X80012EN

8/13/2019 X80012EN

http://slidepdf.com/reader/full/x80012en 1/44

8/13/2019 X80012EN


1MDX80012-EN

Page 2

Version 1.21

Distance protection

September 1997

ABB Network Partner AB

1.5 Secondary injection test

.......................................................28

1.5.1 Measurement with the general three-phase

testing equipment....................................................................29

1.5.1.1 Connection of the testing equipment to the

tested terminal ..............................................................................29

1.5.1.2 Measurement of the operating characteristics of

single-phase-to-earth faults..........................................................30


phase-to-phase faults31


three-phase faults .........................................................................33

1.5.1.5 Operating time and time delay of the different

distance measuring zones ............................................................34

1.5.2 Instructions for the measurement of operating

characteristics with the test set type RTS 21 (FREJA)...........34

1.5.2.1 Measurement of the operating time of distanceprotection zones ...........................................................................35

1.5.3 Directional test of the distance measuring function ...............36

1.6 Technical data

.......................................................................37

1.7 Appendix

...............................................................................38

1.7.1 Terminal diagram ...................................................................38

1.7.2 Signal list ................................................................................40

1.7.3 Setting table ............................................................................42

8/13/2019 X80012EN


Distance protection


Version 1.21

1MDX80012-EN

Page 3

September 1997

The distance protection function remains the most widely spread protec-

tion function in transmission and subtransmission networks. It is becom-

ing increasingly important in distribution networks as well. The two main

reasons for this are:

• there is no dependence on communication links between the line

ends, since for its operation it uses information from locally available

currents and voltages

• in the network the distance protection forms a so-called relatively

selective protection system (non-unit protection system). This means

that it is also able to operate as a remote back-up protection for other

units located in the network.

The basic requirements for a modern line protection such as speed, sensi-

tivity and selectivity, together with the high requirements for availability,

are getting increasingly stringent. In addition to this, modern distance pro-

tections must be able to operate in networks together with existing dis-

tance relays, which are mostly designed in a different technology (static or

even electromechanical relays). The flexibility of a modern distance pro-

tection is therefore of utmost importance. This applies especially when it

is used in a complex network configuration on parallel operating multicir-

cuit lines, on multiterminal lines, etc.

A distance protection is not dependent on communication for selective

operation and can detect faults beyond the current transformer in the

remote terminal. This functionality makes a distance protection an ideal

complement to line differential protections that can not detect faults

beyond the current transformer in the opposite terminal.

The distance protection function optional in REL 561, is primary a protec-

tion for faults beyond the current transformer at the opposite terminal.

This protection function is achieved by the time delayed zone 2, coveringat least the adjacent busbar and thus forming a primary or back-up protec-

tion for the busbar. This function shall be continuously in operation.

An underreaching zone 1 can form a back-up to the line differential pro-

tection. There is no need for this function as long as the differential pro-

tection is in operation. To minimise the risk of unwanted operation from

zone 1, this function can be activated when the differential function is out

of operation.

1 DISTANCE PROTECTION

1.1 Application

1.1.1 General application REL 501, REL 511, REL 521

1.1.2 General application REL 561

8/13/2019 X80012EN


1MDX80012-EN

Page 4

Version 1.21

Distance protection

September 1997


Zone 1 can not protect the entire line. A communication scheme of per-

missive or blocking type will, without time delay, protect the entire line.

This function is only of value when the differential protection is out of

operation. Therefore, to minimise the risk of unwanted operation this

function can normally be blocked and activated when the differential

function is lost. The most likely cause to loose of the differential protec-

tion is communication failure. Therefore the communication scheme

should use another communication channel than the one used by the dif-

ferential protection.

To allow a complementary function in the communication scheme as cur-

rent reversal and weak infeed logic, a reverse zone 3 is available. Zone 3

can also be set forward when needed.

The impedance protection is equipped with phase selector for single-pole

tripping.

The distance protection function, as built into the line protection terminals

REL 5xx, is a full scheme distance protection. This means that it com-

prises individual measuring elements for different types of faults and dif-

ferent zones.

Depending on the type of terminal, it consists of up to five (three in

REL 561) independent impedance measuring zones with a quadrilateral

characteristic, as presented for general case in Fig. 1.

The characteristic in reactive direction is a straight line, parallel with the Raxis. The measuring algorithm used for the reactance part of the character-

istic for phase-to-earth faults compensates for the influence of the load

current on the impedance measurement for distance zone 1. Therefore, the

characteristic presented has no declination against the R axis. Setting of

the reach in reactive direction is independent for each separate zone.

A straight line limits the reach of the distance protection zone in resistive

direction. It is parallel with the line impedance characteristic, Z

L

. This

means that with the R axis it forms a line characteristic angle,

ϕ

L

. Setting

of the reach in resistive direction is independent for each separate zone.

Furthermore, different setting values are possible for phase-to-earth faults

(RFNZn) and for phase-to-phase faults (RFZn), where n designates the

corresponding zone.

The directional characteristic in the second quadrant forms, with the X

axis, an angle of 25

°

. In the fourth quadrant, the corresponding part forms

with the R axis an angle of 15

°

, as presented in Fig. 1.

The characteristics of the distance zones are independent on one another

as far as their directionality and reach in different directions is concerned.

The directionality of each distance zone is programmable. Fig. 2 shows a

typical example of a characteristic of an impedance measuring zone when

directed into forward or reverse direction. A polygon, completed with

dashed lines, represents the characteristic of a non-directional zone.

1.1.3 Basic characteristics

8/13/2019 X80012EN


Distance protection


Version 1.21

1MDX80012-EN

Page 5

September 1997

Fig. 1 Characteristic of an impedance measuring zone

The set value of a reach in resistive direction determines whether the

directional line in the second quadrant meets, as first, the reactive or the

resistive characteristic - see the difference between the characteristics in

Fig. 1 and Fig. 2.

The values of the reaches in reactive and resistive direction for a particular

zone are the same for forward and reverse impedance measuring elements

as well as for the non-directional mode of operation.

The terminal will automatically adapt the line characteristic angle ϕ

L

according to the set value of the line parameters for positive and zero-

sequence reactance and resistance (R1Zn, X1Zn, R0Zn, X0Zn) for each

zone n separately. Thus, the measurement of different faults will follow

the real conditions in a power system. Fig. 3 shows the measuring charac-

teristic of an impedance measuring zone (for the single-phase-to-earth

fault) that faces the forward direction. Here, a phase-to-earth loop measur-

ing impedance, Z

loop

, consists of a line operational impedance Z

L

, an

earth return impedance Z

N

and a fault resistance RFNZn. The characteris-

tic angle of the complete line,

ϕ

line

, will automatically follow the real sys-

tem conditions as well as the loop measuring characteristics.

X

jX

25o

o15

L

LZ

R F FNR

R

(X80012-1.3)

8/13/2019 X80012EN


1MDX80012-EN

Page 6

Version 1.21

Distance protection

September 1997


Fig. 2 Different characteristics of one zone of the impedance measur-

ing function.

In short line applications, the possibility of covering a sufficient fault

resistance will be a major consideration. Load encroachment problems arenot so common. The independent setting possibility of the reach in reac-

tive and resistive direction is a feature that will greatly improve the flexi-

bility of a distance protection.

An optional overreaching scheme communication logic will, for these

short line applications, additionally improve the resistive coverage. The

optimum solution in some applications is to add the optional directional

comparison earth fault overcurrent protection to the distance protection

scheme.

(X80012-2.3)

LZ

jX

25

Forward

Reverse

Lo

o15

FNR

1.1.4 Short line applications

8/13/2019 X80012EN


Distance protection


Version 1.21

1MDX80012-EN

Page 7

September 1997

In long line applications, the margin to the load impedance, to avoid load

encroachment, is usually a major consideration. Quadrilateral characteris-

tics with independent settings of the reach in reactive (to cover sufficient

length of a line) and resistive (to avoid load encroachment) direction willdiminish, to a great extent, the conflict that is very characteristic for circu-

lar characteristics.

A wide setting range of the reach in reactive direction, settable independ-

ently for each zone, together with a good current sensitivity, down to 20%

of the rated current, is an important factor that will improve the perform-

ances of the distance protection when used on long transmission lines.

Fig. 3 Characteristic of the phase-to-earth impedance measuring ele-

ment, presented for the loop measurement

1.1.5 Long line applications

jX

loop

X

Z N

N

25°

Z L

15°

RFNZn

line

L

Z

Rline

loopZ

RFNZn

(X80012-3.3)

8/13/2019 X80012EN


1MDX80012-EN

Page 8

Version 1.21

Distance protection

September 1997


High voltage power cables have two main characteristics that make them,

from the distance protection point of view, different from overhead lines:

• they are relatively short, compared to overhead lines

• the value of their zero sequence reactance is very low, in many cases

even lower than the positive sequence reactance. This results in a

negative value of the characteristic angle for the earth return imped-

ance.

The value of the earth return compensation follows automatically, without

any approximation, the parameters of a power cable for positive and zero

sequence reactance and resistance. This makes the impedance measuring

function, as built into the REL 5xx line protection terminals, suitable for

the protection of short HV power cables. The independent setting of the

reach (in reactive and resistive direction, separately and independently foreach distance zone) will only improve these basic performances.

Zero sequence mutual impedance between different circuits of the multi-

circuit parallel operating lines is a factor that particularly influences the

performance of a distance protection during single-phase-to-earth fault

conditions. In addition to this, a distance protection must, to the greatest

possible extent, operate selectively for intersystem faults and simultane-

ous faults.

The separate and independent setting of the parameters that determine the

value of earth return compensation for different distance protection zones,

enables the compensation of the influence of the zero sequence mutual

impedance on the measurement of the impedance measuring elements for

single-phase-to-earth faults.

The use of separate optional phase selectors with their reach setting inde-

pendent of the reach of the zone measuring elements improves, to a great

extent, the performance of a distance protection on the multicircuit paral-

lel operating lines. At the same time, these phase selectors will reduce to

the lowest possible level the influence of the heavy load current, presentduring a fault, on the phase selection function within the terminals.

1.1.6 Distance protection of the power cables

1.1.7 Application to parallel operating multicircuit lines

8/13/2019 X80012EN


Distance protection


Version 1.21

1MDX80012-EN

Page 9

September 1997

For the selective operation of a distance protection on tied and multitermi-

nal lines, flexibility in scheme communication logics associated with the

distance protection function is a great advantage. Scheme communicationlogic built into the REL 5xx line protection terminals enables the adapta-

tion of any communication scheme to the existing system conditions. The

free selection of overreaching and underreaching zones, together with the

free selection of a conditional zone, and independent settings of the reach

for different zones, makes the REL 5xx line protection terminals

extremely flexible for such applications.

Fault loop equations use the complex values of voltage, current and

changes in the current. Apparent impedances are calculated and checked

with the set limits (R and X represent the line resistance and reactance).

For single-phase-to-earth faults, earth return compensation is applied in a

conventional manner:

For faults without connection to earth, phase-to-phase quantities are used.

This results in the same reach along the line for all types of faults.

Fig. 4 Measuring principle -general presentation of a line, measuring

quantities

1.1.8 Application on tied and multiterminal lines (not applicable for REL 561)

1.2 Measuring principle

Uph Z0 Z1–( ) I0⋅–

Iph

----------------------------------------------- R jX+=

Uph ph–

Iph ph–

------------------ R jX+=

(X80012-4.3)

U

F

IX

Im(U)

Re(U)

R

U

Re

Im

8/13/2019 X80012EN


1MDX80012-EN

Page 10

Version 1.21

Distance protection

September 1997


The measuring elements receive information about currents and voltages

from the A/D converter. The checksums are calculated and compared, and

the information is distributed into memory locations. For each of the six

supervised fault loops, voltage , current , and changes in current

between samples are brought from the input memory and fed to a

recursive Fourier filter. The Fourier filter provides two orthogonal values

for each input. These values are related to the loop impedance according

to the formula:

or as orthogonal values:

where Re designates the real component, and Im the imaginary component

of current and voltage.

It is possible to calculate resistance R from the equation for the real value

of the voltage and substitute it in the equation for the imaginary part. The

equation for reactance X can then be solved. The final result of measure-

ment is equal to:

The calculated R and X values are updated each millisecond andcompared with the set zone reach. The adaptive tripping counter counts

the number of permissive tripping results. This in order to effectively

remove any influence of errors introduced by the capacitive voltage trans-

formers or by other causes. The algorithm used is insensitive to changes in

frequency, transient dc components and harmonics since a true replica of

the protected line has been implemented in the algorithm.

The directional evaluations are performed in both forward and reverse

direction, and for all six fault loops simultaneously. Positive sequence

voltage and a phase locked positive sequence memory voltage are used as

a reference. This will ensure unlimited directional sensitivity for faults

close to the relaying point. The directional indication for both forwardand reverse faults makes it possible to provide carrier blocking schemes,

current reversal logic, and weak infeed logic.

u( ) i( )∆i( )

U R IX

ω0

------ ∆I

∆t------⋅+⋅=

Re U( ) R Re I( ) X

ω0

------ ∆Re I( )

∆t------------------⋅+⋅=

Im U( ) R Im I( ) X

ω0

------ ∆Im I( )

∆t------------------⋅+⋅=

RIm U( ) ∆Re I( ) Re U( ) ∆Im I( )⋅–⋅∆Re I( ) Im I( ) ∆Im I( ) Re I( )⋅–⋅

------------------------------------------------------------------------------------=

X ω0 ∆tRe U( ) Im I( ) Im U( ) Re I( )⋅–⋅

∆Re I( ) Im I( ) ∆Im I( ) Re I( )⋅–⋅--------------------------------------------------------------------------------⋅ ⋅=

8/13/2019 X80012EN


Distance protectionABB Network Partner AB

Version 1.21

1MDX80012-ENPage 11

September 1997

The impedance measurement for the phase to earth faults is performed on

the loop basis by comparing the calculated resistances and reactances withthe set values of the reach in the resistive and reactive direction. If

and represent measured phase voltage and phase current in relay point

and represents the measured residual current in relay point, then the

operating condition for the phase-to-earth fault resistive measurement in

forward direction follows the expression:

The same condition for the measurement in the reverse direction followsthe expression:

Parameter represent in this case line reactance between the relay

point and the location of a fault.

The operating for the phase-to-earth fault reactive measurement in for-

ward direction follows the expression:

Similar expression is valid also for the phase-to-earth measurement in

reverse direction:

The impedance measurement for the phase to phase faults is performed on

the loop basis by comparing the calculated resistances and reactances with

the set values of the reach in the resistive and reactive direction. The oper-

ating condition for the resistive measurement in forward direction follows

the expression:

1.2.1 Measured impedance

1.2.1.1 Phase-to-earth measurement

Uph

Iph

IN

ReUph

Iph

---------

RFNZn X0Zn X1Zn–( ) R0Zn R1Zn–

X0Zn X1Zn–------------------------------------ Re

IN

Iph

-------

⋅ ImIN

Iph

-------

– Re X1m e jϕLine–

⋅( )+⋅+≤

ReUph

Iph

---------

R– FNZn X0Zn X1Zn–( )–R0Zn R1Zn–

X0Zn X1Zn–------------------------------------ Re

IN

Iph

-------

⋅ ImIN

Iph

-------

– Re X1m e jϕLine–

⋅( )+⋅≥

X1m

ImUph

Iph

---------

X1Zn X0Zn X1Zn–( ) R0Zn R1Zn–

X0Zn X1Zn–------------------------------------ Im

IN

Iph

-------

⋅ ReIN

Iph

-------

+⋅+≤

ImUph

Iph

---------

X– 1Zn X0Zn X1Zn–( ) R0Zn R1Zn–

X0Zn X1Zn–------------------------------------ Im

IN

Iph

-------

⋅ Re

IN

Iph

-------

+⋅+≥

1.2.1.2 Phase-to-phase measurement

UL1

UL2

–

IL1 IL2–-------------------------

RFZn Re X1m e j

ϕL–

⋅( )+≤

8/13/2019 X80012EN


1MDX80012-ENPage 12

Version 1.21

Distance protection

September 1997


Similar condition appears also for the operation in reverse direction:

The operating condition for the reactive measurement in forward direction

follows the expression:

Similar condition applies also for reactive measurement in reverse direc-

tion:

The directional measurement is based on the use of a positive sequence

voltage for the respective fault loop. For the L1-N element, the equation

for forward direction is:

The polarising voltage is available as long as the positive sequence

voltage exceeds 4% of Ur . It will thus be usable for all unsymmetrical

faults (single-phase or two-phase) including close-in faults. For three-

phase faults, the memory voltage , based on the same positive

sequence voltage, will ensure correct directional discrimination.

The memory voltage is used for 100 ms, or until the positive sequence

voltage is restored. After 100 ms, the following will take place:

• If the current is still above 20% of Ir , the condition will seal in. If

the fault has caused tripping, the trip will endure. If the fault was

detected in the reverse direction, the measuring element in thereverse direction will remain in operation.

• If the current decreases below 20%, the memory will reset until the

positive sequence voltage exceeds 40 V.

ReUL1 UL2–

IL1 IL2–

-------------------------

R– FZn Re X1m e⋅ jϕL–

( )+≥

ImUL1 UL2–

IL1 IL2–-------------------------

X1Zn≤

ImUL1 UL2–

IL1 IL2–-------------------------

X– 1Zn≥

1.2.1.3 Directional lines

15°0 8, U1L1⋅ 0 2, U1L1M⋅+

IL1

---------------------------------------------------------------- 115°<arg<

U1L1

U1L1M

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 13

September 1997

Three digital signal processors, depending on the type of the REL 5xx line

protection terminal, execute algorithms for up to five full scheme distance

protection zones. Fig. 5 presents an outline of the different measuring

loops for the basic five impedance measuring zones as built into the lineprotection terminal REL 511.

Fig. 5 Location of different measuring loops within the three digital

signal processors in line protection terminal REL 511

The first digital signal processor (DSP) measures different fault loops for

different single-phase-to-earth faults and for different zones (not includedinto the REL 501 line protection terminal). This way, it forms the resistive

and reactive part of a characteristic for single-phase-to-earth faults. The

second digital signal processor performs the same task for the phase-to-

phase fault loops. The third digital signal processor performs the direc-

tional measurement for all types of faults, separately in forward and

reverse direction.

The parallel execution of measurements in three different DSPs permits

the evaluation of each impedance measuring loop for each zone separately

within each millisecond. This gives the distance protection function the

same features as those known for the full scheme design of conventional

distance relays (REZ 1, RAZFE).

Different internal and external conditions influence the operation of the

distance protection function as shown in a simplified logic diagram for a

distance protection zone 1 in Fig. 6.

1.3 Design

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-N L2-N L3-N

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

L1-L2 L2-L3 L3-L1

Z1

Z2

Z3

Z4

Z5

For.

Rev.

(X80012-5 (2))

8/13/2019 X80012EN


1MDX80012-ENPage 14

Version 1.21

Distance protection

September 1997


Fig. 6 Logical diagram of a distance protection function for zone 1

All other zones have the same logical structure. It is possible to influence

the basic operation of each distance measuring zone (ZM1< on Fig. 6) by

setting the “Operation” parameter at “On” (logical 1) or “Off” (logical 0).

&

O p e r a t i o n t 1 =

O n

I M P - - V T S Z

I M P - - B L T Z 1

I M P - - P S B

I M P - - E X T P S B

1

Z B l o c k = O n

O p e r a t i o n = O n

Z M 1 <

U

1

t

&

&

t 1

&

I M P - - Z M 1

I M P - - T R Z 1

I ,

I

(X80012-6.3)

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 15

September 1997

The second setting parameter “ZBlock” will permit two logical signals,

listed below, either to block the operation of a particular zone (when ZBlock

= On), or not (when ZBlock = Off). These two logical signals are:

• The IMP--PSB signal that comes from the optional power swingdetection element, and has a logical value 1 when a power swing has

been detected in the primary system. The signal will always be equal

to the logical 0 if the power swing detection unit is not installed in the

terminal, or when its operation has been switched off.

• IMP--EXTPSB is a signal, connected to one of the binary input ter-

minal from an external power swing detection unit. Its influence on

the operation of the distance measuring zone is the same as that for

the signal IMP--PSB.

The IMP--VTSZ signal, normally connected from the optional fuse failure

detection function has a logical value 1 when a fuse failure has beendetected in the secondary circuits of the voltage instrument transformers.

The signal will always be equal to the logical 0 if operation of the fuse

failure unit has been switched off.

It is possible to delay the operation of each distance zone by setting the oper-

ation of the timer “Operation t1” equal to On. This way, the operation of each

distance zone is delayed for the time set on the corresponding timer (opera-

tion of the zone will not be delayed, when the setting on a corresponding

timer will be equal to 0).

Presence of the external binary signal IMP--BLTZn (n=1,2,3,4 or 5) will

prevent the distance measuring function of the corresponding zone from

issuing a tripping signal (for example IMP-- BLTZ1 and IMP--TRZ1 in Fig.

6). Different external conditions could be wired to the corresponding input

terminal for these purposes.

The two logical output signals from the distance zone measuring unit will

be:

• IMP--ZMn, which informs that the impedance has been seen by the

distance zone n (IMP--ZM1 for zone 1)

• IMP--TRZn, which represents the tripping order from the zone n

measuring element (IMP--TRZ1 for zone 1)

Both output signals are connectable to the binary outputs and to other built

in functions.

The appendix to this description of the full scheme distance protection

function brings the following information:

• a simplified block diagram of the distance protection function

• a connection diagram for the distance protection function

• a description of the connection and production signals for the distance

protection function

• a table of the setting parameters for the distance protection function.

8/13/2019 X80012EN


1MDX80012-ENPage 16

Version 1.21

Distance protection

September 1997


The setting values of all parameters belonging to a distance protection

within the line protection terminals REL 5xx, must correspond to the

parameters of the protected line, as well as to the selectivity plan for the

network. The number of the parameters to be set differs, depending on theoptions included.

Before starting the setting activities for the distance protection function,

check that the setting values of the secondary rated current within the ter-

minal correspond to the current transformers used for the same purposes

as a particular REL 5xx terminal.

It is necessary to convert the primary line impedances to the secondary

sides of the current and voltage instrument transformers. The following

relations apply to these purposes:

and

where:

Iprim is a rated primary current of the used current instrument trans-

formers

Isec is a rated secondary current of the used current instrument

transformers

Uprim is a rated primary voltage of the used voltage instrument trans-

formers

Usec is a rated secondary voltage of the used voltage instrumenttransformers

Zprim is a primary impedance

Zsec is a calculated secondary impedance

1.4 Setting Instructions

1.4.1 Reach setting recommendations

1.4.1.1 Positive-sequence impedance

CTratio

Iprim

Isec

------------= VTratio

Uprim

Usec

--------------=

Zsec

CT ratio

VTratio

------------------ Zprim⋅=

Zsec

Usec

Uprim

--------------Iprim

Isec

------------ Zprim⋅ ⋅=

8/13/2019 X80012EN


8/13/2019 X80012EN


8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 19

September 1997

REL 5xx has a built-in memory capacity for four groups of setting param-

eters, all completely independent of one another. It is possible to set and

pre-test all of them during the commissioning. Their activation is possible

at any time, locally with the aid of a local MMI unit, a personal computer,

or remotely via the SMS or/and SCS (depending on whether the optional

remote communication is built into the terminal or not). Control of the

active setting group by the signals connected to the binary inputs of the

terminals is also possible.

This way, a better adaptation of the REL 5xx settings to different system

conditions can be obtained.

A measuring loop at the single-phase-to-earth faults consists of three

impedances, as shown in Fig. 8:

• the positive sequence impedance of phase conductor

• fault resistance Rf

• earth return impedance

Fig. 8 Equivalent circuits for measurement at single-phase-to-earth

faults.

The earth return impedance is equal to the expression:

The complete measuring impedance, according to Fig. 8b, is equal to:

The reach of a distance protection zone is related to the positive sequence

line impedance, Z1. Therefore, an earth return compensation factor KN has

been introduced into the measuring algorithm. Its value is equal to:

for each particular zone n.

1.4.1.2 Earth return compensation

Z1

ZN

L1 I 1Z

U

rsdI

IU

F

L2

L3

NZR

f

(X80012-8.3)

ZN1

3--- Z0 Z1–( )⋅=

Zloop Z1 ZN Rf + +1

3--- 2Z1 Z0+( ) Rf +⋅= =

KNZn1

3---

Z0Zn Z1Zn–

Z1Zn----------------------------------⋅=

8/13/2019 X80012EN


1MDX80012-ENPage 20

Version 1.21

Distance protection

September 1997


Impedances in the above equation are dependent on the values of the set-

ting parameters for each particular zone:

and

The impedance measuring algorithm within the REx 5xx line protection

terminals will automatically calculate the complex value of the earth

return compensation factor on the basis of the setting values for

the:

• positive sequence reactance of protected line section X1Zn

• positive sequence resistance of protected line section R1Zn

• zero-sequence reactance of protected line section X0Zn

• zero-sequence resistance of protected line section R0Zn

The performance of the distance protection for single-phase-to-earth

faults is of great importance, since normally more than 70% of the faults

on transmission lines are single-phase-to-earth ones.

At single-phase-to-earth faults, the fault resistance is composed of three

parts: arc resistance, resistance of a tower construction and tower footing

resistance.

The arc resistance can be calculated according to Warrington's well-

known formula:

where:

I the actual fault current in A

l the length of the arc (in meters). The arc resistance depends also on

the speed of the wind. This should be considered for higher, time

delayed distance protection zones. For the first approximation, about2-3 times the arc foot spacing is sufficient to be considered for the

time delayed operation of zone two with time delay of approximately

500 ms.

The tower footing resistance must be calculated or measured for the spe-

cific case, since the variation of this parameter is very large.

The distance protection can not detect very high resistive earth faults, as

the load impedance and load transfer limit its reach. For faults with resist-

ances higher than those that can be detected by the impedance measure-

ment, an optional earth-fault overcurrent protection can be included in the

REL 5xx line protection terminals.

Z0Zn R0Zn jX0Zn+=

Z1Zn R1Zn jX1Zn+=

KNZn

1.4.1.3 Fault resistance

Rarc28707 l⋅

I1 4,

---------------------=

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 21

September 1997

When calculating the settings for a distance protection function, it is nec-

essary to consider zero-sequence mutual coupling between the circuits of

the multicircuit lines. The positive and the negative sequence mutual cou-pling have no significant influence on the operation of the impedance

measuring protection schemes.

The distance protection within the REL 5xx line protection terminals can

compensate for the influence of a zero-sequence mutual coupling on the

measurement at single-phase-to-earth faults in two different ways:

• by using the possibility of different values that influence the earth

return compensation for different distance zones within the same

group of setting parameters

• by using different groups of setting parameters for different operat-

ing conditions of a protected multicircuit line.

Most multicircuit lines are double-circuit ones, operating in parallel, as

shown in Fig. 9. The following text describes more in detail the setting

recommendations for this particular type of lines, but the basic principles

apply to other multicircuit lines as well. The “Application Guide on Pro-

tection of Complex Transmission Network Configurations” describes the

problems more in detail. The guide was prepared by the CIGRE Working

Group 04 of Study Committee 34 (Protection), and published in Novem-

ber 1991.

Fig. 9 Double-circuit parallel operating line.

1.4.1.4 Zero-sequence mutual coupling on multicircuit lines

REL 5xx

Zs

A

BI

Z

AI F

B

m0

(X80012-9 (2))

8/13/2019 X80012EN


1MDX80012-ENPage 22

Version 1.21

Distance protection

September 1997


Fig. 10a represents an equivalent zero-sequence impedance circuit for the

double-circuit parallel operating line. Input terminals A and B are related

to the input terminals of each circuit close to the busbar A in Fig. 9. Ter-

minal C is related to the fault point. Connection between different termi-

nals differs according to the operating conditions of the line, as shown in

Fig. 10a, Fig. 10b and Fig. 10c.

The distance protection will tend to overreach for single-phase-to-earth

faults on the protected line when the parallel circuit is disconnected and

earthed on both ends. The equivalent zero-sequence impedance circuit

gets the configuration as shown in Fig. 10b. In this case, the equivalent

zero-sequence impedance is equal to the value:

This influences the value of the total loop impedance as measured by the

distance protection function, thus causing its overreaching. It is necessary

to compensate for this overreaching by adjusting the setting of the zero-

sequence impedance for the particular underreaching zone.

Instead of setting the real line zero-sequence resistance R0 and reactance

X0, it is necessary to calculate the equivalent values R 0E and X0E accord-

ing to the equations below, and set them for the particular underreaching

zone of a distance protection function. (The following two equations are

presented mostly for the theoretical understanding).

In many cases, the zero-sequence mutual resistance is not known. In most

cases, however, it has no significant influence on the final measurement

and therefore it is possible to ignore it. In this case, the components of the

equivalent zero-sequence mutual impedance will be equal to (the follow-

ing two equations are presented for the practical use):

1.4.1.5 The parallel operating double-circuit line, with one circuit disconnected and earthedat both ends

Z0E

Z0

2Z

m0

2–

Z0----------------------=

R0E R0 1

Xm0

2Rmo

2– 2

X0

R0

------- Rm0 Xm0⋅ ⋅ ⋅–

R0

2X0

2+

-------------------------------------------------------------------------------+

⋅=

X0E X0 1

Xm0

2Rmo

2– 2

R0

X0

------- Rm0 Xm0⋅ ⋅ ⋅+

R0

2X0

2+

--------------------------------------------------------------------------------–

⋅=

R0E R( m0 0 ) R0 1Xm0

2

R0

2X0

2+

--------------------+

⋅= =

X0E R( m0 0 ) X0 1 Xm0

2

R0

2X0

2+

--------------------–

⋅= =

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 23

September 1997

Fig. 10 Equivalent zero-sequence impedance circuits for the differentoperating conditions of a double-circuit parallel operating line.

(X80012-10C (2))

c) Equivalent zero-sequence impedance circuit for a single-phase-to-earth on the adjacent busbars with the parallel circuit disconnencted andnot earthed.

(X80012-10A (2))

(X80012-10B (2))

a) Equivalent zero-sequence impedance circuit for a single-phase-to-earth fault

b) Equivalent zero-sequence impedance circuit for a single-phase-to-earthfault on the adjacent busbars with the parallel circuit disconnected andearthed at both ends

on the adjacent busbars with both parallel circuits in operation.

m0

0 m0

C

A

0

m0Z

B

Z -Z

Z -Z

0 m0

m0Z I 0C

B 0 m0

Z -Z

Z -Z

I0

A

C

0 m0

m0B 0

m0Z0I

Z -Z

Z -Z

8/13/2019 X80012EN


1MDX80012-ENPage 24

Version 1.21

Distance protection

September 1997


When the parallel circuit is out of service and not earthed, the equivalent

zero-sequence impedance circuit will be like the one shown in Fig. 10c.

The line zero-sequence mutual impedance will not influence the measure-ment of the distance protection in a faulty circuit. This means that the reach

of the underreaching distance protection zone will be reduced if, due to

operating conditions, the equivalent zero-sequence impedance has been set

with the parallel system out of operation, and earthed at both ends.

The reduction of the reach will be equal to the factor:

This means that the reach will be reduced both in reactive and resistive

direction. If the real and imaginary components of the constant A are

equal to the values:

The real component of the factor is equal to the value (theoretical

presentation):

and the imaginary one to the value (theoretical presentation):

In many cases, the zero-sequence mutual resistance is not known. In most

cases, however, it has no significant influence on the final measurementand therefore it is possible to ignore it. In this case, the components of the

equivalent zero-sequence mutual impedance will be equal to (the follow-

ing two equations are presented for the practical use):

1.4.1.6 The parallel circuit out of service and not earthed

KU

1

3--- 2 Z1 Z0E+⋅( ) Rf +⋅

1

3--- 2 Z1 Z0+⋅( ) Rf +⋅

------------------------------------------------------ 1Zm0( )

2

Z0 2 Z1 Z0 3R f + +⋅( )⋅----------------------------------------------------------–= =

Re A( ) R0 2 R1 R0 3 Rf ⋅+ +⋅( ) X0 2 X1 X0+⋅( )⋅–⋅=

Im A( ) X0 2 R1 R0 3 Rf ⋅+ +⋅( ) R0 2 X1 X0+⋅( )⋅+⋅=

KU

Re KU( ) 1=Re A( ) Xm0

2Rm0

2–( ) 2 Rm0 Xm0 Re A( )⋅ ⋅ ⋅–⋅

Re A( )[ ]2

Im A( )[ ]2

+

------------------------------------------------------------------------------------------------------------------+

Im KU( )Im A( ) Xm0

2Rm0

2–( ) 2 Rm0 Xm0 Im A( )⋅ ⋅ ⋅+⋅

Re A( )[ ]2

Im A( )[ ]2

+

-------------------------------------------------------------------------------------------------------------------–=

Re KU( ) Rm0 0→[ ] 1Re A( ) Xm0

2⋅

Re A( )[ ]2

Im A( )[ ]2

+

------------------------------------------------------+=

Im KU( ) Rm0 0→[ ]Im A( ) Xm0

2⋅

Re A( )[ ]2

Im A( )[ ]2

+

------------------------------------------------------–=

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 25

September 1997

It is necessary to make sure that the underreaching zones from both line

ends will overlap in a sufficient amount (at least 10%) in the middle of the

protected circuit.

The zero-sequence mutual coupling can virtually reduce the reach of a

distance protection on the protected circuit when the parallel circuit is in

normal operation. The reduction of the reach will be most pronounced

with no infeed in the line terminal closest to the fault. This reach reduction

will normally be less than 15%. However, when the reach is reduced at

one line end, it will be proportionally increased at the opposite line end.

Therefore, this 15% reach reduction will not affect the operation of a per-

missive underreach scheme.

Overreaching zones (in general, zones 2 and 3) must overreach the pro-

tected circuit in all cases. The greatest reduction of a reach will occur in

cases when both parallel circuits are in service, and a single-phase-to-

earth fault located at the end of a protected line. The equivalent zero-

sequence impedance circuit for this case is equal to the one presented in

Fig. 10d.

Therefore, the components of the zero-sequence impedance for the over-

reaching zones must be equal to at least:

It is necessary to check the reduction of a reach for the overreaching zones

due to the effect of the zero-sequence mutual coupling. The reach will be

reduced for a factor:

If the real and imaginary components of the B constant are equal to the

values

the real and the imaginary value of the reach reduction factor for the over-

reaching zones is equal to (theoretical presentation):

1.4.1.7 Parallel circuit in service

1.4.1.8 Setting of the overreaching zones

R0E R0 Rm0+=

X0E X0 Xm0+=

K0 1Zm0

2 Z1 Z0 Zm0 3R f + + +⋅-----------------------------------------------------------–=

Re B( ) 2 R1 R0 Rm0 3 Rf ⋅+ + +⋅=

Im B( ) 2 X1 X0 Xm0+ +⋅=

Re K0( ) 1Rm0 Re B( ) Xm0 Im B( )⋅+⋅

Re B( )[ ]2

Im B( )[ ]2

+

---------------------------------------------------------------------–=

Im K0( )Rm0 Im B( ) Xm0 Re B( )⋅–⋅

Re B( )[ ]2

Im B( )[ ]2

+

---------------------------------------------------------------------=

8/13/2019 X80012EN


1MDX80012-ENPage 26

Version 1.21

Distance protection

September 1997


When the zero-sequence mutual resistance is ignored, their values will be

equal to (the following two equations are presented for the practical use):

Each of the REL 5xx line protection terminals has a built-in possibility of

setting four different groups of setting parameters and activating them

according to the system conditions. Different setting groups can also suit

different operating conditions of a multicircuit, parallel operating line.

The advantage of such an approach is a better coverage of the line under

normal operating conditions as well as when the parallel system is out of

operation and not earthed at both ends.

It is necessary to apply the same measures as in the case with a single set

of setting parameters. This means that an underreaching zone must not

overreach the end of a protected circuit for the single-phase-to-earth

faults. The values of the zero-sequence resistance and reactance must

therefore be set equal to (the following two equations are presented for the

practical use):

Normally, the underreaching zone of a distance protection will underreach

for the single-phase-to-earth faults located closer to the opposite end of

the circuit. To overcome this underreaching and trip without a sequential

tripping of the faults along the greatest possible percentage of a line, it is

necessary to increase the value of the equivalent zero-sequence impedance

to the one recommended also for the overreaching zones. This means that

the values of the equivalent zero-sequence resistance and reactance will be

equal to:

Re K0( ) 1Xm0 Im B( )⋅

Re B( )[ ]2 Im B( )[ ]2+

-----------------------------------------------------–=

Im K0( )X– m0 Re B( )⋅

Re B( )[ ]2

Im B( )[ ]2

+

-----------------------------------------------------=

1.4.1.9 Different values of an earth return compensation in different groups of settingparameters

1.4.1.9.1 The parallel circuit switched off with both ends earthed

R0E R( m0 0 ) R0 1Xm0

2

R0

2X0

2+

--------------------+

⋅= =

X0E R( m0 0 ) X0 1Xm0

2

R0

2X0

2+

--------------------–

⋅= =

1.4.1.9.2 Double-circuit parallel line in normal operation

R0E R0 Rm0+=

X0E X0 Xm0+=

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 27

September 1997

The same rules apply to the overreaching zones as in cases with a single

set of setting parameters. It is necessary to assure that they will always

overreach. Therefore, it is essential to increase the setting of the zero-sequence resistance and reactance to the values that correspond to at least:

In many cases it will be sufficient if the influence of the zero-sequence

mutual impedance will be compensated only in the first overreaching zone

(generally, zone 2). The setting of the back-up overreaching zones (zone 3

and higher) is usually so high that no such compensation is necessary.

Instructions for overreaching zones are applicable for normal network configurations. Their settings must always be reconsidered if any special

lines or other elements (cables, power transformers, etc.) follow the dou-

ble-circuit parallel operating line.

It is necessary to pay special attention to the distance protection of double-

circuit parallel operating multiterminal or tapped lines.

The resistive reach is set independently for each zone, and separately for

phase-to-phase, and phase-to-earth loop measurement (see Fig. 1).

It is necessary to set only the expected fault resistance for multiphase

faults (RFZn) and for phase-to-earth faults (RFNZn), since all the line

parameters (R1Zn, X1Zn, R0Zn and X0Zn) are settable independently of

each other for each distance zone n. The terminal automatically performs

a calculation of the complete loop impedance (see Fig. 3 under item

Application).

The final reach in resistive direction for phase-to-earth fault measurement

will automatically follow the values of the line-positive and zero-sequence

resistance, and at the end of the protected zone, it will be equal to:

for the phase measurement

The blinder in the resistive direction will in this case form an angle with

the R axis equal to:

The ratio between the reach in resisitve and the reactive direction should

not exceed the value:

1.4.1.9.3 Overreaching distance protection zones

R0E R0 Rm0+=

X0E X0 Xm0+=

1.4.1.10 Setting of the reach in resistive direction

RNn R1Zn RFNZn+=

ϕLN arcX1Zn

R1Zn---------------tan=

RFNZn

X1Zn------------------- 4 5,≤

8/13/2019 X80012EN


1MDX80012-ENPage 28

Version 1.21

Distance protection

September 1997


This realtion should always apply for the underreaching zone 1 and for all

overreaching zones, which do not permit any additional overreaching due

to strict selectivity reasons.

The fault resistance for phase-to-phase faults is normally quite low, com-

pared to the fault resistance for phase-to-earth faults. The setting of the

zone 1 reach in resistive direction for phase-to-phase loop measurement

should be limited to the relation

This realtion should always apply for the underreaching zone 1 and for all

overreaching zones, which do not permit any additional overreaching due

to strict selectivity reasons

The maximum permissible resistive reach for any zone should be checked

to ensure that there is a sufficient setting margin between the relay bound-

ary and the minimum load impedance.

The minimum load impedance is calculated as:

[Ω /phase]

where:

U is the minimum phase-to-phase voltage in kV

S is the maximum apparent power in MVA

The load is a three-phase condition and Zload is therefore equally

expressed in ohms per phase or ohms per loop.

The load impedance is a function of the minimum operation voltage and

the maximum load current:

[Ω /phase]

Umin and Imax are related to the same operating conditions. Minimum load

impedance occurs normally under emergency conditions.

Since the safety margin is required to avoid load encroachment under

three-phase conditions, and to guarantee correct healthy phase relay oper-

ation under combined heavy three-phase load and earth faults, both phase-

to-phase and phase-to-earth fault operating characteristics should be con-

sidered.

To avoid load encroachment, the set resistive reach of the distance protec-

tion function should be less than 80% of the minimum load impedance.

This way we get the following two conditions:

RFZn

X1Zn--------------- 3≤

1.4.1.11 Margin between the reach in resistive direction and a load impedance

ZloadU

2

S-------=

Zload

Umin

3 I⋅ max----------------------=

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 29

September 1997

for the phase-to-earth measuring elements

and

for the phase-to-phase measuring elements

This equations are applicable only when the loop characteristic angle for

the single-phase-to-earth faults is more than twice as large as the maxi-

mum expected load impedance angle. On the contrary, more accurate cal-

culations are necessary according to the equations below:

for the phase-to-earth measuring elements and

where:

ϑ is a maximum load impedance angle, related to the minimum load

impedance conditions.

This is valid for all measuring zones when no power swing detection ele-

ment is included in the protection scheme. An additional safety marginshould be used in cases when a power swing detection element is

included in the protection scheme (see item “Power swing detection”,

1MDX80013-EN).

The required time delays for different distance protection zones are inde-

pendent of each other. Distance protection zone 1 can also have a time

delay, if so required for selectivity reasons. The time delays for all zones

(basic and optional) are settable in a range of 0 to 10 seconds. The tripping

function of each particular zone can be inhibited by setting the corre-sponding “Operation” parameter to an “Off” value.

It is necessary to check the operating values of the impedance measuring

elements and corresponding functions during the commissioning as well

as during regular maintenance tests. ABB Network Partner AB recom-

mends, although it does not absolutely request, the use of a testing equip-

ment of type RTS 21 (FREJA) for purposes of the secondary injection

testing.

The test equipment used should be able to provide an independent three-

phase supply of voltages and currents to the tested terminal. Furthermore,

it must be possible to change the values of voltages, currents and phase

angles between the measuring quantities, independent of each other, for

RFNZn 0 8 Zload min⋅,≤

RFZn 1 6 Zload min⋅,≤

RFNZn 0 8 Zl oad min ϑ 1

3---

Zl oad min ϑsin⋅

2 X1Zn X0Zn+⋅-------------------------------------------- 2 R1Zn R0Zn+⋅( )⋅ ⋅–cos⋅ ⋅,≤

RFZn 1 6 Zl oad min ϑZl oad min ϑsin⋅

X1Zn--------------------------------------- R1Zn⋅–cos⋅ ⋅,≤

1.4.1.12 Setting of timers for the distance protection zones

1.5 Secondary injection test

8/13/2019 X80012EN


1MDX80012-ENPage 30

Version 1.21

Distance protection

September 1997


each phase separately. The test voltages and currents should have a com-

mon source, with a very small content of higher harmonics. If the test

equipment can not indicate the phase angles between the measured quanti-

ties, a separate phase angle meter will be needed.

It is not necessary to switch off or change the setting of the time-lag ele-

ments for the different impedance measuring zones when testing their oper-

ating values. The corresponding binary signals for the operation of each

distance measuring zone (IMP--ZM1, IMP--ZM2, IMP--ZM3, IMP--ZM4and IMP--ZM5) are available on the local MMI unit under the menu:

Service report

Logical Signals

ImpZones

These signals are configurable to the corresponding binary outputs (relay

contacts) under the menu:

Configuration

Binary Outputs

and connectable to the appropriate terminals on the testing equipment, if

the testing equipment is provided with the automatic facilities for the meas-urement of operating values.

Before testing, it is necessary to connect the testing equipment according tothe valid terminal diagram of the particular REL 5xx terminal. Special

attention should be paid to the correct connection of the input and output

current terminals, and to the connection of the residual current.

Measurement of the operating characteristics should preferably run under

constant current conditions. We recommend to keep the measured current

as close as possible to its rated value or lower, but at any rate it should behigher than 30% of the rated current. If the measurement of the operating

characteristics runs under constant voltage conditions, it will be necessary

to make sure that the maximum continuous current of a terminal does not

exceed four times its rated value.

We recommend keeping the measuring current and reactance as a constant

value, when measuring the operating characteristic in the resistive direc-

tion and the directional boundary in the second quadrant. We also recom-mend keeping the measuring current and the resistance constant, when

measuring the reach in reactive direction and the directional boundary in

the fourth quadrant..

We suggest the measuring of two operating points on each line of the oper-

ating characteristic. Only the characteristic in the direction that corre-

sponds to the direction in question, set for future use, should be measured.

The terminal diagram, as presented under item 11 of this User's Guide, is a

general one for the terminal. The same diagram is not necessarily applica-

ble for each particular delivery, especially regarding the configuration of all

1.5.1 Measurement with the general three-phase testing equipment

1.5.1.1 Connection of the testing equipment to the tested terminal

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 31

September 1997

binary inputs and outputs. It is therefore necessary to check before the test-ing that the available terminal diagram really corresponds to the terminal

itself. The best way to do this is to check the serial number of the terminal

on its front plate, and compare it with the valid serial number on the termi-

nal diagram.

The description of the testing of the operating values of the impedance

measuring zones for single-phase-to-earth faults refers to the testing of

distance zone 1 for the single-phase-to-earth fault L1-N. Testing of other

zones follows the same rules with the corresponding signals and values for

the respective zones. The testing of other phases follows the same rules

with the corresponding changes in the names of the phases.

The necessary operating conditions are presented for the special case,

when the measured residual current has the same value and phase position

as the measured phase current. This corresponds in most cases to the con-

ditions used by different testing equipments when measuring the operat-

ing characteristics for the phase-to-earth faults.

Fig. 11 shows a phasor diagram of the voltages and currents during the

testing of the operating value of an impedance measuring zone under the

single-phase-to-earth fault L1-N in forward and reverse direction.

The procedure for the measurement of one operating point on the operat-

ing characteristic of the zone 1 measuring element is as follows:• Apply to the terminal symmetrical three-phase voltages and the cur-

rent IL1f , which is in phase with the voltage UL1.

• Change the phase angle of the voltage UL1 to an appropriate value

that corresponds to the phase angle at which the measured operating

point is expected.

• Reduce voltage UL1 until the signal IMP--ZM1 appears on the local

MMI unit.

• Record the operating value of the current, voltage and phase angle.

• Compare the measured result with the expected operating value

according to the settings of zone 1. The expected loop measuredoperating values in reactive and resistive direction are equal to (a rep-

resent the relative value of a reactance at which the resistive reach is

measured: 0 on the R axis and 1 at the end of zone reactive reach):

• The measurement of operating points on the directional lines followsthe same procedure, but with constant measuring voltage, and a

changeable phase angle between the voltage and current in phase L1.

The directional lines should form an angle of 15 degrees with the R

1.5.1.2 Measurement of the operating characteristics of single-phase-to-earth faults

Xm

1

3--- 2 X1Zn⋅ X0Zn+( )⋅=

Rm

1

3--- a 2 R1Zn⋅ R0Zn+( ) RFNZn+⋅ ⋅=

8/13/2019 X80012EN


1MDX80012-ENPage 32

Version 1.21

Distance protection

September 1997


axis in fourth quadrant and 25 degrees with the X axis in the second

quadrant.

Fig. 11 Phasor diagram of currents and voltages for measuring of the

impedance operating characteristics of the single-phase-to-

earth fault L1-N in forward or reverse direction.


measuring zones for phase-to-phase faults refers to the testing of distance

zone 1 for the phase-to-phase fault L2-L3. The testing of other zones fol-

lows the same rules with the corresponding signals and values for those

zones. The testing of other phases follows the same rules with the corre-

sponding changes in the names of the phases.

Fig. 12 presents a phasor diagram of the voltages and currents during the

testing of operating values of the impedance measuring zone under the

phase-to-phase fault L2-L3 in forward and reverse direction.

o

10

11

-UL1

9

UL3

operating area

14

(changing the U )

12

13

L1

15

7

UL1

1

16

3

655

o

I

15o

L1F

UL2

Loop

4

(changing the U )operating area

L1

2

6

8

165

115o

(X80012-11C.3)

1.5.1.3 Measurement of the operating characteristics of phase-to-phase faults

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 33

September 1997


ing characteristic of the zone 1 measuring element is as follows:

• Apply to the terminal symmetrical three-phase voltages and current

IL2f and IL3f , which lags the voltage UL2-L3 for 90o

.Observe that IL3 = - IL2.

• Change the phase angle of the voltage UL2-L3 to an appropriate value

that corresponds to the phase angle at which the measured operating

point is expected.

• Reduce the voltage UL2-L3 until the signal IMP--ZM1 appears on the

local MMI unit

• Record the operating value of the current, voltage and phase angle.

• Compare the measured result with the expected operating value

according to the settings of zone 1. The expected loop measured

operating values in reactive and resistive direction are equal to (a rep-resent the relative value of reactance at which the resistive reach is

measured: 0 on the R axix and 1 at the end of zone reactive reach):

• A measurement of the operating points on the directional lines fol-lows the same procedure, but with a constant measuring voltage and

changeable phase angle between voltage UL2-L3 and currents IL2f

and IL3f . The directional lines should form an angle of 15 degrees

with the R axis in fourth quadrant and 25 degrees with the X axis in

the second quadrant.

Xm 2 X1Zn⋅=

Rm a 2 R1Zn⋅ RFZn+⋅=

8/13/2019 X80012EN


1MDX80012-ENPage 34

Version 1.21

Distance protection

September 1997


Fig. 12 Phasor diagram of the currents and voltages for the measuring

of the impedance operating characteristics of the phase-to-

phase faults in forward or reverse direction.

9 o 1


25

16

L3U

4

L

5

IL2

15

o15

3

2

L2-L3

L2

U


10

L3 L2

147

11

I =-I

L1U

12

L

75

8

25

o

o

13

UL2-L3

6

(X80012-12C.3)

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 35

September 1997

Fig. 13 Phasor diagram of the currents and voltages for measuring the

impedance operating characteristics of three-phase faults in

forward or reverse direction.


measuring zones for three-phase faults refers to the testing of distance

zone 1 for the three-phase faults L1-L2-L3. The testing of other zones fol-

lows the same rules with the corresponding signals and values for those

zones.

Fig. 13 shows a phasor diagram of the voltages and currents during the

testing of the operating value of the impedance measuring zone under the

three-phase fault L1-L2-L3 in forward and reverse direction.

1.5.1.4 Measurement of the operating characteristics of three-phase faults

operating area in

forward direction

(simultaneous changing

of U , U and U ).

L2F

operating area in

reverse direction

(simultaneous changing

of U , U and U ).

UL3

10

L1

11

L3L2

9

15

L

12

o

I

6

IL3F

7

1

8 UL2

L1FI

5

L2

4

L3

2

3

L1

(X80012-13.3)

8/13/2019 X80012EN


1MDX80012-ENPage 36

Version 1.21

Distance protection

September 1997



ing characteristic of zone 1 measuring element is as follows:

• Apply to the terminal symmetrical three-phase voltages and currents,

which are in phase with the corresponding phase voltages.• Change simultaneously the phase angles of all three voltages to

appropriate values that correspond to the phase angle at which the

measured operating point is expected.

• Reduce simultaneously all three voltages until the signal IMP--ZM1

appears on the local MMI unit.

• Record the operating value of the currents, voltages and phase angles.

• Compare the measured results with the expected operating values

according to the zone 1 settings. The expected phase measured oper-

ating values in reactive and resistive direction are equal to (a repre-

sent the relative value of reactance at which the resistive reach ismeasured: 0 on the R axix and 1 at the end of zone reactive reach):

• The measurement of the operating points on the directional lines fol-

lows the same procedure, but with constant measuring voltages and

changeable phase angles between the voltages and currents. The

directional lines should form an angle of 15 degrees with the R axis

in fourth quadrant and 25 degrees with the X axis in the second quad-rant.

The same connection schemes apply to the measurement of the operating

times for different distance zones as for the measurement of their operat-

ing values. Besides this, it is necessary to configure the corresponding

zone tripping signals (IMP--TRZn, where n represents the number of the

particular zone) to some binary outputs (relay contacts). These signals

must then be wired to the STOP terminals of the timer.

In addition, it is possible to use the regular tripping signals (relay contacts)

to stop the time measurement.

The simulated fault impedance shall be within 70% of the zone reach

when measuring the operating time or time delay of the different imped-

ance measuring zones.

The testing procedure for the manual testing of the operating characteris-

tics of different impedance measuring zones and different faults is as fol-

lows:

Xm X1Zn=

Rm a R1Zn RFZn+⋅=

1.5.1.5 Operating time and time delay of the different distance measuring zones

1.5.2 Instructions for the measurement of operating characteristics with the test settype RTS 21 (FREJA)

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 37

September 1997

1.1 Configure the zone operating signals (IMP--ZMn, where n = 1 to 5,

depending on the number of optional zones included into the termi-

nal) to one of the binary outputs.

1.2 Set up FREJA for three-phase impedance configuration and 3PZ RXdisplay.

1.3 Connect the IMP--ZMn signal to the FREJA binary input No. 1.

1.4 In the 3PZ display, set FREJA at the following parameters:

1.5 Set fault impedance Z and impedance angle ZΦ for the zone under

test at +10% of the zone setting for one of the suggested testing

points (Fig. 11 to 13).

1.6 Supply the terminal with healthy conditions (press key W) for at least

two seconds.

1.7 Apply fault conditions (press key S).

1.8 Slowly decrease the measured impedance Z until the tested zone

operates. Check that the correct signal (IMP--ZMn) appears on the

local MMI unit. Compare the result of the measurement with the set-

ting values.

1.9 Repeat steps 1.5 to 1.8 for other measuring points of the same imped-

ance measuring zone.

1.10 Repeat steps 1.1 to 1.9 for other measuring zones included into the

terminal (3 or 5).

It is necessary to have the same configuration of test equipment FREJAand of the tested terminal, as for the measurement of the distance protec-tion characteristics. The signals IMP--TRZn must be connected to the cor-responding binary inputs of the testing equipment instead of the zonemeasuring signals IMP--ZMn.

The simulated fault impedance should be within 80% of the zone reach,when measuring the operating time or time delay of the different imped-ance measuring zones.

Parameter Condition

I Greater than 30% Ir

DIgoal 1XXXX XXXXX

Healthy conditions U = 63,5 V, I = 0 A, ZΦ = 0o

R, X scale and

position of Origin

Suitable for the relay settings

Impedance Z Test point

Impedance angle ZΦ Test angle

Digital outputs Not used

1.5.2.1 Measurement of the operating time of distance protection zones

8/13/2019 X80012EN


1MDX80012-ENPage 38

Version 1.21

Distance protection

September 1997


A directional test of the distance protection function within the REx 5xxline protection terminal should always be carried out before it is taken into

service. The directional test can be performed under the menu:

Service Report

Direction

To perform the directional test, the protected line must be in service and

carry at least so much load current that the phase current in the terminal

will be higher than 20% of the terminal rated current Ir .

When the directional test is activated, the display on the local MMI unit

will show whether the current direction in each phase-to-phase measuring

loop is forward or reverse, relative to the direction of zone 1. The displaywill indicate:

• L1L2 = Forward

• L2L3 = Forward

• L3L1 = Forward

if the current flow in the three measuring loops is in forward direction, and

• L1L2 = Reverse

• L2L3 = Reverse

• L3L1 = Reverse

if the current flow in the three measuring loops is in backward direction.

If one of the loops is in the opposite direction than the other two, this indi-cates that the phase sequence of the incoming voltage or current circuits is

incorrect.

In order to perform the directional test, the load impedance must have anangle which is in the range of -15° and +115°, or +165° and 295°, as these

are the sectors supervised by the directional elements.

The actual values of the current and voltage phasors, as seen by the dis-

tance protection function, are available when the optional fault location

function is included in the REx 5xx terminal. Phasors are available on thelocal MMI unit under the menu:

Service ReportPhasors

and they can be used for the directional tests as well.

1.5.3 Directional test of the distance measuring function

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 39

September 1997

*) Specified values should be devided by 5 for Ir = 5A

Table 1:

Function Value

Typical operating time 28 ms for REL 52132 ms for REL 501 and REL 51130 ms for REL 561

Minimum operating current 0,2⋅Ir

Resetting ratio typical 105%

Resetting time typical 40 ms

Tripping mode three phase or single and threephase (not for REL 501)

Setting accuracy included in the measuring accu-

racy

Number of zonebasic version

optional

3, direction selectable forREL 5215, direction selectable forREL 501 and REL 5112, direction selectable forREL 5213, direction selectable forREL 561

Impedance setting range at Ir = 1 A

reactive reach *)positive-sequence reactance X1zero-sequence rectance X0

line resistive reach *)positive-sequence resistance R1zero-sequence resistance R0

fault resistance *)for phase-phase faultsfor phase-earth faults

(0,1-150) ohm in steps of 0,01(0,1-1200) ohm in steps of 0,01(not in REL 501)



Setting range of timersfor impedance zones (0 - 10) s in steps of 1 ms

Static accuracy at 0° and 85° and(0,1-1,1)⋅Ur and (0,5-30)⋅Ir ±5%

Static angular accuracy at 0° and 85°and (0,1-1,1)⋅Ur and (0,2-30)⋅Ir ±5°

Maximum dynamic overreach at85° measured with CVTs and0,5<SIR<30 +5%

1.6 Technical data

8/13/2019 X80012EN


1MDX80012-ENPage 40

Version 1.21

Distance protection

September 1997


Fig. 14 Simplified terminal diagram of the function.

1.7 Appendix

DISTANCE PROTECTION

*2) not in REL 501

IMP--TRZ2

IMP--TRZ4

IMP--TRZ3

IMP--TRZ5

IMP--PSBPOWER SWINGDETECTION(OPTION)

*2)

IMP--EXTPSB

IMP--BLTZ1

IMP-VTSZ

IMP--BLTZ2

IMP--BLTZ3

IMP--BLTZ4

IMP--BLTZ5

*2)

Z5<

*1)

Z4<*1)

Z3<

Z2<

Z1<

IMP--ZM4

IMP--ZM5

IMP--TRZ1

IMP--ZM3

IMP--ZM2

IMP--ZM1

*1) when installed, not available in REL 561

(X80012-14.4)

1.7.1 Terminal diagram

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 41

September 1997

Fig. 15 Terminal diagram for the function.

(X80012-15a.4)

40ms

t

*2) not for REL 501

IMP--BLTZ4

IMP--BLTZ5

IMP--BLTZ3

&

earth faultdetected by Z<

Operation=On

IMP--IPSB

Z2PSB

Z1PSB

ZONE 5

ZONE 4

ZONE 3

DISTANCE PROTECTION

IMP--EXTPSB

IMP--BLTZ1

IMP--VTSZ

IMP--BLTZ2

Operation=On

& 11

ZONE 2

Z<

ZONE 1

ZBlock=On

U

Operation t1=On

IMP--TRZ2

&

PSB*1) *2)

IMP--PSB

1 &

2s

&

IMP--ZM4

IMP--TRZ4

IMP--ZM5

IMP--TRZ3

IMP--TRZ5

IMP--ZM3

&

t

&IMP--TRZ1

IMP--ZM2

t1

IMP--ZM1I, I

*1) when included (option)

*1) *3)

*1) *3)

*3) not available in REL 561

8/13/2019 X80012EN


1MDX80012-ENPage 42

Version 1.21

Distance protection

September 1997


1.7.2 Signal list

C O N N E C T I O N S : T O :

S E T T I N G :

D E S C R I P T I O N :

I M

P - - B L T Z 1

B I

E x

t e r n a l b i n a r y s i g n a l t h a t b l o c k s t r i p p i n g o f d i s t a n c e p r o t e c t i o n z o n e

1

I M

P - - B L T Z 2

B I

E x


2

I M

P - - B L T Z 3

B I

E x


3

I M

P - - B L T Z 4

B I

E x


4

( w

h e n i n s t a l l e d )

I M

P - - B L T Z 5

B I

E x


5

( w

h e n i n s t a l l e d )

I M

P - - E X T P S B

B I

E x

t e r n a l b i n a r y s i g n a l t h a t c a n b e p r o g r a m m e d t o b l o c k o p e r a t i o n o f a

n y

d i s t a n c e m e a s u r i n g z o n e , f o r i n s t a n c e f r o m a n e x t e r n a l p o w e r s w i n g d

e t e c -

t i o

n u n i t , n o r m a l l y c o n n e c t e d t o o n e

o f t h e p r o g r a m m a b l e b i n a r y i n p u t s

I M

P - - V T S Z

F U S E

C o

n n e c t i o n s i g n a l t h a t b l o c k s t h e o p

e r a t i o n o f t h e d i s t a n c e p r o t e c t i o n

f u n c -

t i o

n . N o r m a l l y c o n n e c t e d t o t h e f u s e

f a i l u r e f u n c t i o n , s i g n a l F U S E - V T S

Z

8/13/2019 X80012EN



Version 1.21

1MDX80012-ENPage 43

September 1997

P R O D U

C T I O N :

T O :

S E T T I N G :


I M P - - T R

Z 1

B O T R I P

T r i p c a u s e d b y o p e r a t i o n o f d i s t a n c e p r o t e

c t i o n z o n e 1 ( c o n t r o l l e d b y t h e

o p e r a t i o n o f t i m e r t 1 )

I M P - - T R

Z 2

B O T R I P




I M P - - T R

Z 3

B O T R I P




I M P - - T R

Z 4

B O T R I P


c t i o n z o n e 4 , w h e n i n s t a l l e d

( c o n t r o l l e d b y t h e o p e r a t i o n o f t i m e r t 4 )

I M P - - T R

Z 5

B O T R I P


c t i o n z o n e 5 , w h e n i n s t a l l e d

( c o n t r o l l e d b y t h e o p e r a t i o n o f t i m e r t 5 )

I M P - - Z M

1

B O

O p e r a t i o

n o f z o n e 1 i m p e d a n c e m e a s u r i n g e l e m e n t

I M P - - Z M

2

B O

O p e r a t i o


I M P - - Z M

3

B O

O p e r a t i o


I M P - - Z M

4

B O

O p e r a t i o

n o f z o n e 4 i m p e d a n c e m e a s u r i n g e l e m e n t , w h e n i n s t a l l e d

I M P - - Z M

5

B O

O p e r a t i o

n o f z o n e 5 i m p e d a n c e m e a s u r i n g e l e m e n t , w h e n i n s t a l l e d

I M P - - P S

B

B O

O p e r a t i o

n o f t h e o p t i o n a l p o w e r s w i n g d e t e c t i o n e l e m e n t , w h e n i n s t a l l e d

t o g e t h e r

w i t h d i s t a n c e p r o t e c t i o n .

8/13/2019 X80012EN


1MDX80012-ENPage 44

Version 1.21

Distance protection

September 1997


1.7.3 Setting table

E T E R :

S E T T I N G

R A N G E :

S E T T I N G

A C T U A L

G

r o u p 1

G r o u p 2

G r o u p 3

G r o u p 4


D i s t a n c e p r o t e c t i o n z o

n e n

o n

O n / O f f

O p e r a t i o n o f d i s t a n c e p r o t e c t i o n z o n e n ( n = 1 - - 5 )

( 0 , 1 - 1 5 0 ) o h m

P o s i t i v e - s e q u e n c e r e a c t a n c e a s d e fi n e d b y t h e d i s t a n c e

p r o t e c t i o n z o n e n r e a c h

( n = 1 - - 5 )

( 0 , 1 - 1 5 0 ) o h m

P o s i t i v e - s e q u e n c e r e s i s

t a n c e a s d e fi n e d b y t h e d i s t a n c e


( n = 1 - - 5 )

( 0 , 1 - 1 2 0 0 ) o h m

Z e r o - s e q u e n c e r e a c t a n c e a s d e fi n e d b y t h e d i s t a n c e


( n = 1 - - 5 )

( 0 , 1 - 1 2 0 0 ) o h m

Z e r o - s e q u e n c e r e s i s t a n

c e a s d e fi n e d b y t h e d i s t a n c e


( n = 1 - - 5 )

( 0 , 1 - 1 5 0 ) o h m

F a u l t r e s i s t a n c e f o r p h a s e - t o - p h a s e a n d

t h r e e - p h a s e f a u l t s a s d e

fi n e d b y t h e

d i s t a n c e p r o t e c t i o n z o n e n r e a c h ( n = 1 - - 5 )

( 0 , 1 - 1 5 0 ) o h m

F a u l t r e s i s t a n c e f o r s i n g

l e - p h a s e - t o - e a r t h f a u l t s a s

d e fi n e d b y t h e d i s t a n c e

p r o t e c t i o n z o n e n r e a c h ( n = 1 - - 5 )

O n / O f f

T i m e r f o r t i m e d e l a y e d o

p e r a t i o n , i f a n y , o f d i s t a n c e p r o -

t e c t i o n z o n e n ( n = 1 - - 5 )

0 , 0 0 0 - 1 0 , 0 0 0 s

T i m e d e l a y f o r o p e r a t i o n

o f

d i s t a n c e p r o t e c t i o n z o n e n ( n = 1 - - 5 )

N o n

F o r w a r d

R e v e r s e

D i r e c t i o n a l i t y o f d i s t a n c e p r o t e c t i o n z o n e n ( n = 1 - - 5 )

O n / O f f

B l o c k i n g o f z o n e n b y i n

t e r n a l p o w e r s w i n g d e t e c t i o n

e l e m e n t o r b y e x t e r n a l s

i g n a l I M P - - E X T P S B ( n = 1 - - 5 )

X80012EN

Documents