directional relaying for double circuit line with series compensation

Published in IET Generation, Transmission & DistributionReceived on 16th October 2012Accepted on 4th January 2013doi: 10.1049/iet-gtd.2012.0602

ISSN 1751-8687

Directional relaying for double circuit line with seriescompensationMonalisa Biswal1, Bibhuti Bhusan Pati1, Ashok Kumar Pradhan2

1Department of Electrical Engineering, Veer Surendra Sai University of Technology, Burla, Sambalpur 768018, Odisha,

India2Department of Electrical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India

E-mail: [email protected]

Abstract: In this paper, a directional relaying algorithm for the protection of double circuit line with series capacitor is presented.The method uses four classifiers based on positive and negative sequence components which are combined with a votingtechnique to derive the direction of fault. The technique is evaluated using data simulated with electromagnetic transientsincluding DC/power system computer added design (EMTDC/PSCAD) for a series compensated double circuit line. Resultsfor voltage inversion, current inversion, high resistance far end fault, single pole tripping and cross country fault arepresented. The proposed technique is found to be accurate.

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1 Introduction

Double circuit transmission lines have problems in associatedprotection schemes because of zero-sequence mutualcoupling, in-feed and cross-country fault issues [1–5]. Seriescompensation in the lines further complicates the protectionscheme [6]. Zero-sequence mutual coupling causes error indirection and distance estimations for a double circuit line[7]. Voltage and current inversion situations and operation ofmetal oxide varistor (MOV) protecting series capacitor areother challenges for directional relaying [8–10]. Protectionschemes are proposed for double circuit lines usingmulti-featured protection algorithms to achieve improvedperformance [11–13].Sequence component-based techniques are usually

applied for directional relaying of double circuit lines.Positive-sequence component-based approaches fordirectional relaying are affected during system oscillationsand by fault resistance. Directional relaying involvingzero-sequence components is sensitive to mutual couplingbetween the lines. Negative-sequence component-basedapproaches, although good for addressing fault resistance,are affected during open-pole situations [14, 15] andsuch a component is not available for balanced faults.Superimposed positive-sequence component-baseddirectional relaying has superior performance in general butis affected for load change in the system [16]. Besides usualproblems of double circuit lines on protection, seriescompensation further introduces challenges such as voltage/current inversion and related issue with MOV operation.Complex directional relaying algorithms for double circuitlines are available applying synchronised/unsynchroniseddata of both the ends [17–19], cross differential relaying[20] and wavelet-based approach [21].

IET Gener. Transm. Distrib., 2013, Vol. 7, Iss. 4, pp. 405–413doi: 10.1049/iet-gtd.2012.0602

In this paper, directional relaying issues for double circuitline with the presence of series compensation are addressedand it is understood that a single directional relayingprinciple does not work correctly for all issues of such asystem. Four classifiers based on positive- andnegative-sequence components are selected and they areintegrated to derive direction of fault in a series compensateddouble circuit line. The integration is carried out by a simplevoting technique. This facilitates improved performancewhere shortcomings of each directional relaying principle areovercome. The performance of the algorithm is evaluated forseveral situations such as high resistance fault, close-in fault,single pole tripping, cross-country fault, voltage inversion,current inversion, with and without MOV operations, mutualcoupling effect and load change. The proposed technique isfound to be accurate.

2 Power system

A 400 kV, 50 Hz three-phase power system as shown inFig. 1 is considered. Line-1 and line-2 are of 300 km eachand line-3 is of 40 km. Line-1 and line-2 are 70%compensated (35% at each end). Detail system data areprovided in appendix. For the system CT and PT ratios areof 1500/5 A and 400 kV/110 V, respectively. A directionalrelay located at bus M in line-1 is considered for the studyand faults can be either side of the relay (at Fx or Fy side).A protection scheme is developed using an integratedapproach.

3 Classifiers

The first classifier, out of the four selected, uses thepositive-sequence angle between fault voltage and fault

405& The Institution of Engineering and Technology 2013

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current. The second classifier is based on the angle betweenpositive-sequence fault current and prefault current. Thethird classifier uses the negative-sequence angle betweenfault voltage and fault current and the fourth classifier usesthe positive-sequence angle between superimposedcomponent of voltage and current.

3.1 Classifier-1 (C1): phase angle betweenpositive-sequence component of fault current andfault voltage: f1 = /V 1f −/I1f

( )

The angle between positive-sequence fault voltage andcurrent is an important principle for directional relayingduring fault [22]. For upstream fault (Fx side), φ1 ispositive and for downstream fault φ1 becomes negative.Relay using such a feature only becomes erroneous during

voltage and current inversion, high resistance fault andcross-country fault situations. Figs. 2a and b show thephasors for inversion situations for fault in Fy side. E1 L

and E1N in the diagrams represents the source voltages. I1 L

and I1N are corresponding currents. V 1Mpre and I1Mpre arethe relay voltage and current before the fault. V 1f and I1fare the positive-sequence fault voltage and fault current atrelay location.To overcome the inversion problem the technique requires

both voltage and current inversion detectors. The anglebetween prefault and fault voltage /V 1Mpre −/V 1f can beused as the voltage inversion detector. Current inversioncan be detected using; the difference of magnitude ofpositive-sequence fault and prefault voltage V1f

∣∣ ∣∣− |V1Mpre|.Classifier-1 in the method uses both φ1 and inversiondetectors and as a rule it provides output of 1 for reversefault (Fx) side and −1 for forward fault (Fy).

3.2 Classifier-2 (C2): phase angle betweenpositive-sequence component of fault current andprefault current: f2 = /I1f −/I1Mpre

( )

The second classifier uses the angle betweenpositive-sequence fault current and prefault current [23]. φ2

Fig. 2 Phasor diagrams for Fy side fault

a Voltage inversion caseb Current inversion case

Fig. 1 Three-phase power system


as shown in Fig. 2 is positive for fault at Fx side andnegative for Fy side fault. For positive value of φ2classifier-2 output should be 1 and –1 for negative value.For fault at Fy side during voltage inversion situation, asshown in Fig. 2a, φ2 is negative which is correct. However,for current inversion situation for fault at same Fy side asshown in Fig. 2b φ2 is positive. To address this, a currentinversion detector as mentioned for classifier-1 is used toobtain correct decision by the classifier. Clasifier-2 alsoprovides output 1 for reverse fault and − 1 for forwardfault as per rule.

3.3 Classifier-3 (C3): phase angle betweennegative-sequence component of fault current andfault voltage: f3 = (/− V 2f −/I2f )The third classifier φ3 uses the angle betweennegative-sequence fault current and fault voltage [24]. φ3follows the same rule like other two classifiers.As negative-sequence components are present only for

unbalance faults, the value of classifier-3 output is ‘0’ forbalance faults. To distinguish between the symmetrical andunsymmetrical fault situations the magnitude ratio ofnegative-sequence to positive-sequence fault current phasoris used. Fig. 3 shows the phasor diagram for voltage andcurrent inversion situations using the negative-sequencecomponents. E2L and E2N in the diagrams represent thenegative-sequence source voltages and I2L and I2N arecorresponding currents. V 2f and I2f are thenegative-sequence fault voltage and fault current at relaylocation.

Fig. 3 Negative-sequence phasor diagrams for Fy side fault

a Current inversionb Voltage inversion

Fig. 4 Phasor diagram based on superimposed component

a Fault at Fxb Fault at Fy


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3.4 Classifier-4 (C4): phase angle betweenpositive-sequence superimposed voltage andcurrent
The fourth classifier uses the angle between positive-sequencesuperimposed relay voltage and current [16]. Superimposedcomponents provide fast relay decision during faults,whereas the load change situation creates challenges for it.DVM and DIM are the superimposed component of voltageand current as mentioned below. φ4 is positive for fault atFx side and negative for fault at Fy side. Positive value ofφ4 provides an output 1 and −1 for the negative value.Fig. 4 shows the phasor diagrams for fault in Fx and Fysides using superimposed components. DIM lags DVM forfault at Fx side which provides correct output by theclassifier. Similarly for fault at Fy side DIM leads DVM

D�VM = �V 1f − �V 1Mpre (1)

D�IM = �I1f − �I1Mpre (2)

and

f4 = /D�VM −/D�IM (3)

4 Voting technique

A single principle does not work correctly for all situations.To improve the accuracy of the directional relaying a votingtechnique is proposed. The overall output of the integrationapproach is based on the majority voting technique [25]. Itis observed that all the classifiers do not fail for a particularsituation.For voting technique

y(j) =∑N

i=1

X (i, j), ∀j = 1:C (4)

where y is the summation of decision j obtained from eachclassifier which is a vector of length C. X is the outputbinary vector for all classifiers N. The output at kth instant is

d(k) = argmaxj

y(j) (5)

The output of the voting method using the above relationprovides the direction of fault.

Fig. 5 Flow diagram of the relay algorithm

IET Gener. Transm. Distrib., 2013, Vol. 7, Iss. 4, pp. 405–413doi: 10.1049/iet-gtd.2012.0602 & T

Table

1Three-phas

efault,

volta

geinve

rsionca

se

Faultpositio

nPo

sitiv

e-se

quen

ceprefaultcu

rren

tphas

or

Positiv

e-se

quen

cefaultcu

rren

tphas

or

Positiv

e-se

quen

ceprefaultvo

ltage

phas

or

Positiv

e-se

quen

cefaultvo

ltagephas

or

Curren

tinve

rsion

detec

torDV∣ ∣∣ ∣ ,

VVolta

geinve

rsion

detec

tor

/V

pre−

/V

1f,rad

φ 1,

rad

φ 2,

rad

φ 3,

rad

φ 4,

rad

mag

.,A

angle,rad

mag

.,A

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

Fxside

2.92

0.71

15.04

2.59

53.12

0.41

10.87

0.52

−38

.49

−0.36

2.07

1.88

NAa

0.75

Fyside

(volta

ge)

inve

rsion)

7.78

0.71

50.38

−0.18

51.14

0.48

32.03

−0.30

−17

.85

0.78

0.12

−0.89

NA

−1.68

aNA,n

otap

plic

able

407he Institution of Engineering and Technology 2013

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Table 2 Decision table for three-phase fault using voting technique
Fault position and state of capacitor Classifier-1 (C1) Classifier-2 (C2) Classifier-3 (C3) Classifier-4 (C4) Output

Fx, with capacitor 1 1 0 1 1Fy, with capacitor (voltage inversion) −1 −1 0 −1 −1

In this paper, the directional relaying is considered as athree-class problem (C = 3); reverse and forward faults andthe third one is the without fault situation like load changeor so. These conditions are assigned with 1, −1 and 0values for convenience and are obtained from the angleinformation of each classifier; angle positive implies ‘1’, fornegative angle ‘−1’ and ‘0’ corresponds to without inputsituation to a classifier. As mentioned in the earlier section,four classifiers are selected for the purpose; N = 4. Thus Xis of size 4 × 3. y is obtained using (4) and (5) whichprovides the winner class for a case.

5 Performance of the proposed technique

The system shown in Fig. 1 is simulated using EMTDC/PSCAD and data are collected at a sampling rate of 1 kHz.A least square algorithm [26] modelled withsub-synchronous component of current and voltage is usedto estimate the phasors. The flow diagram of the proposedalgorithm is shown in Fig. 5. Once a fault is detected, the

Fig. 6 Performances for three-phase fault

a Fx sideb Fy side (voltage inversion)


phasors are estimated. A window of one-cycle data sampleswas used for phasor estimation. The technique uses bothpositive- and negative-sequence components as they are lessaffected by mutual coupling in a double circuit line.In the results, the dynamic performance is provided to

access the technique. The cycle-to-cycle comparisonapproach was considered for the fault detection. In theproposed algorithm, a classifier output is assigned ‘1’ if thecorresponding angle of φ is positive and with negativeangle the output becomes ‘−1’. When a classifier does nothave input its corresponding classifier output is assigned‘0’. These outputs are then processed using (5) to derive theoverall output. The algorithm is tested for symmetricalfaults, unsymmetrical faults, voltage inversion, currentinversion situation, high resistance fault, load changecondition, cross-country fault, single pole tripping andMOV operation. All the cases are simulated with thepresence of the both lines to include the effect of mutualcoupling.

5.1 Voltage inversion case

To observe the performance of proposed method for balancefault case, three-phase faults were created at Fx and Fy sidesof the relay at 0.3 s with the consideration of mutual couplingin the circuits. To obtain the voltage inversion situation forthe system one circuit is taking out of service with both thesides grounded. For voltage inversion, a three-phase fault atFy side at a distance 80 km from the relay fault is createdin that condition. The result for each classifier is given inTable 1 and the output of each classifier along with theoverall output by the voting technique are provided inTable 2.For fault at Fx side, classifier-1 provides positive-sequence

angle φ1 of 2.07 rad and corresponding output is 1. Similarly,corresponding angles of classifier-2 and classifier-4 are 1.88and 0.75 rad, respectively and the outputs are 1 and 1. Forthree-phase fault negative-sequence component is notavailable (NA) and classifier-3 output is ‘0’. Thus the inputto the voting technique is [1, 1, 0, 1]. The overall output is1 which clearly shows the fault in reverse side.Owing to voltage inversion for three-phase fault in Fy side

which is evident from the positive-sequence angle betweenprefault and fault voltage (0.78 rad) applied to classifier-1and corresponding output becomes −1. With the input tothe voting technique for this case be [−1, −1, 0, −1] theoutput of voting technique becomes −1. This clearlyshows the fault is in forward side which is correct. Thedynamic performances of the method for the cases areprovided in Fig. 6 for faults at Fx and Fy sides along withindividual classifier output. It has been observed that theoutput provided by the voting method is consistent forboth faults at Fx and Fy sides although the output ofclassifier-3 is zero in both cases. It is to be noted that allthe classifiers consistently provide correct outputs in boththe cases.


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IET Gener. Trans

doi: 10.1049/iet-g

Table

3Double-lin

e-to-groundfault,

curren

tinve

rsionca

se

Fault

positio

nPo

sitiv

e-se

quen

ceprefaultcu

rren

tphas

or

Positiv

e-se

quen

cefaultcu

rren

tphas

or

Positiv

e-se

quen

ceprefaultvo

ltage

phas

or

Positiv

e-se

quen

cefaultvo

ltage

phas

or

Neg

ative-se

quen

cefaultcu

rren

tphas

or

Neg

ative-se

quen

cefaultvo

ltage

phas

or

Volta

ge

inve

rsion

detec

tor

/V

pre−

/V

1f,

rad

Curren

tinve

rsion

detec

tor

DV|| ,V

φ 1,

rad

φ 2,

rad

φ 3 rad

φ 4,

rad

mag

.,A

angle,

rad

mag

.,A

angle,

rad

mag

.,V

angle,

rad

mag

.,V

angle,

rad

mag

.,A

angle,

rad

mag

.,V

angle,

rad

Fyside

(curren

tinve

rsion)

2.92

0.70

22.76

1.61

53.12

0.41

70.89

0.03

14.68

−3.06

26.61

0.57

0.38

17.77

1.58

0.91

−1.16

−1.92

m. Distrib., 2013, Vol. 7, Iss. 4, pp. 405–413td.2012.0602

5.2 Current inversion case

A current inversion situation is simulated for abg fault withground fault resistance of 5 Ω in Fy side at 0.3 s at adistance 10 km from relay point. The value of D V

∣∣ ∣∣ in thiscase is positive as observed from Table 3 for this situationand identifies as a current inversion condition. Thereforecorresponding outputs of classifier-1 (C1) and -2 (C2) aremodified. The overall input vector of [−1, −1, −1, −1] tovoting method which is shown in Table 4. The overalloutput becomes −1 and the direction estimated by themethod (forward side) is correct.Dynamic performance of each classifier and corresponding

overall output by the proposed method are shown in Fig. 7 forcurrent inversion situation. It is to be noted that in such asituation each classifier output is consistently in negativeregion and the overall output is −1 that shows fault is inFy side.

5.3 High resistance far-end fault case

High resistance fault creates problem for many protectionschemes. Another problem arises in case of a fault near busN in line-1. Owing to insufficient fault current from relayend, relaying algorithms fail to identify fault direction. Anag fault with 100 Ω fault resistance is created at a distanceof 270 km from relay location in line-1. From Fig. 8 it isobserved that classifier-1 output varies from positive tonegative value. This is because positive-sequence phaseangle between voltage and current decreases with faultresistance and the in-feed dominates in this case the faultbeing farther from relay end. Similarly classifier-4 output isalso not consistent as superimpose-based approach is notreliable during initial transient period in many cases.However, this classifier supports others after initialtransient, but the outputs of classifier-2 and classifier-3 areconsistently negative. Negative-sequence-based classifier(classifier-3) is not affected by fault resistance [14]. Thusthe proposed method gives correct fault direction (Fy side)after 7 ms of fault inception.

5.4 Single pole tripping case

Single pole tripping schemes are used to enhance the stability,power transfer capability and availability of the transmissionsystem during and after a ground fault. Owing to unbalancesystem condition negative- and zero-sequence componentsare more prominent during such operation and createsproblem to negative- and zero-sequence-based approaches.To test the performance of the integrated approach line-1with phase-a tripped is used at 0.3 s. At this condition bgfault at Fx at a distance of 5 km was created at 0.4 s. Also abg fault at Fy side in line-1 at a distance of 81 km at 0.4 sfrom relay location at 0.4 s was created in another simulation.The results are shown in Table 5. It is observed from the

table that classifier-3 being based on negative-sequencecomponents, its phase angle is still of negative region forfault in Fx side [14]. However, classifier-1, -2 and -4provide correct values and are based on positive-sequencecomponents. For fault in Fy side is φ2 positive and otherpositive-sequence-based classifier outputs are negative.Thus in both the cases the integrated approach providescorrect output. The dynamic performance of each classifierand the overall output for fault at Fx and Fy sides areshown in Fig. 9 where only classifier-3 output is not correctas based on negative-sequence components.


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Table 4 Decision table for double-line-to-ground using voting technique
Fault position and state of capacitor Classifier-1 (C1) Classifier-2 (C2) Classifier-3 (C3) Classifier-4 (C4) Output

Fy, with capacitor (current inversion) −1 −1 −1 −1 −1

5.5 Cross-country fault case

Faults simultaneously in two circuits create problems torelaying algorithm in a double circuit line. To observe theperformance of proposed technique for such conditions anag fault is created at a distance of 80 km from relay end inline-1 and simultaneously in line-2 a bg fault is created atthe same time and same location. Fig. 10 shows theperformance of the proposed technique. Classifier-1 outputis oscillatory because of the transients present in the voltagesignal, but the outputs of other classifiers are consistentlynegative. Thus the overall output of proposed method is –1which clearly shows the fault is in forward side.

5.6 Results with MOV operation

MOV is installed for protection of series capacitor andoperates when the voltage across the capacitor exceeds alimit. Many protection algorithms are sensitive to the

Fig. 7 Performance for abg fault at Fy side (current inversion)

Fig. 8 Performance for high resistance ag fault at Fy side


transient operation of MOV. A typical current throughMOV during conduction for an ag fault is shown inFig. 11. With the presence of MOV, a resistive circuit isinserted in parallel with the capacitor and thus directionalrelaying features are not affected significantly. The transientbecause of MOV operation is filtered out as the methodsuse sequence component-based technique. The performanceof each classifier and the overall output of the directionalrelaying algorithm with the functioning of MOV are shownin Fig. 12 for a fault at Fy side at a distance of 100 km witha fault resistance of 1 Ω at 0.3 s. The results show that withthe operation of the MOV also, the method derives thedecision correctly.

5.7 Effect of mutual coupling

In parallel lines positive- and negative-sequence mutualcouplings are negligibly small, whereas zero-sequencemutual impedance is significant [11]. Zero-sequencecomponents-based directional relaying algorithm makesthe protective system more challenging in double circuitline. In all the earlier simulations, mutual coupling wasconsidered during fault between the circuits. To observethe effect of mutual coupling on the proposed integratedapproach different cases are simulated and comparedwith without mutually coupling results. An ag fault witha fault resistance of 2 Ω is simulated at 0.3 s for bothsides of the relay. For fault in Fx side, current inboth lines will be same and the influence of mutualcoupling is negligible which is evident from Table 6. ForFy side, the fault is simulated at a distance of 250 kmfrom relay. Fig. 13a and b show the plots for ag faultconsidering with and without mutual coupling effects,respectively. As the decision of proposed method isbased on positive- and negative-sequence components,the method is not affected by mutual coupling as evidentfrom the figures.

6 Conclusions

Protection of double circuit line is complex because of theissues of cross-country fault and presence of mutualcoupling. Other issues such as voltage–current inversion ofseries-compensated line further complicate the relaydecision. An integrated approach using four availableclassifiers is proposed to derive improved fault directionestimation for a double circuit line with series capacitor.The classifiers use positive and negative-sequencecomponents of current and voltages at the relay location. Avoting technique is applied to integrate the outputs of theclassifiers. Its performance is observed during highresistance fault, single pole tripping, cross-country fault andfault with MOV operation and is found to be accurate.Being based on positive- and negative-sequencecomponents the effect of mutual coupling on theperformance of the proposed technique is negligible.


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IET Gener. Transm. Di

doi: 10.1049/iet-gtd.201

Table

5BG

fault,

single

pole

trippingca

se

Faultpositio

nwith

prese

nce

of

capac

itor

Positiv

e-se

quen

ceprefaultcu

rren

tphas

or

Positiv

e-se

quen

cefaultcu

rren

tphas

or

Positiv

e-se

quen

ceprefault

volta

ge

phas

or

Positiv

e-se

quen

cefault

volta

gephas

or

Neg

ative-se

quen

ceprefaultcu

rren

tphas

or

Neg

ative-se

quen

cefault

curren

tphas

or

Neg

ativese

quen

ceprefaultvo

ltagephas

or

Neg

ativese

quen

cefaultvo

ltagephas

or

Ф1,

rad

Ф2,

rad

Ф3,

rad

Ф4,

rad

Output

mag

.,A

angle,rad

mag

.,A

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

mag

.,V

angle,rad

Fxside

0.00

821.79

0.64

2.39

34.42

0.31

29.28

0.14

0.01

1.74

0.64

−1.79

17.15

−2.83

23.33

−2.28

2.25

0.6

−2.66

1.78

1Fy

side

0.00

821.79

0.59

−0.33

34.42

0.31

30.55

−0.06

0.01

1.74

0.47

1.66

17.15

−2.83

23.77

−2.12

−0.27

−2.12

0.64

−1.40

−1

strib., 2013, Vol. 7, Iss. 4, pp. 405–4132.0602

Fig. 9 Performance for single pole tripping

a Fx sideb Fy side

Fig. 10 Performance during cross-country fault

Fig. 11 Current waveforms for relay and MOV for ag fault at 0.3 sat Fy side


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Table 6 AG fault, with and without mutual coupling
Fault position Ф1, rad Ф2, rad Ф3, rad Ф4, rad

withmutualcoupling

withoutmutualcoupling

withmutualcoupling


withmutualcoupling


withmutualcoupling


Fx side (line-3) 1.04 1.05 1.33 1.33 2.72 2.72 1.45 1.43Fy side (line-1) −2.62 −2.63 −2.40 −2.40 −0.76 −0.76 −0.85 −0.83

Fig. 12 Performance during operation of MOV for ag fault at Fyside

Fig. 13 Performance for ag fault with and without mutualcoupling

a Fx sideb Fy side


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20 Wang, Q.P., Dong, X.Z., Bo, Z.Q., Caunce, B.R.J., Tholomier, D.,Apostolov, A.: ‘Protection scheme of cross differential relay fordouble transmission lines’, http://www.areva-td.com/solutions/liblocal/docs/116947/1846551-paper_5.pdf


www.ietdl.org
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using wavelet transform’, IEEE Trans. Power Deliv., 2004, 19, (1),pp. 49–55

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23 Pradhan, A.K., Routray, A., Madhan, G.S.: ‘Fault direction estimation inradial distribution system using phase change in sequence current’, IEEETrans. Power Deliv., 2007, 22, (4), pp. 2065–2071

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26 Sachdev, M.S., Nagpal, M.: ‘A recursive least error squares algorithmfor power system relaying and measurement applications’, IEEETrans. Power Deliv., 1991, 6, (3), pp. 1008–1015


8 Appendix

Transmission line parameters:Length of line-1 and line-2: 300 kmLength of line 3: 40 kmPositive-sequence impedance: 0.03293 + j0.3184 Ω/kmPositive-sequence capacitance: 0.01136 μF/kmZero-sequence impedance: 0.2587 + j1.1740 Ω/kmZero-sequence capacitance: 0.00768 μF/km

Source parameters:Positive-sequence impedance: 0.06979 + j1.99878 Ω /kmZero-sequence impedance: 0.2094 + j5.9963 Ω/km

MOV ratings:Rated voltage: 150 kVCurrent level: 1.5 kA
