Line Differential Protection Scheme Modelling for Underground 420 kv Cable Systems

Transcription

1 Lin Diffrntial Protction Schm Modlling for Undrground 4 kv abl Systms EMTD/PSD Rlays Modlling Michal Sztykil, laus Lth ak Dpartmnt of Enrgy Tchnology alborg Univrsity alborg, Dnmark clb@it.aau.dk Wojcich Wichowski, Sbastian Dollrup Protction & ontrol Systms Enrgint.dk Frdricia, Dnmark sdo@nrgint.dk bstract asd on th analysis of a spcific rlay modl and an HV (High Voltag ltrnating urrnt) cabl systm, a nw approach to EMTD/PSD modlling of protctiv rlays is prsntd. Such approach allows to crat complx and accurat rlay modls drivd from th original algorithms. Rlay modls can b applid with various systms, allowing to obtain th most optimal configuration of th protctiv rlaying. Th prsnt papr dscribs modlling mthodology on th basis of Simns SIPROTE 4 7SD5/6. Rlay modl was vrifid xprimntally with its ral quivalnt by both EMTP-simulatd and ral world gnratd currnt signals connctd to th rlay. Kywords lin diffrntial protction; LPE HV cabl; EMTD/PSD rlay modl; SIPROTE 4 7SD5; 7SD6 I. INTRODUTION Rlay computr modlling is an important issu for stablishing propr protction schm for th spcifid systm. Nowadays, it is difficult to obtain accurat rlay computr modl, sinc rlay manufacturrs offr thir products with a varity of algorithms and faturs that may significantly chang opration of rlays undr spcific conditions and stats. For this purpos, ssntial study ovr nw approach for crating rlay modls in EMTD/PSD is givn. Th mthodology rlis on obtaind rlay s tchnical spcification (givn by rlays manufacturr), so that uniqu faturs and algorithms - charactristic for ach rlay typ, can b dvlopd. s a rsult, this would giv complx rlay modl narrowd and usful only for spcifid typ of rlay. In compnsation, rlay computr modl would b vry accurat (mainly in trms of snsitivity and oprating spd) with asy and usr-frindly configuration panl, which is programmd with th sam paramtr valus as in ral dvics. Establishd rlay modls would asily allow to prform simulations of chosn study cass and xamin possibilitis of unwantd tripping that might occur (.g. du to transint powr lctronics switching, ovrvoltags, xtrnal faults, nrgization stats, tc.). This papr prsnts such analysis for Simns lin diffrntial rlays SIPROTE 4 SD5/6, as ths rlays ar plannd to protct HV undrground transmission cabl systm built in Dnmark in yars -4. Larg capacitanc of undrground cabls in comparison to ovrhad lins brings original issus for th diffrntial protction schm to considr, as both stady and transint stats hav to b dply analyzd. For stady stat, charging currnt is th factor that mostly affcts rlays function. For transint stats, rlays may b affctd by inrush currnts that occur du to shunt ractors switching oprations (ncssary for ractiv powr compnsation). In ordr to proprly rflct cabl systm s influnc ovr rlay s currnt signals in mntiond stats, cabl systm is modlld with th usag of EMTD/PSD softwar, as it provids satisfactory accuracy for both stady and transint analysis. Whn both cabl systm and protction schm modls ar compltd, rlay modl s accuracy can b finally vrifid through xprimntal tsting. Having idntical paramtr stting both for rlay modl and ral dvic, snsitivity and oprating spd ar compard thus showing high accuracy of th rlay modl. Rsults from xprimntal analysis prov that prsntd approach for rlay modlling can b succssfully adaptd for spcific rlays with original algorithms and faturs. E II. SV PROTETED LE SYSTEM - KGROUND. abl Systm - Dscription Th singl phas diagram of total cabl systm is shown on Fig.. L KYV SR SR SR3 SR4 Figur. Schmatic Rprsntation of th Undrground 4 kv abl Systm. L E Modrn Elctric Powr Systms, Wroclaw, Poland MEPS' - papr P45

2 P_KYV Q_KYV KYV sourc EN_ Ip 3 KYV shunt ractor SV sourc P_SV Q_SV Fault Lin ircuit rakrs ontrol St LPE Shunt Ractors ircuit rakrs ontrol St EN_ LPE ETERNL FULT KYVr TORr EN_ 3 LPE 3 SV shunt ractor rakr rakr Opn@t rakr Opn@t Fault Tim d INTERNL FULT rakr losd@t losd@t rakr Opn@t rakr Opn@t FULTS EN_ TORr SVr LPE Ip LPE 3 LPE 3 LPE3 3 LPE3 LPE3 3 LPE 3 LPE4 Sourcs ontrol St Faults ontrol St Faults ontrol St Dscription KYV Faults : ontrols Faults : ontrols Fault Typ ontrol Phas ngl_ Phas ngl_ Voltag_ Voltag_ P_KYV Q_KYV Extrnal Fault Intrnal Fault = No Fault 9 9 = Phas to Ground 3 = Phas to Ground = Phas to Ground = Phas to Ground = Phas to Ground 6 6 SV 7 = Phas to Ground = Phas to Ground Phas ngl_ Phas ngl_ Voltag_ Voltag_ P_SV Q_SV 4 9 = Phas = Phas kv kv LPE LPE9 3 LPE4 [ohm ] [ohm ] [ohm ] LPE9 [ohm ] [ohm ] [ohm ] LPE4 LPE9 3 3 LPE5 3 LPE8 3 LPE8 LPE5 LPE8 3 LPE5 LPE7 3 3 LPE7 LPE7 Ip TOR shunt ractor 3 k k k LPE6 3 Ia Ia Ia LPE6 LPE6 3 Main : Phas currnts Ia Ia Ia [ohm ] [ohm ] [ohm ] TOR shunt ractor Phas urrnts Wavforms - both lin nds Ip Th systm consists of th following componnts: ) LPE HV Undrground abl Sctions (L L): Slctd cabl is mad of thr aluminium singl-cor cabls burid undrground on th dpth of,3 m and laid in a flat formation within 3 mm from ach othr. Total cabl is dividd into two sctions of lngths accordingly 8 km and 9,5 km. Mtallic scrns of ach cabl sction ar crossbondd approximatly ach km, and arthd ach 6 km. Dtaild information about cabl structur is prsntd on tabl I. TLE I. TEHNIL DT OF LPE UNDERGROUND 4 KV LE Dscription Valu ross-sction of conductor (mm ) 6 Diamtr of conductor (mm) 5 Insulation thicknss (mm) 7, Diamtr ovr insulation (mm), ross-sction of scrn (mm ) 85 Outr diamtr of cabl (mm) 7, apacitanc (µf/km), Inductanc (mh/km),5 harging currnt pr phas (/km) 4,9 ) Shunt Ractor anks (SR SR4): For ractiv powr compnsation, four switchabl shunt ractors ar installd; ach on SV, KYV bus bars with ractiv powr of MVRs and two btwn cabl sctions with ractiv powr of 4 MVRs. 3) Supply Sourcs (E E): Powr systm on both sids of th cabl is modlld by E and E sourcs that ar Thvnin quivalnts consisting of voltag sourcs and its short-circuit impdancs. Paramtr valus ar listd on tabl II. TLE II. Supply Sourc TEHNIL DT OF LE S SUPPLY SOURES Voltag (kv) Short-circuit impdanc (Ω) E j6.6 E j6.78. EMTD/PSD Modl of abl Systm In Fig., dscribd cabl systm is modlld in EMTD/PSD softwar by frquncy dpndnt (phas) modl, giving highst accuracy among othr availabl modls [5]. Such modlld cabl systm may accuratly rflct bhaviour of th protction schm undr various transint stats that ar likly to appar. Furthr dtaild information about stablishing computr modl of th cabl is availabl in [5]. Shunt ractors ar modlld with sris rsistanc and inductanc paramtr valus for ach phas. V Ph 4 [kv], 5 [Hz] 59 [MV] Z =.89 [ohm] + j6.6 [ohm] 5.6 [H].858 [ohm] KYVr 5.6 [H].858 [ohm] 5.6 [H].858 [ohm] SV V Ph LPE 4 [kv], 5 [Hz] 477 [MV] Z =.839 [ohm] + j6.78 [ohm] 5.6 [H].858 [ohm] SVr 5.6 [H].858 [ohm] DR T 5.6 [H].858 [ohm] dgrs dgrs Figur. EMTD/PSD Rprsntation of th Undrground 4 kv abl Systm. Tabl III shows validation rsults for thr possibl currnts that can flow through protctd cabl. Paramtrs wr chosn that mostly affct propr function of stablishd diffrntial protction. Dtaild mthodology for cabl modl validation along with sris of calculations ar givn in [-3]. TLE III. Dscription Maximum urrnt (k) VLIDTION RESULTS FOR EMTD/PSD UNDERGROUND LE MODEL harging Extrnal Fault at SV substation (k) Intrnal Fault in th middl of th cabl (k) Thortical nalysis FO Protctd Zon EMTD/PSD Modl TORr 4. [H].59 [ohm] 4. [H].59 [ohm] DR T 4. [H].59 [ohm] TORr 4. [H].59 [ohm] 4. [H].59 [ohm] 4. [H].59 [ohm] Rlativ rror r (%),878,85 8,3 9,555,49 6,85,94 8,4 Rlativ rror is calculatd from r = IT - IPSD / IT, whr: IT currnt paramtr valu obtaind algbraically; IPSD currnt paramtr valu obtaind numrically. Rlativ rror originats from cabl gomtry, sinc mutual couplings btwn intrnal conductiv cabl layrs tak plac. This corrsponds to cor conductors and scrns that ar in clos proximity to ach othr. Rsulting inductiv ractanc for singl phas is lowr than calculatd algbraically, thus giving highr currnt valu which riss significantly whn high currnts flow through cabl []. Validation rsults allow to conclud that crtain rror lvl occurs and has to b takn into account. Highr fault currnt valus from EMTD/PSD simulations allow to kp safty margin for th analysis basd on simulation rsults.. Diffrntial Protction Schm Dscription Total diffrntial protction schm for th analyzd cabl systm is prsntd in Fig. 3. Figur 3. Schmatic Rprsntation of th Diffrntial Protction Schm ovr Undrground 4 kv abl Systm. KYV

3 3.3 P.76 Idiffx 3.5 Idiffx 3.5 Idiffxx 7.4 Idiffxx.5 Inrush Rstraint Ratio 6.33 M inrush pak P Idiffx Idiffx Qdiffxx Qdiffxx Main : ontrols cross-blocking OFF ON Inrush Rstraint Ratio M inrush pak Inrush ON / OFF ia ib ic SMPLER SMPLER SMPLER PHSE PHSE PHSE trip_ cros s_ trip_ cros s_ trip_ cros s_ trip_ trip_ trip_ cross _ cross _ cross _ trl trl = EN_ EN_ EN_ EN_ y y EN_ SMPLER SMPLER SMPLER EN_ -s T -s T -s T -s T -s T -s T trip_ cross_ trip_ cross_ trip_ cross_ trip_ trip_ trip_ cross_ cross_ cross_ = trl trl : Graphs : Graphs trip_r trip_r trip_r cros s_r cros s_r cros s_r trl trl = trip_r cros s_r trip_r cros s_r trip_r cros s_r PHSE PHSE PHSE Ia Ia_ S4 phasor_ma phasor_pa SMPLER SMPLER SMPLER ia ib ic Proposd protction schm consists of following componnts: ) urrnt Transformrs (T): Dvics rsponsibl for currnt signal transformation on th lvl applicabl for masuring instrumnts installd in protction rlays. Tabl IV shows currnt transformrs spcification usd for computr modlling purpos. TLE IV. TEHNIL DT OF URRENT TRNSFORMERS (T) Paramtr Valu T manufacturr s modl IM 4 T class 5P Transfomation ratio (/) / ccuracy Limit Factor LF Nominal Powr (V) 5 ) Mono-mod Fibr Optic abls (FO): ommunication channls rsponsibl for propr signal transmission btwn rlays. Du to significant lngth of th protctd cabl (58,5 km), signal attnuation phnomnon must b considrd along with tim dlay btwn snding and raching signal from both sids of th protctd cabl. Rfrnc [] xplains dtaild solution mthodology to statd issus. hannl tim dlay is calculatd basd on datasht providd by fibr optic cabl s and rlay s manufacturrs. Ncssary data ar gathrd in tabl V. TLE V. TEHNIL DT OF FIRE OPTI LES (FO) Indx Paramtr Valu v andwidth Data Spd (bits/s) 5 l FO FO Lngth (km) 58,5 v FO FO Spd of Light (km/s) l HDL Fram Lngth (bits) hannl tim dlay T dlay is,7 ms, calculatd from whr l l l T + FO dlay = Ts + Tt + Tr = +, () v vfo v T s tim for snding signal by th local rlay, T t tim for transmitting signal through FO cabl, T r tim for rciving signal by th rmot rlay. 3) Lin Diffrntial Rlays (DR): Most complx componnts ralizing signal masurmnt, signal comparison and finally - fault dtction principls. Rlays analyzd in this papr ar Simns SIPROTE 4 7SD5. Dtaild tchnical spcification, instruction on stablishing propr configuration paramtr st ar availabl in [], [3] and [4]. D. EMTD/PSD Modl of Diffrntial Protction Schm gnral approach is introducd for protction schm modlling in PSD softwar. asd on prvious componnts dscription, thir uniqu charactristic functions ar prsntd on Fig. 4. Each componnt is rsponsibl for: Ia Ia SIGNL TRNSFORMTION Ia_ Ia Ia_ Ia Ia Ia_ Ia Ia_ Ia -st -st -st SIGNL TRNSMISSION in out D Ia_3 Ia Ia_3 Ia Ia_ Ia_4 Ia Ia_4 Ia Ia Ia_ D Ia_5 Ia Ia_5Ia PHSE PHSE PHSE SIGNL PROESSING Figur 4. EMTD/PSD Rprsntation of th Diffrntial Protction Schm ovr Undrground 4 kv abl Systm. Signal transformation, modlld by urrnt Transformr Lucas modl blocks with spcifid paramtr sttings. Rfrnc [6] provids mor information rgarding T Lucas modl. Signal transmission, modlld by tim dlay blocks with spcifid and calculatd tim dlay valu from (). Signal procssing, modlld with complx block combination, rflcting opration algorithm and original faturs of ral rlays. III. EMTD/PSD RELY MODELLING Rlay EMTD/PSD computr modl is cratd in a shap of box with thr phas moduls includd, so that all oprations ar phas sgrgatd as in ral rlays (s Fig. 7). Input signals for moduls ar prviously sampld with samplr blocks, so that sampld valus appar ach full cycl priod (fixd frquncy) [3]. Output logic signal is rsponsibl for controlling lin circuit brakr in cas of possibl fault occurrnc. Following faturs ar includd in ach phas modul: ) Sampl cquisition: Opration ncssary for furthr phasor and charg computations. Sampl valus i n hav to b stord during full cycl. This opration is availabl by implmnting Sampl/Hold blocks ach controlld by logic puls gnrator block, as prsntd on Fig. 5. Puls gnrator blocks giv command D for ach sampl/ block. Gnratd pulss ar shiftd to ach othr by 8 dgrs of total cycl priod Ia_6 Ia Ia_6Ia Ia_7 Ia Ia_7 Ia Ia_8 Ia Ia_8 Ia Ia_9 Ia Ia_9 Ia Figur 5. EMTD/PSD Rprsntation of Sampl cquisition Tchniqu. Ia_ Ia_

4 ) Phasor Masurmnt: currnt phasor valus I ar obtaind in th shap of complx numbrs through Discrt Fourir Transform tchniqu, basd on whr Hrin ar I = I + j, () S I N = I S sin( ω n t ) i n, (3) N n= N = + + i in I cos( ω n t ) in. (4) N n= n =,,, sampl numbr, i n currnt sampl valu corrsponding to sampl n, ω = f π cycl pulsation, t = (f N) - f = 5 Hz frquncy, sampl tim intrval, N = numbr of sampls ovr on cycl. Equations (3) and (4) ar ralizd by corrlating sampl valus with sin and cosin wavforms and summating thm ach full cycl priod []. 3) harg Masurmnt: harg valus Q ar obtaind basd on 5+ n + n n+ 5 Q = i dt i i ti. (5) i= n Four charg valus ar calculatd ach full cycl priod. y applying signal switch block, final charg signal is switchd ach quartr cycl. This corrsponds to ral rlay fatur, whr charg comparison is prformd four tims mor oftn than phasor comparison. 4) Phasor omparison: basd on rlay s principls givn in [], valus for oprational phasor I OP and rstraint phasor I RES ar obtaind and rlay oprating critrion is for I OP > I RES, (6) P I : I P P I : I P IRES = Idiff > + +, (7) P3 I : I > P P3 I : I > P Rlay stting paramtrs P, P, P3 and I diff> ar chosn basd on procdur givn in [3] and [4]. Paramtrs I and I ar currnt phasor valus corrspondingly masurd by local and rmot rlays. Opration of switching multiplying factors for rstraint phasor (dtrmind by currnt signal valu in fault stat or load stat) is mad with th usag of comparator blocks, which output signal is multiplid by its corrsponding actual phasor currnt signal valu, as shown on Fig. 6. asd on information obtaind from th position of lin circuit brakr installd on th sam sid as dvic, diffrntial rlay can dtct dad lin stat whn no currnt flows through th protctd cabl. abl nrgization stat whn circuit brakr is suddnly switchd on is dtctd by Edg Dtctor block by positiv transition apparanc of signal from lin circuit brakrs. This allows gnrating digital impuls, which is latr xtndd to th spcifid tim intrval - Td stting, which can b changd basd on rlay sttings by Monostabl Multivibrator block. a) b) phasor_ma [Main] Idiffx [Main] EN_ phasor_ma M phasor_ma Y M D + + P F phasor_pa P Y phasor_ma phasor_pa P phasor_ma phasor_ma P [Main] Idiffx M P Idiffx Idiffx Y omparator EN_ M P trl Y Idiffx trl = P trl P < phasor_ma phasor_ma P trl = Edg Dtctor omparator omparator Monostabl T P3 P P F F D + D dyta omparator Low pass uttrwth Ordr = D F Samplr Irs_phasor Iop_phasor Figur 6. EMTD/PSD Rprsntation of Phasor omparison tchniqu: a) Rstraint phasor I RES, b) Oprational phasor I OP. 5) harg omparison: for this tchniqu, th sam algorithm is usd as for phasor comparison. I diff> paramtr is rplacd with minimum thrs valu for chargs: I diff>>. In addition, phasor signals ar rplacd with thir corrsponding oprational Q OP and rstraint Q RES charg valus. 6) Signal Filtring: oprational and rstraint valus ar filtrd using low-pass uttrworth filtr block with stablishd frquncy thrs corrsponding to ach comparison tchniqu. 7) Inrush Rstraint: nd harmonic phasor currnts I nd ar masurd by onlin frquncy scannr blocks. If its valus xcd stablishd ratio k ratio of st harmonic I st, rlay prvnts tripping opration. In EMTD/PSD modl this fatur can b switchd OFF as in ral rlays. ondition statmnt (9) has to b fulfilld in ordr to activat inrush rstraint blocking fatur. Uppr limit for non-tripping opration is stablishd with I max_pak paramtr ( I nd > kratio I st ) ( I st < I max_ pak ). (9) I OP = I + I. (8) omparison principls ar obtaind with a combination of comparator blocks. Output signals from comparators can thn

5 cross_ b combind with logic gats so that tripping signal dpnds on th rsulting signal from th inrush rstraint fatur. 8) ross-blocking: in ordr to prvnt tripping signals from all thr phass whn inrush fatur is activ in only singl phas, cross-blocking fatur is introducd. Its PSD rprsntation is shown on Fig. 7. EN_ SMPLER SMPLER SMPLER EN_ PHSE PHSE PHSE trip_ trip_ cross_ trip_ cross_ trip_ trip_ trip_ cross_ cross_ cross_ trl trl = Figur 7. EMTD/PSD Rprsntation of ross-locking Tchniqu. In EMTD/PSD computr modl, cross-blocking utilizs singl phas tripping and inrush activation signals as th output signals of ach phas modul. ombining thm all with logic gats givs final tripping signal dcision. Hnc, dscribd fatur has to b implmntd outsid phas moduls. s in ral rlays, fatur can b prmanntly switchd OFF during normal opration. Original EMTD/PSD fils with fully stablishd and configurd modls of rlays and protctd cabl systm ar availabl at main author on rqust. PHSE : Graphs Iop_phasor Irs_phasor Qop_charg Qrs_charg a) 5. b) IRES rstraint phasor IRES oprational phasor IOP phas () phas () phas () IV PHSE : Graphs PHSE : Graphs Iop_phasor Irs_phasor Iop_charg Irs_charg Iop_phasor Irs_phasor Iop_charg Iop_phasor Irs_phasor Iop_charg Irs_charg Tim (s) EMTD/PSD SIMULTION SES. Two-Phas Extrnal Fault at KYV substation Extrnal fault simulation in phass and allows analysis on how rlay computr modl racts whn high currnts flow through th protctd cabl. Fault is clard aftr 55 ms by virtual bus protction installd in plac whr fault occurrd. ll shunt ractors ar disconnctd (highst charging currnt). Simulation graphs ar prsntd on Fig. 8. IOP rstraint charg QRES oprational charg QOP phas ( s) phas ( s) phas ( s) PHSE : Graphs Iop_phasor Irs_phasor Qop_charg Iop_phasor Irs_phasor Iop_charg Tim (s) Figur 8. Extrnal Fault Stat at ms: a) Phasor omparison Tchniqu, b) harg omparison Tchniqu. Du to high currnts flowing through phass and which ar highr than calculatd P valu [4], transition taks plac rsulting in switching multiplying factors from P to P3 QRES QOP valu. This mans that transformd scondary currnt lis within fault ara and scurity margin is incrasd in corrsponding phass. On prsntd plots, rstraint thrs is highr for th tim whn xtrnal fault currnt flows. ftr fault claring, rstraint valus rturn to its normal thrs lvls sinc transformd currnt lis onc again within load ara. n incras of oprational valus in phass with high currnt appars aftr fault claring, giving larg safty margin in ordr to prvnt unwantd tripping. It is sn that during whol simulation oprational valus do not xcd rstraint ons. s a rsult, rlay proprly dos not dtct any fault within protctd cabl and dos not snd tripping signal.. Singl-Phas Intnal Fault at KYV substation Simulation tst involvs intrnal fault apparanc in phas within protctd cabl. s th worst cas scnario, singl - phas fault is applid with high rsistanc R fault = Ω and all shunt ractors ar switchd ON (lowst charging currnt). omputr modl with stablishd stting paramtrs should b abl to proprly dtct and rcogniz fault stat within phass. Figur 9 prsnts dscribd simulation cas rsults. PHSE : Graphs Iop_phasor Irs_phasor Qop_charg Qrs_charg a) b) IRES IOP rstraint phasor IRES oprational phasor IOP phas () phas () phas () PHSE : Graphs PHSE : Graphs Iop_phasor Irs_phasor Iop_phasor Irs_phasor Iop_charg Irs_charg PHSE_ : Graphs PHSE_ : Graphs rstraint charg QRES oprational charg QOP Iop_phasor Irs_phasor Iop_charg Irs_charg Iop_phasor Iop_phasor Irs_phasor Irs_phasor PHSE : Graphs Tim (s) phas ( s) phas ( s) phas ( s) QRES QOP Tim (s) Figur 9. Intrnal Fault Stat at ms: a) Phasor omparison Tchniqu, b) harg omparison Tchniqu. s xpctd, intrnal fault occurrd in phas and is dtctd by rlay computr modl both with phasor and charg comparison tchniqus. Oprational valus significantly xcd rstraint ons aftr ms from fault occurrnc for phasor and 5ms for charg comparison principls. Earlir fault dtction with charg tchniqu rsults in snding tripping signal aftr 5ms in ordr to disconnct faultd cabl. V. RELY TESTING. Dscription Rlay xprimntal tsting is possibl with th usag of modrn quipmnt and softwar capabl of convrting currnt signals from EMTD/PSD softwar into currnt wavforms injctd into ral diffrntial rlays. Simplifid diagram of xprimntal tst stup is prsntd on Fig..

6 FO cabl TLE VII. VLIDTION RESULTS OF SENSITIVITY FOR EMTD/PSD RELY MODEL dvancd Transplay DIGSI 4.8 U D supply Ia Ib Ic Figur. Exprimntal Tst Stup. U D supply Ia Ib Ic Six currnt signals ar snt: Ia, Ib, Ic, Ia, Ib, Ic from which thr ntr to ach rlay accordingly to th sid from which thy wr masurd. Rlays intrconnctd togthr with fibr optic cabl, rspond basd on dlivrd signals with masurd valus and annunciation mssags savd as logs. Ths logs can thn b snt to P and rad in DIGSI softwar for furthr analysis and for comparison purposs.. Rsults ll tsts from xprimntal analysis and EMTD/PSD simulations wr prformd with th sam stting paramtr valus. Rlay s oprating spd and snsitivity hav bn xamind. ) Oprating Spd: Oprating spd analysis givs ida on how fast rlay is abl to dtct fault stats. y th analysis of rstraint/oprational plots in EMTD/PSD computr softwar, tim intrval btwn xcding thrs by oprational charg valu Q OP and phasor valu I OP can b compard with th ons obtaind from DIGSI logs. nalyzd study cas rsults ar prsntd on tabl VI. TLE VI. as dscription Singl-phas to ground intrnal fault in th middl Singl-phas to ground intrnal fault at KYV busbar Two-phas to ground intrnal fault at KYV busbar Thr-phas to ground intrnal fault KYV busbar VLIDTION RESULTS OF OPERTING SPEED FOR EMTD/PSD RELY MODEL Exprimntal Rsults Tim intrval (ms) PSD Simulation Rsults ) Snsitivity: Rlay s snsitivity analysis is critical for propr intrnal fault stats rcognition. For this rason, intrnal faults with vry high rsistanc valus wr analyzd. Diffrntial thrs paramtr I diff> for phasor comparison was adjustd in ordr to obtain its critical thrs valus. Rsults ar listd and compard in tabl VII. Phasor comparison is xamind sinc it is mor snsitiv and ncssary for propr fault dtction. ritical valus ar ths on which rlay still dtcts fault and - if incrasd of a singl stting stp - maks no raction for th sam fault conditions. Intrnal fault rsistanc (Ω) Diffrntial phasor I diff> thrs for tripping PSD Exprimntal Simulation Rsults Rsults Diffrntial phasor I diff> thrs for non-tripping PSD Exprimntal Simulation Rsults Rsults 55 4, 4,5 4,3 4,6 7 3,3 3,5 3,4 3,6 45,7,73,73,74,3,3,3,33 VI. ONLUSIONS EMTD/PSD rlay computr modl provs to b rliabl and fficint from takn simulation cass with stablishd paramtr st. part from intrnal and xtrnal fault stats, analyzd simulation cass includd transmission cabl s nrgization and shunt ractor s nrgization stats, giving ovrall diffrnt study cass []. ll simulation rsults hav bn succssfully compliant with th xpctd ons. ccording to simulation rsults, rlay modl is abl to accuratly dtct intrnal faults and diffrntiat thm with mntiond othr stats that may b mislading. Vry high fault rsistancs from which rlay cannot dtct faults marks fficincy of spcific algorithms implmntd and usd for masurmnt and comparison purposs of th obtaind signals. VII. KNOWLEDGMENT Th first author gratfully acknowldgs rsarch support from th Danish TSO - Enrgint.dk, which dlivrd all ncssary tchnical data of th analyzd systm along with Simns SIPROTE 4 7SD5 rlays. VIII. REFERENES [] G. Ziglr, Numrical Diffrntial Protction: Principls and pplications, Nurmbrg, Grmany: Simns G, Jul. 5. [] M. Sztykil, Protction philosophis for HV transmission ntwork, M.S. thsis, IET, alborg Univ., alborg, Dnmark, 9. [3] SIPROTE 4 Diffrntial Protction 7SD5 V4. Manual, Simns G, Nurmbrg, Grmany,. [4] T. Szi at al., Fild Exprinc Summary with a Lin Diffrntial Rlay Using omplx ommunication Infrastructur, Simns Enrgy, Inc., Nurmbrg, Grmany, Sp. 9. [5] pplications of PSD/EMTD pplication Guid, Manitoba HVD Rsarch ntr Inc., Winnipg, anada. [6] J. Rohan Lucas, Rprsntation of Magntisation urvs ovr a wid rgion using a non-intgr powr sris, IJEEE: Manchstr Univ. Prss, vol. 5, No 4, pp , Oct. 988.