8.Line Distance Protection
Short Description
distance...
Description
Module 10B: Line Distance Protection The year of Profitable Growth
Global network of innovation
Power Transmission and Distribution
Why impedance protection? Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Situation:
Meshed network and two infeeds Directional overcurrent time relays
0,6s
0,3s
0,6s
0,3s
0,6s
0,3s
0,6s
0,3s
non-selective trip
Power Automation
2
Power Transmission and Distribution
Basic principle of impedance protection Power Automation Progress. It‘s that simple.
Localization of short-circuits by means of an impedance measurement: - fault on the protected line
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1
relay A
- fault outside the protected line Z2 relay A
selectivity
Power Automation
3
Power Transmission and Distribution
Distance measurement (principle) Power Automation Progress. It‘s that simple.
IL1 ZL ZL = RL + j XL
IL2 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
IL3 IE
ZE = RE +j XE
ZE
UL1 UL2 UL3 6 loops:
3 phase- phase loops and 3 phase- ground loops
phase- phase -loop:
UL1-L2 = ZL ( IL1 - IL2) Measured current measured voltage
The same applies to the remaining loops 06.08.97 dtgerdis3
Power Automation
4
Power Transmission and Distribution
Distance measurement (principle) Power Automation Progress. It‘s that simple.
IL1 ZL IL2
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
ZL = RL + j XL
IL3 IE
ZE = RE +j XE
ZE
UL1 UL2 UL3 phase-ground-loop:
UL1 = L1 · ( RL + j XL )- E · ( RE +j XE)
L1, E measured current UL1
measured voltage
The same applies to the remaining loops
06.08.97 dtgerdis3
Power Automation
5
Power Transmission and Distribution
Load and short-circuit impedances Power Automation Progress. It‘s that simple.
ZL
distance relay operating characteristic
ZLF1 ZLF2
Fault area
X
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
ZL
D
ZLF2
RR
RF F1
RF F2
ZLoad
Phase - Phase Fault
ZF2
RR RF / 2
ZLoad RR
ZLF1
ZF1
as Incre
L SC2
Fault in reverse direction
SC1
oad ing l
Phase - Earth Fault RR RF /(1 + RE/RL) Maximum Load: Minimum voltage 0,9 Un Maximum current 1,1 In Nominal angle 30°
R Load area
Power Automation
6
Power Transmission and Distribution
Graded distance zones Power Automation Progress. It‘s that simple.
Z3
t = grading time Z2
time Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1
t3 t2
t1
A
B D1
C D2
D D3 distance
Grading rules:
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
Power Automation
7
Power Transmission and Distribution
Determination of grading times (With numerical relays 250 ms is possible) Power Automation Progress. It‘s that simple.
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 feeder mechanical 25 - 80 ms static: 15 - 40 digital: 15 - 30
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
+ circuit breaker operating time
HV / EHV: MV
60 ms (3 cycles) / 40 ms (2 cycles) up to about 80 ms (4 cycles)
+ distance relay reset time
mechanical: approx. 60-100 ms static: approx. 30 ms digital: 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: static/digital-mechanical or vice versa: digital-digital or static-static
100 ms 75 ms 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.
Power Automation
8
Power Transmission and Distribution
Determination of fault direction Power Automation Progress. It‘s that simple.
Fault location
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Where is the fault ? Current area for forward faults
USC
SC
X
Impedance area for forward faults
SC
ZSC
SC R
SC Current area for reverse faults
current / voltage diagram
Z'SC Impedance area for reverse faults
impedance diagram
The impedance also shows the direction, but .... Power Automation
9
Power Transmission and Distribution
Alternatives for the directional measurement Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
~
~
~
~
~
~
~
~
~
Zgrid
relay
fault L1-E
Zline
Method 1
Method 2 Vf
VL1 Vf
VL1
VL1
If
VL3
Vf
VL2
If
VL3
VL2-L3
VL2
healthy-phase voltage (phase to phase voltage)
faulty phase voltage
If VL3
VL2
voltage memory (pre-fault voltage)
Power Automation
10
Power Transmission and Distribution
Voltage controlled overcurrent fault detection Power Automation Progress. It‘s that simple.
SC
G
line
Power system
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
USC
G
Relay
ZS E
USC
ISC
digital
U
electro-mechanical
UN
ZSC
UI> UI>>
E
I>
I>>
I
USC
Power Automation
11
Power Transmission and Distribution
Voltage and angle controlled overcurrent fault detection (U-I--starting) Power Automation
X
Progress. It‘s that simple.
X 2
2 1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
1
R
R
U /U N 100 %
U (I > > )
U (I > )
50 %
I>
I> 1
I> > 2
3
I/I N
This method is used in Germany Power Automation
12
Power Transmission and Distribution
Impedance zones of digital relays (7SA6 and 7SA52) w for
Power Automation Progress. It‘s that simple.
ard
X
s
Line
Distance zones Inclined with line angle Angle prevents overreach of Z1 on faults with fault resistance that are fed from both line ends
Z5 Z4
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z2 Z1B rev e
Z1 rse
Load
Load
R
forw
Z3
ard
s
Fault detection
ers rev e
no fault detection polygon: the largest zone determines the fault detection characteristic simple setting of load encroachment area with Rmin and Load
Power Automation
13
Power Transmission and Distribution
Conventional relays: limiting of the starting characteristic area for phase-selective fault detection Power Automation
UL1 - UL2
Progress. It‘s that simple.
IL1 IL2
L1 L2
IL3
L3
IE
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
UL1 UL2 UL3
UL1 K
Z L 1 -E
UL3
UL2 UL3 - UL1
quadrilateral
ZL3-L1
=
IL1
IE
X
ZL1-E
IL1
E
distance relay
ZL1-L2
im p e d a n c e o f fa u lte d lo o p :
im p e d a n c e o f h e a lth y lo o p s : U L2 Z L 2 -E = IL2 - K E · IE Z L 3 -E
=
IL3
=
U L1 - U L2 IL1 - IL2
Z L 2 -L 3
=
U L2 - U L3 IL2 - IL3
Z L 3 -L 1
=
U L3 - U L1 IL3 - IL1
R ZL2-E
U L3 - K E · IE
Z L 1 -L 2
MHO
ZL3-E
U L1 - K E · IE
Power Automation
14
Power Transmission and Distribution
Distance protection Modern methods of phase selection Power Automation Progress. It‘s that simple.
X Z
Intelligent phase selection: quadrilateral
L1-L2 Z
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z
Impedance comparison
L3 - L1
Symmetrical component analysis Load compensation
MHO
L1-E
Pattern recognition
R Z
G
G
L3-E Z
L1 I2
L2-E
I0 G
I1
G
I2 L3
L2
IF/3
I0
Power Automation
15
Power Transmission and Distribution
Distance protection Stepped process of phase selection Power Automation Progress. It‘s that simple.
fault
n = number of detected fault loops Impedance comparison N of fault loop impedances
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Comparison of I2 and I0 components comparison of Load compensated currents
N
N
n=1
Y
Y n=1
Y n=1
Y n=1 N Trip three-phase
Trip single-phase
Power Automation
16
Power Transmission and Distribution
Phase selection Differenciating between single and double Ph-E fault Power Automation Progress. It‘s that simple.
Sector A
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
I 0 1 I L1 I L2 I L3 3 I 2 1 I L1a2 I L2 a I L3 3 I0 I2 I 0 a2 I 2 I 0 a I 2
: L -E or L -L -E fault : L -E or L -L -E fault : L -E or L -L -E fault 1
2
3
2
3
1
3
1
2
gin r ma
I2
Sector C
a I2
a2 I2
Sector B
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 Power Automation
17
Power Transmission and Distribution
Method used in 7SA52 and 7SA6 to measure I and V Using a signal model (Kalman-Filter) Power Automation Progress. It‘s that simple.
I Earth FaultEarth Fault Protection in Systems with Earthed Neutral V = I
R
L
V
Phasors
Z = R + jL
Z
Estimate the phasors V and I using the least squares method (minimised errors) t y k A sin 0 k T A B cos 0 k T A e
C cos 0 k T A
yk is the sampled value (v or i) - by assuming = 60 ms the following simplification results
y k a sin 0 k T A b cos 0 k T A
Im
current a
voltage a b
b
Power Automation
Re
18
Power Transmission and Distribution
Fast adaptive impedance measurement Filters with different lengths Power Automation Progress. It‘s that simple.
E. g. Zone Z1
Earth FaultEarth Fault Protection in Systems with Earthed Neutral Estimate 1 (n=5) Estimate 2 (n=6) Estimate 3 (n=8) Estimate 4 (n=10) Estimate 5 (n=13) Estimate 6 (n=15) Normal 1 (n = 21) Normal 2 (n = 26) Normal 3 0 Jump detected
10
20
30
40
50
60
70
80 ms
Least Square Estimate with quality control Adaptive Zone restriction Power Automation
19
Power Transmission and Distribution
Conclusion Power Automation Progress. It‘s that simple.
X Earth FaultEarth Fault Protection in Systems with Earthed Neutral
R
1. Fast operation Use short data window 2. High accuracy
High selectivity
3. Signal distortion do not cause delay or maloperation
Power Automation
20
Power Transmission and Distribution
SIR - Definition Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
SIR (Source Impedance Ratio) describes the ratio between the source impedance and the line impedance!
If ZL
G
E
VF
distance relay
SIR
ZS ZL
E Vf 1 SIR
High SIR = Small loop voltage V F in case of a fault at the end of the line Note: SIR trip time curves are mostly related to zone 1, i.e. ZL = Z1
Power Automation
21
Power Transmission and Distribution
SIR - Considerations about line length and infeed Power Automation Progress. It‘s that simple.
The SIR gives some information about the power of infeed and the line length! Earth FaultEarth Fault Protection in Systems with Earthed Neutral
SIR > 4 SIR < 4 and >0.5 SIR < 0.5
short line* medium line* 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
Power Automation
22
Power Transmission and Distribution
Trip time curves at SIR = 1 Power Automation Progress. It‘s that simple. I R =11 (A (A -GG) ) SIRS = 50
45
40
Other relays
35
t rip p in g t im e ( m s )
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
30
25
20
7SA522
15
10
5
0 0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
% o f z o n e s e t t in g
Power Automation
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Power Transmission and Distribution
Trip time curves at SIR = 30 Power Automation Progress. It‘s that simple.
S IR = 3 0 ( A - G )
SIR = 30 (A G) 50
45
40
Other relays 35
t rip p in g t im e ( m s )
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
30
25
20
7SA522
15
10
5
0 0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
% o f z o n e s e t t in g
High SIR (low voltage) doesn’t effect the tripping time in numerical relays
Power Automation
24
Power Transmission and Distribution
Zone grading chart, radial feeder Power Automation Progress. It‘s that simple.
Z3 Z2 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1
A
D
B
C
D
D
D
>> ZT >t
Z1 = 0.85 ZA-B
Z2 = 0.85 (ZA-B + 0.85 ZB-C) Z3 = 0.85 [ ZA-B + 0.85 (ZB-C+ 0.85 ZC-D) ]
Grading according the recommendation with the safety margin of 15%.
Power Automation
25
Power Transmission and Distribution
Ring feeder: with grading against opposite end Power Automation Progress. It‘s that simple.
gradingtime (s) 0.6 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
0.3
The same grading from both sides
Power Automation
26
Power Transmission and Distribution
Grading in a branched radial system Power Automation Progress. It‘s that simple.
Z3
L2
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1
L1
L3
Z2
L4 The impedances of the Z2 and Z3 must be grading with the shortest impedance Power Automation
27
Power Transmission and Distribution
Distance protection: Earth fault in system with solid, isolated or compensated system neutral earthing Power Automation Progress. It‘s that simple.
D
A ZT Z1
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
C
B
Z2...
G D
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. Power Automation
28
Power Transmission and Distribution
Earth Fault Current - Pick-Up Characteristic Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Measuring errors and non-symmetry may not cause incorrect pick-up by earth fault current threshold Power Automation
29
Power Transmission and Distribution
Earth Fault Detection Logic Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Normal pick-up:
3I0
Heavy load on long line:
3I2
For very small earth current: compensated system)
3U0 (isolated or
Power Automation
30
Power Transmission and Distribution
Earth fault detection during one pole open condition Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
During the 1 pole open condition, load current flows in the earth path. Magnitude comparison of the remaining 2 phases prevents incorrect pick-up Power Automation
31
Power Transmission and Distribution
Distance measurement Fault loop formulas Power Automation Progress. It‘s that simple.
IL1
Relay location
RL + j XL
IL2 IL3 VL1 VL2 VL3
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
IE
Phase-to-Earth loop:
RE + j XE
VL1 I L1 RL jX L I E RE jX E R X VL1 RL I L1 E I E jX L I L1 E I E RL XL Line and earth impedance are measured
Phase-to-Phase loop:
VL1 L 2 RL jX L I L1 I L 2 Only the Line impedance is measured
Power Automation
32
Power Transmission and Distribution
Numeric impedance calculation, ph-ph-loop Power Automation
relay location
Progress. It‘s that simple.
fault location
L1
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
fwd
L2
ret Infeed
L3
Rfwd
Xfwd(Lfwd)
Rret
Xret(Lret)
to remote line end
Ufwd Uret
E
ZL2 - L3 =
U L2 - U L3 IL2 - IL3
U L2 - U L3 RL2 - L3 = Re IL2 - IL3
U L2 - U L3 XL2 - L3 = Im IL2 - IL3
With the measurement of phase to phase voltages and currents the fault impedance (impedance to fault location) is correct calculated
Power Automation
33
Power Transmission and Distribution
Estimation of arc resistance Power Automation Progress. It‘s that simple.
Worrington formula:
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Rough estimation: UARC = 2500 V/m
X
Variable R/X-setting
R ARC
R ARC
28700 IA
1,4
lm Ohm
2500 V/m dm Ohm I F A
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)
R
l= l= l=
1x1,3 = 1,3 m (110 kV 2x1,3 = 2,6 m (220 kV) 3x1,3 = 3,9 m (380 kV)
Power Automation
34
Earth Fault Protection in Systems with Earthed Neutral The year of Profitable Growth
Global network of innovation
Power Transmission and Distribution
7SA522 High Resistance Earth Fault Protection: Features Power Automation Progress. It‘s that simple.
3 definite-time stages Earth (zero sequence) current protection, 4 stages 1 inverse-time stage: IEC, logarithmic inverse or ANSI characteristic
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
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 Power Automation
36
Power Transmission and Distribution
Example: Single phase fault with infeed from 2 sides Power Automation Progress. It‘s that simple.
IL1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
IL2 IL3
Zf IE
Power Automation
37
Power Transmission and Distribution
Symmetrical Component representation: L1-E Fault Power Automation Progress. It‘s that simple.
A
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
I1A
I1B
I2A
I2B
B
Pos. Seq.
Neg. Seq.
U 2A
U 2B
I0A Zero Seq.
U 0A
3x R Fault
I0B U 0B
Power Automation
38
Power Transmission and Distribution
Polarizing Options for Directional Earth Fault Relays Power Automation Progress. It‘s that simple.
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
Power Automation
39
Power Transmission and Distribution
Directional Characteristic (U0 and IY) Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Power Automation
40
Power Transmission and Distribution
7SA522 High Resistance Earth Fault Protection: functional diagram Power Automation Progress. It‘s that simple.
Earth fault direction Inrushstabilisation
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
EF IE> Echo EF Fault Det.
SOTF
Teleprotection
>EF Trip rel.
P
Direc. 3I0>>>
P
3I0>>>
= & EF>>> Trip
T
&
3I0>>> Def. Time Stage
>EF>>> block
3I0>> Def. Time Stage 3I0> Def. Time Stage P Direc. 3I0p P 3I0p
&
= &
EFp Trip
P3146 AddTdelay T(3I0/IN)
T
Inverse Time Stage
>EFp block
= Input signal (binary input)
P
= Parameter
= Output Signal (alarm, command)
Power Automation
41
Power Transmission and Distribution
7SA522 - Directional earth fault protection: Settings Power Automation Progress. It‘s that simple.
General settings: Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Settings for direction: Settings of the stages:
Power Automation
42
Power Transmission and Distribution
Principle of phase selection logic with U and I Example L1-E Power Automation Progress. It‘s that simple.
UL1E < 0.6 UNOM Earth FaultEarth Fault Protection in Systems with Earthed Neutral
&
UL2E > 0.7 UNOM UL3E > 0.7 UNOM OR
Select L1-E with U / I
IL1E > 2 INOM IL2E < 1.2 INOM
&
IL3E < 1.2 INOM If selection with U / I is not successful (U too large or I too small) then symmetrical component method is used Power Automation
43
Power Transmission and Distribution
Phase Selection Logic - Sequence Components Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Angle difference I2/I0 -60° .. 60° 60° .. 180° 180° .. 300°
Faulty Phase L1-E L3-E L2-E
I2 = a*I0 L3-E
L1-E I2 = I0 L2-E
I2 = a2*I0
Power Automation
44
Power Transmission and Distribution
DEF protection, Critical application issues Power Automation Progress. It‘s that simple.
U0P or U2P may fall below critical value (approx. 1 V secondary) and limit relay high resistance earth fault sensitivity Zero or negative sequence sources to be available behind relay location
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Minimum settings at least > 3 times VT and CT inaccuracies Current setting above line unsymmetry (M0 = Z01/Z0 or M2 = Z21/Z1) compensated lines require higher current setting due to possibility of unsymmetrical gap flashover)
(series
Separate current threshold setting for tele-protection : 3I0 to avoid false operation with CT saturation
Power Automation
45
Power Transmission and Distribution
7SA522 - Earth fault protection Directional comparison teleprotection scheme Power Automation Progress. It‘s that simple.
A Earth FaultEarth Fault Protection in Systems with Earthed Neutral
E/F. frwd.
&
&
B
TS
1
transm.
transm
trip
1
trip
rec.
TS
&
E/F. frwd.
&
rec.
TS
*Three-terminal schemes are supported as well Power Automation
46
Tele Protection The year of Profitable Growth
Global network of innovation
Selectivity in distance protection, Teleprotection is the solution Power Automation Progress. It‘s that simple.
Power Transmission and Distribution
Normal setting: X1 = 0.85 XL
2
1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
15% Faults in this area are tripped from side 2 in t2
70% Faults in this area are tripped from both sides in first-zone time
15% Faults in this area are tripped from side 2 in t2
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) Power Automation
48
Power Transmission and Distribution
Teleprotection Schemes Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Permissive Underreach PUTT Permissive Overreach POTT Blocking Unblocking
Power Automation
49
Power Transmission and Distribution
Application of Teleprotection Schemes Power Automation Progress. It‘s that simple.
PUTT
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
POTT
Blocking
Unblocking
Middle + long lines with FS-Carrier or FO
Pref. short lines with FS-Carrier (2-Ph coupling) FO or MW
All lines with AM-Carrier (less reliable channel)
EHV-lines with FS-Carrier. Continuous signal sending necessary (must be admissible)
If second zone tripping for near end faults not allowed. Not applicable to lines with weak in feed.
Only forward overreaching zone necessary
Reverse looking blocking zone (fast) additionally necessary
No reverse looking blocking zone necessary
Simple logic! Complex logic! Current reversal guide ECHO-logic (W I-logic)
PUTT - Permissive Under-reach Transfer Trip
No monitoring of the AM-channel!
POTT - Permissive Overreach Transfer Trip
Power Automation
50
Power Transmission and Distribution
7SA522 - Permissive underreach transfer trip (PUTT) Power Automation Progress. It‘s that simple.
Z1(A)
A
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z 1B(B)
Z1 (A) Z1B T1B (A)
Z 1B(A)
Z 1(B)
TS T1
& Further zones
B
OR
transmit
Trip receive
transmit
Trip receive
TS T1
OR
Z1 (B) Z1B T1B (A)
& Further zones
TS
Power Automation
51
Power Transmission and Distribution
7SA522 - Permissive overreach transfer trip (POTT) Power Automation Progress. It‘s that simple.
Z1(A)
A
Z 1B(B)
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1B T1B (A)
Z 1B(A)
Z 1(B)
& TS
& Z1 or further zones
B
OR
OR
transmit
Trip receive
transmit
Trip
OR
TS
OR
receive
&
Z1B T1B (B)
& Z1 or further zones
TS
Power Automation
52
Power Transmission and Distribution
7SA522 - Blocking Power Automation
FD (B)
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1 (A)
A
FD (A)
Progress. It‘s that simple.
Z1B (B)
Z1B(A) FD (A)
B
FD (B)
Z1 (B)
d dt
(u,i) (A)
d dt 40 ms
40 ms
Forw. (A) FD (A)
Forw. (B) &
1
TS
transm.
1
transm.
TS
TV
Z1B T1B (A) Z1 or further zones
(u,i) (B)
&
FD (B)
TV
&
1
trip
rec.
1
trip
Z1B T1B (B)
&
Z1 or further zones
rec.
TV
TS
Power Automation
53
Power Transmission and Distribution
7SA522 - Unblocking Power Automation Progress. It‘s that simple.
Z1 (A)
A
Z1B (B)
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Z1B T1B (A)
Z1B (A)
Z1(B)
&
& Z1 or further zones
B
fU
1
TS
1
Unblocklogic
fU
transm. f 0
trip
U rec.
rec.
f0 – Off frequency (monitoring frequency) fU – Unblock frequency (send frequency)
TS
1
trip
U B
1
f0 transm.
B
&
Z1B T1B (B)
&
Unblocklogic
Z1 or further zones
U – Unblocking signal B – Blocking signal
TS
Power Automation
54
Power Transmission and Distribution
7SA522 - Phase segregated Teleprotection Power Automation Progress. It‘s that simple.
2
Z1
Z1B A Earth FaultEarth Fault Protection in Systems with Earthed Neutral
2
1
L1-E
Z1
1
B
L2-E
Z1B
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
Power Automation
55
Power Transmission and Distribution
7SA522 - Teleprotection with three-terminal lines Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Software provides teleprotection of threeterminal lines without additional logic
Power Automation
56
Power Transmission and Distribution
7SA522 and 7SA6 Teleprotection via serial remote relay interface Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
PUTT and POTT schemes available: “plug and protect” Echo, 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
> Power Automation
57
Power Transmission and Distribution
SIPROTEC 4 Communication topology: Ring and Chain Power Automation Progress. It‘s that simple.
side 2
side 2
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Automatic change from closed ring to chain, if one connection is lost or not available
side 2
side 3 side 3
side 1
side 1
2 terminal line 3 terminals: Closed ring
side 1
3 terminals: Chain
Power Automation
58
Power Transmission and Distribution
SIPROTEC 4: Familiar with digital communication networks Features of the relay to relay communication Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Synchronous data transmission by HDLC- protocol Permanent 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
Power Automation
59
Power Transmission and Distribution
Communication Options Power Automation Progress. It‘s that simple.
O
820 nm 1,5 km / 3 km
internal Earth FaultEarth Fault Protection in Systems with Earthed Neutral
O
FO5: FO6 :
distance 1.5 km (with clock feed-back) distance 3.5 km
1300 nm 10 km
FO7 :
distance 10 km
1300 nm 35 km
FO8:
distance 35 km
internal
O internal
O
E
external
X21 G703
KU : hook-up to communication network Note: km data are valid for worst-case conditions
Power Automation
60
Power Transmission and Distribution
Transient Blocking for Permissive Schemes Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Power Automation
61
Power Transmission and Distribution
Weak Infeed Echo Logic Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Receive Signal
No Distance Pickup Power Automation
62
Power Transmission and Distribution
7SA522 - Echo and Tripping in case of no-infeed or weak-infeed Power Automation Progress. It‘s that simple.
Configuration Settings
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Matrix The receive signal is derived from : and *Three-terminal schemes are supported as well
Phase segregated weak-infeed tripping Note: The echo signal must be routed in addition to the send signal on the transmission signal contact
!
17.10.97 en513ase2
Power Automation
63
Power Transmission and Distribution
Overreach zone setting for POTT and Unblocking Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
incorrect!
Reverse looking zone (A)
Z1B(B)
Z1B(A)
A
B
Reverse looking zone (B)
correct
Power Automation
64
Power Swing
The year of Profitable Growth
Global network of innovation
Power Transmission and Distribution
Power swing: Voltage diagram Power Automation
LZS1
Progress. It‘s that simple.
Two Machine Problem E1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
E2 ZL
ZS1
UA
LZL
LZS2 E2 = E'2
E1
UA
ZS2
UB U'B
UB
U'A E'1
'
'L
L
If the angle becomes too large, the system stability can be lost
Power Automation
66
Power Transmission and Distribution
Power swing locus and relay characteristic in the impedance diagram Power Automation Progress. It‘s that simple.
E1 > E2
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
X
ZS2
B
E1 = E2
ZL
'
A
load point R
ZLoad
E1 < E2 ZS1
Power Automation
67
Power Transmission and Distribution
Dynamic system stability, equal area criterion Power Automation
U1
Progress. It‘s that simple.
E1
ZS2
ZS1 D
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
U2
ZL
1
E2
E1 · E2 PTP =
ZL
· sin
XT
5
P 3 3 4 B
0 PT
A
C
1
6
D 2
2 2
D
1 0
0
1
90°
2
3
180°
D
Power Automation
68
Power Transmission and Distribution
Power swing locus in the impedance plane Power Automation Progress. It‘s that simple.
X ZS1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
1
2 ZL 2
6
4 5
3 0 0
ZS1
Zload
R
Power Automation
69
Power Transmission and Distribution
Power swing detection: Classic Method (Not used in 7SA52 and 7SA6) Power Automation Progress. It‘s that simple.
Classic power swing detection is restricted to slow swings Earth FaultEarth Fault Protection in Systems with Earthed Neutral
The setting of Z may not be too large to avoid load encroachment (typ. 5 )
Z
During fast swings the time available (t) for detection of impedance vector in the power swing zone is too short.
t = time for transition of Z from outer to inner zone
Power Automation
70
Power Transmission and Distribution
Advanced Power swing blocking techniques (7SA513, 7SA522, 7SA6) Power Automation Progress. It‘s that simple.
•Novel space vector based principle Unstable swing Earth FaultEarth Fault Protection in Systems with Earthed Neutral
X
•Self-setting •Small Z (1 Ohm at In=5 A)
Z
•Blocking up to high slip frequencies (7 Hz) •Recognition of all fault types during swing
R
•Remains effective during single pole ARC open time (3-phase set-up) dZ/dt measurement
Stable swing
Calculation of swing centre and plausibility check (+90O< EB) Slip frequency
Example: i/kA
-90O
6 3 -3
500
90O
Xm t/ms
u/kV 200
500
t/ms
180O
Relay
R
Power Automation
73
Power Transmission and Distribution
Novel power swing detection provides secure operation with swing frequencies of up to 7 Hz Power Automation Progress. It‘s that simple.
Earth FaultEarth Fault Protection in Systems with Earthed Neutral
Example: 400 kV 400 km fPS 2 Hz 3-pole fault
iL1/A 0 -2
0,2
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
0,2
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
0,2
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
0,2
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
0,2
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
0,2
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
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
t/s
-4
iL2/A 0 -2
t/s
iL3/A 2
t/s
0 -2
uL1/V 0 -50
t/s
uL2/V 50 0 -50
t/s
uL3/V 50 0 -50
t/s
Power Swing >DisTel Rec.Ch1 Dis.T.SEND Dis. forward Dis. reverse Relay PICKUP Relay TRIP DisTRIP3p Z1Bmf 0,2
0,3
Power Automation
t/s
74
Power Transmission and Distribution
Fault detection during power swing Power Automation Progress. It‘s that simple.
I1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
I2
V1 The Power swing passes through the trip characteristic several times. Trip Single phase fault is detected and cleared.
Power Automation
75
Power Transmission and Distribution
Three phase fault during Power Swing Power Automation Progress. It‘s that simple.
I1 Earth FaultEarth Fault Protection in Systems with Earthed Neutral
V1
V2
V3 Trip
Three phase fault during power swing is detected and cleared Fault inception while swing is inside trip characteristic
Power Automation
76
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