interconnecting transformer
Different locations of reactor
© ABB Group
April 30, 2017 | Slide 53
Internal Faults
Faults occur in shunt reactors due to insulation breakdown, ageing
of insulation, overheating due to over excitation, oil contamination
and leakage
Dry air-core reactors


Phase-to-phase faults , resulting in high magnitude phase
current

Phase-to-earth faults ,, resulting in a low-magnitude earth-fault
current, dependent upon the size of the system earthing.

Turn-to-turn faults within the reactor bank, resulting in a very
small change in phase current
Oil-immersed reactors

High current phase-to-phase and phase-to-earth faults.

Turn-to-turn faults within the reactor winding.

Miscellaneous failures such as loss of cooling or low oil
© ABB Group
April 30, 2017 | Slide 54
Abnormal Conditions

Inrush currents

Inrush currents flow in connection with energisation

Inrush currents usually lower than 200% of rated
current

Transient overvoltages

Temporary overvoltages
© ABB Group
April 30, 2017 | Slide 55
Shunt Reactor Protections
© ABB Group
April 30, 2017 | Slide 56

Differential protection

Distance protection

Phase over current protection

Restricted earth fault protection

Mechanical fault detectors

Oil temperature and winding temperature
protection
Reactor Monitors


Mechanical fault detectors

Sudden gas pressure protection

Buchholz protection

Oil level monitoring
Temperature Monitoring
© ABB Group
April 30, 2017 | Slide 57

The oil thermometer

The winding thermometer
• Recommendations for provision of protection and monitoring equipment
for Reactors are as follows:
(a) Reactor differential Protection
(b) Reactor REF Protection
(c) Reactor backup protection(Impedance type or definite time O/C and E/F)
(d) Protections and monitors built into reactor (buchholz, winding
temperature, oil temperature, pressure relief, oil level, Fire protection)
2.0 Special Comments
2.1
• No duplication of reactor protections needs to be done but the
protections and monitors shall be divided in two groups viz Gr A
and Gr B.
Group A
Group B
• Reactor differential relay
Buchholz trip
• Reactor backup relay
Reactor R.E.F relay
• Oil temperature trip
Winding temperature trip
• Pressure relief trip
Oil level high / low trip, Fire protection
trip
• DC sources shall be supervised
• Both Gr A and Gr B protections shall give out tripping impulses to HV,
MV AND LV (if applicable), circuit breakers.
© ABB Group
April 30, 2017 | Slide 61
Transmission Line
© ABB Group
April 30, 2017 | Slide 62
Electrical faults in the power system

Transmission lines
85%

Busbar
12%

Transformer/ Generator
3%
100%
© ABB Group
April 30, 2017 | Slide 63
Fault types


© ABB Group
April 30, 2017 | Slide 64
Transient faults

are common on transmission lines, approximately 80-85%

lightnings are the most common reason

can also be caused by birds, falling trees, swinging lines
etc.

will disappear after a short dead interval
Persistent faults

can be caused by a broken conductor fallen down

can be a tree falling on a line

must be located and repaired before normal service
Measuring principles
© ABB Group
April 30, 2017 | Slide 65

Overcurrent protection

Differential protection

Phase comparison

Distance protection

Directional- wave protection
Overcurrent protection

Are normally used in radial networks with system voltage
below 70 kV where relatively long operating time is
acceptable.

On transmission lines directional or nondirectional over
current relays are used as back-up protections.
I>
block
© ABB Group
April 30, 2017 | Slide 66
I>
I>
I>
Digital differential communication
L1
L2
L3
DL1
DL2
DL3
© ABB Group
April 30, 2017 | Slide 67
Digital communication with
optical fibres or by
multiplexed channels
DL1
DL2
DL3
The principle of distance protection
ZK=Uk/Ik
Uk
Uk=0
metallic fault
Zk
A
Z<
© ABB Group
April 30, 2017 | Slide 68
Ik
B
Distance protection on short lines
jX

Quadrilateral characteristic improves
sensitivity for higher RF/XF ratio

It still has some limitations:

RF
XF
© ABB Group
April 30, 2017 | Slide 69
R
the value of set RF/XF ratio is
limited to 5
jX
Distance protection on long lines

Load impedance limits the reach in
resistive direction

High value of RF/XF ratio is generally not
necessary

Circular (mho) characteristic


R
© ABB Group
April 30, 2017 | Slide 70
Has no strictly defined reach in
resistive direction
Needs limitations in resistive
direction (blinder)
PLCC equipment
© ABB Group
April 30, 2017 | Slide 71
1.1 400 kV Lines
• There should be two independent high speed main protection schemes
called Main-I and Main-II with at least one of them being carrier aided
non-switched three zone distance protection.
• The other protection may be a phase segregated current differential
(this may require digital communication) phase comparison, directional
comparison type or a carrier aided non-switched distance protection.
• If Main-I and Main-II are both distance protection schemes, then they
should be preferably of different types. They need not necessarily of
different make. Both should be suitable for single and three phase tripping
•In addition to above, following shall also be provided
i) Two stage over-voltage protection. However in such cases where
system has grown sufficiently or in case of short lines, utilities on their
discretion may decide not to provide this protection.
ii) Auto reclose relay suitable for 1 ph / 3 ph (with deadline charging and
synchro check facility) reclosure.
iii) Sensitive IDMT directional E/F relay
1.2 220 kV Lines
• There should be at least one carrier aided non-switched three zone
distance protection scheme.
• In addition to this another non-switched / switched distance scheme
or directional over current and earth fault relays should be provided
as back up.
• Main protection should be suitable for single and three phase tripping.
• Auto-reclose relay suitable for 1 ph / 3 ph reclosure shall be provided.
• In case of both line protections being Distance Protections, IDMT type
E / F relay shall also be provided additionally.
© ABB Group
April 30, 2017 | Slide 75
765 kV 1056 MVAR Series capacitor
Reasons for using series capacitors

To avoid voltage collapse (IN,SE,ZA,US)

To increase transient stability(CO,IN,GS,SE,ZA,US )

To optimize load distribution (CO,IN,NO,SE)

To improve quality of supply (BR,ZA,US)

To increase power transfer capability (GS,ZA,US)
Typical connection diagram of Fixed Series
Capacitor
1)Capacitor
2)MOV
3)Spark Gap
4)Bypass switch
5)Reactor
6)Resistor
8)Platform
9)Disconnector
10)Bypass
disconnector
11)Earth switch
Increased power transfer capability by raising
the first swing stability limit
P [pu]
b) with SC
P [pu]
a) without SC
ASM
ADEC
ADEC
PMech
ASM
PMech
AACC
d0
AACC
dC
dEA
dCR
d0
d
dC
dEA
dCR
d
VisioDocument
Thyristor controlled series capacitor
Voltage inversion on Series Compensated line
Voltage UM at relay point will lag fault current IF if XC> XL1.
Voltage inversion causes false decision in conventional directional
relays.
Current inversion on Series Compensated line
Fault current will lead source voltage by 90 degrees if
XC> XS +XL1.
Current inversion causes a false directional decision of
distance relays (voltage memories do not help in this case)
Impact of series compensation on protective
relays of adjacent lines
Due to intermediate in feeds protection far away
from the faulty line can mal operate by its
instantaneous zone
An important Conclusion
System studies , Use of on line
Simulator (e.g.; RTDS), Tests using
EMTP files are very important when
applying protections for series
compensated lines.
Such studies should be specific to
each line.
© ABB Group
April 30, 2017 | Slide 86
Auto reclosing Cycle
OH-lines
High fault-rate
(80-90%)
Fast
simultaneous
Fault clearing
© ABB Group
April 30, 2017 | Slide 87
AUTORECLOSING CYCLE
OH-lines
Intermittent faults
(80-90%)
Successful
AR-rate :
High (80-90%)
© ABB Group
April 30, 2017 | Slide 88
Auto reclosing principles

95% of faults are transient type

3 Ph autoreclosing synchrocheck is used


1 Ph autoreclosing needs identification of
faulty phase

© ABB Group
April 30, 2017 | Slide 89
Helps verify phase angles are not out of phase
e.g: due to heavy power swing
Phase identification is difficult for high resistance
faults
Single-pole Reclosing
Single-Pole Reclosing
A B C
© ABB Group
April 30, 2017 | Slide 90
A B C
Artificial extinction of secondary arc by Fixed
Four-reactor Scheme
ABC
ABC
L
R
Lp Lp Lp
Ln
© ABB Group
April 30, 2017 | Slide 91
© ABB Group
April 30, 2017 | Slide 92
Need for Busbar protection

In its absence fault clearance takes place in Zone-II of
distance relay by remote end tripping

This means slow and unselective tripping and wide spread
black out
Effect of delayed clearance
© ABB Group
April 30, 2017 | Slide 93

Greater damage at fault point

Indirect shock to connected equipments like shafts
of Generator and windings of transformer.
Types of BB Protections

High impedance

Medium impedance

Low impedance

Blockable O/C relay ( For radial systems in
distribution systems)
© ABB Group
April 30, 2017 | Slide 94
High impedance bus differential relay
Basic features
SETTING VR > IF ( RCT + 2 RL)
VK > 2 VR
RL
A
VR
RCT
B
FOR VR TO BE ZERO FOR
EXTERNAL FAULT
nA = nB 1 + RA / ZA
1 + RB / ZB
n = TURNS RATIO
R = RCT + 2 RL
Z = MAGNETIZING IMPEDANCE
© ABB Group
April 30, 2017 | Slide 95
RADSS medium
impedance relay
IR1
T MD
n MD
Ud3
dR
D2
US
© ABB Group
April 30, 2017 | Slide 96
D1
REB500 - Numerical Busbar
and Breaker Failure Protection
ABB Network Partner AG
REB 500
C
E
Distributed installation
ABB Network Partner AG
REB 500
ABB Network Partner AG
C
E
Bay Unit
Central Unit
REB 500
ABB Network Partner AG
REB 500
C
E
Bay Unit
C
E
Bay Unit
REB 500
C
E
Bay Unit
E
© ABB Group
April 30, 2017 | Slide 97
ABB Network Partner AG
E
Advantages of medium/ Low impedance relays

Free from any need for Identical CT ratios or matched CTs

Other relays can be included in the same CT core

Increasing fault levels have no impact
© ABB Group
April 30, 2017 | Slide 98
1.0 GENERAL
• Bus bar protection is provided for high speed sensitive clearance
of bus bar faults by tripping all the circuit breakers connected to
faulty bus
• Recommendations for providing bus bar protection at different
voltage levels are as follows:
(i) Bus bar protection must be provided in all new 400kV and 220kV
substations as well as generating station switchyards.
(ii) For existing substations, provision of bus bar protection is
considered must at 400kV level and at 220kV level.
In case of radially fed 220kV substations, having more than one bus
it is desirable to have bus bar protection but is not a must.
© ABB Group
April 30, 2017 | Slide 100
Interrupters
Interrupter design
© ABB Group
April 30, 2017 | Slide 101
Breaker back-up
5
1
6
2
Z<
7
8
3
4
For uncleared fault shown CB’s to be tripped are 1, 3, 4 & 6
© ABB Group
April 30, 2017 | Slide 102
Classical CBFP
Breaker Failure Protection
I>
I>
I>
I>
+
if trip
from
relay
© ABB Group
April 30, 2017 | Slide 103
t
trip
• Recommendations for providing LBB protection at different voltage
levels are as follows:
(i) In all new 400kV and 220kV substations as well as generating stations
switchyards, it must be provided for each circuit breaker
(ii) For existing switchyards, it is considered a must at 400kV level and
also at 220kV switchyards having multiple feed
In case of radially fed 220kV substations, provision of LBB protection is
desirable but not essential
© ABB Group
April 30, 2017 | Slide 105
Products
Capacitors – HV Products / Filter Capacitor Banks
Improving the performance, quality
and efficiency of electrical systems
© ABB Group
April 30, 2017 | Slide 106
Capacitor banks- General

Normally used in MV networks to generate reactive power

Series reactors are used to limit inrush current

Harmonic filters for thyristor controlled reactors are also
variation of capacitor banks having reactance tuned to
capacitance
Shunt
Capacitors-General
Shunt Capacitor Faults

Terminal shunt faults

Capacitor unit failures

Capacitor unit over voltages

Capacitor rack arc-over
Abnormal Conditions

Inrush currents

Transient over voltages

Temporary over voltages

Out rush currents
Capacitor Bank Protections

Short -circuit protection
(3I >>)

Ground-fault protection
(I )

Overload protection(3I/U >)

Under current protection
(I/U <)

Unbalance protection
(IN-N)
Fusing
Capacitor Fusing
Internally Fused
Fuse
© ABB Group
April 30, 2017 | Slide 112
Externally Fused
Discharge Resistor
Internal Strings
Fuseless
Conventional
Wide Area Monitoring System
Global measurements provided by a WAMS
improve voltage stability assessment
GPS synchronised current and
voltage phasor measurement
Im
U1
I3
Time resolution: <10-6 s
GPS
Satellite
Re
U3
Wide Area
Monitoring
Center
I1
U2
I2
PMU
Transmission Network
PMU
PMU
Im
Im
U1
I3
U3
I1
Re
U2
I2
U3
Im
Im
U1
I3
PMU
PMU
I1
Re
U2
I2
U1
I3
U3
I1
Re
U2
I2
U1
I3
U3
I1
Re
U2
I2
Traditional versus Smart Grids – a transition
Traditional Grid

Centralized power generation

Uni-directional power flow

Operation based on historical
experience
Smart Grids

Centralized and distributed power generation
(renewable)

Multi-directional power flow

Operation based on real time data
© ABB Group
April 30, 2017 | Slide 115