Identification of Fault Locations using Transient State Estimation

Transcription

1 denificaion of Faul Locaion uing Tanien Sae Eimaion K. K.C. Yu, Suden Membe, EEE and N. R. Waon, Senio Membe, EEE Abac n a lage cale elecical powe yem, idenificaion of yem faul can be a ediou ak. Unexpeced faul even, which affec all cuome, mu be idenified quickly o appopiae acion can be aken ou. Due o he unknown change in he yem opology duing faul condiion, accuae faul aemen hough EMTP/ATP i pohibied. Fuhemoe, exhauive each pefomed hough adiional mehod i ime conuming and equie good knowledge of he faul even pio o he each. n hi pape, an alenaive mehodology in faul idenificaion via Tanien Sae Eimaion (TSE) i peened. The TSE algoihm model he a.c. yem in i equivalen cicui a e of cuen and volage ae equaion can be developed o fom he meauemen yem. Eimaion of he complee yem ae fom limied meauemen i achieved by olving he meauemen yem equaion and hence he faul poiion and i magniude can be deemined by looking a he nodal cuen mimach in he yem. Simulaion eul fom he Lowe Souh land of he New Zealand yem ae ued o validae hi appoach. Keywod: Faul idenificaion, Sae eimaion, Elecomagneic anien. NTRODUCTON WHEN a faul ha occued in a lage powe yem, i i uually a difficul ak o deemine he faul poiion. Regadle of whehe i occued a anmiion o load level, all cuome ha ae conneced o i will be affeced o ome degee. i impoan he faul poiion i quickly idenified o appopiae acion can be caied ou. Due o he meauemen co, complee monioing of he yem o deemine he faul even i impacical. Theefoe, when a anien even i ecoded, he faul infomaion available i ofen vey limied. One mehod i o imulae he poible faul even hough compue imulaion EMTP/ATP []-[] and hen compae he imulaion eul wih he acual ecoded anien epone. A good indicaion of he faul i achieved if he anien epone ae cloely mached. Thi exhauive each mehod i abiay; he fac ha i need o imulae he poible faul even and compae wih he acual epone i ime conuming and equie a good knowledge of all he poible The wok peened in hi pape wa ponoed by he Foundaion fo Reeach Science and Technology (FRST) Bigh Fuue Scholahip. The auho would like o hank FRST fo i financial uppo. The auho ae wih he Depamen of Elecical and Compue Engineeing, Univeiy of Canebuy, Chichuch, New Zealand Peened a he nenaional Confeence on Powe Syem Tanien (PST 5) in Moneal, Canada on June 9-3, 5 Pape No. PST5-64 faul even pio o he each. n hi pape, a new faul idenificaion mehodology via anien ae eimaion echnique i peened. The popoed mehod eimae he complee yem ae and powe flow fom paial meauemen a each ime-ep. Once he complee yem ae i known, he faul poiion can be deemined fom he powe flow accodingly. An elecical powe yem expanded in i dicee equivalen RLC banche can be decibed by a e of cuen and volage ae equaion. By combining hee equaion wih appopiae ae vaiable, he complee ae model of he powe yem i achieved. The e of yem equaion can be fomed wihou knowing he e of independen ae vaiable, bu ae bounded by opological conain (i.e. ineconnecion) and algebaic conain. Thi i beneficial paiculaly in lage powe yem independency of he ae vaiable i no obviouly appaen due o he peence of newok inevening. Complee eimaion of he yem ae equie he yem o be fully obevable. The yem i aid o be fully obevable if he meauemen yem olve he ae vaiable uniquely. By conveing he yem diffeenial equaion o dicee ime equaion uing Eule ule, hioy value a peviou ime-ep can be ued a addiional meauemen when foming he meauemen yem. Thee addiional meauemen ac a meauemen noie file in ove-deemined yem o povide exa meauemen infomaion in unde-deemined yem. The e yem ued o validae he popoed mehod i aken fom he Lowe Souh land of he New Zealand.. FORMULATON OF THE STATE EQUATONS Powe yem modelled by i lumped RLC equivalen can be decibed a a e of fi ode diffeenial equaion. Thee equaion decibe he ineconnecion beween he RLC banche and he ae vaiable. The elevan yem componen ae modelled a follow:. Geneao: hee ae modelled by a volage ouce wih hei equivalen R-R//L impedance.. Tanfome: hey ae epeened uing wo winding model depending on he ype of magneic cicui and on he connecion of he eminal and he neual. i.e. dela o wye. Coe loe ae epeened inenally wih an equivalen hun eiance aco each winding in he anfome. 3. Tanmiion line: hee ae modelled by he hee-phae

2 P model and hence capable of incopoaing non ymmeic condiion. 4. Load: The eal and eacive powe componen ae epeened by i equivalen eiance and inducance epecively. A Tanfome Model A wo winding anfome model i ued in he TSE algoihm. i capable of modelling diffeen impedance o he diffeen componen of cuen depending on he ype of magneic cicui and on he connecion of he eminal & he neual. Fig. how he wo winding Y-G/Y-G conneced anfome model. i poible o implify he hee-phae anfome model by ignoing he inephae muual and educing he equaion o hee independen e of he hee phae. Thi i accuae when bank of ingle-phae uni ae ued. Effec like phae hif, zeo equence ciculaing cuen, ec ae caeed fo by he eminal connecion. Off-nominal ap on eihe pimay o econday winding can be epeened by caling he elf and muual elemen accodingly. B Tanmiion Line Model A hee phae P model i ued o epeen ho o medium lengh anmiion line in he TSE algoihm. The model include anmiion line coupling effec. Fig. how he anmiion line P model. Kichhoff law ae ued o fom he algebaic equaion a hown in (). Thee equaion ae ued o deive he anmiion line model expeed in (3). h = L h = L () dl = [ R] L [ L] d [ L] [ R] [ L] [ L] L L L L L L Ch Ch Ch L d L (3) = R h d L L L L L L C h Ch C h 3 R h,, L, h ae ending end cuen, eceiving end cuen, induco cuen and hun cuen, ae ending and eceiving end volage. Fig.. Thee phae Y-G/Y-G conneced anfome Neglecing coe loe, he diffeenial equaion fo a hee phae anfome can be expeed a: i i, i i, i L L i L, i L, i d i Li, i Li. i = Ki K v d L. i L, Li, i L i, L, i L, fo Y-G/Y-G configuaion, Ki = Kv = K and v () K i ae he banch-node incidence (connecion) fo volage and cuen epecively. L i he elf inducance. ii L, L ae he muual inducance. i i Fig.. Thee phae anmiion line P model C Load Model The algoihm model he yem load by i equivalen eiance and eacance a hown in Fig. 3. ae equaion ae decibed in (4).

3 Fig. 3. Thee phae load model d ( x k ) d La xk d ( x ) k x Lb k d L x c k d ( x ) = k Ra d k Rb k k R k c k k. DFFERENCE EQUATONS TSE i pefomed ecuively fo each ime-ep, hence diceiaion of he coninuou ime diffeenial equaion i neceay. The opeao d/d can be appoximaed uing Eule fomula a hown in (5). Equaion (), (3) and (4) can hen be expeed a in (6), (7) and (8) epecively. [ L] y = y f i i i i i i i i i = Ki L K v (4) L L ii, i, L L i,, L L i, i i. = L L. i, L L L L i, i i,, i, (5) (6) [ M ] L L L = [ M] L [ L ] [ R ] [ L ] [ L ] L L L L L Ch Ch Ch [] = Rh L L L L L Ch Ch C h 3 Rh xk L a xk x k x Lb k x k L x c k = k Ra k k Rb k k R c k The diceied ae equaion in em of ae vaiable a peviou ime ep ae advanageou in foming he meauemen yem. allow hioy value ( ) o be ued a viual meauemen (i.e. meauemen do no need meeing) a well a eal-ime meauemen. By inpecing (7), i i hown ha he anmiion line induco cuen can be ued a meauemen when foming he meauemen yem, howeve, given ha i i uually no a well defined vaiable (i.e. difficul o meaue) in a pacical yem, he ending end and eceiving banch cuen ae ued inead. The ae equaion become: Ch, C h, C h, L ' Rh R, h R, h, L h, h, h, C C C = L Rh R, h R, h, Ch, C h, C, h Rh R, h R, h, C C C h, h, h, ' C C C h, h, = h, C C C h, h, h, (7) [] (8) (9)

4 Ch, C h, C h, L Rh R, h R, h, L ' h, h, h, C C C = L Rh R, h R, h, Ch, C h, C, h R h R, h R, h, C C C h, h, h, ' C C h, h = C, h, C C C h, h, h,. TRANSENT STATE ESTMATON The main pupoe of TSE i o eimae he powe flow of he whole newok fom limied ynchonized meauemen. deally, an accuae TSE equie:. Accuae modelling of he yem opology.. The yem o be fully obevable fo he given e of meauemen (i.e. ove-deemined yem). 3. Abence of bad meauemen. Conide a geneal meauemen yem which elae he meauemen veco z o he ae vaiable x expeed in () z = [ H] x ε () ε i he eo veco and [ H ] i he meauemen maix. To build up he meauemen yem, ow ae picked fom he diffeenial equaion (6)-() fo he coeponding meauemen. n he cae field meauemen daa ae aben, meauemen daa obained fom imulaion can be ued o upply o he TSE algoihm and ae conide a he ue meauemen of he yem ae. The ae vaiable o be eimaed ae he induco cuen and nodal volage. Once hey ae obained, he powe flow of he whole newok can be calculaed accodingly. The pocedue of he TSE can be decibed a follow:. Eablih appopiae ae model fo linea and non linea yem componen, uch a anfome and anmiion line.. Equae complee diffeenial and algebaical equaion fo he powe yem. Eule fomula i ued o diceie hee equaion in hi cae. 3. Read off-line (hioy) and on-line meauemen fom eleced meauemen locaion. 4. Build up he meauemen equaion by adding ow of dynamic equaion which elae he meauemen o he ae vaiable. [ ] z = H x ε 5. Solve he meauemen yem fo cuen ime-ep. () T ([ ] [ ]) [ ] x = H H H z 6. Calculae dependen vaiable uch a banch cuen. 7. Recod eimaion and ue a offline meauemen ( ) fo he nex ime-ep. z 8. Repea -7 fo he nex ime-ep.. TEST SYSTEM AND SMULATON RESULTS The e yem choen i he Lowe Souh land of he New Zealand yem. The yem coni of 7 node and 87 banche. Thee linea load ae locaed a Tiwai k, nvecagill 33k and Roxbugh k. The ymmeic and aymmeic meauemen placemen ae hown in Fig. 4. Due o he lack of field meauemen, he meauemen daa ued ae obained fom he Tanien Convee Simulaion (TCS) [3] baed imulaion. TCS i a nodal appoach wih diakopical egegaion of he plan componen, pecially developed o analye he dynamic behavio of HDC yem. mehod developed A.5 cycle duaion ymmeical line-o-gound faul i imulaed in he e yem. The faul locaion i hown by he black coe (doub cc. anmiion line) in Fig. 4. Fig. 5-9 how he eimaed volage a Tiwai k and eceiving end line cuen a Manapoui-Tiwai k anmiion line. The acual and eimaed value ae hown a doed and olid line epecively. The diffeence i hown a he boom half of he figue. Depie he diffeence occued duing he faul aniion peiod (wiched in/ou), which i caued by an inceae eo in he Eule appoximaion fo vey fa anien, he eul how TSE i capable of eimaing he newok behavio fom he paial meauemen. T Fig. 4. Lowe Souh land of he New Zealand Syem

5 4 x 5 Tiwai k, phae A 3 Manapoui-Tiwai k, phae A Buba olage () x 4 Banch Cuen (A) Fig. 5. Buba volage a Tiwai k, phae A Fig. 8. Banch cuen a Man-Tiw k, phae A, eceiving end x 5 Tiwai k, phae B Manapoui-Tiwai k, phae B Buba olage () Buba olage () x Fig. 6. Buba volage a Tiwai k, phae B x 5 Tiwai k, phae C x Fig. 7. Buba volage a Tiwai k, phae C Banch Cuen (A) Eimaed TCS Fig. 9. Banch cuen a Man-Tiw k, phae B, eceiving end To epeen he unexpeced faul even in he e yem, he yem opology upplied o he TSE duing he faul peiod emained unchanged i.e. he faul i no modelled in he TSE. Thi caue inconien eimaion eul and hence cuen mimach a he faul locaion duing he faul peiod. Fig. how he nodal cuen mimach of he e yem. A indicaed by he ignifican cuen mimach poiioned a node -3 (Tiwai k), he following ae deduced:. The faul poiion i locaed a Tiwai k (node -3). The cuen mimach a he Tiwai k node epeen he faul cuen. Fig. -3 how he compaion of he cuen mimach wih he imulaed faul cuen a each phae. 3. The faul i ymmeical a he faul cuen ae balanced. 4. Low faul eiance (eimaed by he nodal volage/faul cuen) ugge he ype of faul i a line-o-gound faul.

6 .5 x 4 Faul cuen, phae C Faul Cuen (A) Fig. Nodal cuen mimach (abolue value) Fig. 3. Faul cuen a phae C Faul Cuen (A) Faul cuen, phae A Fig.. Faul cuen a phae A. CONCLUSON A peen, when a faul ha occued, he faul infomaion available o idenify i poiion i uually inufficien. n hi pape, he ue of TSE fo faul idenificaion, by eimaing he complee yem ae fom paial meauemen, i peened. The dicee ime ae-pace fomulaion allow hioical yem ae o be ued a meauemen o povide addiional meauemen infomaion. Howeve, he ime-ep mu be adequae o cae fo fa anien when he opeao d/d i appoximaed uing Eule fomula. Fom he e eul, he TSE oluion howed ageemen wih he TCS baed imulaion. Thee impoan faul chaaceiic: ) he faul poiion, ) faul ype and 3) he magniude of he faul cuen, ae obained by inpecing he nodal cuen mimach of he yem. Faul idenificaion via TSE echnique i accuae, efficien and eay o implemen. Faul Cuen (A) x 4 Faul cuen, phae B REFERENCES [] W. Long, D. Coche, D. Ruiu, P. Adam, S. Lee and R. Adapa, EMTP-a poweful ool fo analyzing powe yem anien, EEE Compue Applicaion in Powe, vol. 3, no. 3, pp. 36-4, 99 [] J. J. Mai and L. R. Linae, Real-Time EMTP- baed anien imulaion, EEE Tan. Powe Syem, vol. 9, no. 3, pp , 994 [3] J. Aillaga, C. P. Anold and B. J. Hake, Compue modeling of elecical powe yem, J.Wiley & Son, London, 983. BOGRAPHES Ken Yu compleed hi B.E. (Hon) in and i a peen a Ph.D. candidae. Hi aea of eeach i ae eimaion echnique Fig.. Faul cuen a phae B Neville Waon eceived hi B.E. (Hon) and Ph.D. degee in elecical and eleconic engineeing fom he Univeiy of Canebuy (New Zealand) he i now a Senio Lecue. Hi inee include powe qualiy, eady-ae and dynamic analyi of ac/dc powe yem.