8.Line Distance Protection

7/27/2019 8.Line Distance Protection

1/76

The year of Profitable Growth

Global network of innovation

Module 10B:

Line Distance Protection


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Power Automation 2

Power Transmission and Distribution

Power Automation

Progress. Its that simple.

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?


3/76

Power Automation 3


Power Automation

Progress. Its that simple.

Earth

FaultEarth

Fault Protection


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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Power Automation 5


Power AutomationProgress. Its that simple.

Earth

FaultEarth

Fault Protection


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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Power Automation 6



Earth

FaultEarth

Fault Protection


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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Power Automation 7



Earth

FaultEarth

Fault Protection


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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Power Automation 8



Earth

FaultEarth

Fault Protection


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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Power Automation 9



Earth

FaultEarth

Fault Protection


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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Power Automation 11



Earth

FaultEarth

Fault Protection


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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Power Automation 12



Earth

FaultEarth

Fault Protection


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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Power Automation 13



Earth

FaultEarth

Fault Protection


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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Power Automation 14



Earth

FaultEarth

Fault Protection


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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Power Automation 15



Earth

FaultEarth

Fault Protection


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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Power Automation 16



Earth

FaultEarth

Fault Protection


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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Power Automation 17



Earth

FaultEarth

Fault Protection


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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Power Automation 18



Earth

FaultEarth

Fault Protection


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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Power Automation 19



Earth

FaultEarth

Fault Protection


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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Power Automation 20



Earth

FaultEarth

Fault Protection


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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Power Automation 21



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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Power Automation 22



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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Power Automation 23



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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Power Automation 24



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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Power Automation 25



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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Power Automation 26



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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Power Automation 28



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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Power Automation 29



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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Power Automation 30



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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Power Automation 31



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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Power Automation 32



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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Power Automation 33



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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Power Automation 34



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


36/76

Power Automation 36



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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Power Automation 37



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

Example: Single phase fault with infeed from 2 sides

IL1

IL2

IL3

IE

Zf


38/76

Power Automation 38



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


39/76

Power Automation 39



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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Power Automation 40



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

Directional Characteristic (U0 and IY)


41/76

Power Automation 41



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


42/76

Power Automation 42



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

7SA522 - Directional earth fault protection: Settings

Settings of the stages:

Settings for direction:

General settings:


43/76

Power Automation 43



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


44/76

Power Automation 44



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


45/76

Power Automation 45



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


46/76

Power Automation 46



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


48/76

Power Automation 48



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)


49/76

Power Automation 49



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

Teleprotection Schemes

Permissive Underreach PUTT

Permissive Overreach POTT

Blocking

Unblocking


50/76


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Power Automation 51



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


52/76

Power Automation 52



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


53/76

Power Automation 53



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


54/76

Power Automation 54



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


55/76

Power Automation 55



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


56/76

Power Automation 56



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


57/76

Power Automation 57



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


58/76

Power Automation 58



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


59/76

Power Automation 59



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



60/76

Power Automation 60



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



61/76

Power Automation 61



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

Transient Blocking for Permissive Schemes



62/76

Power Automation 62



Earth

FaultEarth

Fault Protection

in Systems with

Earthed Neutral

Weak Infeed Echo Logic

No Distance Pick-

up

Receive

Signal



63/76

Power Automation 63



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

!


64/76


65/76



Power Swing


66/76



67/76

Power Automation 67


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



68/76

Power Automation 68


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



69/76

Power Automation 69


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



70/76

Power Automation 70


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



71/76

Power Automation 71


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<


72/76

Power Automation 72


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



73/76

Power Automation 73


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



74/76

Power Automation 74


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



75/76

Power Automation 75


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.



76/76


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

Documents

8.Line Distance Protection