Electric power distribution feeders are frequently subjected

Transcription

1 21 nternatinal Cnference n Pwer System > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < Lcating Fault Using Vltage Sags Prfile fr Undergrund Distributin System H. Mkhlis, Member, EEE, H.Y.Li, Member, EEE, AH.A Bakar, Member, EEE, Mhamad, Student Member, EEE Hasmaini Ahstract-This paper presents an alternative fault lcatin algrithm t estimate shrt-circuit faults lcatin in electrical distributin netwrks using nly vltage sags data. The prpsed algrithm uses vltage sags prfile as a means t lcate fault. The pssible fault lcatins is estimated by incrprating the measured vltage sags magnitude and its crrespnding phase angle int an equatin f vltage sag as a functin f fault distance. A ranking prcedure is als intrduced t rank pssible fault lcatins due the same electrical distance. The uncertainty f fault resistance is als cnsidered in this algrithm. The perfrmance f the technique is presented by testing it using an actual undergrund distributin netwrk. The simulatin results indicated a pssibility f practical implementatin. ndex Terms- Fault lcatin, distributin netwrks, vltage magnitude, phase shift. 1. NTRODUCTON Electric pwer distributin feeders are frequently subjected t shrt circuit fault caused by variety f cnditins such as adverse weather cnditins, animal cntacts, equipment failure and accident. When fault ccurs, it causes disturbance t the pwer supply and interruptins t the system. Such interruptin ften leads t lsses t the utilities and custmers. n rder t minimize the lsses and prvides high quality f service, it is crucial fr utilities t lcate fault as quickly as pssible. The need f fast and accurate fault lcatin leads t prpsal f varius autmated fault lcatin techniques and algrithms. Unfrtunately mst f the develped techniques and algrithms are fr transmissin system, which cannt be easily adpted fr distributin netwrk due t the limitatin f mnitring in distributin system as well as cmplexity f the netwrk. This wrk was supprted by gvernment f Malaysia under UMRG Research Grant (Grant cde: RG77/9AET). H. Mkhlis is with the Centre f Research UMPEDAC, Department f Electrical Engineering, Faculty f Engineering, University f Malaya, Kuala Lumpur, Malaysia ( hazli@um.edu.my). H. Y. Li is with the Schl f Electrical & Electrnic Engineering, University f Manchester ( haiyu.li@manchester.ac.uk). A.H.A Bakar is with the Centre f Research UMPEDAC, Department f Electrical Engineering, Faculty f Engineering, University f Malaya, Kuala Lumpur, Malaysia ( a.halim@um.edu.my). Hasmaini Mhamad is with the Schl f Electrical Engineering, University Teknlgi Mara, Shah Alam, Malaysia. ( hasmaini@salam.uitm.edu.my). Distributin system ften mnitred nly at the primary substatin that caused limitatin f data that can be used t assist in lcating fault. Distributin netwrk als cmplicated due t varius factrs such as nn-hmgeneity f line, uncertainty n fault resistance value, lateral branches, distributed lads and lading variatin. All f these factrs limited the used f sme fault lcatin techniques. Due t the cmplexity f distributin netwrk, autmated fault lcatins utilizing data frm real time measurement f the system have been prpsed. These techniques are like Artificial Neural Netwrk, Fuzzy Lgic and Genetic Algrithms [1]-[3]. These techniques depend n external infrmatin such as frm SCADA system, circuit breaker peratin in substatin, and feeder measurements. The accuracy f this technique is highly depending n the amunt and accuracy f the data. These techniques may nt be suitable fr mst distributin netwrk that has limited mnitring equipments. Mre suitable techniques fr distributin netwrk with limited data were prpsed in [4]-[6). The techniques are invlving iterative calculatin t lcate fault. Due t single measurement, multiple pssible fault lcatins are btained using the prpsed technique. The mst likely fault lcatin is fund by identifying the perated prtective device such as re-clser and fuses upn fault ccurrence. The devices can be identified based n the wavefrm pattern f the measured current when fault ccurs. By knwing the perated device and its lcatin, the mst likely fault lcatin can be selected frm the pssible lcatins. Fault lcatin utilizing pwer quality data als has been prpsed in literature [7]-[9). The underlying principal f these methds is based n the fact that fault at different lcatins presents different vltage sag characteristic as seen at a measured lcatin [1). By identifying the patterns at different lcatin, the lcatin f fault can be determined. The earliest reprted wrk n fault lcatin using vltage sag data was in [7). n this methd, a fault in transmissin line system is lcated based n vltage sag data frm measurements at varius lcatins. Similar apprach als has been prpsed, but applied fr distributin netwrk [8]. The algrithm is based n matching during-fault vltage sag magnitudes t find fault lcatin. As in [7], the prpsed algrithm requires multiple measurements f vltage sags. The mst recent methd f fault lcatin using vltage sag data was prpsed in [9]. Different frm [8] and [7], the methd requires single measurement f vltage sag at the primary substatin. n this methd, an algrithm was intrduced t identify the pssible faulted sectin by matching the measured ne with the vltage sag l/$ EEE

2 > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 2 patterns in the database. Since the methd nly identifies a faulted sectin, maintenance crew needs t patrl alng the suspected faulted sectin t find the exact lcatin f fault. The lcating prcess may cnsume time if the sectin is lng and may delay the restratin prcess. This paper presents a fault lcatin technique based n similar apprach as in [7]-[9]. Hwever, different frm [9], the nn-linearity f the vltage sag functin is cnsidered. The prpse technique nt nly lcate a faulted sectin, but at the same time estimate the distance f fault frm sending end f the suspected faulted sectin. The vltage sags wavefrm captured by pwer quality mnitring equipment at the primary substatin befre and during the fault are used fr this technique. Due t single measurement and uncertainty f fault resistance the prpsed technique may prduces multiple fault lcatins. This prblem is addressed by a ranking prcedure intrduced in this research. The lcatins are ranked accrdingly t prvide the inspectin sequence.. BASC PRNCPLE OF THE TECHNQUE The basic principle f vltage sag characteristic used in this prpsed technique is based n the relatinship between fault lcatin and vltage sags, measured at the primary substatin. This is pssible since vltage sag changes as fault ccur at different lcatin as seen at the mnitred lcatin [1]. A. Fault Lcatin in Distributin System Mst f undergrund distributin netwrks cnsist f different type f cables and size. As a result, the impedance is nt distributed equally thrugh-ut the netwrk. Due t this, the prcess f lcating fault using the vltage sag cncept needs t cnsider each cable as a separate functin f fault distance between tw adjacent ndes (sectin). Each sectin has its wn vltage sag as a functin f fault distance. T illustrate the fault lcatin apprach fr a distributin system, a netwrk with ne main line and 2 lateral branches is cnsidered, as shwn in Fig. 1. Each sectin, which represented by a-b, b-c and s n is assumed has it wns impedance value. A pwer quality device is placed at the primary substatin netwrk f nde a t mnitr and recrd vltage sags activities during fault. this apprach. nstead f using actual fault data, this wrk used fault analysis t generate vltage sag and its crrespnding fault lcatin. This data are stred in database. The actual vltage sag due t fault can be cmpared with the generated nes in database. By using simulatin, fault can be simulated at any lcatin and therefre any vltage sags value can be cmpared. Since fault culd ccur at any lcatins, the prblem is t decide hw many fault lcatins need t be simulated and stred the vltage sags int the database. f the simulated lcatins are t many, the database can be t huge that can lead t a high prcessing time f finding the pssible lcatin. On the ther hand, if the simulated faults nt cver the entire system, there is a pssibility f getting incrrect lcatin. n rder t reslve this prblem, a functin representing the changes f vltage sags ver a distance as mnitred at the primary substatin between tw adjacent ndes f a sectin is used as the basis f this wrk. n rder t derive the equatin f vltage sags as a functin f fault distance, a few lcatins between tw adjacent ndes are simulated with fault. The lwest magnitude and its crrespnding phase angle f the three phases are taken. Using the btained vltage magnitudes and its crrespnding fault lcatins measured frm nde i, curve fitting methd is used t estimate the equatin f the vltage sags as a functin f fault distance measured at nde a. This equatin derivatin is illustrated in Fig. 2. n the figure, vltage magnitude as a functin f distance between nde i-j is btained by simulating fault at.,.25,.5,.75, and 1. per-unit f distance frm nde i. Frm initial study, it was fund ut that the curve can be a nn-linear as in Fig. 2, r almst linear r cnstant changes, which depends n the impedance f the line f the sectin. -v Bi " v, c Ol E Ol g v Fig. 1. Typical distributin netwrk H---=-k----t" Main line c Branch When fault ccurs fr example n sectin i-j, a vltage sags is detected at nde a. The fault lcatin can be estimated by matching this vltage sags with previus vltage sags due t actual fault at that sectin. Hwever, if the actual fault never ccurs at this lcatin, the lcatin cannt be determined using.5,75 1, Nde i :c-c----c:--: ). Nde j Distance (in pu) measured frm nde i twards nde j Fig. 2. Estimated vltage sag prfile curve fr sectin i-j By having the general equatin f vltage magnitude between tw adjacent nde ndes, the distance f fault frm nde i is can be estimated by incrprating the measured vltage at nde a int the equatin. This is illustrated in Fig. 1, where vltage magnitude f Vf (the lwest vltage magnitude) at nde a prduces the distance f fault measured frm nde i. The equatin f phase angle can als be created in the same way as the vltage magnitude equatin and use t estimate fault lcatin. The reasn f using bth types f equatins is t cmpare the distances in rder t identify the mst likely fault

3 > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 3 lcatin. Since this technique cnsiders single measurement at the primary substatin, multiple pssible faulty sectins culd be prduced. This ccurs fr netwrks that have parallel branches likes the netwrk shwn in Fig. 2. f fault ccur at ne f the parallel branches, the electrical impedance as viewed frm the mnitred nde t the lcatin f fault are the same, which prduce the same vltage. Fr example, if fault ccurs at the main line f sectin i-j, there is pssibility f getting the same vltage as if fault ccurs at branch 1 r branch 2. Cnsidering this prblem, the pssible faulty sectins are ranked accrding t a sequence f inspectin.. DESCRPTON OF THE TECHNQUE The equatin f vltage sag as a functin f fault distance is assumed t be a secnd rder f a plynmial equatin. Althugh there is a linear type changes, this secnd degree equatin still valid. Hwever, fr a cnstant type changes, different apprach is taken. The general equatins f vltage sags as a functin fault distance are as fllws: where, V vltage magnitude phase angle v = av,d 3 + a V,ld V +a V,2 = a,dj + a,ld +a,2 d,, d fault distance (in per unit) fr vltage magnitude and phase angle equatin respectively a OY ' a, v' a 2, v cefficients f the vltage magnitude equatin a,, ai,, a2, cefficients f the phase angle equatin Fr nn-linear changes, the fault distance can be calculated by slving the quadratic equatin (1) and (2). Since there will be tw pssible answers fr each equatin, the selected slutin f distance shuld fulfil the fllwing cnditin: (1) (2) where Vk and k are represent vltage magnitude and phase angle f nde k respectively. These data are simulated nes and stred in the database. a is the specified threshld value t determine the matching between the actual value frm the simulated ne. The threshld is required because it is nt pssible t btain exactly the same value f bth the simulatin and actual measurement. A. Algrithm f the Prpsed Technique The fault lcatin estimatin prcess is illustrated in the flw chart f Fig. 3. t starts with the extractin f vltage sags wavefrm int fundamental cmpnents using Fast Furier Transfrm (FFT). The RMS value f the vltage magnitude is calculated nce every cycle fr each phase. When the magnitude detected t be lwer than threshld value f the nminal vltage fr example.9 pu, the sags wavefrm is captured and stred until the magnitude recvers back t a minimum f threshld value. The btained fundamental vltage cmpnents are then used t estimate the type f fault. The main reasn f fault type identificatin is t narrw dwn the search area. Only the respective database f the fault type needs t be checked rather than checking the entire databases. Databases Simulated Vltage sag.:s; dv :s; 1. and.:s; d :s; 1. (3) Fr cnstant changes, the distance f the fault frm particular nde cannt be calculated since at any fault lcatin in the sectin the vltage r phase angle is remains the same. Hwever, if ne f the equatins is nt a cnstant type, the distance can be estimated either using slutin f (1) r (2). On the ther hand, if bth types f equatins are a cnstant type, nly the sectin where fault ccur is pssible t be estimated. The type f vltage sag changes can be identified by checking the cefficients in (1) and (2). f the fllwing cnditins ccur, fault is assumed ccur at nde r clse t a nde. (4) Fig. 3. Flw chart f the fault sectin estimatin List f pssible fault lcatin After the fault has been identified, the lwest vltage magnitude and its crrespnding phase angle are selected fr the input t the algrithm. The search algrithm cnsists f glbal search and lcal search. n the glbal search, faulted sectins and the pssible fault resistance are estimated based n the simulated vltage sags in the database. The measured vltage sag magnitude is cmpared with the simulated data f vltage sag magnitude in the database t find all the pssible fault lcatin candidates. n the lcal search, the btained candidates frm the glbal search are evaluated further t find the final pssible fault lcatin/lcatins by cnsidering the

4 - > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 4 phase angle equatin as well. Finally, the selected lcatins are ranked accrdingly. The final result is all the pssible faulty sectins ranked accrding t inspectin pririty. This ranking is imprtant t assist the technical crew t start at particular lcatin fr visual inspectin. n the case the first chice is nt the actual faulty lcatin, the ther lcatins need t be checked until the crrect fault lcatin is fund. V. SEARCH ALGORTHM A. Glbal Search - Selectin f Pssible Faulted Sectin The glbal search finds sectin where its curve f vltage magnitude intersects with the measured magnitude (VJ). n rder t explain this, cnsider Fig. 4. There are three curves representing an equatin f vltage magnitude as a functin f fault distance fr three different fault resistance values. Vltage magnitude (pu) Fault Resistat ce (pu) Nde i O d- s i ta n ce ( p ---<; R f = 2. ; i R f = 1. _---,; R f =O.O >--- U ,e1 : de j ) Fig. 4. General pattern f vltage magnitude with different fault resistance values The intersectins f VJ with all the curves mean that there are pssibility that fault culd ccur n sectin ij with the fault resistance ranging frm. pu t 2. pu. Hence, the sectin ij is taken as the candidate with the fault resistance between. pu t 1. pu and 1. pu t 2. pu as the pssible fault resistance. B. Lcal Search - Selectin f Faulted Sectin and Fault Resistance The btained faulted sectin candidate with it's crrespnd fault resistance range are further evaluated t determine the final pssible faulted sectins with the pssible fault resistance. This is dne by slving (1) and (2) iteratively with different fault resistance values. The ne that fulfill (3) will be cnsidered as the mst pssible faulted sectin tgether with the fault resistance. C. Ranking Prcedure The ranking prcess is based n the degree f matching between the simulated data with the actual measurement. The matching is measured by calculating the mismatch between the distance btained frm (1) and (2): (5) The matching is cnsidered 1% accurate if u "".. The lwer the value f u, the higher the matching will be. The candidate with t lwest value f u is cnsidered as the mst matching pair and assigned as the first rank. All the btained lcatins are cnsidered fr inspectin due t varius uncertainty factrs in the prcess f fault lcatin. These including uncertainty in the fault resistance value, errr in measurement, different between actual measurement data and simulated nes. V. SMULATON TESTS AND RESULTS The prpsed methd was evaluated using an undergrund rural distributin netwrk. The ne-line diagram f the tested netwrk is shwn in Fig. 5. The netwrk cnsists f a 132 kv surce, ne units f step dwn kv transfrmer and ne main feeder with 3 branches. All cables in the netwrk are three-phase balanced undergrund system. The netwrk is divided int 4 branches with ttal 17 line sectins and 17 ndes. Substatin 17 Branch 1 Branch ]-._. Mainline = i Branch y 6 Measured Nde Fig. 5. Subsystem f kv distributin netwrks The system is mdelled and simulated using PSCAD/EMTDC sftware. Lads were mdelled as cnstant impedance. At the measured nde 2, the btained vltage wavefrm is prcess using Fast Furier Transfrm (FFT) t calculate the vltage sag magnitude and phase angle during the fault. The lwest value vltage magnitude is taken as an input t the algrithm tgether with its crrespnding phase angle. n this paper, the perfrmance f the algrithm is measured by testing fault at the middle f each line fr all sectin in the system. n this test, SLGF is simulated at all sectin n the middle f the line. SLGF is applied fr the test since it is mst frequent type f fault happen in distributin system. A fault resistance f Q, 5 Q, 1 Q, 2 Q and 25 Q are applied fr the simulated fault.. A. Overall Ranking The verall ranking f the crrect selected faulted sectin is presented in the frm f bar graph in Fig. 6 and Fig. 7. The x-axis presenting the sectin and the y-axis is fr the rank number f the crrect fault sectin. The first, secnd, third, frth and fifth bar fr each sectin is representing the fault resistance f, 5, 1, 2 and 25 hm respectively. Frm the graphs, it can be seen that there is n direct relatinship between the ranking numbers f the crrect

5 > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 5 lcatin with the value f fault resistance. The high value f fault resistance des nt necessary increase the ranking number. This ccurs n sectins 12-13, and where the 2 n fault resistance prduced higher ranking as cmpared t the 25 n fault resistance. On the ther hand, ther sectins like 5-6, 8-9, 1-11 and shw the higher fault resistance increases the number f ranking. The higher ranking f the crrect fault sectin fr this test case is fur, which is fr sectins 8-9 and Althugh the rank is quite high, it is much better than guessing the lcatin f the faulted line. After the furth attempt f visual inspectin the fault can be lcated crrectly and apprpriate actin can be taken. 3 C) r::: 2 "' t: 'l;ectin Fig. 6. Ranking f the actual faulty sectin with different fault resistance frm sectin 2-3 t sectin , ,----!:l O.Ohm B 5hm 1hm hm.25 hm &ittl6n Fig. 7. Ranking f the actual faulty sectin with different fault resistance frm sectin 1-11 t sectin There are als sectins where their ranking number des nt change with different fault resistance. This can be seen n sectins 2-3, 3-4, 6-7, 9-1 and There are tw pssible reasns. The first ne is because the invlve sectins nt in parallel with any ther line sectin. The secnd pssible reasn is that the sectin is selected as the first rank due t the distances btained frm vltage magnitude and phase angle are nearly the same. n rder t understand why certain sectins are selected crrectly in the first rank, the verall pattern f the vltage magnitude r phase angle as a functin f fault distance is pltted. The graph is shwn in Fig. 8, where the pints in the graphs are representing the vltage magnitude and phase angle (measured at the primary substatin) due t fault at the specific lcatin between the tw adjacent ndes..81.,----, t.!: i! " ]...78 x.'2 x ts x.77 " S.76 " >.75 Lenght f line (km) r:: : " ::: -.55.t:.. J!ex f to" + 7.L.. ---' Fig. 8. Overall pattern f vltage sag magnitude and phase angle as a functin f fault lcatin between tw adjacent ndes (fault resistance 1 hm) t can be seen clearly that the value f vltage magnitude r phase angle fr sectins 2-3, 3-4, 6-7 and (shwn by a straight line) d nt verlap with ther sectin values. Any fault n these sectins will prduce a vltage sag in the range f that sectin nly. Thus, a single sectin where fault mst likely ccur can be identified. The fault in this sectin can be estimated accurately withut getting ther pssible faulted sectin. On the ther hand, if fault ccurs at ther than these sectins, multiple pssible sectins will be selected. The graph in Fig. 9 is an example f ther sectin in a clse-up lk. There are three imprtant bservatins can be seen in the pattern shwn in Fig. 8 and 9, which are as fllws: i) Nn-verlapping range f vltage magnitude r phase angle with ther sectin, fr example sectin 2-3, 3-4, 6-7 and As a result nly ne pssible faulty sectin will be selected. ii) Overlapping range vltage magnitude r phase angle with ther sectin, fr example sectin 4-14 with 5-6 and 6-7. This cnditin will prduce multiple pssible fault lcatin. iii) Overlapping values, fr example sectin 4-5 with sectin 4-14 and sectin 7-12 with sectin 7-8. The reasn behind this is because the verlap sectin has the same value f sequence impedance per unit length. The different is n the length. Any fault n the verlap characteristic will prduce at least 2 pssible faulted sectins.

6 > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 6.795,----,.79 'ft g _l w c: ,.J L -t:, _l w Lenght f line (km) ' %ecti Fig. 1. Errr estimatin fr fault n the middle f the line fr sectin 2-3 t sectin '-----' Fig. 9. Clse-up lks f vltage magnitude and phase angle functin fr ther sectins in the system B. Errr Estimatin An estimatin f errr fault lcatin between tw adjacent ndes is calculated using (6). The fault lcatin is based n the calculatin f (1), which based n the vltage magnitude as a functin f fault distance. g 3 w c: 2 "" en W l- ff if: b.rJirlfl: r,]: ].J J Sectin Fig. 11. Errr estimatin fr fault n the middle f the line fr sectin 1-11 t sectin destimated - dcalculated %errr = x 1 Ttal Lenght f Sectin The graphs in Fig. 1 and Fig. 11 shw the btained errr estimatin f fault n the middle f the sectin fr the netwrk. t can be bserved that at fault resistance zer, the estimatin errr is very lw and at sme sectin it can't be seen at all in the graph. n general, the increment f the fault resistance increases the estimatin errr. Hwever, the increment f fault resistance value des nt necessary increase the errr estimatin. This can been seen fr example n sectin 5-6, where the 2 hm fault resistance prduced higher errr estimatin as cmpared t 25 hm fault resistance. The highest errr estimatin calculated ccurs fr sectin 7-8 with the highest fault resistance, which is arund 4.4 %. This errr is quite lw and therefre the fault distance can be estimated within a high accuracy. The accuracy f the estimated distance is highly depending t the length f the line. rt can be seen a lng line fr example sectins 2-3, 3-4 and 4-14 have a lw estimatin errr, which is less than 1 % fr all fault resistance values. This is because these sectins have a lng line cmpared t the thers. On the ther hand, sectin 4-5 and 7-8 have a shrt line. Despite the accuracy f the estimated fault distance, at less a faulted sectin can be determined crrectly. (6) V. CONCLUSON n this paper, a new technique based n vltage sags characteristic has been presented t estimate fault lcatin fr distributin system. The technique prduces a ranked f multiple pssible faulty sectins. At the same time, the lcatin f fault measured frm particular nde is als calculated. The effect f fault resistance is als being cnsidered. The test shwed prmising results with a lw errr estimatin and lw ranking number. The technique is ecnmical since it uses a single measurement at the primary substatin. Mre ver, an existing vltage sags mnitring equipment at the primary substatin can be utilised t btain the vltage sags. Since the technique depends n the pre-develped database, any changes such as lad variatins r netwrk recnfiguratin can be adapted by this technique by updating the database. REFERENCES [1] Hng-Tzer Yang; Wen-Yeau Chang; Ching-Lien Huang, "A new neural netwrks apprach t n-line fault sectin estimatin using infrmatin f prtective relays and circuit breakers", EEE Trans n Pwer Delivery, vl. 9, N, Jan 1994, Page(s): [2] P Jarventausta, P. Verh, J Partanen, "Using fuzzy sets t mdel the uncertainty in the fault lcatin prcess f distributin netwrks ", EEE Trans n Pwer Delivery, Vl 9, N 2, April 1994 Page(s):954-96

7 > REPLACE THS LNE WTH YOUR PAPER DENTFCATON NUMBER (DOUBLE-CLCK HERE TO EDT) < 7 [3] F.S. Wen, C.S. Chang, "Prbabilistic apprach fr fault-sectin estimatin in pwer systems based n a refined genetic algrithm", lee Prceedings, Vl. 144, N 2, March 1997 Page(s): [4] Seung-Jae Lee, Myen-Sng Chi, Sang-Hee Kang, B-Gun Jin, Duck-Su Lee, Bk-Shin Ahn, Nam-Sen Yn, H-Yng Kim, Sang-Bng Wee, "An intelligent and efficient fault lcatin and diagnsis scheme fr radial distributin systems", EEE Trans n Pwer Delivery, Vl. 19, N 2, Apri24, Page(s) [5] E.c. Senger, G. Manasser, C. Gldemberg, E.L. Pellini, "Autmated fault lcatin system fr primary distributin netwrks", EEE Trans n Pwer Delivery, Vl. 2, N 2, April 25, pp [6] Jun Zhu, D.L. Lubkeman, A.A. Girgis, "Autmated fault lcatin and diagnsis n electric pwer distributin feeders", Trans n Pwer Delivery, Vl. 12, N 2, April 1997, pages [7] Z. Galijasevic, A. Abur, "Fault lcatin using vltage measurements," EEE Trans. Pwer Delivery, vl. 17, pp , April 22. [8] R.A.F. Pereira, L.G.W. da Silva, M. Kezunvic, JR.S. Mantvani, "mprved Fault Lcatin n Distributin Feeders Based n Matching During-Fault Vltage Sags", EEE Trans. Pwer Delivery, v1.24, pp , April 29. [9] H. Mkhlis, HYLi, A.R. Khalid, 'The Applicatin f Vltage Sags Pattern t Lcate a Faulted Sectin in Distributin Netwrk", nternatinal Review f Electrical Engineering (REE), vl. 5, n 7, February 21, pp [1] Math H.J. Bllen, "Fast assessment methds fr vltage sags in distributin systems", EEE Trans. ndustry Applicatin, vl. 32, pp , Nv Hazlie Mkhlis (M'O) received his B. Eng in Electrical Engineering in 1999 and M. Eng. Sc in 22 frm University f Malaya, Malaysia. His btained PhD degree frm the University f Manchester, UK in 29. Currently he is a Lecturer in the Department f Electrical Engineering, University f Malaya. His main research interest is in distributin autmatin area and pwer system prtectin. H.Y.Li (M'99) received Ph.D. degree frm the University f Bath, U.K.,in Currently he is a Lecturer in the Schl f Electrical and Electrnics Engineering, The University f Manchester (frmerly UMST). His interests are pwer system autmatin and infrmatin systems, including pwer system cmmunicatins, prtectin, integratin f distributed generatin, HV measurements and signal prcessing. He is a Member f EEE and lee. Ab halim Abu Bakar received his B.Sc. in Electrical Engineering in 1976 frm Suthamptn University UK and M.Eng. and PhD frm University Technlgy Malaysia in 1996 and 23. He has 3 years f utility experience in Malaysia befre jining academia. Currently he is a Lecturer in the Department f Electrical Engineering, University f Malaya, Malaysia. Dr. Halim is a Member f EEE, CGRE, let and a Chartered Engineer. His research interests include pwer system prtectin and pwer system transient. Hasmaini Mhamad was brn in Kta Bharu,Kelantan, Malaysia in n 1999 and 24, she received the Bsc and MsEng degrees respectively frm the University f Malaya, Malaysia where she is currently pursuing her PhD degree. Her majr research interest include islanding peratin f distributed generatin, hydr pwer plant perating system, lad sharing technique, and lad shedding scheme.