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Module 10B:
Line Distance Protection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Situation: Meshed network and two infeedsDirectional overcurrent time relays
0,6s
0,6s
0,3s
0,3s
0,6s
0,6s
0,3s
0,3s
non-selective trip
Why impedance protection?
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Localization of short-circuits by means of an impedance measurement:
- fault on the protected line
- fault outside the protected line
Z1
relay A
selectivity
relay A
Z2
Basic principle of impedance protection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
phase-ground-loop:UL1 = L1 ( RL + j XL )- E ( RE +j XE)
L1,
E measured current
UL1 measured voltage
06.08.97
dtgerdis3
The same applies to the remaining loops
IL1
IL2
IL3
IE
ZL
ZE
UL1 UL2 UL3
ZL = RL + j XL
ZE = RE +j XE
Distance measurement (principle)
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
ZL
ZLF1
ZLF2
RF RF
ZLoad
DF1 F2
X
R
ZL
ZLF2
SC1
SC2
L
RR
ZF1
ZF2
RR
ZLoad
ZLF1
Fault area
distance relayoperating
characteristic
Increasin
g load
Fault in
reverse
directionLoad area
Maximum Load:Minimum voltage 0,9 Un
Maximum current 1,1 In
Nominal angle 30
Phase - Phase Fault
RR RF / 2
Phase - Earth Fault
RR RF /(1 + RE/RL)
Load and short-circuit impedances
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
time
D1 D2 D3
t1
t2
t3
Z1
Z2
Z3
distance
t = grading time
A CB D
Z1 = 0,85 ZAB
Z2 = 0,85 (ZAB + 0,85 ZBC)
Z3 = 0,85 (ZAB + 0,85 (ZBC + 0,85 ZCD))
Safety margin is 15 %:
- line error
- CT, VT error
- measuring error
Grading rules:
Graded distance zones
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
2nd Zone: It must initially allow the 1st zone on the neighbouring feeder(s) to clear the fault.
The grading time therefore results from the addition of the following times:
operating time of the neighbouring feedermechanical 25 - 80 msstatic: 15 - 40
digital: 15 - 30
+ circuit breaker operating time HV / EHV: 60 ms (3 cycles) / 40 ms (2 cycles)
MV up to about 80 ms (4 cycles)
+ distance relay reset time mechanical: approx. 60-100 ms
static: approx. 30 msdigital: approx. 20 ms.
+ errors of the distance relay internal timers mechanical: 5% of the set time, minimum 60-100 ms
static: 3% of the set time, minimum 10 ms
digital: 1% of the set time, minimum 10 ms
+ distance protection starting time *) mechanical: O/C starter: 10 ms, impedance starter: 25 ms
static: O/C stater: 5 ms, impedance starter: 25 ms
digital: generally 15 ms
+ safety margin (ca.) grading; mechanical-mechanical: 100 msstatic/digital-mechanical or vice versa: 75 ms
digital-digital or static-static 50 ms
*) only relevant if the set relay times relate to the instant of fault detection / zone pick-up. This is the case with all
Siemens relays. There are other relays where the time is adapted by software to relate to the instant of fault
inception. In the latter case the starting time has to be dropped.
Determination of grading times(With numerical relays 250 ms is possible)
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
SC
Current area forforward faults
SC
Current area forreverse faults
SC
USC
R
ZSC
Z'SC
Impedance area forforward faults
Impedance area forreverse faults
X
SC
current / voltage diagram impedance diagram
Fault location Where is the fault ?
The impedance also shows the direction, but ....
Determination of fault direction
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
II>>I>
UI>>
UI>
UN
Udigital
electro-mechanical
Powersystem
Relay
line
E
E
ZSUSC
ZSCISC
USC
SC
USC
G
G
Voltage controlled overcurrent fault detection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
5 0 %
1 0 0 %
U / UN
I/IN1 2 3
I> I
> I> >
U (I
> ) U (I > > )
X X
R R
211
2
This method is used in Germany
Voltage and angle controlled overcurrent faultdetection (U-I--starting)
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
X
R
forwards
forw
ards
reverse
revers
e
LoadLoad
Z1
Z2
Z4
Z3
Z1B
Z5
Line
Distance zones
Inclined with line angle Angle prevents overreach of Z1
on faults with fault resistance
that are fed from both line ends
Fault detection
no fault detection polygon: the
largest zone determines the
fault detection characteristic
simple setting of load
encroachment area with
Rmin and Load
Impedance zones of digital relays (7SA6 and 7SA52)
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
ZL2-E
ZL3-E
ZL1-L2
ZL3-L1
ZL1-E
X
R
quadrilateral
MHO
UL1
- UL2
UL3 - UL1
UL3
IE
UL2
IL1
UL1
K
IL1
IL2
IL3
IE
L1
L2
L3
EUL1 UL2 UL3
distance relay
im p e d a n c e o f h e a l th y l o o p s :
ZL 2 - E =
UL 2
IL 2 - KE IE
ZL 3 - E =U L 3
IL 3 - KE IE
UL 1
- UL 2ZL 1 - L 2 =
IL 1 - IL 2
ZL 2 - L 3 =UL 2 - UL 3IL 2 - IL 3
ZL 3 - L 1 =
UL 3 - UL 1IL 3 - IL 1
im p e d a n c e o f f a u l te d lo o p :
ZL 1 - E =U L 1
IL 1 - KE IE
Conventional relays: limiting of the startingcharacteristic area for phase-selective fault detection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Intelligent phase selection:
Impedance comparison
Symmetrical component analysis
Load compensation
Pattern recognition
I1
I2
I0
G
GG
G
IF/3
ZL3-E
ZL1-L2
ZL3 - L1
ZL1-E
X
R
quadrilateral
MHO
L2
L1
L3
I2I0
ZL2-E
Distance protection Modern methods of phaseselection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
fault
Impedance comparison
of fault loop impedances
Comparison ofI2 and I0 components
comparison of Load
compensated currents
n=1
n=1
n=1
n=1
Trip three-phase Trip single-phase
n = number of detected fault loops
NY
N Y
N Y
N
Y
Distance protection Stepped process of phase selection
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Sector A
Sector C Sector B
margin
I2
a I2 a2 I2
1-Ph-E fault:After load compensation: Currents in the healthy phases are zero or have opposite
phase position
Ph-Ph-E fault:
After load compensation: Currents in faulted phases have same amplitude and show a
phase difference of 120 to 180 degree dependent on earthing conditions
20
22
0
L3L22
L1
L3L2L1
a
a
aa3131
II
II
II
IIII
IIII
20
2
0
: L1-E or L2-L3-E fault: L2-E or L3-L1-E fault
: L3-E or L1-L2-E fault
Phase selection Differenciating between single anddouble Ph-E fault
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Method used in 7SA52 and 7SA6 to measure I and VUsing a signal model (Kalman-Filter)
R
V
I L
Z = R + j LPhasorsV = I ZEstimate the phasors V and I using the least squares method (minimised errors)
At
AAk TkCeTkBTkAy
000coscossin
yk is the sampled value (v or i) - by assuming = 60 ms the following simplification results
AAk TkbTkay 00 cossin
Im
Rebb
a
a
current
voltage
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
Fast adaptive impedance measurementFilters with different lengths
0 10 20 30 40 50 60 70 80
ms
Estimate 1 (n=5)
Estimate 2 (n=6)
Estimate 3 (n=8)
Estimate 4 (n=10)
Normal 1 (n = 21)
Normal 2 (n = 26)Normal 3
Jump detected
Estimate 5 (n=13)
Estimate 6 (n=15)
Least Square Estimate with quality control
Adaptive Zone restriction
E. g. Zone Z1
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Earth
FaultEarth
Fault Protection
in Systems withEarthed Neutral
1. Fast operation Use short data window
2. High accuracy High selectivity3. Signal distortion do not cause delay or maloperation
X
R
Conclusion
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral G VF
ZL
E
If
distance relay
SIR (Source Impedance Ratio) describes the ratiobetween the source impedance and the line impedance!
L
S
Z
ZSIR
High SIR = Small loop voltage V Fin case of a fault at the end of the line
SIR
EVf
1
SIR - Definition
Note: SIR trip time curves are mostly related to zone 1, i.e. ZL = Z1
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
The SIR gives some information about the power of infeed and
the line length!
SIR > 4 short line*
SIR < 4 and >0.5 medium line*SIR < 0.5 long line*
For a distance relay it is more hard to operate on a short line
(large SIR)
than on a long line (small SIR)!
*Classification according IEEE-Guide
SIR - Considerations about line length and infeed
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
S I R = 1 ( A -G )
0
5
10
15
20
25
30
35
40
45
50
0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0
% o f z o n e s e t t i n g
tripping
tim
e
(
Trip time curves at SIR = 1
7SA522
Other relays
SIR = 1 (A G)
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
S I R = 3 0 ( A - G )
0
5
10
15
20
25
30
35
40
45
50
0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0
% o f z o n e s e t t i n g
tripping
tim
e
(
Trip time curves at SIR = 30
7SA522
Other relays
SIR = 30 (A G)
High SIR (low voltage) doesnt effect the tripping time in numerical relays
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral D
A
D
B
D
C
>>
D
>t
ZT
Z1
Z2
Z3
Z1
= 0.85 ZA-B
Z3
= 0.85 [ ZA-B
+ 0.85 (ZB-C
+ 0.85 ZC-D
) ]
Z2
= 0.85 (ZA-B
+ 0.85 ZB-C
)Grading according
the recommendation
with the safety margin
of 15%.
Zone grading chart, radial feeder
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
0.6
0.3
gradingtim(s)
The same grading from both sides
Ring feeder: with grading against opposite end
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Distance protection: Earth fault in system with solid, isolated or
compensated system neutral earthing
G
BA C
D
Z1
Z2...
D
ZT
Neutral Earthing with
Peterson Coil or Isolated or Solid
During single phase earth fault:
The short circuit current magnitude depends on the
neutral earthing method.
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Earth Fault Current - Pick-Up Characteristic
Measuring errors and non-symmetry may not cause
incorrect pick-up by earth fault current threshold
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Earth Fault Detection Logic
Normal pick-up: 3I0
Heavy load on long line: 3I2
For very small earth current: 3U0 (isolated or
compensated system)
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Earth fault detection during one pole open condition
During the 1 pole open condition, load current flows
in the earth path.
Magnitude comparison of the remaining 2 phases
prevents incorrect pick-up
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Phase-to-Earth loop:
Phase-to-Phase loop:
Distance measurement
Fault loop formulas
2121 LLLLLL IIjXRV
RL
+ j XLIL1
RE + j XE
VL1 VL2 VL3
IL2IL3
IE
Relay
location
Line and earth imp edance are measur ed
Only the Line imp edance is measured
E
L
ELLE
L
ELLL
EEELLLL
IX
XIjXI
R
RIRV
jXRIjXRIV
111
11
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Numeric impedance calculation, ph-ph-loop
Infeed
L1
L2
L3
E
Rfwd
Xfwd
(Lfwd
)
Rret
Xret
(Lret
)to remoteline end
fwd
ret
Ufwd
Uret
relaylocation
faultlocation
UU
=X
L3L2
L3L2
mL3-L2-
-
III
L3L2
L3L2L3-L2
-
-e=
II
UURR
L3L2
L3L2L3-L2
-
II-
UU=Z
With the measurement of phase to phase voltages and currents the
fault impedance (impedance to fault location) is correct calculated
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Estimation of arc resistance
X Variable
R/X-setting
R
Worrington formula:
Ohmml
AI
28700R
1,4ARC
Rough
estimation:
UARC = 2500 V/m
OhmAI
mdV/m2500
ARCR
F
Phase-to-phase distances
d = 3,5 m (110 kV)
d = 7 m (220 kV)
d = 11 m (380 kV)
Insulator lengths (long-rod insulator)
l= 1x1,3 = 1,3 m (110 kV
l= 2x1,3 = 2,6 m (220 kV)
l= 3x1,3 = 3,9 m (380 kV)
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Earth Fault Protection
in Systems with Earthed Neutral
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
3 definite-time stages
Earth (zero sequence) current protection, 4 stages
1 inverse-time stage: IEC, logarithmic inverse or ANSI characteristic
this stage can also be used as a 4th definite-time stage
Directional determination with 3V0 and/or Ipol of an earthed power trafo
Directional determination with V2 and I2 (negative sequence)
Sensitive 3I0-measurement with a dynamic from 0.005 A to 100 x In
Elimination of higher harmonics with special digital filters
Inrush-stabilisation with I0/100Hz
Teleprotection: Directional comparison, Blocking or Unblocking
Operation with weak infeed trip and echo
Instantaneous trip after switch-onto-fault
7SA522High Resistance Earth Fault Protection: Features
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Example: Single phase fault with infeed from 2 sides
IL1
IL2
IL3
IE
Zf
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Symmetrical Component representation: L1-E Fault
B
Pos.Seq.
I1A
Neg.Seq.
ZeroSeq.
I1BA
I2A
I2B
I0A
I0B
3 xR
Fault
U0A
U2A
U2B
U0B
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
*)
I0P U0P U2P I0L, I2L
*) not needed for numerical relays,
U0P may also be internally calculated
Polarizing Options for Directional Earth Fault Relays
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Directional Characteristic (U0 and IY)
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Earth fault
direction
=
EF IE> Echo
3I0>>>
EF>>> Trip
P
EFp Trip
Inrush-stabilisation
T(3I0/IN)
T
Tele-protection
T
SOTF
= &
&
3I0>>> Def. Time Stage
Inverse Time Stage
&
&
P
>EF>>> block
Direc. 3I0>>>
P Direc. 3I0p
>EFp block
P 3I0p
EF Fault Det.
>EF Trip rel.
3I0>> Def. Time Stage
3I0> Def. Time Stage
= Input signal(binary input)
P = Parameter = Output Signal(alarm, command)
P3146 AddTdelay
7SA522 High Resistance Earth Fault Protection:functional diagram
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Directional earth fault protection: Settings
Settings of the stages:
Settings for direction:
General settings:
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Principle of phase selection logic with U and I -Example L1-E
UL1E < 0.6 UNOM
UL2E > 0.7 UNOM
UL3E > 0.7 UNOM
IL1E > 2 INOM
IL2E < 1.2 INOM
IL3E < 1.2 INOM
&
&
OR
Select
L1-E
with U / I
If selection with U / I is not successful (U too large or I too small) then
symmetrical component method is used
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Phase Selection Logic - Sequence Components
L2-E
L3-E
L1-E
I2 = I0
I2 = a2*I0
I2 = a*I0
AngledifferenceI2/I0
Faulty Phase
-60 .. 60 L1-E60 .. 180 L3-E180 .. 300 L2-E
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
U0P or U2P may fall below critical value (approx. 1 V secondary) and limit relay highresistance earth fault sensitivity
Zero or negative sequence sources to be available behind relay location
Minimum settings at least > 3 times VT and CT inaccuracies
Current setting above line unsymmetry (M0 = Z01/Z0 or M2 = Z21/Z1) (series
compensated lines require higher current setting due to possibility of
unsymmetrical gap flashover)
Separate current threshold setting for tele-protection : 3I0 to avoid false operation with CT saturation
DEF protection, Critical application issues
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Earth fault protectionDirectional comparison teleprotection scheme
rec.
transm.
A B
E/F.
frwd. TS
& trip
rec.
&1 E/F.frwd.S
&rip
transm &1
*Three-terminal schemes are supported as well
TS
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Tele Protection
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Power Automation 48
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed NeutralFaults in this area aretripped from side 2 int2
Faults in this area are trippedfrom both sides in first-zonetime
Faults in this area aretripped from side 2 int2
Normal setting: X1 = 0.85 XL
1 2
Selectivity in distance protection,Teleprotection is the solution
15% 70% 15%
Faults on approximately 70% of the line length are cleared
without delay at both line ends
Faults in the remaining 30% of the line length
are cleared with a time delay.
Remedy: Exchange of information between the two line ends
Required: Communication channel (PLC, microwave radio, fibre optic, etc.)
Teleprotection logic (dedicated device or internal
function in numerical protection devices)
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Power Automation 49
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Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Teleprotection Schemes
Permissive Underreach PUTT
Permissive Overreach POTT
Blocking
Unblocking
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Power Automation 51
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Permissive underreach transfer trip (PUTT)
Z1(A)
Z1
A B
Z1(B)
Z1B(A)
Z1B(B)
& &
(A)
Z1
(B)
OR
TS
TripTripFurtherzones
T1
Z1BT1B(A)
trans-
mit
re-ceive
Furtherzones
trans-
mit
re-ceive
TS
OR
Z1BT1B(A)
T1
TS
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Power Automation 52
Power Transmission and Distribution
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Z1(A)
T1BZ1B
A B
Z1(B)
Z1B(A)
Z1B(B)
&
&
&
&(A)T1BZ1B
(B)OR
OR
OR
OR
TS
Z1 orfurtherzones
trans-mit
re-ceive
TripTrip
re-ceive
trans-mit
Z1 orfurtherzones
TS
7SA522 - Permissive overreach transfer trip (POTT)
TS
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Power Automation 53
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Blocking
A BZ1(A)
Z1(B)
Z1B(A)
Z1B(B)
Z1BT1B 1 trip
rec.
&
ddt 40ms
Forw.(A)
TS& 1
(u,i)
FD(A)
(A)
TV
1trip
rec.furtherzones
&
Z1 or
ddt40ms
Forw.(B)
TS &1
(u,i)
FD(B)
(B)
TV
FD(A)
FD(B)
FD (A)
FD (B)
(A)Z1BT1B(B)
transm. transm.
furtherzonesZ1 or
TSTV
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Power Automation 54
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Unblocking
A BZ1(A)
Z1(B)
Z1B(A)
Z1B(B)
Z1B
T1BTS
& 1 trip
transm.
rec.furtherzones
&
Z1or
1 TS
&1rip
transm.
rec.
&1fU fU
f00
Unblock-logic
Unblock-logic
UB
f0 Off frequency (monitoring frequency)fU Unblock frequency (send frequency)U Unblocking signalB Blocking signal
(A)Z1BT1B(B)
furtherzonesZ1or
TS
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Power Automation 55
Power Transmission and Distribution
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral Z1 Z1B
L1-E
L2-EA B1 1
2 2Z1Z1B
A1 trips single-phase in L1 with a phase-segregated L1-receive-signal
Maximum of Selectivity
Note: 3 binary channels for both directions are required or one serial link
7SA522 - Phase segregated Teleprotection
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Power Automation 56
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 - Teleprotection with three-terminal lines
Software provides
teleprotection of three-
terminal lines without
additional logic
i i d i ib i
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Power Automation 57
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
7SA522 and 7SA6Teleprotection via serial remote relay interface
PUTT and POTT schemes available: plug and protectEcho, weak infeed trip and direct trip
Phase segregated
Communication prepared for 2 or 3 terminal lines
Transmission of operational measured values from the remote end(s)
28 remote signals can be configured in addition to the
teleprotection scheme
Number of remote relay interfaces: 7SA522 -> 2 7SA6 -> 1
>
P T i i d Di ib i
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Power Automation 58
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
SIPROTEC 4Communication topology: Ring and Chain
2 terminal line
side 1
side 2 side 2
3 terminals: Chain
side 1
side 3
Automatic change fromclosed ring to chain, ifone connection is lostor not available
3 terminals: Closed ring
side 1
side 2
side 3
P T i i d Di t ib ti
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Power Automation 59
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Synchronous data transmission by HDLC- protocolPermanent supervision of the data transmission
Measurement and display of signal transmission time
Relay counts number of invalid telegrams:
If transmission failure rate is too high the teleprotection scheme will be blocked ->
switching to normal zone grading
Settings for the data transmission:64 kBit/s, 128 kBit/s or 512 kBit/s
Communication device addresses
-> Protection devices are clearly assigned to a defined protection section
Detection of unwanted reflected data in the loops in communication network
Data reflection for test purposes settable
SIPROTEC 4: Familiar with digital communication networksFeatures of the relay to relay communication
Power Transmission and Distribution
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Power Automation 60
Power Transmission and Distribution
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
FO5: distance 1.5 km (with clock feedFO5: distance 1.5 km (with clock feed--back)back)
FO6 : distance 3.5 kmFO6 : distance 3.5 km
O
O 1300 nm1300 nm10 km10 km
O 1300 nm1300 nm35 km35 km
O
E X21X21
G703G703
internal
internal
internal
external
820 nm820 nm1,5 km / 3 km1,5 km / 3 km
FO7 : distance 10 kmFO7 : distance 10 km
FO8: distance 35 kmFO8: distance 35 km
KU : hookKU : hook--up to communication networkup to communication network
Note: km data are valid for worstNote: km data are valid for worst--case conditionscase conditions
Communication Options
Power Transmission and Distribution
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Power Automation 61
Power Transmission and Distribution
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Transient Blocking for Permissive Schemes
Power Transmission and Distribution
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Power Automation 62
Power Transmission and Distribution
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Weak Infeed Echo Logic
No Distance Pick-
up
Receive
Signal
Power Transmission and Distribution
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Power Automation 63
Power Transmission and Distribution
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Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
17.10.97en513ase2
7SA522 - Echo and Tripping in case of no-infeed orweak-infeed
Configuration
Settings
Note: The echo signal must be routed in
addition to the send signal on the transmission
signal contact
Matrix
The receive signal is derived from :
and
Phase segregated weak-infeed tripping
*Three-terminal schemes are supported as well
!
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The year of Profitable Growth
Global network of innovation
Power Swing
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Power Automation 67
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
E1
= E2
E1 > E2
E1
< E2
X
R
ZS2
B
ZL
A
ZS1
ZLoad
' load point
Power swing locus and relay characteristic in theimpedance diagram
Power Transmission and Distribution
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Power Automation 68
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
ZS1
U1
E1
U2
E2ZS2
ZL
ZL
D PTP = sin
E1 E2
XT
1
D
2
D
3
D
A
C
1
3
2
1
2
30
4
5
6
0
1
20 90 180
PT
P
B
Dynamic system stability, equal area criterion
Power Transmission and Distribution
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Power Automation 69
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral56
1
34
X
RZload
ZS1
ZS1
ZL
2
2
0
0
Power swing locus in the impedance plane
Power Transmission and Distribution
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Power Automation 70
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Power swing detection: Classic Method(Not used in 7SA52 and 7SA6)
Classic power swing detection
is restricted to slow swings
The setting ofZ may not be too largeto avoid load encroachment (typ. 5 )
During fast swings the time available
(t) for detection of impedance vectorin the power swing zone is too short.Z
t = time for transition of Z from outer to inner zone
Power Transmission and Distribution
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Power Automation 71
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Novel space vector based principle
Self-setting
Small Z (1 Ohm at In=5 A)
Blocking up to high slip frequencies (7 Hz)
Recognition of all fault types during swing
Remains effective during single pole ARC
open time (3-phase set-up)
dZ/dt measurement
Calculation of swing centre
and plausibility check
(+90O<
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Power Automation 72
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Power Swing detection: New method
dR
dX
(k-n)
(k-n)
dR(k)
dX(k)
Power swingX
R
Fault entry
Fault
impedance
Loadimpedance
Transition from load to fault is fast
Power swing transition is slow
Continuos monitoring of the impedance trajectory
Monitoring of trajectory continuity
Monitoring of trajectory velocity
Evaluation of trajectory ellipse
Power Transmission and Distribution
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Power Automation 73
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Example:
i/kA
t/ms500
u/kV
t/ms500
200
-3
6
3
R
Power swing
locus(EA>EB)
-90
O
180O
0O
90OXm
Slip
frequency
EB
A ZA a Zl b ZB B
~ ~ ~ ~ ~EARelay
Relay
Evaluation of the power swing process
Power Transmission and Distribution
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Power Automation 74
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
iL1/A
-4
-2
0
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
iL2/A
-2
0
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
iL3/A
-2
0
2
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
uL1/V
-50
0
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
uL2/V
-50
0
50
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
uL3/V
-50
0
50
t/s0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6
DisTRIP3p Z1Bmf
Relay TRIP
Relay PICKUP
Dis. reverse
Dis. forward
Dis.T.SEND
>DisTel Rec.Ch1
Power Swing
Example:400 kV400 kmfPS 2 Hz3-pole fault
Novel power swing detection provides secureoperation with swing frequencies of up to 7 Hz
Power Transmission and Distribution
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Power Automation 75
Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Fault detection during power swing
I1
I2
V1
Trip
The Power swing passes through
the trip characteristic several times.
Single phase fault is detected and
cleared.
Power Transmission and Distribution
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Power AutomationProgress. Its that simple.
Earth
FaultEarth
Fault Protection
in Systems with
Earthed Neutral
Three phase fault during Power Swing
Three phase fault during power swing
is detected and cleared
Fault inception while swing is inside
trip characteristic
I1
V1
V2
V3
Trip