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4.Инновационная защита от ОЗЗ

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EARTH-FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Earth-fault protection in compensated distribution networks
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Experience and know-how
ABB Technology leadership
 There are over 1,500,000 ABB
Distribution Automation products
installed around the world
 Pioneering products and innovations
over 50 years
 Service and spare sparts available even
for products delivered over 40 years ago
REX640, SSC600
2018
Relion product
family
2009
The first native IEC 61850
2007
feeder protection relay REF615
Communication
Gateway COM610
2004
610
series
2003
RED 500 series protection
relays and terminals
1995
Feeder protection
relay SPAJ 140 C
Integration of prot & control
into one unit – SPAC terminal
1989
1987
SPACOM series relay featuring 1985
serial communication
© ABB Group
November 19, 2018 | Slide 4
Microprocessor-based multifunction relay SPAJ 3M5 J3
1982
Static protective relays for
distribution networks
1965
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Content of the presentations
Part 1:
Fundamentals of earth-fault current compensation and
earth-fault protection in compensated networks
 Basics of earth-fault current compensation
 Compensated earth-fault current
 Interpretation of coil controller values
Part 2: Effect of earth-fault current compensation into directional
earth-fault protection
 Fundamentals of measurements of Uo and Io, polarities, accuracy
 Basic earth-fault operation point analysis, affecting quantities
 Measurement at healthy and faulty feeder
© ABB Group
November 19, 2018 | Slide 15
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Content of the presentations
Part 3: Different earth fault types and their challenges
 Earth-fault types and their characteristics
 Re-striking, intermittent earth fault
 Available earth-fault protection methods in ABB Relion MV-relays
Part 4: Multi-frequency admittance based earth-fault protection
 Background and motivations for the new function
 Operation principle and advantages
 Application, settings, secondary testing
 Practical experience, field test results
© ABB Group
November 19, 2018 | Slide 16
ABB
EARTH-FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Fundamentals of earth-fault current compensation and
earth-fault protection in compensated networks
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
RIO600
REF615
Single
phase
earth
fault
RIO600
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
MV-neutral
point
A
B
?
C
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
100 years of resonant earthed networks!
© ABB Group
November 19, 2018 | Slide 7
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
“Compensated” networks
 Compensated
network
 Arc Suppression
Coil (ASC) or
Petersen coil
earthed network
© ABB Group
November 19, 2018 | Slide 8
• Resonant(ly)
earthed network
• High impedance
earthed network
ABB
EARTH-FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Earth-fault current compensation
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Unearthed network
• Composition of earth-fault current
Capacitive earth-fault
current contribution of
over-head line
~0.06A/km@20kV
+Uo
IEF
UvS,
UvT
Capacitive current
Resistive current
UE
UE = Earth potential raise, earthing voltage
= IEF * ZE
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Unearthed network
• Composition of earth-fault current
Capacitive earth-fault
current contribution of
over-head line
~0.06A/km@20kV
+Uo
Capacitive earthfault current
contribution of
3-ph cable
~3…5A/km@20kV!
IEF
UvS,
UvT
Capacitive current
Resistive current
UE
UE = Earth potential raise, earthing voltage
= IEF * ZE
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
“Compensated” network
+Uo
IEF
UvS,
UvT
Capacitive current
Inductive current
Resistive current
UE
UE = Earth potential raise, earthing voltage
= IEF * ZE
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Alternative ways to
implement earth-fault
current compensation:
L1 L2 L3
110/20kV
åIL = Io
Ro
Co
• Centralized
compensation
• Coil is installed either
into neutral point of the
feeding main traformer
+Uo
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 13
Rpar
Parallel
resistor
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Alternative ways to
implement earth-fault
current compensation:
L1 L2 L3
110/20kV
åIL = Io
Ro
Co
• Centralized
compensation
• Coil is installed either
into neutral point of
the feeding main
traformer
• or at the neutral
point of grounding
transformer
Grounding
transformer
ZN-connection
500V
LCOIL
© ABB Group
November 19, 2018 | Slide 14
Petersen
coil
Rpar
Parallel
resistor
+Uo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Alternative ways to
implement earth-fault
current compensation:
L1 L2 L3
110/20kV
åIL = Io
Ro
Co
• Centralized
compensation
• Coil is installed either
into neutral point of the
feeding main traformer
• or at the neutral point
of grounding
transformer
Grounding
transformer
ZN-connection
+Uo
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 15
Rpar
Parallel
resistor
LFIX
• ‘Plunger’ core
(continuously tunable)
or fixed value
• Typical rating: up to
several hundreds of
amperes per coil
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Alternative ways to
implement earth-fault
current compensation:
L1 L2 L3
110/20kV
åIL = Io
Ro
Co
• Centralized
compensation
• Coil is installed either into
neutral point of the
feeding main traformer
• or at the neutral point of
grounding transformer
Grounding
transformer
ZN-connection
+Uo
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 16
• ‘Plunger’ core
(continuously tunable) or
fixed value
• Typical rating: up to several
hundreds of amperes per
coil
Rpar
Parallel
resistor
LFIX
I par 
500V
500V

 8.7 A
2.5ohm 20000 / 3V
• Parallel resistor at PAWwinding is used to
increase the value of
Iocos used by feeder
protection
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
MV/LV
110/20kV
åIL = Io
Ro
Co
LCOIL_DST
L1
L2
L3
PEN
• Alternative ways to implement
earth-fault current
compensation:
• Distributed compensation
• Applied to limit capacitive
current contribution of long
cable feeders
L1
L2
L3
åIL = Io
Yo
• Typical rating: 5-15Aind/coil
• Several different device
configurations available
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 17
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Distributed compensation,
recommendations
• SWEDEN: When capacitive earthfault current of protected feeder
contribution exceeds 50 A is is
recommend to install distributed
coils
• NORWAY: When capacitive earthfault current of protected feeder
contribution exceeds 40 A is is
recommend to install distributed
coils
© ABB Group
November 19, 2018 | Slide 18
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
MV/LV
110/20kV
åIL = Io
Ro
Co
LCOIL_DST
Yo
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 19
• Distributed compensation
• Applied to limit capacitive
current contribution of long
cable feeders
L1
L2
L3
åIL = Io
L1
L2
L3
PEN
• Alternative ways to implement
earth-fault current
compensation:
Yo
• Typical rating: 5-15Aind/coil
• Several different device
configurations available
• If earth-fault current
compensation is done with
only distributed coils, then
feeder earth-fault
protection is based on
imaginary part of Io
(Iosin-method)
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
MV/LV
110/20kV
åIL = Io
Co
LCOIL_DST
L1
L2
L3
LFIX
åIL = Io
+Uo
Ro
Yo
500V
LCOIL
Petersen
coil
Rpar
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 20
L1
L2
L3
PEN
• Alternative ways to implement
earth-fault current
compensation:
• Centralized or/and
distributed compensation
• Centralized and tunable coil
is used to compensated
’base’ part of earth-fault
current
• Distributed coils are applied
to limit capacitive current
contribution of long cable
feeders
• Feeder earth-fault
protection is based on real
part of Io (Iocos-method)
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Compensated network: Petersen coil controller
+Uo
IEF
UvS,
UvT
Capacitive current
UE
REX640, Petersen coil tuner application
UE = Earth potential raise, earthing voltage
= IEF * ZE
Inductive current
Resistive current
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Compensated network: Petersen coil controller
+Uo
IEF
Fundamental parameters of compensated network
UvS,
UvT
1. Network unbalance

Unbalance of phase-to-earth capacitance (𝐶0_𝐿1 ≠ 𝐶0_𝐿2 ≠ 𝐶0_𝐿3 )
2. Network resonance point
 Inductive current of the coil(s), which matches the capacitive
earth-fault current of the network
3. Network compensation degree (detuning)

Coil (de)tuning value, setting (% or A)
4. Network damping


Total losses of the zero-sequence circuit,
~real-part of earth-fault current, estimated by the controller
Capacitive current
UE
UE = Earth potential raise, earthing voltage
= IEF * ZE
Inductive current
Resistive current
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Compensated network: Petersen coil controller
+Uo
IEF
Fundamental parameters of compensated network
UvS,
UvT
1. Network unbalance

Unbalance of phase-to-earth capacitance (𝐶0_𝐿1 ≠ 𝐶0_𝐿2 ≠ 𝐶0_𝐿3 )
2. Network resonance point
 Inductive current of the coil(s), which matches the capacitive
earth-fault current of the network
Capacitive current
UE
UE = Earth potential raise, earthing voltage
= IEF * ZE
Coil (de)tuning value, setting (% or A)
4. Network damping


Resistive current
Earth-fault current magnitude:
3. Network compensation degree (detuning)

Inductive current
Total losses of the zero-sequence circuit,
~real-part of earth-fault current, estimated by the controller
𝐼𝐸𝐹 =
2
2
2
2
2
𝐼𝐷𝑎𝑚𝑝𝑖𝑛𝑔
+ 𝐼𝐷𝑒𝑡𝑢𝑛𝑖𝑛𝑔
+ (𝐼𝐻𝑎𝑟𝑚2
+𝐼𝐻𝑎𝑟𝑚3
+ ⋯ + 𝐼𝐻𝑎𝑟𝑚𝑛
)
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Interpretation of values calculated by the
coil controller
© ABB Group
November 19, 2018 | Slide 28
Resonance curve with
operation point
• Behavior of Uo-voltage during
healthy-state as a function of
Petersen coil current
(detuning)
• Shape depends on the degree
of admittance imbalance and
total damping of the network
• Indication of maximum Uo
value at resonance
• Affected by the connection
status of parallel resistor of
the coil
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Interpretation of values calculated by the
coil controller
Network resonance point
seen by the Petersen coil
controller
• This value includes the
effect of fixed and
distributed coils
• At this coil current value,
Uo reaches maximum
level
© ABB Group
November 19, 2018 | Slide 29
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Interpretation of values calculated by the
coil controller
Coil detuning in amperes
•This value determines the
actual fault current
during earth fault
•Pos. value  over-comp.
•Neg.-value  under-comp
•0  resonance
© ABB Group
November 19, 2018 | Slide 30
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Interpretation of values calculated by the
coil controller
© ABB Group
November 19, 2018 | Slide 31
Total damping of the
network
• This the real-part of fault
current at galvanic fault
that is not compensated
by the Petersen coil
• This value is used by
protection and it provides
damping to the
oscillations
• Value depends on the
value and connection
status of the parallel
resistor of the coil
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Interpretation of values calculated by the
coil controller
Fault current magnitude
when RF = 0ohm
I_FLT = ABS(I_DAMPING + j*I_DETUNING)
•
I_FLT: A
Icoil: A
© ABB Group
November 19, 2018 | Slide 32
This is the expected
fault current value with
current detuning and
total losses of the
network during
galvanic fault
• Possible fault
resistance will reduce
this value
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Compensated systems
Benefits
vs.
Drawbacks
IMPROVED SAFETY AND
SERVICE QUALITY
CHALLENGING EARTH-FAULT
(EF) PROTECTION
• The inductive current of the
coil reduces the capacitive
fault current, 95…97%
• High sensitivity
requirements
• Self-extinguishing of
arcing faults
• Network operation
possible during a sustained
earth fault
• Accurate measurement
required
• Special functionality
required due to multitude
nature of earth faults
• Improved power quality and
reliability for the customer
© ABB Group
November 19, 2018 | Slide 34
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Compensated neutral
earthing is prevailing
MV-neutral earthing
practice globally!
© ABB Group
November 19, 2018 | Slide 35
ABB
EARTH FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Effect of earth-fault current current compensation into directional earth-fault protection
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
EARTH-FAULT PROTECTION
SHORT-CIRCUIT PROTECTION
Z = U/I= R + j*X
Im (Io)
OPERATE SECTOR
Im (Z)
-(Uo)
Re (Io)
Re (Z)
© ABB Group
November 19, 2018 | Slide 2
OPERATE SECTOR
Y =Io/Uo= G + j*B
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Main transformer
L1
L2
L3
110/20kV
L1
L2
L3
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 4
Rpar
Parallel
resistor
L1
L2
L3
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
Substation busbar
L1
L2
L3
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 5
Rpar
Parallel
resistor
L1
L2
L3
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
Outgoing feeders
L1
L2
L3
500V
LCOIL
Petersen
coil
© ABB Group
November 19, 2018 | Slide 6
Rpar
Parallel
resistor
L1
L2
L3
ABB
Taking earth-fault protection to the next level
Earth fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
L1
L2
L3
Petersen coil or Arc
Suppression coil (ASC)
500V
LCOIL
Petersen
coil
Rpar
Parallel
resistor
L1
L2
L3
Parallel resistor
© ABB Group
November 19, 2018 | Slide 7
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
åIL = Io
L1
L2
L3
åIL = Io
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 8
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
• During a solid earth fault (RF=0 ohm),
neutral point voltage Uo will be same
as system phase-to-earth voltage:
11.547kV in 20kV system
• Typically this equals 100V or 110V in
the open-delta winding
åIL = Io
•
L1
L2
L3
Recommended accuracy class 3P:
 Amplitude error: ±3%
 Phase displacement: ±2o
åIL = Io
L1
L2
L3
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
√3
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 9
20
A
A
N
dn
N
dn
A
PRIMARY
WÌNDING
kV
100
3
N
dn
V
da
da da
TERTIARY
3U0 WINDINGS
OPEN-DELTA
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Polarity of Uo voltage:
• ABB Relion MV-relays are
connected to measure
+Uo voltage!
REF6XX
+Uo
+
-
+
-
© ABB Group
November 19, 2018 | Slide 10
+
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
åIL = Io
• Current Io is
measured
preferably with
accurate cable
core CT (CBCT)
KOKM 1RL12, 0.5S/5P10, 100/1, 1VA, 180mm
Neutral point voltage
L1
measurement
L2
L3
åIL = Io
PRIMARY
WÌNDING
500V
LCOIL
+Uo
Petersen
coil
A
B
C
A
Rpar
FAULT LOCATION,
N
N N
phase L1 dn dn dn
Parallel
resistor
V
åIL = Io
da
da
Residual current
measurement
Uo
Io
Io
A
kV
da
© ABB Group
November 19, 2018 | Slide 11
A
Protection
relay
CBCT
L1
L2
U L3
o
TERTIARY
WINDINGS
OPEN-DELTA
ABB
Taking earth-fault protection to the next level
Kompensoidun verkon maasulkusuojaus
REF6XX
• Polarity of Io current:
• ABB Relion MV-relays
are connected to
measure -Io current!
Note: Minus polarity!
-
-Io
© ABB Group
November 19, 2018 | Slide 12
+
+
-
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Longitudial impedance vs.
shunt admittance:
L1 L2 L3
Z1
L1
L2
L3
110/20kV
åIL = Io
Ro
Co
Z1
L1
L2
L3
åIL = Io
Yo
• 10km conductor:
Longitudial impedance:
Z1 =~ few ohms
500V
LCOIL
+Uo
Petersen
coil
Rpar
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 13
Shunt admittance:
FAULT LOCATION,
phase L1
Z1
Yo
Xco 
1
1

  Co 100    Co
XCo =~ thousends of ohms
 Longitudial impedance can
be ~ignored!…
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Longitudial impedance vs.
shunt admittance:
L1 L2 L3
Z1
L1
L2
L3
110/20kV
åIL = Io
Ro
Co
Z1
L1
L2
L3
åIL = Io
Yo
• 10km conductor:
Longitudial impedance:
Z1 =~ few ohms
500V
LCOIL
+Uo
Petersen
coil
Rpar
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 14
Shunt admittance:
FAULT LOCATION,
Z1 phase L1
Yo
Xco 
1
1

  Co 100    Co
XCo =~ thousends of ohms
 Longitudial impedance can
be ~ignored!…
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
• There are always some
“natural losses”, resistive
shunt losses present
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 15
• In practice, the network
admittances are
dominantly capacitive as
they are due to the phaseto-earth capacitances of the
electrical conductors:
overhead lines and
underground cables
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
500V
LCOIL
+Uo
Petersen
coil
Rpar
x 50!!
Larger Co
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 16
• In practice, the network
admittances are
dominantly capacitive
• Their practical value
depends on the share of
cables in the network!
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Usage of underground cabling is increasing in MV-level!
• Affects to the earth-fault current magnitude!
© ABB Group
November 19, 2018 | Slide 17
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• Usage of underground cabling is increasing in MV-level!
• Affects to the earth-fault current magnitude!
© ABB Group
November 19, 2018 | Slide 18
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• What earth-fault
protection measures
during healthy state?
© ABB Group
November 19, 2018 | Slide 19
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1
L1 L2 L3
Capacitive current
Inductive current
L2
L3
L1
L2
L3
Resistive current
110/20kV
Ro
åIL = Io
Co
~very small value
• During the HEALTHY STATE
residual current and voltage
are (typically) very small.
• The exact value depends on
the natural asymmetry of
the network.
L1
L2
L3
åIL = Io ~very small value
Yo
500V
LCOIL
+Uo
Rpar
~small value
Petersen
coil
Parallel
resistor
FAULT LOCATION,
phase L1
L1
L2
L3
åIL = Io ~very small value
© ABB Group
November 19, 2018 | Slide 20
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• What earth-fault
protection measures
during fault?
HEALTHY FEEDER
© ABB Group
November 19, 2018 | Slide 21
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 22
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
• Residual current Io measured
at the beginning of a healthy
feeder equals the earth fault
current produced by the phaseto-earth admittances of that
feeder!
• Practical magnitude depends
on the cable km in feeder
• It is dominantly capacitive!
• It flows from line towards
busbar!
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
åIL = Io
© ABB Group
November 19, 2018 | Slide 24
Re(Io)
L1
L2
L3
Yo
-Uo
Io
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
• Residual current Io measured
at the beginning of a healthy
feeder equals the earth fault
current produced by the phaseto-earth admittances of that
feeder!
• Practical magnitude depends
on the cable km in feeder
• It is dominantly capacitive!
• It flows from line towards
busbar!
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
åIL = Io
© ABB Group
November 19, 2018 | Slide 25
Re(Io)
L1
L2
L3
-Uo
Yo
Io
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
• Residual current Io measured
at the beginning of a healthy
feeder equals the earth fault
current produced by the phaseto-earth admittances of that
feeder!
• Practical magnitude depends
on the cable km in feeder
• It is dominantly capacitive!
• It flows from line towards
busbar!
Im(Io)
500V
LCOIL
+Uo
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 26
OPERATE
SECTOR
Petersen
coil
Rpar
Re(Io)
-Uo
Yo
Io

ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
L1
L2
L3
110/20kV
åIL = Io
• Current Io is
measured
preferably with
accurate cable
core CT (CBCT)
KOKM 1RL12, 0.5S/5P10, 100/1, 1VA, 180mm
Neutral point voltage
L1
measurement
L2
L3
åIL = Io
PRIMARY
WÌNDING
500V
LCOIL
+Uo
Petersen
coil
A
B
C
A
Rpar
FAULT LOCATION,
N
N N
phase L1 dn dn dn
Parallel
resistor
V
åIL = Io
da
da
Residual current
measurement
Uo
Io
Io
A
kV
da
© ABB Group
November 19, 2018 | Slide 27
A
Protection
relay
CBCT
L1
L2
U L3
o
TERTIARY
WINDINGS
OPEN-DELTA
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
!
• Current Io is
measured
preferably with
accurate cable
core CT (CBCT)
KOKM 1RL12, 0.5S/5P10, 100/1, 1VA, 180mm
Neutral point voltage
measurement
A
B
C
PRIMARY
WÌNDING
A
A
Protection
relay
Residual current
measurement
Uo
Io
Io
A
kV
CBCT
N
dn
N
dn
N
dn
V
Uo
da
da
da
TERTIARY
WINDINGS
OPEN-DELTA
© ABB Group
November 19, 2018 | Slide 28
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
!
• Current Io is
measured
preferably with
accurate cable
core CT (CBCT)
KOKM 1RL12, 0.5S/5P10, 100/1, 1VA, 180mm
Neutral point voltage
measurement
A
B
C
PRIMARY
WÌNDING
A
A
Protection
relay
Residual current
measurement
Uo
Io
Io
A
kV
CBCT
N
dn
N
dn
N
dn
V
Uo
da
da
da
TERTIARY
WINDINGS
OPEN-DELTA
© ABB Group
November 19, 2018 | Slide 29
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
“Combi-class CBCT”
Recommended!
KOKM 1RL12, 0.5S/5P10, 100/1, 1VA, 180mm
© ABB Group
November 19, 2018 | Slide 30
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Not all CBCTs are equal!
• “Window”-type CBCT have larger phase
displacements compared with Ring-type
• “Window”-type CBCT are not applicable for
sensitive directional earth-fault protection
© ABB Group
November 19, 2018 | Slide 31
• With Split-core CBCT, the “true” accuracy
depends on the installation quality
• Especially any air gap should be avoided as it
introduces large phase displacement!
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
• What earth-fault
protection measures
during fault?
FAULTY FEEDER
© ABB Group
November 19, 2018 | Slide 32
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
L1
L2
L3
åIL = Io
Yo
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 34
• Residual current Io measured
at the beginning of a faulty
feeder is affected by the
inductive current of the coil
(ASC) i.e. compensation degree
• The inductive current of the coil
(ASC) is ONLY seen in the faulty
feeder
• Also the additional resistive
current of the parallel resistor
is only measured at the faulty
feeder
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNEARTHED
NEUTRAL
POINT
Co
L1
L2
L3
åIL = Io
• Coil is disconnected and
the network becomes
unearthed network
(isolated neutral)
• The earth-fault current is
determined by the total
phase-to-earth
admittances (capacitances)
of the network
Yo
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 35
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNEARTHED
NEUTRAL
POINT
Co
L1
L2
L3
åIL = Io
Yo
Io Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 36
• In unearthed network
residual current Io
measured at the beginning
of a faulty feeder is
dominantly capacitive!
• It is due to phase-to-earth
admittances of the
“background network”
• It flows from busbar
towards line!
Re(Io)
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNEARTHED
NEUTRAL
POINT
Co
L1
L2
L3
åIL = Io
Yo
Io Im(Io)
FAULTY
500V
LCOIL
+Uo
Petersen
coil
Rpar
OPERATE
SECTOR (Iosin)
FAULT LOCATION,
phase L1
Parallel
resistor
Re(Io)
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 37
• In unearthed network
residual currents Io
measured at the beginning
of a faulty and healthy
feeders are both
dominantly capacitive!
• But their direction is
opposite (~180 apart)!
• Easy discrimination based
on the reactive part of Io
Yo
-Uo
Io
HEALTHY
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNEARTHED
NEUTRAL
POINT
Co
L1
L2
L3
åIL = Io
Yo
Io Im(Io)
FAULTY
500V
LCOIL
+Uo
Petersen
coil
Rpar
OPERATE
SECTOR (Iosin)
FAULT LOCATION,
phase L1
Parallel
resistor
Re(Io)
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 38
• In unearthed network
residual currents Io
measured at the beginning
of a faulty and healthy
feeders are both
dominantly capacitive!
• But their direction is
opposite (~180 apart)!
• Easy discrimination based
on the reactive part of Io
Yo
-Uo
Io
HEALTHY
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Io
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 39
• Compensation coils is
connected and the coil
current is gradually
increased…1
Re(Io)
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
• Compensation coils is
connected and the coil
current is gradually
increased…2
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 40
Io
Re(Io)
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
• Compensation coils is
connected and the coil
current is gradually
increased…3
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 41
Io
Re(Io)
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 42
• Compensation coils is
connected and the coil
current is gradually
increased…4
• Now level of undercompensation equals
feeder earth-fault current
• Protection does not see any
reactive component!
Io
Re(Io)
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 43
• Compensation coils is
connected and the coil
current is gradually
increased…5
• Phasor turns in same
direction as in healthy
feeder!
Re(Io)
Io
-Uo
Yo
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
RESONANCE
STATE
Co
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
Re(Io)
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 44
• Compensation coils is
connected and the coil
current is gradually
increased…6
• Phasor turns in same
direction as in healthy
feeder!
• Resonance state: Only
resistive component and
harmonics present in the
earth-fault current!
Yo
-Uo
Io
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
RESONANCE
STATE
• In compensated network
residual currents Io
measured at the beginning
of a faulty and healthy
feeders are seen similarly,
the reactive part
• Discrimination must be
based on the resistive part
L1
L2
L3
åIL = Io
Yo
Im(Io)
500V
LCOIL
+Uo
Petersen
coil
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
åIL = Io
© ABB Group
November 19, 2018 | Slide 45
Re(Io)
L1
L2
L3
Yo
-Uo
HEALTHY
Io
Io FAULTY
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
RESONANCE
STATE
L1
L2
L3
åIL = Io
Yo
• In compensated network
residual currents Io
measured at the beginning of
a faulty and healthy feeders
are seen similarly, the
reactive part
• Discrimination must be
based on the resistive part
• Reliable detection requires
typically additional resistive
component from parallel
resistor
Im(Io)
500V
LCOIL
+Uo
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
OPERATE
SECTOR
Petersen
coil
Ipar
L1
L2
L3
åIL = Io
Yo
Io
Re(Io)
-Uo
Io
Ipar
© ABB Group
November 19, 2018 | Slide 46
ABB
Taking earth-fault protection to the next level
Interpretation of values calculated by the coil controller
Total damping of the
network
• This the real-part of fault
current at galvanic fault
that is not compensated
by the Petersen coil
• This value is used by
protection and it provides
damping to the
oscillations
• Value depends on the
value and connection
status of the parallel
resistor of the coil
© ABB Group
November 19, 2018 | Slide 47
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Resistive part of fault current ~resistive part of Io: information from coil regulator: damping!
Parallel resistor CONNECTED
Parallel resistor DISCONNECTED
2.7
I_DAMPING
(Parallel resistor
switched off)=
Shunt losses of
the network +
Losses of the
coil(s) =
2.7A/66A=~4%
”Total losses/damping of the network”: I_DAMPING [A or %]
Losses of the parallel resistor (ON/OFF!)
Losses of the coil(s)
Shunt losses of the network
Approximate value of resistive current measured at the faulty feeder by
protection during galvanic (RF = 0ohm) earth-fault!
 Provides damping to the transient oscillations!
•
•
•

© ABB Group
November 19, 2018 | Slide 48
ABB
Taking earth-fault protection to the next level
Parallel resistor logic
(Rf = 5000 ohm):
OFF-ON
• Disconnection of
parallel resistor may
result in delayed
operation of
protection
 Recommendation to
keep parallel resistor
connected or connect
immediately when
earth-fault is
detected!
© ABB Group
November 19, 2018 | Slide 49
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Effect of
under- and over-compensation?
© ABB Group
November 19, 2018 | Slide 50
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
OVERCOMPENSATED
STATE
Co
• In compensated network
residual currents Io
measured at the beginning of
a faulty and healthy feeders
are seen similarly, the
reactive part
• Discrimination must be
based on the resistive part
•
L1
L2
L3
åIL = Io
Yo
Over-compensated state:
earth-fault current has
inductive and resistive
component
Im(Io)
500V
LCOIL
+Uo
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
OPERATE
SECTOR
Petersen
coil
Ipar
L1
L2
L3
åIL = Io
Yo
HEALTHY
Io
FAULTY
Io
© ABB Group
November 19, 2018 | Slide 51
Ipar
Re(Io)
-Uo
Amount
of overcompen
sation
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
UNDERCOMPENSATED
STATE
Co
• In compensated network
residual currents Io
measured at the beginning of
a faulty and healthy feeders
are seen similarly, the
reactive part
• Discrimination must be
based on the resistive part
•
L1
L2
L3
åIL = Io
Yo
Under-compensated state:
earth-fault current has
capacitive and resistive
component
Im(Io)
500V
LCOIL
+Uo
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 52
OPERATE
SECTOR
Petersen
coil
Ipar
Yo
HEALTHY
Io
I
Ipar o
FAULTY
Re(Io)
-Uo
Amount
of undercompensation
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Effect of
high eart-fault current contribution of
faulted feeder?
© ABB Group
November 19, 2018 | Slide 53
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
•
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
Co
•
RESONANCE
STATE
L1
L2
L3
åIL = Io
At the beginning of a faulty
feeder, the reactive part
depends:
•
On the phase-to-earth
capacitance of the feeder
•
On the tuning degree of
the coil
Fault in the long cable feeder
moves operation point
towards the boundary
Yo
Im(Io)
500V
LCOIL
+Uo
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 54
OPERATE
SECTOR
Petersen
coil
Rpar
Re(Io)
-Uo
Yo
Io
Io
Ipar
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
•
L1 L2 L3
Capacitive current
Inductive current
L1
L2
L3
Resistive current
110/20kV
åIL = Io
Ro
OVERCOMPENSATED
STATE
Co
L1
L2
L3
åIL = Io
Yo
At the beginning of a faulty
feeder, the reactive part
depends:
•
On the phase-to-earth
capacitance of the feeder
•
On the tuning degree of the
coil
•
Fault in the long cable feeder
moves operation point towards
the boundary
•
Over-compensation of
centralized coil emphasizes this
effect!
Im(Io)
500V
LCOIL
+Uo
Rpar
FAULT LOCATION,
phase L1
Parallel
resistor
L1
L2
L3
åIL = Io
© ABB Group
November 19, 2018 | Slide 55
OPERATE
SECTOR
Petersen
coil
Ipar
Re(Io)
-Uo
Yo
Io
Ipar
Io
Amount of overcompensation
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
IEFFd [A]
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
© ABB Group
November 19, 2018 | Slide 56
[A]
b b bIIEFFd
b[A]
EFFd
45 63 72 76 55
10
27 45 56 63 10
15
18 34 45 53 15
20
14 27 37 45 20
25
11 22 31 39 25
30
9 18 27 34 30
35
8 16 23 30 35
40
7 14 21 27 40
45
6 13 18 24 45
50
6 11 17 22 50
55
5 10 15 20 55
60
5 9 14 18 60
65
4 9 13 17 65
70
4 8 12 16 70
75
4 8 11 15 75
80
4 7 11 14 80
85
3 7 10 13 85
90
3 6 9 13 90
95
3 6 9 12 95
100
3 6 9 11100
[A] 55 10
10 15
10 15
15 20
20
IIPar
15IPar
20
20[A] 5 10 1555 20
10
Par [A]
bEFFdb
b[A]b
b b
b
b
I
45 63
63
72 76
76
45
27 72
518
14
27
4510
56 63
63
27
63 45
56
34
27
18
34
53
18
72 34
5615
45
45 53
37
14
27
37 45
14
76 27
6320
37
53
45
11
22
31 39
39
11
79 22
6825
31
59
51
18
27 34
34
81
99 18
7230
27
63
56
16
23 30
30
82
88 16
7435
23
67
60
14
21 27
27
83
77 14
7640
21
69
63
13
18 24
24
84
66 13
7745
18
72
66
11
17 22
22
84
66 11
7950
17
73
68
10
15 20
20
85
55 10
8055
15
75
70
14 18
18
85
55 81
99 60
14
76
72
13 17
17
86
44 81
99 65
13
77
73
12 16
16
86
44 82
88 70
12
78
74
11 15
15
86
44 82
88 75
11
79
75
11 14
14
86
44 83
77 80
11
79
76
10 13
13
87
33 83
77 85
10
80
77
13
87
33 84
66 9081
99 13
77
12
87
33 84
66 9581
99 12
78
11
87
33 84
6610081
99 11
79
b b b b  
45 76
27 18
18 14
14
45 63 72
45
27
63 63
45 34
34 27
27
27 45 56
63
45
72 53
56 45
45 37
37
18 34 45
72
56
76 45
63 53
53 45
45
14 27 37
76
63
79 39
68 59
59 51
51
11 22 31
79
68
81 34
72 63
63 56
56
9 18 27
81
72
82 30
74 67
67 60
60
8 16 23
82
74
83 27
76 69
69 63
63
7 14 21
83
76
84 24
77 72
72 66
66
6 13 18
84
77
84 22
79 73
73 68
68
6 11 17
84
79
85 20
80 75
75 70
70
5 10 15
85
80
85 18
81 76
76 72
72
5 9 14
85
81
86 17
81 77
77 73
73
4 9 13
86
81
86 16
82 78
78 74
74
4 8 12
86
82
86 15
82 79
79 75
75
4 8 11
86
82
86 14
83 79
79 76
76
4 7 11
86
83
87 13
83 80
80 77
77
3 7 10
87
83
84 81
81 77
77
3 6 87
987 13
84
84 81
81 78
78
3 6 87
987 12
84
84 81
81 79
79
3 6 87
987 11
84
5 10 15 20
Resistive current from the parallel resistor
   
45 27 18 14
63 45 34 27
72 56 45 37
76 63 53 45
79 68 59 51
81 72 63 56
82 74 67 60
83 76 69 63
84 77 72 66
84 79 73 68
85 80 75 70
85 81 76 72
86 81 77 73
86 82 78 74
86 82 79 75
HEALTHY
86 83 79 76
87 83 80 77
87 84 81 77
87 84 81 78
87 84 81 79
Earth fault current of the protected feeder
IPar [A] 5 10 15 20
I

 I Par 
  a tan EFFd 
Amount of undercompensation
FAULTY
Io
Amount of overcompensation
ABB
EARTH FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Check of correct polarity of Uo and Io
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Check of correct polarity
Uo and Io
© ABB Group
November 19, 2018 | Slide 59
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Petersen
coil
Check of correct polarity: Uo and Io
Im(Io)
2
2
4
6
Typical faulty feeder
Io-phasor
8
10
Io
© ABB Group
November 19, 2018 | Slide 60
4
OPERATION SECTOR
Typical faulty feeder
Io-phasor,
INCORRECT polarity
6
Earth fault
inside the
protected
feeder
-Uo
8
10
12
14
Re(Io)
DEFLPDEF:
• Iocos-moodi
• Angle correction 5o
• Start value = 1 A
Result of incorrect polarity:
•
No indication in the faulted
feeder
•
Incorrect polarity is ’easy’
to identify
12
14
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Petersen
coil
Check of correct polarity: Uo and Io
Im(Io)
2
2
4
6
8
10
© ABB Group
November 19, 2018 | Slide 61
Typical healthy feeder
Io-phasor (capacitive)
Io
12
14

4
OPERATION SECTOR
Healthy feeder Io-phaser,
INCORRECT POLARITY
6
Earth-fault
outside
protected
feeder
-Uo
8
10
12
Result of incorrect polarity:
14
Re(Io)
DEFLPDEF:
• Iocos-moodi
• Angle correction 5o
• Start value = 1 A
•
No indication in the healthy
feeder -> Incorrect polarity
is ’difficult’ to identify
•
Disturbance Recording (DR)
analysis of healthy feeders
during an earth fault must
be conducted!
•
For example, Uo triggering
of DR
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Check of correct polarity: Uo and Io

Connection according to manual: +Uo, -Io

Validation with primary fault recordings:
 Best and most secure method (validation of whole
measurement chain: CT+VT+relay)
 Analysis of disturbance records both from faulty AND
healthy feeder!
 Analysis of faulty feeder is not sufficient!
 Can be used to evaluate accuracy (phase displacement)
© ABB Group
November 19, 2018 | Slide 62
ABB
EARTH-FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Different earth fault types and their challenges
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Classification of single phase earth-faults, affecting parameters
Single phase earth-fault (E/F)
November 19, 2018
Slide 5
Network
parameters
Fault
parameters
Detuning degree
Fault resistance
Network damping
Ignitation moment
Network imbalance
Fault continuity*
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Classification of single phase earth-faults, fault continuity
Single phase earth-fault (E/F)
Permanent
Non-permanent
Self-extinguished
Continuous
Transient
Low
ohmic
November 19, 2018
High(er)
ohmic
Slide 6
Low
ohmic
High(er)
ohmic
Re-striking
Low
ohmic
High(er)
ohmic
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Classification of single phase earth-faults: Transient E/F
•
Transient or temporary earth fault is characterized by single or few arc transient(s), which have the ability
to self-heal (idea of earth-fault compensation accomplished!)
•
For transient earth faults it is neither necessary nor desirable to trip the circuit breaker at the substation
•
Typically not detected by ‘normal E/F protection’, requires ‘Transient E/F’ protection functionality
•
Long lasting ‘post-fault oscillation may result in unselective operation of E/F protection
November 19, 2018
Slide 7
Uo [pu]
Uo [pu]
Uo [pu]
Io [pu]
Io [pu]
Io [pu]
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Classification of single phase earth-faults: Permanent & continuous
With higher fault resistance values harmonics and fundamental frequency component is dampened
•
Damping is determined by fault resistance value and network parameters
•
ZERO-SEQ.
VOLT earth
1xU0 fault needs
ZERO-SEQ.
VOLT
VOLT 1xU0
Detection of
high(er) ohmic
sensitivity
from1xU0
protection, VTZERO-SEQ.
& CT
Uo [pu]
0
-2
0.4
0.5
0.6
0.7
0.8
RES. CURR. 3xI0
FAULTY FEEDER
1
Io [pu]
0
-1
0.4
0.5
0.6
0.7
0.8
BINARY SIGNALS
FAULTY FEEDER
FAULTY FEEDER
RF = 500 OHM
2
Uo [pu]
0
-2
0.4
0.5
0.6
0.7
0.8
RES. CURR. 3xI0
FAULTY FEEDER
0.4
0.2
0
-0.2
-0.4
0.4
Io [pu]
0.5
0.6
0.7
0.8
BINARY SIGNALS
FAULTY FEEDER
BLK
OP
PER UNIT
2
PER UNIT
PER UNIT
FAULTY FEEDER
RF = 0 OHM
PER UNIT
•
PER UNIT
In case of solid earth fault (RF = 0 ohm), harmonic components are often included
PER UNIT
•
FAULTY FEEDER
RF = 5500 OHM
2
Uo [pu]
0
-2
0.4
0.5
0.6
0.7
0.8
RES. CURR. 3xI0
FAULTY FEEDER
0.1
0.1
0.05
0
0
-0.1
-0.05
0.4
Io [pu]
0.5
0.6
0.7
0.8
BINARY SIGNALS
FAULTY FEEDER
BLK
OP
BLK
OP
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Classification of single phase earth-faults: Permanent & re-striking
•
Restriking faults are the most common type of permanent earth faults in compensated networks.
•
These faults have generally broad frequency content and they are often low ohmic.
•
They are formed by succession of self-extinguishing faults, where the time duration between recurring reignitions is typically in the order of few tens to some hundreds of milliseconds.
•
Restriking fault creates highly non-sinusoidal and irregular voltage and current waveforms, which conventional
fundamental frequency based methods are not designed for.
Restriking, type II
Restriking, type I
ZERO-SEQUENCE VOLTAGE 1xU0
4
1
2
PER UNIT
PER UNIT
ZERO-SEQUENCE VOLTAGE 1xU0
2
0
-1
-2
0
0.2
0.4
0.6
0.8
0
-2
-4
1
0
0.05
RESIDUAL CURRENT 3xI0
2
0
-2
-4
0.2
0.4
0.6
TIME (SEC.)
0.2
0.25
0.3
0.25
0.3
2
0
-2
-4
0
0.15
4
~400 A
PER UNIT
PER UNIT
4
0.1
RESIDUAL CURRENT 3xI0
0.8
1
0
0.05
0.1
0.15
TIME (SEC.)
0.2
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Restriking or intermittent earth-fault!
 Unique fault pattern, every time different
 Affected by many system and fault parameters
 Typically a result of insulation failure in cable sheaths, in cable joints or in cable
terminations.
© ABB Group
November 19, 2018 | Slide 14
ABB
Intermittent (restriking) earth-fault, typical fault in underground cables
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
 Restriking or intermittent earth-fault!
• ‘Piikin’ leveys tyyp. ~ 0.4-0.8 ms
• ‘Piikkien’ välinen aika ~ 5-300 ms
• Io huippuarvo ~ x 102…103 A
 verkkoparametrien ja vikapaikan
jännitekestoisuuden funktio
© ABB Group
November 19, 2018 | Slide 16
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
New challenges: Restriking or
intermittent earth-faults
0.4
• Unique fault pattern, every
time different
0.3
0.2
Io (kA)
Uo x 102 (kV)
• Affected by many system and
fault parameters
Io
• Pulse width ~ 0.4-0.8 ms
• Time between pulses ~ 5-300 ms
• Peak amplitude ~ x 102…103 A
 f(Ictot, K, Re, Utres)
Uo
0.1
0
-0.1
-0.2
-0.3
Restriking earth-fault is characterised by repetitive
and recurrent of earth-fault arcs with very short
duration. This results in highly irregular and
intermittent waveforms of residual quantities, which
challenges the operation of conventional earth-fault
protection functions.
© ABB Group
November 19, 2018 | Slide 18
UPhfaulty -0.4
Un
Ubrk
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
ubrk
20
UA
UB
UC
0
-20
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
50
UAB
UBC
UCA
0
-50
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
20
Uo = (UA+UB+UC)/3
0
-20
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
500
IA
IB
IC
0
-500
0.8
1
1.2
1.4
1.6
1.8
2
2.2
200
2.4
Io = IA+IB+IC
0
-200
-400
© ABB Group
November 19, 2018 | Slide 19
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Uo>
!
FAULTY FEEDER
0.2
0.4
0.6
0
0.2
0.4
0.6
Io (p.u.)
0
0
0.2 0.4 0.6
Time (s)
Io
OPERATE-AREA
?
0o
-Uo
Io
NON-OPERATE
AREA
Io
OPERATE-AREA
© ABB Group
November 19, 2018 | Slide 20
!
NON-OPERATE
AREA
Io>
Time (s)
Io
Uo
Io>
HEALTHY FEEDER
Io (p.u.)
• ”Basic” earth-fault protection
functions are designed for sinusoidal
50 Hz signals
 very unstable operating
quantity during a restriking E/F!
0o
-Uo
RISKS FOR PROTECTION MALOPERATION
•
Healthy feeders: unselective operation
•
Faulty feeder: unsuccesfull or delayed tripping
•
May lead to tripping of the busbar E/F protection
 RECOMMENDATION TO USE DEDICATED FUNCTION
FOR RESTRIKING E/F
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Single phase earth-fault may evolve in time…
Low current
single phase
earth-fault (E/F)
November 19, 2018
Slide 21
Voltage stress
on the two
healthy phases
Insulation
breakdown on
other phase
High current
double earth-fault
(cross.country E/F)
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
– Evolving earth-fault (in cables)
• In case restriking E/F is not disconnected, earth-fault may evolve into more serious fault
(cross-country E/F or short-circuit) due to successive detoration of insulation
ZERO-SEQUENCE VOLTAGE 1xU0
PER UNIT
1
0.5
0
-0.5
-1
0
0.5
1
1.5
2
PER UNIT
RESIDUAL CURRENT 3xI0
2
0
-2
0
© ABB Group
November 19, 2018 | Slide 22
0.5
Initial damage of
insulation
1
1.5
TIME (SEC.)
Succesive
detoration of
insulation
2
Permanent fault
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
PERMANENT E/F
© ABB Group
November 19, 2018 | Slide 26
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
-20
-22
-24
-26
-28
-30
-32
0.2
0.4
0.6
0.8
Temporary transient
over-voltages
introduced during
re-striking E/F
INTERMITTENT E/F
1
1.2
1.4
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
-20
-22
-24
-26
-28
-30
-32
0.2
0.4
0.6
0.8
1
1.2
1.4
ABB
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
 Earth-fault protection in a
compensated networks is
challenging task due to
multitude of different
possible fault types!
 Earth-fault pattern in unique
every time and may include
characteristics from
“permanent” and “arcing”
faults!
November 19, 2018
Slide 27
 U0
 Io
Taking earth-fault protection to the next level
Earth-fault protection in compensated networks
MOTIVATIONS FOR NEW FUNCTION
Contradiction of requirements:
– High requirement for sensitivity requires very
sensitive settings,
– High requirement for selectivity and security;
restriking earth faults endanger correct
operation of basic EF-protection
• Basic E/F functions are not capable in
operating selectively during intermittent
earth faults
• Traditional transient/intermittent
functions are not capable in detecting
higher ohmic earth-faults
© ABB Group
November 19, 2018 | Slide 28
Security
Sensitivity
ABB
Novel method taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
Current based (Io)
f=50Hz
Fundamental
frequency
based
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 29
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power based (So)
WPWDE
• Po/Qo
Admittance based (Yo)
EFPADM
• Go/Bo
Multifrequency
Admittance based
MFADPSDE
Harmonic based
HAEFPTOC
Transient-based E/Fprotection against
restriking/Intermitte
nt earth faults
INTRPTEF
’Basic’ E/F
protection
’Basic’ +
’Restriking’
E/F
protection
’Restriking’ E/F
protection
ABB
Novel method taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
Current based (Io)
f=50Hz
Fundamental
frequency
based
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 30
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power based (So)
WPWDE
• Po/Qo
Admittance based (Yo)
EFPADM
• Go/Bo
Multifrequency
Admittance based
MFADPSDE
Harmonic based
HAEFPTOC
Transient-based E/Fprotection against
restriking/Intermittent
earth faults
INTRPTEF
’Basic’ E/F
protection
’Basic’ +
’Restriking’
E/F
protection
’Restriking’ E/F
protection
ABB
EARTH-FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Multi-frequency admittance protection (MFADPSDE)
Ari Wahlroos. Senior Principal Engineer, ABB Oy, Finland
Multi-frequency admittance protection – general presentation
2017-01-25
”Earth fault locating technology by ABB Finland awarded as the “Network Initiative of the Year 2017”
”An innovative Earth-fault protection and fault indication method developed by ABB in Finland won the Network Initiative
of the Year 2017 award.
The new technology is very topical, as the share of underground cables and renewable energy production increase. It
enhances a grid company’s fault management and thus improves the reliability of power distribution.”
The award was presented by Harri Jaskari, Member of Parliament, and Kenneth Hänninen,
director responsible for the network business at the Finnish Energy association
Novel method taking earth-fault protection to the next level
Multi-frequency admittance-based earth-fault protection, MFADPSDE
BACKGROUND
• Based on deep theoretical understanding of the earth-fault phenomenon
• Complemented with practical knowledge gained from numerous field
tests and comprehensive disturbance analysis
© ABB Group
November 19, 2018 | Slide 3
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Current (Io)
f=50Hz
Uo, Io
© ABB Group
November 19, 2018 | Slide 4
Fundamental
frequency
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
’Basic’ E/F
protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Current (Io)
f=50Hz
Fundamental
frequency
based
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
Uo, Io
f>>50Hz
© ABB Group
November 19, 2018 | Slide 5
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
’Basic’ E/F
protection
’Transient/Restriking’
E/F protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Current (Io)
f=50Hz
Fundamental
frequency
based
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
Uo, Io
f>>50Hz
© ABB Group
November 19, 2018 | Slide 6
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
’Basic’ E/F
protection
’Transient/Restriking’
E/F protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method,
Current (Io)
f=50Hz
Fundamental
frequency
based
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Harmonic based
HAEFPTOC
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 7
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
’Basic’ E/F
protection
’Special’ E/F
protection
’Transient/Restriking’
E/F protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
Current (Io)
f=50Hz
Fundamental
frequency
based
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 8
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Multi-frequency
Admittance based
MFADPSDE
Harmonic based
HAEFPTOC
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
’Universal’
EF-protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
Current (Io)
f=50Hz
Fundamental
frequency
based
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 9
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Multi-frequency
Admittance based
MFADPSDE
Harmonic based
HAEFPTOC
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
’Universal’
EF-protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
f=50Hz
Fundamental
frequency
based
Admittance (Yo=Io/Uo)
Uo, Io
f=n*50Hz
© ABB Group
November 19, 2018 | Slide 10
Harmonic
based
Multi-frequency
Admittance based
MFADPSDE
’Universal’
EF-protection
ABB
Taking earth-fault protection to the next level
Available protection methods and functions, Relion, Q4/2018
Reliable and selective protection scheme can be provided, which fullfills set
operation speed and sensitivity requirements:
• Fundamental frequency based method + Transient based method, OR
• Multi-frequency admittance based protection
Current (Io)
f=50Hz
Fundamental
frequency
based
Uo, Io
f=n*50Hz
f>>50Hz
© ABB Group
November 19, 2018 | Slide 11
Harmonic
based
Transient
based
DEFxPDEF
• Iocos/Iosin
• Phase angle
Power (So=Io*Uo)
WPWDE
• Po/Qo
Admittance (Yo=Io/Uo)
EFPADM
• Go/Bo
Multi-frequency
Admittance based
MFADPSDE
Harmonic based
HAEFPTOC
Transient-based
E/F-protection against
transient/restriking/
Intermittent earth faults
INTRPTEF
’Universal’
EF-protection
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Comparison on the functionality of MFADPSDE with
traditional methods in resonant earthed networks
Earth-fault type
Transient
Traditional
Iocos
Treditional
Wischer
MFADPSDE
© ABB Group
November 19, 2018 | Slide 13
Continuous
Re-striking/Intermittent



Low-ohmic
High-ohmic







ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
MULTI-FREQUENCY ADMITTANCE, MFADPSDE
Operation principle and advantages
© ABB Group
November 19, 2018 | Slide 14
ABB
Commissioning tests of multi-frequency admittance 17.-18.5.2017
Primary earth fault tests: restriking earth fault
Cumulative Phasor Summing (CPS)
tend


t end

Y osum_ CPS HEALTHY
osum (i )  j   Im Y osum (i )
 Re Y FEEDER:
i t start
i t start

Uo
Io
Iocos
Iocos(CPS)
ABB
Utilization of harmonics:
Multi-frequency
admittance
HEALTHY FEEDER:
Uo
Io
Iocos
Iocos(CPS)
ABB
Utilization of harmonics:
Multi-frequency
admittance
HEALTHY FEEDER:
Uo
Io
Iocos
Iocos(CPS)
ABB
Utilization of harmonics:
Multi-frequency
admittance
HEALTHY FEEDER:
Uo
Io
Iocos
Iocos(CPS)
XCoil = ω ∙ LCoil
ABB
Current supervision:
I oCPS HEALTHY FEEDER:
1
Y
1
o stab

1
 U oCPS

 Re Y
I
1
o stab
1
o stab
 j  ImY  G
1
o stab
 (Gostab  j  Bostab )  U PE
I
1
oCosstab
 jI
1
oSinstab
ostab
Uo
 j  Bostab
Io
Iocos
Iocos(CPS)
ABB
Multi-frequency admittance protection - Taking earth-fault protection to the next level
High sensitivity during high(er) ohmic earth faults!
© ABB Group
November 19, 2018 | Slide 28
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Multi-frequency admittance function (MFADPSDE)
Single function capable in protection and detection
against all kinds of earth faults!
• Easy setting principles based on basic network data
• The operation characteristic provides universal applicability i.e. it is valid
both in compensated and unearthed networks (e.g. Petersen coil is out of
service)
• Fault direction indication both in operate direction (START/OPERATE) and
non-operate direction (BLK_EF), which may be utilized during fault location
process
• Inbuilt transient detector to identify restriking/intermittent earth faults
(INTR_EF), and discriminate them from permanent/continuous earth faults
• Dedicated operation mode for alarming-mode of earth-fault protection
• Sensitivity basically only limited by network healthy-state residual voltage
value (degree of asymmetry): practical sensitivity of several kilo-ohms
possible
© ABB Group
November 19, 2018 | Slide 35
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
MULTI-FREQUENCY ADMITTANCE, MFADPSDE
 One protection function for all fault types
 Superior selectivity; dependable and secure
 Easy to set and configure
 Applicaple both in compensated and unearthed network
 Sensitivity up to several kilo-ohms
© ABB Group
November 19, 2018 | Slide 36
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Benefits compared with DEFxPDEF + INTRPTEF

Simpler engineering
Only one function block covers all 1-ph fault cases
 No need to co-ordination (DEF with INTRPTEF)


Simpler setting
Same settings are valid for all feeders and both during coil on and coil off (no need for change base angle)
 Can be determined with basic network data

•
Better selectivity and security
•
•
•
MFADPSDE is designed to operate correctly during restriking earth-fault
With DEF, there is a risk for protection maloperation especially on the healthy feeders during restriking
earth-fault as DEF is measuring unstable 50Hz component
Better dependability and sensitivity
•
MFADPSDE is based on admittance measurement: measured admittance is not affected by fault resistance.
Sensitivity is limited by the system healthy-state asymmetry (healthy state Uo). Practical sensitivity of
several kilo-ohms can be achieved.
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Benefits compared with competitors solutions

Simpler engineering
Only one function block covers all 1-ph fault cases
 No need to co-ordination (many parallel functions)
 No need for separate fault type dedicated protection devices (such as transient fault detectors)


Simpler setting
Same settings are valid for all feeders and both during coil on and coil off (no need for change base angle)
 Can be determined with basic network data. No need to consider transient magnitudes, etc.

•
Better selectivity and security
•
•
•
MFADPSDE is designed to operate correctly during restriking earth-fault
With prior-art 50Hz-methods, there is a risk for protection maloperation especially on the healthy feeders
during restriking earth-fault as all prior-art 50Hz methods are measuring unstable 50Hz component
Better dependability and sensitivity
•
•
MFADPSDE is based on admittance measurement: measured admittance is not affected by fault resistance.
Sensitivity is limited by the system healthy-state asymmetry (healthy state Uo). Practical sensitivity of
several kilo-ohms can be achieved.
Better than any current (Io) or power (Po) based methods
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Performance is validated with tens of practical field tests and
thousands of individual tests:
© ABB Group
November 19, 2018 | Slide 39





Vattenfall, 2012 FAT
Elenia, Vilppula, 2013
ESB Irlanti, 2014
Caruna, Pusula, 2014
Jenergia, Hämeenlahti, 2014





SVV, Lapinlahti, 2014
Linköping, Ruotsi, 2015
VSS, Sundom, 2015
HSV, Ilmalantori, 2015
HSV, Herttoniemi, 2016




Elenia, Orivesi, 2016
Caruna, Sastamala, 2016
SEI-verkot, Seinäjoki, 2017
Caruna, Taivalvaara, 2017
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Multi-frequency admittance protection, reference installations (2018, Q3)
Primary substation, protection application (Relion series)
•
•
•
•
•
Jyväskylän Energia, several substations, Finland
Sei-verkot, Kärmeskytö substation, Finland
Vaasan Sähkö, several substations, Finland
Pohjois-Karjalan Sähkö, several substations, Finland
Degerfors Energi AB, Sweden
Primary substation, protection application (centralized protection, SSC600)
• Caruna, Noormarkku substation, Finland
Secondary substation, fault passage indication application (RIO600)
• Elenia, Finland (MFA)
• Caruna, Finland (MFA)
© ABB Group
November 19, 2018 | Slide 40
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Summary
Single, ‘Universal’, earth-fault protection
function for high impedance earthed
(compensated) networks
• Covers all single phase earth faults with
high reliability, selectivity and sensitivity
Easy to
configure
Total protection
coverage
Simple to
set
Cost
efficient
• Easy to use
• Part of normal feeder protection relay
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Multi-frequency admittance protection (MFADPSDE)
Relion® series
615 series
620 series
630 series
640 series
615 series
RIO600
Interconnec
tion
protection :
REF615 5.0
FP1 L ja N
REF620 2.0 FP1
REF630 1.3
REX640
Feeder EF-protection
extension package
REC615/
RER615 2.0
RIO600 1.7 SIM8F
Applikaatio
Feeder
protection
Feeder
protection
Feeder
protection
Feeder protection
Feeder protection
(distribution
automation)
Fault indication
(distribution
automation)
MFADPSDE
x
x
x
x
x
x
November 19,
2018
Slide 42
EARTH FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Multi-frequency admittance protection –
Easy settings based on basic network data
Multi-frequency admittance protection - Taking earth-fault protection to the next level
HEALTHY FEEDER:
FAULTED FEEDER:
Uo
Uo
Io
Io
Iocos
Iocos
Iocos(CPS)
Iocos(CPS)
Voltage start value
Min operate current
Tilt angle
Operate delay time
ABB
Multi-frequency admittance protection - Taking earth-fault protection to the next level
Easy setting principles based on basic
network data: Voltage start value
The setting Voltage start value defines the basic sensitivity of
the MFADPSDE be function. To avoid unselective start or
operation, Voltage start value must always set to a value which
exceeds the maximum healthy-state zero-sequence voltage
value, taking into consideration of possible network topology
changes, compensation coil and parallel resistor switching
status and compensation degree variations.
Example of selection of setting ‘Voltage start value’ in order to
maximize the earth-fault detection sensitivity based on the
resonance curve calculated by the coil controller.
X.XX
© ABB Group
November 19, 2018 | Slide 45
ABB
Multi-frequency admittance protection - Taking earth-fault protection to the next level
Table. Comparison on setting Operating quantity of MFADPSDE
with traditional methods.
Traditional
Setting ‘Operating quantity’ of
method
MFADPSDE
Amplitude
Resistive
Adaptive
Iosin

Iocos

Iosin/Iocos

When Operating quantity = “Amplitude” is selected, the set minimum operate
current threshold (setting Min operate current) is compared to the amplitude of
𝐼𝑜1 𝑠𝑡𝑎𝑏 in the whole defined operate sector.
When Operating quantity = “Resistive” is selected, the set minimum operate
current threshold (setting Min operate current) is compared to the resistive
component of 𝐼𝑜1 𝑠𝑡𝑎𝑏 in the whole defined operate sector.
When Operating quantity =“Adaptive” is selected, the method adapts the
principle of current magnitude supervision (amplitude or resistive) automatically
to the system earthing condition. This is done by monitoring the phase angle of
accumulated sum admittance phasor.
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Easy setting principles based on basic
network data: Min operate current
© ABB Group
November 19, 2018 | Slide 47
X.XX
The direction of the MFADPSDE function is supervised by a
settable current magnitude threshold. The setting Min operate
current should be set to value: < p*IRtot,
where IRtot is the total resistive earth-fault current of the
network corresponding to the resistive current of the parallel
resistor of the coil and the natural losses of the system.
p = security factor = 0.5…0.7
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Easy setting principles based
on basic network data
© ABB Group
November 19, 2018 | Slide 48
•
The tilt of the operation sector, setting Tilt angle, should be
selected based on the measurement errors of the applied
residual current and voltage measurement transformers.
•
Based on practical experience, the most critical source of
measurement errors is the measurement accuracy of Io.
Especially the accuracy of measurement of phase angle (i.e.
phase displacement).
•
In the compensated networks, the residual current (Io) is
typically much lower than rated current of phase current CT.
Therefore the preferred and recommended method of
measuring the Io is with a dedicated Core Balance CT. Typical
and recommended ratio would be e.g. 100/1A
•
For protection class CT, the phase displacement at low values
of current is typically not known. In the standard IEC 61869-2,
the phase displacement is not defined for 10P-class. And for
class 5P, the phase displacement is only defined at rated
primary current.
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
Operation logic
MFADPSDE supports four operation modes selected with setting ‘Operation mode’:
• “General EF”,
•
Applicable in all kinds of earth faults in high-impedance earthed networks, that is, in compensated, unearthed and high resistance
earthed networks. It is intended to detect all kinds of earth faults regardless of their type (transient, intermittent or restriking,
permanent, high or low ohmic) and provide definite operate time for protection regardless of actual fault type.
• “Alarming EF”,
•
Dedicated operation mode when fault detection is only alarming
• “Intermittent EF”
•
Operation mode “Intermittent EF” is dedicated for detecting restriking or intermittent earth faults. A required number of
intermittent earth fault transients set with the Peak counter limit setting must be detected for operation. Therefore, transient
faults or permanent faults with only initial fault ignition transient are not detected in “Intermittent EF” mode. The application of
“Intermittent EF” mode is limited to low ohmic intermittent or restriking earth faults.
• “Transient EF”
•
Operation mode “Transient EF” is dedicated for detecting fast transient faults where the fault current stays on only for a very
short time. It is recommended method in networks, where network damping has very small value or when parallel resistor of the
coil is not used, for example in sub-transmission networks.
© ABB Group
November 19, 2018 | Slide 49
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
DEFxPDEF vs. MFADPSDE: Same settings
DEFxPDEF
MFADPSDE
Comment
Operation
Pol reversal
Io signal Sel
Uo signal Sel
Directional mode
Voltage start value
Operate delay time
Correction angle
Reset delay time
Operation
Pol resersal
Io signal Sel
Uo signal Sel
Directional mode
Voltage start value
Operate delay time
Tilt angle
Reset delay time
Allow Non Dir
Measurement mode
Pol quantity
Enable voltage limit
Operating curve type
Start value Mult
Min operate voltage
-
Same setting. Function activation.
Same setting. Polarity reversal.
Same setting. Io measurement: measured or calculated.
Same setting. Uo measurement: measured or calculated.
Same setting. Operation direction (Fwd/Rev)
Same setting. Function Uo-start threshold
Same setting. Operate delay time.
Same setting. Tolerance against (VT+CT+IED) phase displacement.
Same setting. MFADPSDE recommendation 300-500ms. Avoids resetting of
protection during intermittent earth-fault.
MFADPSDE is always directional (fwd or rev)
MFADPSDE is always based on DFT-phasors
MFADPSDE is always polarized with Uo
MFADPSDE has always Uo-start element enabled
MFADPSDE has always Definite timer operation
© ABB Group
November 19, 2018 | Slide 50
MFADPSDE has fixed minimum Uo voltage limit: 0.01xUn
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
DEFxPDEF vs. MFADPSDE: New settings
DEFxPDEF
MFADPSDE
-
Operating quantity
-
-
© ABB Group
November 19, 2018 | Slide 51
Peak counter limit
Start delay time
Comment
When detected number of earth-fault transient reaches ”Peak
counter limit”, fault is identified being intermittent type,
output: INTR_EF is activated. Note that INTR_EF is ”nondirectional” i.e. for detection in the faulted feeder only, it
must be externally AND:ed with START-output.
”Adaptive” equals simultaneous use of Iocos/Iosin-mode.
Operating quantity ”Adaptive” is valid both in compensated
and unearthed networks.
”Amplitude” equals Iosin-mode, application is in unearthed
networks.
Delay of START-output. Default value 30ms is ok. Practical
application is only ”Alarming EF”-mode.
ABB
Multi-frequency admittance protection
Taking earth-fault protection to the next level
DEFxPDEF vs. MFADPSDE: Different settings!
DEFxPDEF
Min operate
current
MFADPSDE
Comment
Different meaning in DEFLPDEF vs. MFADPSDE!!!
In MFADPSDE:n minimum operation current abs(Io) is internally fixed to 0.01xIn.
Start value
Min operate
current
Different meaning in DEFLPDEF vs. MFADPSDE!!!
In DEF:n ”Start value” is the magnitude of operate quantity, i.e. Iocos. In DEF, one has to
consider the damping effect of fault resistance.
In MFADPSDE:n ”Min operate current” is the magnitude of operate quantity. But due to
admittance based calculatation, the damping effect of fault resistance must not be
considered
Different meaning in DEFLPDEF vs. MFADPSDE!!!
• In MFADPSE ”General EF” equals tripping earth-fault protection application regardless
of fault type (transient, intermittent, katkeileva, pysyvä) or fault resistance value.
• In MFADPSE ”Intermittent EF” equals protection against intermittent or restriking EF.
For ”permanent EF” separate protection function must be applied.
• In MFADPSE ”Alarming EF” equals alarming EF application. Operate-output is not
activated.
Operation mode Operation mode
© ABB Group
November 19, 2018 | Slide 52
ABB
EARTH FAULT SEMINAR, 2018
Taking earth-fault protection to the next level
Multi-frequency admittance protection – secondary testing
Testing Multi-Frequency Admittance-Based Earth-Fault Protection Function MFADPSDE with Omicron
© ABB Group
November 19, 2018 | Slide 54
ABB
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