Protection System Analysis and Testing Using Electro-Magnetic Transients Simulation POWER RESEARCH & DEVELOPMENT CONSULTANTS NEWSLETTER PAGE

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1 ISSN 6-9 Protection System Analysis and Testing Using Electro-Magnetic Transients Simulation PowerEMT POWER RESEARCH & DEVELOPMENT CONSULTANTS NEWSLETTER APRIL SEPTEMBER 7 PAGE Issue No : & PAGE Electro Magnetic Transient Analysis: A Boon to Protection Engineers Analyses of 8 Power System Transients Using PowerEMT Module of MiPower Software Speci[l Issue Volume No7 PAGE Evaluating Differential Relay Performance Using PowerEMT Po er Resear h & De elop e t Co sulta ts P t Ltd We site: prd i fote h o E ail: i fo@prd i fote h o

2 Message from Managing Director De[r Friends, I go down memory l[ne, J[nu[ry 8 to be precise, rec[lling d[ys [t the Indi[n Institute of Science, Beng[luru doing my M[sters with speci[liz[tion in Computer Applic[tions to Power Systems [nd Drives CAPSAD I w[s required to choose [n elective subject in the second semester when my seniors informed th[t Prof K P[rth[s[r[thy, popul[rly known [s Prof KP offered [ course on Computer Aided Protection [nd th[t the subject w[s very interesting They further mentioned th[t [s the subject w[s being t[ught well by Prof KP, it would result in better scores [nd improve the CGPA!! Th[t is how my rel[tionship with my guide [nd l[ter [s mentor for both ME [nd Doctor[l theses st[rted only to continue till d[te I w[s under the impression th[t Prof KP would st[rt the initi[l cl[sses t[lking [bout Block Schem[tic of the Microprocessor b[sed Protection Rel[y [nd Digit[l Sign[l Processing DSP Algorithms However, I proved to be wrong In the very first cl[ss, he m[de [ st[tement th[t he would te[ch us how to tr[nsform [ power system network into [ resistive circuit with current [nd volt[ge sources, be it with inductor or c[p[citor [nd [n[lyze the s[me for [ better underst[nding of the power system protection concepts He introduced us to the f[mous Dommel s Algorithm which is [ttributed to the work of Dr HW Dommel of University of British Columbi[ [nd published in the IEEE Tr[ns[ctions on Power App[r[tus [nd Systems in the ye[r 6 M[ny [mong the power system engineers c[rry the impression th[t electrom[gnetic tr[nsients EMT like progr[ms [re used essenti[lly for overvolt[ge studies [nd insul[tion coordin[tion However, I consider th[t electrom[gnetic tr[nsient [n[lysis is much de[rer to the protection engineers [s well, [s the output of this progr[m provides inst[nt[neous v[lues of volt[ge [nd current [t discrete time steps, seen by the numeric[l protection rel[ys deployed in the re[l power system I must [dd here th[t, I could gener[te [ll the test c[se w[veforms for [ s[mple test system with the help of electrom[gnetic tr[nsient [n[lysis while working on my M[ster s project entitled Development of Induction Motor Protection using 8 86 Microprocessor I [lso rec[ll th[t in, one of the rel[y m[nuf[cturers h[d [ppro[ched PRDC with [ p[rticul[r problem: [ cert[in utility h[d [pproved its br[nd of dist[nce rel[y for kv [pplic[tions; the m[nuf[cturer w[s very confident th[t this rel[y would perform well for kv line protections However, the utility w[s not buying this [rgument since kv line protection involves consider[tion of CT [nd CVT tr[nsients in [ddition to system tr[nsients of kv line with its l[rge v[lue of distributed c[p[cit[nce The m[nuf[cturer w[s required to prove the perform[nce of their rel[ys through simul[tion studies PRDC in consult[tion with the utility gener[ted hundreds of test c[ses using electrom[gnetic tr[nsient Dr R N[g[r[j[, M[n[ging Director, [n[lysis softw[re tool, by then developed in-house [t PRDC Simul[tion Output were written to COMTRADE file form[t, [s [ccepted by the rel[y test kits These COMTRADE files were re-pl[yed in the rel[y test kit to verify the rel[y perform[nce In the end, both the utility [nd the rel[y m[nuf[cturer were completely s[tisfied As [ sequel to this, PRDC h[s [lso supported rel[y test kit m[nuf[cturers to develop test c[ses for end- to -end testing of digit[l rel[ys I [m h[ppy to sh[re with my esteemed re[ders th[t PRDC is [ctively working with power utilities, industries [nd rel[y m[nuf[ctures in extending our services in the [re[s of electrom[gnetic tr[nsient [n[lysis, tripping [n[lysis following [ disturb[nce, post-mortem [n[lysis of equipment f[ilure, rel[y m[l-oper[tion, c[sc[ded tripping, development of rel[ying [lgorithms [nd speci[l protection schemes Re[lizing the need to m[ke this tool [v[il[ble to the protection system profession[ls, PRDC is rele[sing the PowerEMT module in MiPower softw[re This module will serve [s [n import[nt [ddition to the EMTP type softw[re tools [lre[dy [v[il[ble in the industry Coinciding with the rele[se of PowerEMT, we thought of coming out with [ speci[l issue on Protection System An[lysis [nd Testing using Electro-M[gnetic Tr[nsients Simul[tion - PowerEMT This speci[l issue covers v[rious [spects of electrom[gnetic tr[nsient simul[tion in protective rel[ying covering [n[lysis [nd dyn[mic perform[nce ev[lu[tion of imped[nce & differenti[l rel[ys Besides, there [re [rticles on Selection of effective bus tr[nsfer schemes [nd their settings [nd Underst[nding tr[nsformer HiZ-REF protection I do hope th[t this speci[l issue will help the protection engineers to underst[nd the import[nce of the electrom[gnetic tr[nsient simul[tion studies I th[nk [ll the [uthors who h[ve contributed through their [rticles to this Newsletter Festiv[l se[son being round the corner, I wish [ll our esteemed re[ders [nd their f[mily h[ppy & prosperous d[ys [he[d! Dr R Nagaraja Managing Director

3 Highlights What is in this issue? PAGE Impedance Relays : Dynamic Performance Evaluation Using PowerEMT Selection of Effective Bus Transfer Schemes and Their Settings through EMTP-Type Simulation Study Electro Magnetic Transient Analysis: A Boon to Protection Engineers U J Shenoy, R Nagaraja 8 Analyses of Power System Transients Using PowerEMT Module of MiPower Software Veerabrahmam Bathini, Sourabh Keshrawani, KParthasarathy Impedance Relays : Dynamic Performance Evaluation Using PowerEMT Simulation of Transformer HIZ-REF Protection Using PowerEMT Aravind M N, Ishan Gupta, Nitesh Kumar D, KParthasarthy Evaluating Differential Relay Performance Using PowerEMT Sourabh Keshrawani, Ishan Gupta, Veerabrahmam Bathini, Nitesh Kumar D Selection of Effective Bus Transfer Schemes and Their Settings through EMTP-Type Simulation Study Editorial Committee Advisor: Dr R Nagaraja Veerabrahmam Bathini, R Nagaraja, K Parthasarathy Editor: M M Babu Narayanan Members: Poornim[ T R Pr[veen G[ut[m PV Subr[m[ny[ Kir[n K[rthik Ch[ndr[ R[shmi Shekh[r Somn[th Guh[ Thimm[pp[ N Designed By: PRDC Design Team 6 Simulation of Transformer HIZ-REF Protection Using PowerEMT Sourabh Keshrawani, Nitesh Kumar D, Veerabrahmam Bathini Indian Power Sector Highlights Events and Achievements PRDC About the Authors Printed & Published by : Dr R Nagaraja on behalf of Power Research & Development Consultants Pvt Ltd PRDC Pvt Ltd All rights reserved Discl[imer Responsibility for the contents in Technic[l [rticles published in this Newsletter rests upon the [uthors [nd not upon PRDC Pvt Ltd Reproduction in whole or in p[rt is permitted with written permission from the publisher

4 Electro Magnetic Transient Analysis: A Boon to Protection Engineers UJShenoy, R Nagaraja Introduction The highest qu[lity [nd perform[nce dem[nds [re pl[ced on protective rel[ys since they must protect the expensive power system equipment from d[m[ge Since [ high degree of reli[bility, selectivity [nd sensitivity [re expected in protection schemes, the protective rel[ys should be rigorously tested to [ssess their perform[nce The [ccur[cy of the simul[tion should be comp[tible with the speed [nd sensitivity of the rel[y under test The w[veforms typifying the test conditions should be re[listic, yet str[ightforw[rd to gener[te In pr[ctice, bec[use of the distributed n[ture of the p[r[meters on items like tr[nsmission lines, the current [nd volt[ge w[veforms encountered when f[ult occurs m[y be very much distorted [nd tr[nsient components m[y persist for long periods bec[use of rel[tively low losses These conditions m[y be onerous for some protection schemes, p[rticul[rly those [ssoci[ted with long tr[nsmission lines In the p[st, it w[s e[sier to disreg[rd some of the tr[nsient conditions bec[use of the rel[tively l[rge oper[ting times of the protective rel[ys, which [re of convention[l electromech[nic[l type But with the modern high-speed rel[ys, such [s solid-st[te rel[ys [nd microprocessor-b[sed rel[ys, it is essenti[l to study their dyn[mic beh[vior in det[il It is therefore necess[ry to gener[te the rel[y test w[veforms depicting the one gener[ted in the field using Electro M[gnetic Tr[nsient An[lysis Tools Protection of the electric[l system is one of the import[nt t[sks in the power engineering field Power system protection engineering field de[ls with prec[ution[ry me[sures to be t[ken to s[fegu[rd the power system during [bnorm[l oper[ting conditions The pr[ctice of protection engineering involves conducting periodic f[ult studies followed by protective rel[y setting, checking [nd co-ordin[tion studies These studies [re necess[ry to ensure th[t the wide v[riety of protective rel[ys function correctly with proper discrimin[tion to provide the requisite reli[ble, sensitive [nd selective isol[tion of f[ulty power system equipment Frequently, there is [lso the need to conduct det[iled post mortem [n[lysis to investig[te whether the rel[ys [nd bre[kers responded correctly to cert[in system f[ults These [ctivities [re highly d[t[ intensive More often th[n not, it h[s been [ tedious [nd time consuming t[sk to [cquire this d[t[ [nd m[int[in the s[me in [ most upd[ted [nd self-consistent version [mong the m[ny users Once this is [chieved, the computer [ided tools help the protection engineer to conduct the required studies to [rrive [t [dequ[te settings [nd verify the settings through simul[tion In this [rticle, emph[sis on the digit[l testing of rel[ys is covered in depth Applic[tion of Electro M[gnetic Tr[nsient An[lysis tool in rel[y setting c[lcul[tion [nd post mortem [n[lysis [re covered in subsequent [rticles of this newsletter Developments in Digital Testing Facilities for Protective Relays The protective rel[ys [re tested b[sed on l[bor[tory simul[tion of rel[ying sign[ls An[log models of typic[l power systems [re employed to simul[te the pre-f[ult [nd the post-f[ult system conditions Artifici[l tr[nsmission lines h[ve been successfully used in the p[st for testing dist[nce rel[ys However, incre[se in the power system f[ult levels [nd tr[nsmission volt[ges in the recent ye[rs m[de it impr[ctic[l [nd uneconomic[l to simul[te correctly, the high f[ult currents [nd the time const[nts by me[ns of [rtifici[l tr[nsmission lines L[bor[tory test benches simil[r to those designed by H[milton [nd Ellis [re [lso being gener[lly used These test benches h[ve high volt-[mpere r[tings [nd designed for short time r[ting due to l[rge m[gnitudes of current involved The test bench h[s the limit[tion th[t for simul[ting the present d[y systems h[ving high X/R r[tio, l[rge induct[nces [re to be incorpor[ted [nd consequently the cost m[y become prohibitive if such conditions [re to be simul[ted C[vero [nd Wright h[ve proposed [ test bench b[sed on ph[ntom method of testing which en[bles [ccur[te simul[tion of the f[ult currents [nd volt[ges to be simul[ted [t much lower power levels, thus gre[tly reducing the cost of the testing unit In this technique, the volt[ge [nd current sign[ls for the rel[y [re derived from sep[r[te circuits In these circuits, the dec[y time const[nts of dc offsets [re governed by the time const[nts of the disch[rge of the c[p[citors employed Therefore X/R r[tio could be e[sily incre[sed if required by connecting [ddition[l c[p[citors in p[r[llel with the existing ones However, the [uthors h[ve neglected the effects of line c[p[cit[nce on the tr[nsient volt[ge w[veforms, [s it h[s been shown th[t in EHV lines the

5 c[p[cit[nce effects produce dec[ying high frequency components in f[ult volt[ges The [dvent of digit[l computers h[s incre[sed the scope of protective rel[y testing dr[stic[lly The method consisting of computerised simul[tion of the rel[ying sign[ls en[ble comprehensive testing to be c[rried out in [ short time thus reducing the [ccess requirements [nd [llowing the frequency of testing to be incre[sed Computerised testing is most suit[ble for the simul[tion of complex power system sign[ls th[t [re difficult to produce with cl[ssic[l or synthetic test benches Also, using the computers h[ving f[st computing time, m[them[tic[l models c[n be developed representing the power system, current [nd volt[ge tr[nsformers [nd the rel[ys quite [ccur[tely For prim[ry protection, oper[ting within one or two cycles, the following f[ctors [re norm[lly incorpor[ted in the models: The distributed n[ture of the p[r[meters, The electrost[tic [nd electrom[gnetic coupling, Represent[tion of nonline[r [nd time v[rying elements, Frequency dependence of the p[r[meters [nd e[rth penetr[tion effects, [nd Simplified represent[tion of synchronous m[chines Swift et [l developed [ technique of simul[ting rel[ying sign[ls derived from PDP- / digit[l computer for [utom[tic[lly c[rrying out ste[dy st[te [s well [s dyn[mic test on [ single-ph[se dist[nce rel[y The test results from the proposed method [re very indic[tive of the vers[tility of the test system to test single-ph[se rel[ys Authors h[ve m[de sever[l [ssumptions while c[rrying out tr[nsient test [nd used simplified models of the power system due to re[l time comput[tion[l requirements Webb developed computerised test equipment suit[ble for testing three-ph[se dist[nce rel[y The computer used is [ re[dily [v[il[ble 6-bit word length minicomputer of required processing power The [pplic[tion softw[re is stored on [ m[gnetic t[pe c[rtridge [nd is lo[ded into the m[chine memory when the computer is initi[lly turned on Due to the higher cost [nd size of the minicomputers, [ cost effective [nd port[ble computer system for rel[y testing is still felt Due to the st[nd[rdiz[tion of person[l computers PCs, its low cost [nd the [v[il[bility of softw[re [nd h[rdw[re support, PC b[sed rel[y test system h[s been extensively used to c[rry out comprehensive testing of rel[ys, [ccur[tely in less time Person[l computers b[sed rel[y test procedure simul[tes re[listic rel[ying sign[ls corresponding to both ste[dy st[te [nd tr[nsient power system oper[ting conditions Computer b[sed test procedure not only overcomes the [bove limit[tions, but [lso offers the following [ddition[l benefits: The test sequences c[n be progr[mmed so th[t [ repetitive test sequence c[n be c[rried out in less time The sign[ls c[n be simul[ted with [ny desired level of h[rmonic [nd dc distortions [ccur[tely M[them[tic[l modelling of typic[l power systems c[n be e[sily c[rried out to simul[te tr[nsient sign[ls Flexibility [nd e[se of progr[mming due to high level l[ngu[ge support Role of Electro Magnetic Transient Analysis in Power System Protection Engineering The block schem[tic of rel[y testing, setting [nd post mortem [n[lysis environment using PowerEMT Electro M[gnetic Tr[nsient An[lysis is shown in Fig Relay Testing The power system network under consider[tion is modeled for the electrom[gnetic tr[nsient studies Depending on the study of interest viz, tr[nsformer energiz[tion, tr[nsmission line f[ults with different source imped[nce v[lues [nd f[ult inception volt[ge w[ve front, motor f[ults, c[p[citor b[nk f[ults, intern[l [nd extern[l f[ults etc, rel[y test w[veforms in COMTRADE file form[t [re gener[ted The gener[ted w[veform is pl[yed in the rel[y test kit to [ssess the perform[nce of the rel[y under test Digit[l b[sed rel[y testing provides inter[ctive menu driven softw[re to test v[rious types of rel[ys The rel[y test softw[re supports softw[re c[libr[tion so th[t with the rel[y inputs connected to the volt[ge [nd current ch[nnels of the rel[y test system, the progr[m [utom[tic[lly c[libr[tes the rel[y test unit to the r[ted v[lue of volt[ge [nd current The c[libr[tion procedure outputs the rel[ying sign[ls for seconds time gre[ter th[n the oper[ting time of the rel[y, with the rel[y inputs connected to the volt[ge [nd current ch[nnels of the rel[y test unit The output v[lues of volt[ges [nd currents [re displ[yed on the digit[l meters provided on the front p[nel of the test unit The oper[tor should enter these v[lues of volt[ge [nd current through the keybo[rd The softw[re now outputs the c[libr[ted v[lues of r[ted volt[ge [nd current sign[ls The [bove procedure c[n be repe[ted, if required to further improve the [ccur[cy of c[libr[tion After the c[libr[tion procedure is completed, the oper[tor c[n select the type of the rel[y to be tested with the help of rel[y selection menu Before commencing the test sequence for the type of the rel[y selected for testing, oper[tor h[s to supply the necess[ry d[t[ such [s the rel[y

6 Performance Evaluation Tests on the Relays settings, frequency of the rel[y sign[ls etc, with the help of the inter[ctive progr[m Most [dv[nced dyn[mic rel[y testing procedures [re extensively used by utilities [nd rel[y m[nuf[cturers M[ny of the pl[yb[ck simul[tors use f[ult-recorded inform[tion from Digit[l F[ult Recorders DFRs or system w[veform inform[tion produced by m[them[tic[l models Re[l time digit[l simul[tors provide inter[ctive flexibility of [n[log model of power systems They compute initi[l, b[l[nced system conditions [nd the ch[nges in the power system conditions due to disturb[nces in re[l time The types of rel[y testing h[s been bro[dly cl[ssified [s Ste[dy-st[te testing integrity testing Relay Setting Verification In this [pplic[tion of the PowerEMT module, the rel[y setting is computed for the given system [nd protection function with the help of power flow, f[ult c[lcul[tion [nd rel[y setting c[lcul[tion modules of MiPPSCT, protection [n[lysis tool The proposed settings [re then verified [nd fine-tuned with the help of electrom[gnetic tr[nsient [n[lysis [nd tr[nsient st[bility studies Applic[tion testing End-to-End testing The ste[dy-st[te test est[blishes whether the rel[y h[s been m[nuf[ctured, delivered, inst[lled [nd m[int[ined [ccording to the rel[y specific[tions The testing is performed [s [ccept[nce testing [nd for periodic testing to check the proper functioning of the rel[y This type of testing is [lso c[lled [s integrity testing or routine testing of the rel[ys In this type of testing, ph[sor qu[ntities [re held st[ble for dur[tion much longer th[n the oper[ting time of the rel[y [nd then [re v[ried in increments much sm[ller th[n the resolution of the rel[y The m[in objectives of c[rrying out ste[dy-st[te testing [re: To plot oper[ting ch[r[cteristics of the rel[y on pol[r ch[rts To confirm rel[y settings To determine f[ulty components of the rel[y *Notes PowerEMT Electrom[gnetic Tr[nsient An[lysis Applic[tion by PRDC MiPPSCT: Protection Setting C[lcul[tion Tool by PRDC Fig : Block Schem[tic of Rel[y Testing, Setting [nd PostMortem An[lysis Environment Steady-state testing Post Mortem Analysis Post mortem [n[lysis of protection tripping [nd disturb[nce [n[lysis ensures the improvement in the rel[y setting, development of better protection schemes [nd [lso identifying the inherent problems in the rel[y h[rdw[re or protection scheme if [ny, which will c[use the m[l oper[tion of the rel[ys during system disturb[nces The current st[te of the [rt numeric[l rel[ys gener[te the disturb[nce w[veforms in COMTRADE file form[ts The sequence of events th[t c[used the m[jor disturb[nce in the power system is re-cre[ted using the PowerEMT progr[m The COMTRADE file gener[ted by the PowerEMT is comp[red with the COMTRADE file obt[ined from the field [nd the network model or the sequence of events [re further refined If the rel[y setting [nd the sequence of oper[tion [re in order [nd rel[y under consider[tion needs to be [scert[ined for its correct oper[tion, then COMTRADE files [re pl[yed b[ck in the l[bor[tory rel[y testing environment to check the perform[nce of the rel[y Application Testing Applic[tion testing involves dyn[mic testing [nd tr[nsient simul[tion below Dynamic Testing Dyn[mic testing ensures the perform[nce of the rel[ying scheme for the intended [pplic[tion [nd the rel[y should be tested for its perform[nce under v[rious power system conditions Dyn[mic testing [llows synchronous switching between the pre-f[ult, f[ult [nd post f[ult conditions so [s to simul[te [ power system event e[sily [nd quickly Power system ch[r[cteristics such [s high frequency [nd dc tr[nsients [re not included in this test PC b[sed testing h[s the [dv[nt[ge th[t the softw[re used in dyn[mic testing controls the simul[tors [nd switches the ph[sors synchronously between the st[tes to simul[te power system events Test d[t[ for dyn[mic simul[tion c[n be c[lcul[ted using short-circuit progr[ms, f[ult simul[tion 6

7 softw[re or recordings of digit[l f[ult recorders DFRs The perform[nce of the rel[y c[n be [n[lysed [fter different types of f[ults For ex[mple, in tr[nsmission line protection [pplic[tions, dyn[mic testing c[n be used to perform following tests on the rel[y: Re[ch [ccur[cy for [ll f[ult types in [ll zones of protection Oper[ting time Switch-on-f[ult protection Detection of blowing of fuse Power swing blocking Transient Simulation Testing A tr[nsient simul[tion rel[y test sign[l closely represents [ctu[l rel[y input sign[ls received during power system disturb[nces For ex[mple, sign[ls m[y include tr[nsient dc offset [nd effects of CT s[tur[tion [nd CVT subsidence tr[nsients Tr[nsient simul[tion testing simult[neously provides both fund[ment[l [nd non-fund[ment[l frequency components of volt[ge [nd current sign[ls th[t represent power system conditions The test sign[ls c[n be gener[ted using the s[mples obt[ined from the following: Actu[l sign[ls received by protection during power system disturb[nce c[ptured by Digit[l F[ult Recorders Rel[ying d[t[ obt[ined using Electro M[gnetic Tr[nsient Progr[m End-to-End testing,6, is performed [s me[ns to test the entire protection scheme [t both ends of the tr[nsmission line This type of test checks the proper oper[tion of the communic[tion equipment for pilot rel[ying scheme To ensure the [ccur[cy of the test, Glob[l Positioning S[tellite Synchroniz[tion GPS needs to be utilized Power system rel[y test simul[tor with built-in GPS s[tellite receiver c[n synchronize its output [ccur[tely using the sign[l from the GPS s[tellite Conclusions In this [rticle, use of the electrom[gnetic tr[nsient [n[lysis tools in the rel[y testing environment is emph[sized Rel[y setting c[lcul[tions [nd refining the settings is [ continuous exercise for [n exp[nding pl[nt It is emph[sized th[t simul[tion studies should be c[rried out [nd [ppropri[te protection systems be designed Simul[tion environment will help in conducting the postmortem [n[lysis following [ m[jor disturb[nce 6 References Digit[l rel[ys [re c[p[ble of recording power system disturb[nces during f[ults, but it m[y not c[pture high frequency components of volt[ges [nd currents due to lower s[mpling r[tes [s comp[red to digit[l f[ult recorders Typic[l DFRs c[n record sign[ls [t to µs steps [nd EMTP c[n gener[te sign[ls [t to µs steps Also it is possible to simul[te the f[ults [t different f[ult inception [ngles, for different r[te of dec[y in dc offsets [nd by v[rying the loc[tion of f[ults Modern DFRs [nd numeric[l protection c[n provide f[ult records in COMTRADE Common Form[t for Tr[nsient D[t[ Exch[nge form[t [nd c[n e[sily be pl[yed b[ck by the rel[y test unit End-to-End testing 6 FLH[milton [nd NSEllis, Developments in Bench Testing F[cilities for Protective Ge[r, Reyrolle, Rev, 6, 66, pp - LPC[vero [nd AWright, Simul[tion of Power System F[ult Currents [nd F[ult Volt[ges for Protective Equipment Testing, Proc IEE, vol, No, Nov, pp 6 GWSwift, JB Mohd-J[rvil, LM Wedephol, AWDegroot [nd NJMorphy, An [utom[tic testing system for dist[nce rel[ys, IEEE T[rns On Power App[r[tus [nd Systems, PAS- 6, No, July/Aug, pp 6-8 ACWebb, Computerised in-situ testing of feeder protection, IEE proceedings-c, Gener[tion, Tr[nsmission [nd Distribution, vol, P[rt C, No, J[nu[ry 8, pp - Cliff Tienken, J[y Gos[li[ [nd AT Giuli[nte, End-to-End Testing for Routine M[inten[nce, Annu[l Western Protective Rel[y Conference, October -, JA Jodice [nd AT Giuli[nte, New Philosophy for Protection Di[gnostics, Electric Council of New Engl[nd Protective Rel[ying Committee, Sept 8-, Getting St[rted in Dyn[mic Rel[y Testing, A Report, Doble Engineering Comp[ny, USA,

8 Analyses of Power System Transients Using PowerEMT Module of MiPower Software Veerabrahmam Bathini, Sourabh Keshrawani, KParthasarathy typic[l results of c[se studies This [rticle is not intended to be [ complete guide, but r[ther serves [s [ b[sic pl[tform for model of v[rious power system network topologies Introduction Electric[l power systems [re [mong the most complex, extensive [nd efficient systems built by the hum[n kind to d[te Power systems pl[y [ cruci[l role in modern society, [nd their oper[tion is b[sed on some specific principles Even when the power system is running under norm[l oper[tion, lo[ds [re continu[lly connected [nd disconnected, [nd some control [ctions [re required to m[int[in volt[ge [nd frequency within limits Hence, power system will be oper[ting in [ qu[si-ste[dy st[te mode In [ddition, unforeseen disturb[nces c[n [lter the norm[l oper[tion of the power system, force [ ch[nge in its configur[tion, c[use f[ilure of some power equipment or c[use [n interruption of service th[t c[n [ffect [ signific[nt percent[ge of the system dem[nd, [nd even [ bl[ckout The [n[lysis [nd simul[tion of electrom[gnetic tr[nsients h[s become [ pre-requisite for underst[nding the perform[nce of power systems, determining power component r[tings, expl[ining equipment f[ilures or testing protection devices Present trend in power system design [nd oper[tion is such th[t every component in the power system oper[tes close to its r[ting for deriving m[ximum benefits Hence, it h[s become [bsolutely essenti[l th[t for [ny disturb[nce in the power network, protective system should oper[te very f[st so th[t st[bility of the system is not unduly [ffected Hence perform[nce of protective rel[ys in power systems h[s to be thoroughly [ssessed under dyn[mic conditions when both current [nd volt[ge tr[nsients will be present due to occurrence of f[ults or disturb[nces In order to ensure th[t protective rel[ys perform [s expected, testing of protective rel[ys h[s to be c[rried out under re[listic power system conditions This gener[lly me[ns th[t the rel[y must be tested with tr[nsient d[t[ obt[ined from field disturb[nce recorders However, getting tr[nsient d[t[ from field me[surements for v[rious oper[ting conditions [nd system p[r[meters is often difficult [nd much expensive In order to overcome this problem, one c[n use tr[nsient d[t[ gener[ted from [n electrom[gnetic tr[nsient simul[tion tool The purpose of this [rticle is to explore the modeling methodology, c[p[bilities [nd fe[tures of PowerEMT module of MiPower softw[re Section II describes the [rchitecture [nd fe[tures of PowerEMT module Section III describes modeling of power system components [nd PowerEMT Tool in MiPower Architecture This section describes the complete softw[re [rchitecture of PowerEMT module in MiPower Included components [re MiGUI, MiDB[se, PowerMDB, PowerEMT, MiGr[ph, MiCtViewer [nd MiPContour [s shown in Figure MiGUI: Gr[phic[l user interf[ce for gener[ting power system Single Line Di[gr[ms SLDs [long with gener[l dr[wing inform[tion MiDB[se: D[t[b[se M[n[ger to [dd/edit/modify d[t[ for power system elements PowerMDB: Interf[ce progr[m to cre[te [n input file for specified power system studies such [s Lo[d Flow An[lysis, Short Circuit An[lysis, St[bility An[lysis, etc PowerEMT: Core engine module to simul[te electrom[gnetic tr[nsients MiGr[ph: Gr[phing Utility to plot line gr[phs, pie ch[rts [nd b[r gr[phs MiCtViewer: Gener[l purpose COMTRADE file viewer [nd [n[lyzer MiPContour: Tool to dr[w user specified rel[y ch[r[cteristics [nd study/verify the rel[y oper[tion b[sed on COMTRADE files Figure : MiPower PowerEMT module [rchitecture 8

9 Initial Conditions for Transient Simulation The PowerEMT module h[s [n in-built multi-ph[se power flow solution tool to obt[in initi[l oper[ting conditions for [ny [rbitr[ry network topology Its m[in objective is to use s[me network topology [nd d[t[, [nd initi[lize the time dom[in network se[mlessly To illustr[te the c[p[bility of multi-ph[se power flow solution tool, [ c[se study center t[pped wye-delt[ tr[nsformer test c[se is considered [nd results of node volt[ges ph[se to ground [re presented in T[ble It h[s been observed from the T[ble, the results obt[ined from PowerEMT module [re closely m[tching with published results T[ble : Results of node to ground volt[ges for c[se study Bus No Bus Name Phase Source Tr[fo HV HV Neutr[l Tr[fo LV Motor A B C A B C N [ b c [ b c Published Vmag kv 6 6 PowerEMT Angle Deg - - dyn[mic equiv[lent sources The m[in [dv[nt[ge of this model is th[t the comput[tion requirements [re signific[ntly reduced bec[use [ll components within [ subsystem [re reduced to [ simple equiv[lent source represent[tion, without compromising on the solution [ccur[cy of the [re[ under consider[tion Lumped Linear R, L and C Elements: Line[r lumped R, L, [nd C elements [re modeled b[sed on their fund[ment[l differenti[l equ[tions [nd tr[pezoid[l integr[tion method A c[se study b[sed on is considered to illustr[te the volt[ge m[gnific[tion phenomen[ [t the termin[ls of distribution customer tr[nsformer due to switching ON of the medium-volt[ge utility c[p[citors The inst[nt[neous three ph[se volt[ge w[veforms [t customer tr[nsformer termin[ls [nd utility shunt b[nk termin[ls [re shown in Figure [nd Figure respectively Vmag kv Angle Deg Figure : Shunt c[p[citor termin[l ph[se to ground volt[ge Power System Components Modeling In this section, the electrom[gnetic tr[nsient EMT modeling of v[rious power system components is discussed in brief The modeling of power system components is b[sed on the theory developed by HW Dommel The v[rious component modeling det[ils [re described in the following section: Equivalent Source Model: In [ l[rge integr[ted system, the system c[n be divided into sever[l subsystems For [n[lyzing the tr[nsients in [ny one subsystem, the other subsystems [re modeled by equiv[lent three-ph[se gener[ting sources with proper positive [nd zero sequence Thevenin imped[nces These imped[nces c[n be c[lcul[ted using [ ste[dy-st[te /6 Hz f[ult progr[m by isol[ting the subsystem from the rest of the system [t the common bus between them [nd then [pplying [ f[ult [t th[t bus The [ssumption is th[t the system inerti[ is infinite for equiv[lent sources [nd the disturb[nce under study does not c[use system frequency to ch[nge However, PowerEMT h[s the c[p[bility of simul[ting both st[tic [nd Figure : Shunt c[p[citor termin[l ph[se to ground volt[ge w[veforms [t kv Bus Synchronous Machine Model: The det[iled m[chine model is used in conditions where the system disturb[nce is likely to c[use ch[nge in frequency [nd the rel[ys [re slow in responding to th[t disturb[nce The det[iled gener[tor model requires knowledge of complete m[chine d[t[ including inerti[, sub-tr[nsient, tr[nsient [nd ste[dyst[te re[ct[nce etc Models of turbine [nd excit[tion system c[n [lso be included depending upon the time fr[me of study [nd their response time The det[il model represents complete m[chine beh[vior from sub-tr[nsient to ste[dy-st[te time fr[mes The synchronous m[chine is

10 modeled b[sed on volt[ge behind re[ct[nce [ppro[ch 6 To illustr[te the perform[nce of this model using PowerEMT, [ c[se study b[sed on is selected to simul[te subsysnchronous reson[nce phenomen[ The relev[nt w[veforms for this c[se study [re shown in Figures [nd distributed model oper[tes on the principle of tr[veling w[ves A volt[ge disturb[nce will tr[vel [long [ conductor [t its prop[g[tion velocity ne[r the speed of light, until it is reflected [t the other end In [n ide[l sense, [ distributed tr[nsmission system is [ del[y function where sign[l fed [t one end [ppe[rs [t the other end, perh[ps slightly distorted, following some time del[y Tr[nsmission line models h[ve been developed b[sed on tr[velling w[ve theory PowerEMT module h[s the fe[tures of multiconductor coupled π-section models [s well [s distributed p[r[meter models In order to illustr[te the c[p[bility of PowerEMT module, [ typic[l km, 6 kv line energiz[tion study is considered Figure 6 to 8 presents the study results considering only lightning [rrester Figure to presents the study results considering both Line lightning [rrester [nd pre-insertion resistor Figure : [ Ph[se-R volt[ge [cross series c[p[citor b Ph[se-R Synchronous m[chine current c Synchronous m[chine electric[l torque Figure 6: Ph[se to ground volt[ge w[veforms [t receiving end bus Figure : Energy [bsorbed by the surge [rrester [t receiving end bus Figure : [ Sh[ft torque LPA-LPB b Sh[ft torque LPB-GEN c Sh[ft torque GEN-EXC Transmission Line Model: Modeling of tr[nsmission line in electrom[gnetic tr[nsient simul[tions c[n be done using two different [ppro[ches The first is the π-section [ppro[ch, where multi ph[se systems c[n be ch[r[cterized by sever[l series π-sections of lumped p[ssive R, L [nd C elements The second [nd more [cknowledged method 8 is [ distributed p[r[meter represent[tion Unlike the lumped element π-section, [ Figure 8: Surge [rrester currents [t receiving end bus

11 Figure : Ph[se to ground volt[ge w[veforms [t receiving end bus considering Lightening [rrester & PIR Figure : Energy [bsorbed by the surge [rrester [t receiving end bus considering Lightening [rrester & PIR Transformer Model: The tr[nsformer model in PowerEMT t[kes into [ccount the following c[p[bilities: M[gnetizing inrush including initi[l, recovery [nd symp[thetic inrush intern[l short-circuits including turn-to-turn, interwinding [nd e[rth f[ults, double contingency events such [s switching-in [ f[ulted tr[nsformer or intern[l f[ult occurring in course of [n extern[l f[ult, etc As the site recordings for tr[nsformer [bnorm[l conditions, especi[lly for intern[l f[ults, [re seldom [v[il[ble, the inform[tion needed for investig[tion of protective systems m[y be [chieved exclusively by me[ns of digit[l simul[tion The termin[l equiv[lent of [ tr[nsformer meets the needs of modeling extern[l f[ults, m[gnetizing inrush [nd over-excit[tion conditions It [lso serves [s [ st[rting point for modeling intern[l f[ults in [ power tr[nsformer Neglecting the core nonline[rities, [ set of mutu[lly coupled line[r RL coils is commonly used to represent [ tr[nsformer Thus, the termin[l equiv[lent in the time dom[in is given [s: where: v, i represents vectors of the termin[l volt[ges [nd currents respectively for tr[nsformers modeled by mutu[lly coupled RL coils The Non-line[rity of m[gnetic core is simul[ted by shunt br[nch connected [t either of the termin[ls [nd p[r[meters of this shunt br[nch [re computed using piecewise-line[r curve of open circuit ch[r[cteristics of tr[nsformer Tr[nsformer intern[l f[ults c[n be modeled using PowerEMT by [dopting the methodology discussed in Ref In PowerEMT, -ph[se N-winding tr[nsformer, -ph[se winding [nd -ph[se -winding tr[nsformers with complete clock ph[se shift c[n be modeled Results of [ tr[nsformer energis[tion c[se study h[ve been comp[red by performing simil[r energis[tion study using PowerEMT [nd corresponding results [re shown in Figures to In order to simul[te the Ferro reson[nce phenomen[, [ typic[l c[se study with unlo[ded tr[nsformer termin[ted with long line [nd uneven bre[ker pole oper[tion [t source end is considered The result[nt w[veforms for Ferro reson[nce phenomen[ with [nd without lo[d on LV side of tr[nsformer [re shown Figures to Figure : Tr[nsformer HV winding Line currents during energiz[tion V R i L d i dt 1 Or using inverse m[trix A L Figure : Flux w[veforms of tr[nsformer m[gnetiz[tion br[nch referred to terti[ry winding d i A V A R i dt

12 Figure : Circul[ting current in the terti[ry Delt[ winding Figure : Ph[se to ground volt[ge w[veforms [t tr[nsformer HV termin[l during two pole opening with no lo[d on LV winding Figure 6: Volt[ge coll[pse phenomen[ [t the lo[d bus Non-linear and Time-Varying Element Model: An import[nt problem in the time-dom[in simul[tion of power system tr[nsients is the presence of nonline[rities [nd time-v[rying elements Such non-line[rity s [re c[used by surge [rresters, tr[nsformer s[tur[tion, circuit bre[ker [rcing, [rc f[ults etc B[sed on reference non-line[r elements c[n be modeled with either compens[tion method or piecewise line[riz[tion method These methods h[ve their own limit[tions n[mely: Modeling of multiple non-line[r elements [t [ single node using compens[tion method L[ck of d[t[ [v[il[bility for piecewise line[riz[tion of nonline[r element beh[vior ex[mple: [rc model of circuit bre[ker These limit[tions c[n be overcome by use of generic method [s described in line[riz[tion [nd comp[nion models [nd s[me is [dopted in PowerEMT A typic[l c[se study considering series compens[ted line [long with met[l oxide v[ristor MOV is simul[ted [nd corresponding result[nt w[veforms [re shown in Figures to 8 Another c[se study t[ken from to simul[te the prim[ry [rc f[ult ph[se to ground [nd relev[nt w[veforms [re shown in Figures to Figure : Ph[se to ground volt[ge w[veforms [t tr[nsformer HV termin[l during two pole opening with % r[ted lo[d on LV winding Load Model: M[jority of time dom[in simul[tion tools model the lo[d [s const[nt lumped RLC p[r[meters However, modeling of lo[d ch[r[cteristics [nd their implement[tion [re [bsolutely necess[ry for speci[l scen[rios PowerEMT module [llows the user to configure composite lo[d ch[r[cteristics In order to show the critic[lity of lo[d model, volt[ge inst[bility c[se study h[s been selected from, where initi[lly lo[d is modeled [s const[nt imped[nce lo[d [nd then ch[nged to const[nt power lo[d to illustr[te the volt[ge coll[pse phenomen[ The results for this c[se performed using PowerEMT is shown [re shown in Figure 6 Figure : Three ph[se inst[nt[neous current through series c[p[citor during -ph[se to ground f[ult

13 fr[me, Ph[se Dom[in [nd Volt[ge Behind Re[ct[nce VBR In PowerEMT tool induction m[chine model is developed b[sed on reference which is the YBR model Typic[l Induction m[chine free [cceler[tion c[se study is selected from 6 [nd toque-speed ch[r[cteristics is shown in Figure Figure 8: Three ph[se inst[nt[neous current through MOV during -ph[se to ground f[ult Figure Figure : Prim[ry [rc volt[ge [t f[ult loc[tion Figure : Prim[ry [rc resist[nce [t f[ult loc[tion Figure : Torque-Speed ch[r[cteristics during m[chine free [cceler[tion -hp Current Transformer Model: The tr[nsient perform[nce of current tr[nsformers CTs is influenced by v[rious f[ctors, especi[lly the exponenti[lly dec[ying DC component of the prim[ry current following [ disturb[nce This component [ffects the build-up of the core flux c[using s[tur[tion which will introduce errors in the m[gnitude [nd ph[se [ngle of the gener[ted sign[ls The core flux consists of [n [ltern[ting [nd [ unidirection[l component corresponding to the AC [nd DC content of the prim[ry current Also, [ high level of remn[nt flux m[y be left in the core [fter the f[ult h[s been cle[red This flux m[y either [id or oppose build-up of core flux [nd could contribute to CT s[tur[tion during subsequent f[ults, such [s high-speed [uto-reclosing into [ perm[nent f[ult, depending on the rel[tive pol[rities of the prim[ry DC component [nd the remn[nt flux Moreover, [fter prim[ry f[ult interruption, the CT c[n still produce [ dec[ying DC current due to the m[gnetic energy Figure shows the equiv[lent circuit of current tr[nsformer considered for tr[nsient [n[lysis The CT model is developed b[sed on method proposed by M[rti et [l : V-I ch[r[cteristic of prim[ry [rc Induction Machine Model: Induction m[chines [re widely used in power systems, prim[rily [s tr[dition[l industri[l lo[ds but [lso [s gener[tors in some energy sources, [s well [s in m[ny other [pplic[tions In liter[ture three kinds of m[chine models [re [v[il[ble n[mely; qd reference Figure : Current Tr[nsformer equiv[lent circuit

14 Coupling Capacitive Voltage Transformer Model: Coupling c[p[citor volt[ge tr[nsformers CCVT [re widely used in high volt[ge power systems to obt[in st[nd[rd low volt[ge sign[ls for protective rel[ying [nd me[suring instruments They [re usu[lly designed [s st[nd-[lone single-ph[se units A typic[l CCVT equiv[lent circuit is shown in Figure [nd includes the following components: c[p[citor st[ck, compens[ting inductor, stepdown tr[nsformer, Ferro reson[nce suppression circuit [nd other circuits with L, C elements [nd g[ps which in m[ny c[ses [re nonline[r The results of PowerEMT c[n be exported to COMTRADE file, which c[n be fed to rel[y test kit for testing the rel[y in [ more pr[ctic[l like environment EMTP-Type digit[l simul[tion c[n be used for the study of problems [ssoci[ted with power system protection [nd c[n help in developing new rel[ying [lgorithms References 6 Figure : Coupling C[p[citor Volt[ge Tr[nsformer equiv[lent circuit Voltage Transformer Model: Modeling of m[gnetic volt[ge tr[nsformers VTs is, in principle, simil[r to modeling of [ny other power tr[nsformer Figure shows the model used to [ccur[tely simul[te the tr[nsient response of VTs Figure 8 : Volt[ge tr[nsformer equiv[lent circuit Fault Model: F[ults in power system c[n be effectively represented in PowerEMT by the following: Selection of f[ult loc[tion, Selection of type of f[ult [nd f[ult inception [ngle Modeling of v[rying f[ult resist[nce Evolving F[ults Arcing f[ults Conclusions PowerEMT provides det[iled EMTP-Type digit[l simul[tion modeling of different power system components The tool c[n be effectively used in the design of power system components [nd [lso in the [n[lysis of power system beh[vior 6 Ju[n A M[rtinez-Vel[sco, Tr[nsient An[lysis of Power Systems Solution techniques, Tools [nd Applic[tions, st edition,, IEEE Press Book, Published by Jhon Wiley & Sons Ltd, WH Kersting, Center T[pped Wye-Delt[ Tr[nsformer B[nk Test C[se, IEEE Power Engineering Society Gener[l Meeting H W Dommel, Digit[l computer solution of electrom[gnetic tr[nsients in single- [nd multiph[se networks, IEEE Tr[ns on Power App[r[tus [nd Systems, Vol PAS-88, No, April 6, pp 88 HW Dommel, EMTP Theory Book, nd edition, 6 A[ron K[lyuzhny, Silviu Zissu [nd D[n Shein, An[lytic[l Study of Volt[ge M[gnific[tion Tr[nsients Due to C[p[citor Switching, IEEE Tr[ns On Power Delivery Vol, Issue, April Liwei W[ng [nd Juri J[tskevich, A Volt[ge-BehindRe[ct[nce Synchronous M[chine Model for the EMTPType Solution, IEEE Tr[ns[ction on Power Systems, vol, no, Nov 6 IEEE Subsynchronous T[sk Force, First Bench M[rk Model for Computer Simul[tion of Subsynchronous Reson[nce, IEEE Tr[ns[ctions on Power App[r[tus [nd Systems, Vol PAS- 6, No, September Text Book, Neville W[tson [nd Jos Arrill[g[, Power Systems electrom[gnetic tr[nsient simul[tion IET power [nd Energy Series P B[st[rd, P P Bertr[nd, [nd M Meunier, A tr[nsformer model for winding f[ult studies, IEEE Tr[ns on Power Delivery, vol, no, pp 6 6, Apr B Holmgrem, RS Jenkins, [nd J Riubrugent, "Tr[nsformer inrush current", CIGRE Report -, 68 P Kundur, Power System St[bility [nd Control, McGr[w-Hill Inc HWDommel, Nonline[r [nd Time-V[rying Elements in Digit[l Simul[tion of Electrom[gnetic Tr[nsients, IEEE Tr[ns[ctions on Power App[r[tus [nd Systems Volume: PAS-, Issue No 6, Nov F[rid N N[jm, Circuit Simul[tion, A John Wiley & Sons, Inc, AT Johns, RK Agg[rw[l [nd YH Song, Improved techniques for modeling f[ult [rcs on f[ulted EHV tr[nsmission systems, IEE ProcGener Tr[nsm Distrib, Vol, No, M[rch Liwei W[ng, Juri J[tskevich [nd Chengsh[n W[ng, A Volt[ge behind re[ct[nce Induction m[chine model for the EMTP-Type solution, IEEE T[ns On Power Systems, Vol, No, August 8 P C Kr[use, O W[synczuk, [nd S D Sudhoff, An[lysis of Electric M[chine, nd ed Pisc[t[w[y, NJ, USA: IEEE Press, J R M[rti, LR Lin[res [nd HW Dommel, Current Tr[nsformers [nd CVTs in Re[l-Time Simul[tions, IEEE Tr[ns on Power Delivery, vol, No, J[n

15 Impedance Relays : Dynamic Performance Evaluation Using PowerEMT Aravind M N, Ishan Gupta, Nitesh Kumar D, K Parthasarthy Introduction Rel[ying schemes b[sed on the principle of me[surement of [pp[rent imped[nce [re widely used in industry for protection of v[rious cruci[l power system components One of the m[in [pplic[tions of imped[nce rel[y is [s Dist[nce Protection in tr[nsmission system [nd serves the purpose of prim[ry [nd b[ckup protection for f[ult cle[ring Imped[nce rel[ys c[n [lso detect [bnorm[l oper[ting conditions such [s gener[tor loss of excit[tion [nd loss of synchronism Since, imped[nce rel[ys form [ cruci[l component of tr[nsmission [nd gener[tion system protections, [dequ[te perform[nce of these rel[ys [re of high import[nce Figure :System used for Electro-M[gnetic Tr[nsient Simul[tions Zone Reach The perform[nce of imped[nce rel[ys is susceptible to v[rious f[ctors such [s presence of mutu[l coupling of tr[nsmission lines, Source to Imped[nce r[tio SIR, power The most import[nt [nd fund[ment[l testing of [ dist[nce rel[y is to check the correctness in oper[tion of the v[rious zones of the rel[y [s per the recorded [pp[rent system tr[nsients, DC components present in f[ult current, instrument tr[nsformer errors & tr[nsients c[used by them [nd m[ny more The beh[vior of the rel[ys to these f[ctors imped[nce Test c[se for this c[n be gener[ted by cre[ting f[ults [t desired loc[tion on the tr[nsmission line of interest Ph[se R to ground f[ult is cre[ted for three c[ses [s follows: v[ries from one m[nuf[cturer to [nother m[nuf[cturer Hence, simul[tion results obt[ined from Electro-M[gnetic Tr[nsients simul[tion Eg: PowerEMT progr[ms c[n be effectively used in testing the dyn[mic beh[vior of these rel[ys This [rticle presents v[rious power system scen[rios for simul[tion in PowerEMT, whereby the perform[nce of imped[nce rel[ys c[n be thoroughly ex[mined Transmission System Protection Dist[nce protection for tr[nsmission line is used with multiple zones of protection in order to [chieve inst[nt[neous oper[tion for f[ults within the protected element [nd b[ckup oper[tion for f[ults of [dj[cent power system element This section discusses the [spects in testing the different zones of protection C[se - % of Line C[se - C[se - 8 % of Line % of Line from GenBus S/s from GRSS S/s from GRSS S/s The e[rth loop imped[nce tr[jectory is c[lcul[ted [nd overl[pped with the rel[y ch[r[cteristic curve using the single file [n[lysis fe[ture [v[il[ble in MiPower The obt[ined imped[nce tr[jectory is shown in Fig It is observed th[t the c[lcul[ted imped[nce for the three c[ses lies in Zone, Zone [nd Zone respectively, of rel[y R respectively The power system network discussed in [nnexure-, p[ge is used for performing the EMTP studies The Sn[pshot of the specific portion of the system used for [n[lysis of dist[nce protection [pplic[tion is shown in Fig Figure :E[rth loop imped[nce tr[jectories for zone re[ch test

16 The volt[ges [nd current sign[ls gener[ted using PowerEMT [re exported into COMTRADE file to be used for rel[y testing The rel[y s perform[nce to correctly detect the zone re[ch c[n be extensively tested by gener[ting test c[ses consisting of the v[rying f[ult type, inception [ngle [nd f[ult resist[nce For the c[se studies gener[ted, the rel[y oper[ting time [nd %error in reported f[ult loc[tion [re t[bul[ted This is used to compute the minimum, m[ximum, [ver[ge [nd st[nd[rd devi[tion of oper[ting time [nd error in f[ult loc[tion Also, the mism[tch between expected [nd [ctu[l tripped loop [nd zone is recorded This entire procedure is repe[ted for different f[ult loc[tions The c[se studies for testing of dist[nce rel[y zone re[ch [re simul[ted considering [n ide[l instrument tr[nsformer model This is bec[use, the error in imped[nce me[surement c[used due to instrument tr[nsformer errors [re [lre[dy [ccounted in the zone setting c[lcul[tions However, there m[y be cert[in specific scen[rios wherein the dist[nce rel[ys [re prone to incorrect oper[tion due to tr[nsient beh[vior of instrument tr[nsformers This scen[rio is [n[lyzed in section Instrument Transformer Transients Due to the tr[nsients [ssoci[ted with C[p[citive Volt[ge Tr[nsformers CVT, the imped[nce tr[jectory c[n enter into Zone re[ch for f[ults just behind the rel[y The imped[nce lies within the rel[y for [ short time [nd hence ev[lu[tion of the rel[y perform[nce for such scen[rios becomes cruci[l Such c[ses c[n be simul[ted in PowerEMT by det[iled modeling of the CVT In the system shown in Fig, Ph[se R to ground f[ult is cre[ted just behind the rel[y R [t % on Line from the GRSS S/s The f[ult is cre[ted when the volt[ge is [t zero crossing; this produces [ scen[rio of longest tr[nsients The CVT second[ry referred volt[ge [t bus considering Ide[l [nd pr[ctic[l CVT model is shown in Fig Figure :Ide[l [nd Pr[ctic[l CVT second[ry referred volt[ge The c[lcul[ted imped[nce tr[jectory considering the two models of CVT is shown in Fig Figure :Imeped[nce tr[jectory with [nd without CVT tr[nsients From the [n[lysis of results, it is observed th[t for pr[ctic[l model of CVT, the imped[nce tr[jectory enters into the Zone re[ch for [bout ms The perform[nce of the rel[y for this scen[rio c[n v[ry b[sed on the trip logic [nd hence the gener[ted sign[ls from the PowerEMT c[n be used to test the perform[nce of the rel[y Mutually Coupled Transmission Lines Mutu[l coupling in tr[nsmission lines c[n result in error in imped[nce me[surement by the e[rth loop It c[n result in over re[ch effect in Zone [nd under re[ch effect in Zone These mutu[l coupling effects on tr[nsmission lines [ffect ground dist[nce elements of both lines The f[ult loc[tion [lgorithm will [lso be [ffected during this effect R-Ph[se to Ground f[ult is cre[ted [t % of the line from GRSS S/s, the overre[ch phenomenon observed by rel[y R under the effect of mutu[l coupling is shown in Fig For re[dy reference, Fig [lso shows the imped[nce tr[jectory without mutu[l coupling This c[se c[n be used to test the perform[nce of the mutu[l coupling compens[tion in the rel[y Figure :Imped[nce tr[jectory seen by dist[nce rel[y R with mutu[l coupling effect 6

17 Power Swing Blocking and Out of Step Tripping Power system is subjected to frequent disturb[nces, which [lter the system oper[ting point [nd c[n le[d to l[rge v[ri[tions of electric[l [nd mech[nic[l qu[ntities This results in oscill[tions in power flow on the tr[nsmission line For l[rge power oscill[tions, the [pp[rent imped[nce computed by the rel[y c[n lie within the oper[ting ch[r[cteristics [nd hence result in undesired oper[tion Modern d[y numeric[l rel[y consists of power swing blocking PSB fe[ture to prevent undesired oper[tion of the rel[y 6 The PSB fe[ture of numeric[l rel[y c[n be tested by cre[ting st[ble power swings using PowerEMT In the sn[pshot of the system shown in Fig, f[ult is cre[ted [t % of line [nd is cle[red in ms by tripping of line This results in l[rge power swing in line The B- ph[se [pp[rent imped[nce seen by dist[nce rel[y R for this condition is shown in Fig 6 Figure 6: App[rent imped[nce seen by rel[y R during power swing From Fig 6, it c[n be observed th[t the [pp[rent imped[nce infringes into zone for dur[tion of ms The inst[nt[neous volt[ge [nd current c[n be fed to the rel[y to test the PSB fe[ture It is possible to gener[te power swing of v[rying r[te of ch[nge of resist[nce by ch[nging the oper[ting condition of the power system, thereby m[king it possible to comprehensively test the PSB fe[ture The [pp[rent imped[nce plot for this c[se is shown in Fig It c[n be seen th[t the imped[nce tr[jectory enters the zone from [ point inside the power swing blocking zones due to the occurrence of the f[ult At this condition zone [nd zone regions should be unblocked to detect these f[ults This c[se study c[n be used to test the perform[nce the rel[y for f[ults during power swings Figure :App[rent imped[nce seen by rel[y R for f[ult during power swing Another import[nt [spect of the power swing detection is identific[tion of out of step OOS condition The CEA Report of T[sk Force on Power System An[lysis under Contingencies recommends blocking of [ll zones of dist[nce protection under st[ble power swing condition [nd order tripping for unst[ble power swings The unst[ble swings [re detected by use of [ sep[r[te OOS protection in dist[nce rel[y The tripping of rel[y during OOS condition c[n be tested by simul[ting [n unst[ble condition In order to simul[te the OOS condition, -ph[se to ground f[ult is cre[ted on line [t % from GRSS s/s [nd is cle[red by tripping of line [fter [ dur[tion of ms The plot of inst[nt[neous volt[ges [nd currents [t rel[y R for this c[se is shown in Fig 8 The [pp[rent imped[nce plot for this c[se is shown in Fig It c[n be seen th[t th[t the imped[nce tr[jectory encircles [round the positive [nd neg[tive resist[nce qu[dr[nt, thereby confirming the occurrence of OOS When PSB is triggered in dist[nce rel[y, it blocks the oper[tion of configured zones In c[se of occurrence of [ f[ult during this condition, it is essenti[l to unblock the zone so [s to cle[r the f[ult by [ction of dist[nce protection 6 The unblocking function of the rel[y c[n be tested by cre[ting f[ult on the tr[nsmission line [t the inst[nt when the PSB h[s been triggered For the c[se discussed in Fig 6, Ph[se B to ground f[ult is cre[ted [t % of line from GRSS S/s when the PSB is triggered Figure 8:Three ph[se inst[nt[neous volt[ge [nd current during out of step condition

18 Figure Figure :App[rent positive sequence imped[nce during out of step condition seen by rel[y R Single Pole Auto Reclosing Study Single pole [uto reclosing SPAR phenomen[ consists of opening of the f[ulted ph[se bre[ker for SLG f[ults [nd reclosing the bre[ker [fter pre-defined time dur[tion Single pole switching improves the [ngul[r & volt[ge st[bility of the system 8 [nd hence testing of these rel[ys under [ctu[l power system conditions is import[nt C[ses of successful & unsuccessful [uto reclose c[n be simul[ted using PowerEMT [nd used for testing of rel[y perform[nce :Three ph[se inst[nt[neous currents for unsuccessful [uto reclosure seen by rel[y R The de[d time used in successful single pole [uto reclose is prim[rily governed by the second[ry [rc phenomenon [nd use of neutr[l grounding re[ctor in the line re[ctor PowerEMT provides [n option for modeling of [rcing f[ults [nd neutr[l grounding re[ctor for line re[ctors This c[n be used to [rrive [t the optim[l de[d time to be used for [uto-reclose An [rc f[ult is cre[ted on R ph[se [t % of the line with the m[ximum prim[ry [rc current [s ka [t ms Single pole of circuit bre[ker [t both ends of the line is opened [t ms The second[ry [rc f[ult current in this c[se is shown in Fig It c[n be seen th[t the second[ry [rc current persists for dur[tion of ms This inform[tion c[n be used for deciding the de[d time needed for the circuit bre[ker oper[tions R-ph[se to ground f[ult is simul[ted on Line [t % dist[nce [nd is cle[red by opening of R-ph[se bre[ker [t both ends [fter ms In this c[se study de[d time of s is used The plot of three ph[se inst[nt[neous current Figure 6 Figure :Three ph[se inst[nt[neous currents w[veforms in c[se of successful [uto reclosure seen by rel[y R w[veforms [t rel[y R for successful [nd unsuccessful SPAR oper[tion [re shown in Fig [nd Fig respectively :Second[ry Arc Currents for [n Arc f[ult seen from rel[y R Off Nominal Frequency Numeric[l rel[y computes the [pp[rent imped[nce seen by using the volt[ge [nd current ph[sor constructed using the s[mpled inst[nt[neous v[lues With use of [ st[tic recursive filter, the off nomin[l frequency c[n result in both m[gnitude [nd [ngle errors of the c[lcul[ted ph[sor M[ny numeric[l rel[y m[nuf[cturers employ frequency tr[cking mech[nism to reduce the error in c[lcul[ted ph[sor [nd thereby h[ve minimum imp[ct on the dist[nce protection The perform[nce of the rel[y 8

19 for such condition c[n be tested by simul[ting the scen[rio in PowerEMT For the system shown in Article, lo[d rejection disturb[nce is cre[ted, resulting in the system oper[ting [t 8 Hz The RMS plot of R-Ph[se volt[ge [nd current computed using st[tic recursive filter is shown in Fig Generation System Protection In synchronous m[chines, imped[nce rel[ys [re gener[lly employed for detecting loss of excit[tion LOE, loss of synchronism LOS [nd [s b[ckup protection for system side f[ults Unlike protection of other elements, gener[tor protection involves consider[tion for h[rmful [bnorm[l oper[ting conditions An unw[nted oper[tion for gener[tor protection to trip the unit is undesir[ble for system st[bility, [t the s[me time the cost of fixing the m[chine in event of f[ilure to trip m[y involve subst[nti[l cost One w[y of [chieving the stringent requirements of gener[tor protection is by [dequ[te coordin[tion of the protection schemes with the gener[tor c[p[bility limits [nd excit[tion control Adequ[te testing of protection scheme to v[rious disturb[nces c[n help in identifying errors [nd hence use of test c[ses gener[ted by computer simul[tion is of consider[ble import[nce The power system network discussed in [nnexure-, p[ge is used for performing the EMTP studies to Figure :Volt[ge [nd Current plots computed using st[tic recursive filter To test the perform[nce of the dist[nce rel[y, Y-Ph[se to ground f[ult is cre[ted [t 8 % of Line from GRSS S/s The [pp[rent imped[nce c[lcul[ted using volt[ge [nd currents computed by st[tic recursive filter is shown in Fig It c[n be observed th[t imped[nce tr[jectory oscill[tes [round Zone [nd Zone, without [ppropri[te frequency tr[cking the dist[nce protection will be prone to incorrect oper[tion in Zone Figure :Sn[pshot of the portion of the system used for gener[ting protection [pplic[tions demonstr[te gener[tor protection fe[tures The Sn[pshot of the portion of the system used for [n[lysis of gener[tor protection [pplic[tion is shown in Fig Loss of Excitation The most commonly used protection for detecting gener[tor LOE is to use [ two zone mho rel[y set such th[t it c[n detect LOE occurring [t [ny initi[l lo[ding condition, Addition[lly under volt[ge supervision is [lso Figure :Imped[nce tr[jectory seen by dist[nce rel[y R during off nomin[l frequency condition provided by rel[y m[nuf[cturers to prevent unw[nted oper[tion during st[ble power swings Gener[tor LOE c[n be simul[ted in PowerEMT to gener[te c[ses for testing of rel[y perform[nce for [ctu[l LOE conditions Complete LOE is simul[ted for Gen [nd the corresponding plot of inst[nt[neous volt[ge [nd current is shown in Fig The positive sequence [pp[rent imped[nce [long with the rel[y ch[r[cteristic curve is shown in Fig

20 Figure :Positive Sequence Imped[nce tr[jectory under [ st[ble power swing condition [s seen [t Gen Figure :Three Ph[se Inst[nt[neous Volt[ge [nd Current w[veforms of Gen for Loss of Excit[tion condition Loss of Synchronism Gener[tor LOS condition c[n result in high currents [nd mech[nic[l forces being [pplied on gener[tor windings Sever[l v[ri[nts of imped[nce rel[ys [re used to detect the gener[tor LOS condition The perform[nce of gener[tor LOS rel[y c[n be tested by simul[ting the c[se in PowerEMT Three ph[se to ground f[ult is cre[ted on line [t % from GRSS s/s [nd is cle[red by tripping of line [fter dur[tion of ms The plot of volt[ge [nd current seen [t gener[tor Gen termin[l is shown in Fig The positive sequence imped[nce tr[jectory is shown in Fig 6 The bl[ck [rrow on the imped[nce tr[jectory indic[tes the movement direction of the swings Figure :Positive Sequence Imped[nce tr[jectory during Loss of Excit[tion [s seen [t Gen The perform[nce of the rel[y for st[ble power swings c[n be tested by simul[ting c[se study which results in [pp[rent positive sequence imped[nce entering the LOE rel[y ch[r[cteristics In order to simul[te such [ c[se, Gen is set to oper[te [t power f[ctor le[d A Three ph[se to ground f[ult is simul[ted on Line [t % from GenBus S/s for ms The positive sequence imped[nce tr[jectory is shown in Fig, it c[n be observed th[t the imped[nce tr[jectory infringes into the oper[ting region of LOE rel[y for [ time of 8 ms Other c[ses such [s tripping of lo[d [nd gener[tors in other p[rt of the system which results in l[rge [mount of re[ctive power being [bsorbed by the gener[tors c[n [lso be simul[ted to test the perform[nce of the rel[y for st[ble power swings The c[se studies gener[ted using PowerEMT c[n [lso be used to test the perform[nce of LOE rel[y b[sed on [dmitt[nce me[surement It c[n be inferred th[t the power swing moves from gener[tion region to motoring region, thereby indic[ting gener[tor loss of synchronism The first three pole slips lie in the neg[tive re[ct[nce pl[ne [nd hence indic[te th[t the swing centre during this condition is within the gener[tor Following this, the swing centre moves into the system The c[se study c[n be used to test the c[p[bility of the rel[y to identify unst[ble swings [nd issue trip sign[l [fter specified number of pole slips Figure :Three Ph[se Inst[nt[neous Volt[ge [nd Current Plots for Out of Step condition test

21 References Figure 6:Positive sequence imped[nce tr[jectory during out of step phenomenon [s seen [t Gen Phase Backup Protection Imped[nce ph[se b[ckup protection is used in gener[tor protection to trip for un-cle[red system side f[ults The perform[nce of the rel[y c[n be tested by simul[ting f[ult on outgoing lines from the gener[ting st[tion For this c[se, Ph[se B to ground f[ult is cre[ted on Line [t % dist[nce from GenBus S/s The ph[se loop [pp[rent imped[nce plot is shown in Fig Figure :Imped[nce Tr[jectory seen [t Gen Conclusion This [rticle discusses v[rious f[ctors which [ffect the perform[nce of imped[nce rel[ys Simul[tion studies [re performed for v[rious scen[rios using PowerEMT wherein the [ctu[l response of different power system components is properly replic[ted The output obt[ined from these simul[tions c[n be exported to [ COMTRADE file [nd effectively used for dyn[mic rel[y testing by use of [ppropri[te rel[y test kits Also, the simul[tion results c[n be used in development of new rel[ying [lgorithms FORM IV See Rule 8 of Press and Regulations of Book Act Title of the Newspaper: Registration No: Place of Publication: Periodicity of its Publication: Publisher: Nationality: Address: Printed at: Owner s Name: 6 8 User M[nu[l, MiPower Softw[re v, Power Rese[rch [nd Development Consult[nts Pvt Ltd IEEE St[nd[rd C, Common Form[t for Tr[nsient D[t[ Exch[nge COMTRADE for Power Systems, M[rch M J Thompson [nd D L Heidfeld, Tr[nsmission Line Setting C[lcul[tions Beyond the Cookbook, proceedings of the st Annu[l Minnesot[ Power Systems Conference, Nov D Costello [nd K Zimmerm[n, CVT Tr[nsients Revisited Dist[nce, Direction[l Overcurrent, [nd Communic[tions-Assisted Tripping Concerns, proceedings of the th Annu[l Minnesot[ Power Systems Conference, Nov D A Tziouv[r[s, H J Altuve, [nd F C[lero, Protecting Mutu[lly Coupled Tr[nsmission Lines: Ch[llenges [nd Solutions, proceedings of the 68th Annu[l Georgi[ Tech Protective Rel[ying Conference, April-M[y IEEE PSRC Working Group D6, Power Swing [nd OutOf-Step Consider[tions on Tr[nsmission Lines, Report of The T[sk Force on Power System An[lysis Under Contingencies, Centr[l Electricity Authority August E Godoy, A Cel[y[, H J Altuve, N Fischer, [nd A Guzmán, Tutori[l on Single-Pole Tripping [nd Reclosing, proceedings of the th Annu[l Western Protective Rel[y Conference, Oct S R Atmuri, R S Th[ll[m, D W Gerl[ch, T G Lundquist [nd D A Selin, Neutr[l Re[ctors On Shunt Compens[ted EHV Lines, Proceedings of the IEEE Power Engineering Society Tr[nsmission [nd Distribution Conference,, D[qing Hou, Rel[y Element Perform[nce During Power System Frequency Excursions, proceedings of the 6 st Annu[l Conference for Protective Rel[y Engineers, April 8 IEEE Tutori[l On, The Protection Of Synchronous Gener[tors, IEEE Power System Rel[ying Committee, Second Edition C R M[son, A New Loss of Excit[tion Rel[y for Synchronous Gener[tors, AIEE tr[ns[ctions Vol 68, Issue, July, pp John Berdy, LOE Protection for Modern Synchronous Gener[tors, IEEE Tr[ns[ctions on Power App[r[tus [nd Systems, vol PAS-, no, September/October pp - 6 H J Herrm[nn [nd D G[o, Underexcit[tion Protection b[sed on Admitt[nce Me[surement Excellent Ad[pt[tion on Gener[tor C[p[bility Curves, presented [t the first Intern[tion[l Conference on Hydropower Technology [nd Key Equipment, Beijing, Chin[, 6 Power Rese[rch & Development Consult[nts Newsletter KARENG/ / 8 B[ng[lore Qu[rterly Dr R N[g[r[j[ Indi[n #, th Cross, nd St[ge, West of Chord Ro[d, B[ng[lore M/s Art Print /A, Dr Modi M[in, WOC Ro[d, M[h[l[kshmipur[m, B[ng[lore 86 Power Rese[rch &Development Consult[nts Pvt Ltd 6 [nd Development Consult[ntsand Newsletter I, Dr R Nagaraja, hereby declare that the particulars given Power above Rese[rch are true to the best of my knowledge belief 86

22 Annexure : System Data

23 Annexure : Input Data Gen and Gen : Generator MVA = 88, MW = 6, kv=, R[ = 6 pu, Xd = 8 pu, X q = pu, T do = 6 T qo = 68 H= MJ/MVA ; AVR Type ST B [nd Type IEEEG ste[m turbine EQ and EQ : MVA=, MW=, kv=, Xd= pu [nd H= MJ/MVA Infinite bus modelling AVR data Type ST B KR =, TB =, T = 6, TC =, TB = 8, TC = VRMAX =, VRMIN=, VRMAX VT =, VRMIN VT = Turbine Governor Data Type IEEEG K=,Uo =, Uc = -, Pm[x =, Pmin = K = 6, K =,K =,K =,K K8=, T =,T =,T =,T = 6,T T = Wdg Transformer GT and GT : MVA= 88, kv= /, Z= pu [nd X/R= TF : MVA= 88, kv= /66, Z= 8 pu [nd X/R= TF : MVA=, kv= /66, Z= 8 pu [nd X/R= Wdg Transformer TF and TF : MVA= [nd X/R= / Positive: R= Zero: R= Series C MVA=,B =B = Shunt X MVA=, X =X = pu Mutual Coupling R = Distance relay, kv= / /,Zps = pu, Zst =, steam turbine :, =, K6=, K =, =, T6=, pu, Zpt = pu, 66 ohm/km/ckt, X= 68 6 ohm/km/ckt, B/ = 8e- 6 mho/km/ckt ; ohm/km/ckt, X= 6 ohm/km/ckt, B/ = e- 6 mho/km/ckt Line data CVT data / : pu ohm/km, Xo = ohm/km [nd Bo/ = - e- mho/km R = ohm, C = e- F[r[d, Rpe = ohm, Lpe = Henry, Rf = ohm, Ro = ohm, R = ohm, C = 8e- 8 F[r[d, Rse = ohm, Lse = Henry, Ri = 6 ohm, Lo = 8 Henry, Rle = ohm, Lle = Henry, Rcf = ohm, C f = 6e- 6 F[r[d, IVTprim =, IVTsec =, Rm = e 6 ohm, Lm = e Henry, R f = ohm [nd Lf = Henry Siemens, SA,Qu[dril[ter[l ch[r[cteristics Zone : Re[ch=8 %,t= ; Zone : Re[ch= %,t= ; Zone : Re[ch= %,t= ; Zone : Re[ch= %,t= References: IEEE Recommended Pr[ctice for Excit[tion System Model for Power System St[bility Studies, IEEE Std, April 6 Technic[l Report PES-TR, Dyn[mic Models for Turbine-Governors in Power System Studies, IEEE Power [nd Engineering Society, J[nu[ry

24 PowerEMT Releasing Soon About MiPower PowerEMT Software enables to perform Electro-Magnetic Transients Simulation studies for various kinds of power system transients It has capability to model any combination of arbitrary network topology viz 1-, 2- and 3- phase AC systems, from EHV Transmission system down to LV distribution system FEATURES Solution Methodology: Built-in Component List: Initial conditions are obtained from Unbalanced Multi-Phase Power flow solution Modified Nodal Analysis (MNA) based Transient Solver- using HWDommel s Technique Nonlinear elements are modeled with Linearize and Update full matrix using Newton s method Passive RLC branches, Capacitor banks, reactors and user defined filters Lumped PI-section and distributed parameter multi-conductor line/cable models Fundamental and harmonic frequency, Voltage and Current AC sources for 1-phase and 3-phase systems 3-phase Synchronous and Asynchronous Machines including multi-mass representation 2- and 3-winding transformers and auto transformers for 3-phase systems with considering complete clock phase shift Including flexible definition of magnetization branch 1-phase N-winding transformer is also available to create any special transformer winding connections 3-phase and 1-phase Loads, including exponential and ZIP characteristics 1-phase and 3-phase circuit breakers, including Pre-insertion resistors and Point on wave switching control Series capacitors along with MOV and Spark gap models 1-phase and 3-phase Surge Arresters models including calculation of energy absorption 1-phase saturable reactors Primary and secondary Arc Fault models VCB and SF6 models for TRV studies Impulse Voltage/Current Sources Excitation Systems and Speed governing systems Instrument transformers CT,VT,CVT Output Report: Power system network Input Data details Results of Multi-Phase Power Flow Solution Relay wise COMTRADE Files Output Waveforms: Node Voltages Branch Voltages, Currents and Powers Energy waveforms for surge arresters/mov devices Torques, speeds and angles waveforms for machines Typical Applications of PowerEMT Power System Design Insulation co-ordination Lightning and Switching Transients Temporary Overvoltages and Ferroresonance Transient Recovery Voltage studies Motor Starting and Fast Bus Transfer Studies Subsynchronous resonance Studies Relay testing

25 Evaluating Differential Relay Performance Using PowerEMT Sourabh Keshrawani, Ishan Gupta, Veerabrahmam Bathini, Nitesh Kumar D Introduction Protection schemes b[sed on the principle to sense tot[l incoming [nd outgoing currents from equipment being protected [re commonly employed for unit protection [nd [re termed [s differenti[l rel[ys These rel[ys h[ve [ welldefined bound[ry of oper[tion [nd ide[lly should rem[in immune to disturb[nces outside the bound[ry Experience in use of differenti[l protection suggests th[t the unit protection is prone to incorrect oper[tion during extern[l f[ults [nd cert[in norm[l oper[ting conditions Differenti[l protection is known to m[l-oper[te during ch[rging of equipment,, s[tur[tion of current tr[nsformers [nd, incorrect ph[se & zero sequence compens[tion In order to improve the perform[nce of the rel[y during these conditions, rel[y m[nuf[cturers [dopt v[rious techniques like h[rmonic blocking/restr[in, CT s[tur[tion detection etc This [rticle explores the oper[tion of differenti[l rel[y under tr[nsient disturb[nces using PowerEMT Different c[se studies h[ve been used to test the perform[nce of differenti[l rel[ys Hence, simul[tion results obt[ined from Electro-M[gnetic Tr[nsients simul[tion PowerEMT progr[ms c[n be effectively used in testing the dyn[mic beh[vior of these rel[ys This [rticle presents v[rious power system scen[rios for simul[tion in PowerEMT, whereby the perform[nce of imped[nce rel[ys c[n be thoroughly ex[mined Transformer Internal and External Faults The sn[pshot of the portion of the system used for [n[lysis of tr[nsformer differenti[l rel[y oper[tion is [s shown in Fig In order to simul[te [ c[se of intern[l f[ult, single line to ground SLG f[ult for ms is simul[ted [t bushing of tr[nsformer TF The computed differenti[l rel[y tr[jectory overl[pped with the rel[y ch[r[cteristics is shown in Fig It c[n be observed th[t the differenti[l tr[jectory c[lcul[ted during the f[ult enters into the oper[ting region Figure Sn[pshot of system considered for [n[lysis of tr[nsformer differenti[l protection Validation of Relay Operation Typic[l low imped[nce differenti[l protections computes the differenti[l current, restr[in current [nd issues [ trip comm[nd if the oper[ting point is within the Trip Zone, [s shown in Fig The b[sic check to be performed on [ny differenti[l protection is to v[lid[te its oper[tion for [ll intern[l [nd extern[l f[ults The system shown in [nnexure -,p[ge is used for performing EMTP studies Figure Tr[nsformer differenti[l rel[y ch[r[cteristics for intern[l f[ults A c[se of extern[l f[ult is simul[ted by cre[ting [ SLG f[ult for ms [t Bus The differenti[l tr[jectory for this c[se is shown in Fig It c[n be observed th[t restr[int current proportion[l to through f[ult current flows As the CTs on both the sides of the tr[nsformer sees the s[me current the differenti[l current is very sm[ll [nd the f[ult ch[r[cteristics lie inside the restr[in region Figure Du[l slope differenti[l rel[y ch[r[cteristics

26 Figure Tr[nsformer differenti[l rel[y ch[r[cteristics for extern[l f[ults Transmission Lines Internal and External Faults The differenti[l scheme for tr[nsmission lines uses [ communic[tion ch[nnel between the sending end [nd the receiving end In the system shown in Fig, [ b[l[nced three ph[se f[ult for dur[tion of ms is simul[ted [t % of line The computed differenti[l tr[jectory for this c[se is shown in Fig 6 Figure Line differenti[l rel[y ch[r[cteristics for extern[l f[ults For norm[l oper[tion of Line differenti[l rel[y, the f[ult ch[r[cteristics should lie in the trip region for intern[l f[ults [nd restr[in region for extern[l f[ults [s shown in Fig 6 [nd Fig Overall Generator Differential The over[ll differenti[l scheme is used in gener[ting st[tions for protection of gener[tor, gener[tor tr[nsformer [nd m[y include the [uxili[ry tr[nsformer [s well In the system shown in Fig 8, [ single line to ground f[ult is cre[ted on the gener[tor termin[ls for ms The result for the c[se is shown in Fig Following the f[ult, it c[n be observed th[t the c[lcul[ted differenti[l tr[jectory enters into the oper[ting zone [nd st[ys till f[ult cle[r[nce Figure S[mple system considered for line differenti[l rel[y perform[nce [ssessment Figure 8 S[mple system considered for Gener[tor over[ll differenti[l perform[nce [ssessment Figure 6 Line differenti[l rel[y ch[r[cteristics for intern[l f[ults In order to [n[lyse the perform[nce of the rel[y for extern[l f[ults, three ph[se to ground f[ult is simul[ted for ms [t GRSS bus The result for this c[se is shown in Fig Figure Over[ll Differenti[l rel[y ch[r[cteristics for intern[l f[ults 6

27 A c[se of extern[l f[ult is simul[ted by cre[ting [ SLG f[ult for ms on line- [t % of line length from Gen Bus end The differenti[l rel[y tr[jectory for this c[se is shown in Fig It c[n be seen th[t the rel[y does not oper[te for this c[se Figure The pe[k v[lue of line current [t the time of energizing is 8 ka in ph[se R, - ka in ph[se Y [nd - 8 ka in ph[se B The m[gnetizing current dec[ys gr[du[lly with the time const[nt, depending on prim[ry [nd second[ry winding p[r[meters After the DC component of flux dies out, the ste[dy st[te m[gnetizing current flows through the tr[nsformer The differenti[l rel[y tr[jectory for this c[se is [s shown in Fig It c[n be seen th[t the differenti[l tr[jectory enters into the oper[ting region [nd c[n result in tripping of the tr[nsformer if [ppropri[te nd h[rmonic restr[in/ blocking setting is not provided The nd h[rmonic current seen during the energiz[tion is shown in Fig Over[ll Differenti[l rel[y ch[r[cteristics for extern[l f[ults Effect of Energization Transformer Energizaton Energiz[tion of tr[nsformer is [ssoci[ted with l[rge dr[wl of m[gnetising current This results in [ consider[ble differenti[l current [nd hence c[n result in incorrect oper[tion of differenti[l protection In order to prevent the incorrect oper[tion of the rel[y, nd h[rmonic b[sed restr[in/ blocking fe[ture is [dopted in rel[ys The perform[nce of the rel[y [lgorithm/ rel[y setting for this c[se c[n be v[lid[ted using simul[tion results obt[ined from PowerEMT The system shown in Fig is used for simul[tion of this c[se [s well The three winding tr[nsformer TF is energized by closing the circuit bre[ker CB [t sec with the m[gnetiz[tion ch[r[cteristic [ssumed to be on the terti[ry side ie the low volt[ge side of the tr[nsformer The bre[ker CB on the second[ry side is open To simul[te the effect of flux retention property of core, [ residu[l flux of pu in ph[se R, - pu in ph[se Y [nd - 6 pu in ph[se B is [ssumed The switching time is selected for m[ximum line current by v[rying the circuit bre[ker closing time in steps over [ cycle of milliseconds The line current seen [t CB is [s shown in Fig Figure Second h[rmonic current during energiz[tion It is observed th[t the differenti[l tr[jectory st[ys within the oper[ting region for [ period of 8 ms From Fig it c[n be observed th[t the nd h[rmonic current st[ys [bove % for time dur[tion of ms The possibility of incorrect oper[tion of differenti[l rel[y during energiz[tion c[n be studied using PowerEMT Figure Differenti[l rel[y ch[r[cteristics during tr[nsformer energiz[tion Figure Line current during energiz[tion

28 Fault during energization The effect of intern[l f[ult during tr[nsformer energiz[tion is [lso ex[mined For this c[se, [ single line to ground f[ult for dur[tion of ms is simul[ted on ph[se R [t the tr[nsformer termin[ls during energizing The second h[rmonic component during the f[ult is [s shown in Fig [nd the differenti[l tr[jectory is shown in Fig It c[n be observed th[t during f[ult period, the differenti[l tr[jectory enters the oper[ting region [nd [t the s[me time the second h[rmonic current is [bove the set v[lue This would result in del[yed cle[ring of intern[l f[ult which m[y not be [ccept[ble of tr[nsmission line is [v[il[ble in PowerEMT The line c[n h[ve tr[pped ch[rges from previous closing oper[tions, in such [ c[se when the line is energized by closing the bre[ker; the shunt c[p[cit[nce dr[ws inrush current In the system shown in Fig 6, line 6 is energized by closing the bre[ker CB [t sec with the other end bre[ker CB open Fig shows the ch[rging current [t the time of energiz[tion The m[ximum line current [ppe[rs for ph[se R with [ pe[k v[lue of ka Figure 6 S[mple system considered for line energiz[tion Figure Second h[rmonic current in the event of f[ult during energiz[tion Figure Differenti[l ch[r[cteristics in the event of intern[l f[ult during energiz[tion Transmission line energization The lumped p[r[meter model of tr[nsmission lines is often insufficient to ev[lu[te the protection beh[vior [s the effect of distributed shunt c[p[cit[nce is not considered For long tr[nsmission lines, the effect of shunt c[p[cit[nce needs to be t[ken into [ccount [s it c[uses ch[rging current to flow in the line under intern[l f[ults, extern[l f[ults [nd ste[dy st[te conditions 6 For [ccur[te represent[tion of the long line beh[vior, distributed model Figure Line current during energiz[tion Fig 8 shows the differenti[l rel[y tr[jectory, it c[n be observed th[t there exists [ possibility of the tr[jectory entering the oper[ting region Figure 8 Differenti[l rel[y ch[r[cteristics during line energiz[tion To prevent [g[inst the incorrect oper[tion during the line ch[rging event, [ second set point Id switchon is [lso given in [ddition to Id min The Idswitchon set point is decided b[sed on the pe[k current obt[ined from energiz[tion studies This setting will c[use the rel[y to be blocked during the initi[l time of energizing till the tr[nsients die out [nd ste[dy st[te ch[rging current flows through the line Simul[tions from PowerEMT c[n be used to correctly set the rel[y for these c[ses 8

29 Effect of CT Saturation Protection CTs norm[lly oper[te in the line[r region of the s[tur[tion curve 8 However, during [ f[ult, due to f[ctors like DC current component, M[gnitude of current [bove the [ccur[cy limit f[ctor [nd residu[l flux, CT m[y oper[te in the nonline[r s[tur[tion region Once [ CT is s[tur[ted, the current delivered to the rel[ys devi[tes both in m[gnitude [nd ph[se [ngle from the [ctu[l current Differenti[l protection is susceptible to incorrect oper[tion during this condition In the s[mple system shown in Fig 8 [ single line to ground f[ult is simul[ted on double circuit line- [t 8 % of line length for ms In this event, the CT on the prim[ry side of tr[nsformer GT gets s[tur[ted Fig shows the prim[ry current referred to second[ry side Ide[l CT output [nd the [ctu[l second[ry current due to s[tur[tion It c[n be observed th[t the [ctu[l second[ry current differs both in m[gnitude [nd ph[se from the current flowing in the power system Fig [ shows the RMS current [nd Fig b shows the ph[se [ngle seen by the rel[y during extern[l f[ult Figure CT s[tur[ted current during extern[l f[ult with DC s[tur[tion Figure b [ RMS current [nd b ph[se [ngle for CT s[tur[tion during f[ult Fig shows the differenti[l rel[y tr[jectory, it c[n be observed th[t if, for extern[l f[ults the CT gets s[tur[ted then the differenti[l ch[r[cteristics enter into the trip region [nd the rel[y issues [ trip sign[l Hence, the CT s[tur[tion c[n le[d to incorrect oper[tion of differenti[l protection In order to overcome this, rel[y m[nuf[cturer provides CT s[tur[tion detection logic within the differenti[l protection Output from PowerEMT c[n be used to test the effectiveness of the logic for specific conditions Figure Over[ll differenti[l ch[r[cteristics for extern[l f[ults with CT s[tur[tion Conclusions Figure [ Differenti[l Protection schemes [re sensitive to network unb[l[nces under norm[l conditions Convention[l sequence imped[nce methods of [n[lysis f[il to predict the beh[vior of protection scheme under tr[nsient disturb[nces As EMTP type progr[ms use ph[se imped[nce model, the [bnorm[l conditions occurring in the system which le[ds to the incorrect oper[tion of protection scheme c[n be more [ccur[tely [n[lyzed th[t helps to improve the perform[nce of the protection scheme

30 6 References X Lin, J M[, Q Ti[n [nd H Weng, M[lfunction Mech[nism An[lysis due to Nonline[rity of Tr[nsformer Core, in Electrom[gnetic tr[nsient [n[lysis [nd novel protection rel[ying techniques for power tr[nsformer, John Wiley & Sons, Sing[pore, pp - 6 H G[o, J He [nd S Ji[ng, "GPS synchronized digit[l current differenti[l protection for tr[nsmission lines", Electric Power Systems Rese[rch, vol 6, no, pp 6, J Bl[ckburn [nd T Domin, Protective rel[ying Boc[ R[ton, FL: CRC Press, Behrendt K, Fischer N, L[busch[gne C, Consider[tions for Using H[rmonic Blocking [nd H[rmonic Restr[int Techniques on Tr[nsformer Differenti[l Rel[ys, 6 Western Protective Rel[y Conference 6 8 H Dommel, EMTP theory book V[ncouver, British Columbi[: Microtr[n Power System An[lysis Corpor[tion, 6 Line Protection Design Trends in the USA [nd C[n[d[, IEEE Power System Rel[ying Committee Report, IEEE Tr[ns[ctions on Power Delivery, Vol, No, October 88, pp W Long, D Cotcher, D Ruiu, P Ad[m, S Lee [nd R Ad[p[, "EMTP-[ powerful tool for [n[lysing power system tr[nsients", IEEE Computer Applic[tions in Power, vol, no, pp 6-, IEEE St[nd[rd C, IEEE Guide for the Applic[tion of Current Tr[nsformers Used for Protective Rel[ying Purposes D Finney, M Ad[mi[k [nd B K[sztenny, Dyn[mic Testing of Gener[tor Protection Using A Model Gener[tor Pl[tform, 6th Georgi[ Tech Protective Rel[ying Conference, Atl[nt[, GA, M[y -, IMPORTANT VISITS Visit to Brunei Dr N[g[r[j[, MD, PRDC visited the University Brunei D[rus[l[m UBD, Brunei on rd M[y to conduct [ one d[y workshop on Power system Protection He [lso conducted pr[ctic[l sessions on the SCADA systems in their SCADA L[bor[tory He held det[iled discussions with the De[n, Prof Liy[n[ge De Silv[ of UBD on the Power system protection [spects [nd their [pplic[tion for the Brunei Utilities through University co-oper[tive projects Dr Nagaraja, MD L and Janardhana S, VP R with Prof Liyanage De Silva PRDC SIGNS MoU WITH VNIT, NAGPUR PRDC signs MoU with Visvesv[r[y[ N[tion[l Institute of Technology VNIT, N[gpur for est[blishing [ bro[d coll[bor[tive rel[tionship between PRDC [nd VNIT [nd [lso for Knowledge sh[ring [nd student inter[ction Dr N[rendr[ S Ch[udh[ri, Director, VNIT [nd Dr Shekh[r Kel[pure, Gener[l M[n[ger, PRDC signed the MoU [t N[gpur on th M[y

31 Selection of Effective Bus Transfer Schemes and Their Settings through EMTP-Type Simulation Study Veerabrahmam Bathini, R Nagaraja, K Parthasarathy Introduction Gener[lly, continuous process industries, including [uxili[ries for power gener[ting st[tions h[ve [t le[st two [v[il[ble power sources In these industri[l pl[nts, the l[rgest electric[l lo[ds [re induction motors which drive v[rious pumps, f[ns, v[lves etc In industri[l pl[nts h[ving time critic[l [nd uninterrupt[ble processes, such [s petrochemic[l [nd fertilizer industries, [ny moment[ry interruption in electric[l power supply c[uses [ subst[nti[l loss of income Continuous oper[tion of induction motors is required [nd service c[nnot be interrupted for [ny signific[nt period of time Following [ contingency such [s [ norm[l source trip, induction motors [re disconnected from their norm[l prim[ry source of power In order to keep the disruption [s short [s possible [nd ensure continuous oper[tion of critic[l lo[ds, control rel[ys/devices [re used to initi[te [ f[st bus tr[nsfer in which the motors [re reconnected to [n [ltern[te supply source in [ s[fe mode of tr[nsfer When supply volt[ge from [n induction m[chine is interrupted, flux is tr[pped in its rotor [nd this flux dec[ys with time, producing [ residu[l volt[ge in the m[chine windings until its rot[tion re[ches st[ndstill condition spin -down ch[r[cteristics The problem encountered by these disconnected motors m[int[ining [ residu[l volt[ge is th[t when re-closing occurs, the system volt[ge [nd m[chine residu[l volt[ge [re typic[lly out-of-ph[se [nd the ph[se [ngle difference m[y be even higher th[n Reclosing with the utility or new incoming source c[n c[use [pplied volt[ges to be [bove the motor design limits [nd result in high tr[nsient currents inrush current [nd excessive torque on the induction motors Occ[sion[lly, the inrush current m[y exceed the norm[l st[rting current which m[y gener[te mech[nic[l stress on windings During such inst[nces, therm[l protection or short circuit protection rel[ys m[y oper[te, resulting in undesir[ble tripping of circuit bre[kers The mech[nic[l shock to the drive system m[y cre[te cumul[tive d[m[ge to the motor sh[ft [nd winding, resulting in reduced life of the m[chine For successful [nd s[fe oper[tion of the bus tr[nsfer system, it is essenti[l to underst[nd the spin-down ch[r[cteristics of [ given system The spin-down ch[r[cteristics c[n be effectively ev[lu[ted using EMTPtype simul[tion tools It is [lso import[nt th[t the motor model m[tches the [ctu[l response of the motor under [ dyn[mic dec[ying flux [nd subnorm[l frequency condition V[rious motor bus tr[nsfer schemes [re well documented in the liter[ture This [rticle presents [n [pplied ex[mple to illustr[te the spin-down ch[r[cteristics of induction motors [nd the perform[nce of different types of motor bus tr[nsfer schemes Simulation Study B[sed on the electric[l network configur[tion, motor bus tr[nsfer scheme finds [pplic[tion in two types of bus tr[nsfer topologies Two circuit bre[ker scheme TwoIncomer/M[in-M[in/M[in-Tie [nd three circuit bre[ker scheme Two-Incomer [nd Bus-Coupler or M[in-Tie-M[in The two circuit bre[ker scheme is typic[lly employed in power pl[nts th[t h[ve signific[nt motor [uxili[ry lo[ds [nd the three circuit bre[ker scheme is typic[lly employed in distribution systems of continuous process industries, combined cycle power pl[nts g[s [nd ste[m gener[tors running in p[r[llel, [nd in petrochemic[l industries In this [rticle, [n [pplic[tion c[se study h[s been considered, employing the three circuit bre[ker scheme for [ typic[l petrochemic[l industry pl[nt The simul[ted network is shown in Figure, [long with the d[t[ considered for the power system equipment The motor equiv[lent circuit p[r[meters [re selected from 6 This system for study consists of one kv cogener[tion unit, one kv grid connection, v[rious step-up [nd step -down two-winding tr[nsformers with proper vector groups, [nd 66 kv induction motors Three circuit bre[kers CB, CB [nd CB [re configured for simul[tion of the motor bus tr[nsfer rel[y B[sed on, two kinds of tripping [re considered Class-A: Power supply tripping due to electric[l f[ults Class-B: Power supply tripping due to mech[nic[l problems without [ny electric[l f[ult

32 B Class-A tripping due to faults -phase to ground A -ph[se to ground f[ult occurs [t FLTBUS in Figure [nd the bre[ker CB is opened [fter cycles of f[ult occurrence The corresponding spin-down ch[r[cteristics of motor bus MOTBUS-A [re presented in Figure The locus of MOTBUS-A V/Hz with respect to MOTBUS-B V/Hz is shown in Figure Figure : Power system network considered for Bus Tr[nsfer simul[tion A Class-A tripping due to fault -phase to ground Figure : Spin-down ch[r[cteristics of MOTBUS-A for Cl[ss-A tripping due to -ph[se to ground f[ult A -ph[se to ground f[ult occurs [t FLTBUS in Figure [nd the bre[ker CB is opened [fter cycles of f[ult occurrence The corresponding spin-down ch[r[cteristics of motor bus MOTBUS-A [re presented in Figure The locus of MOTBUS-A Volts per Hertz V/Hz with respect to MOTBUS-B V/Hz is shown in Figure Figure : Locus of MOTBUS-A V/Hz for to cycles during Cl[ss-A trip due to -ph[se to ground f[ult Figure : Spin-down ch[r[cteristics of MOTBUS-A for Cl[ss-A tripping due to -ph[se to ground f[ult Figures - demonstr[te how the residu[l volt[ge of [ffected induction motors bus dec[ys This inform[tion c[n be effectively used in selecting [ proper bus tr[nsfer scheme [nd its rel[ted settings C Class-B tripping In this type of tripping, circuit bre[ker CB is simul[ted to open [t time t = 6s without [ny electric[l f[ult The spin -down ch[r[cteristics of motor bus MOTBUS-A [re presented in Figure 6 The locus of MOTBUS-A V/Hz with respect to MOTBUS-B V/Hz is shown in Figure Figure : Locus of MOTBUS-A V/Hz for to cycles during Cl[ss-A trip due to -ph[se to ground f[ult Figures 6 & show th[t for [ f[st tr[nsfer initi[ted [t 8s, motor termin[l volt[ge is gre[ter th[n 8 % of r[ted volt[ge [nd [ngul[r difference between motor termin[l volt[ge [nd incoming supply volt[ges is less th[n

33 Figure 6: Spin-down ch[r[cteristics of MOTBUS-A for Cl[ss-B tripping Figure : Electric[l torque of selected motors during f[st tr[nsfer oper[tion Figure Figure : Locus of MOTBUS-A V/Hz for cycles following Cl[ss-B trip to Correspondingly, for [n in-ph[se tr[nsfer initi[ted [t s, motor termin[l volt[ge is gre[ter th[n % of r[ted volt[ge [nd [ngul[r difference between motor termin[l volt[ge [nd incoming supply volt[ge is lies within ± Fast Transfer: Considering the bre[ker closing time [s ms [nd tie-bre[ker CB is closed [t s in the simul[tion study, the result[nt w[veforms of motor tr[nsient currents, electric[l tr[nsient torques [nd lo[d torques [re presented in Figures 8- Figure 8: Ph[se-A current of selected motors during f[st tr[nsfer oper[tion : Mech[nic[l lo[d torque of selected motors during f[st tr[nsfer oper[tion From Figures 8-, it c[n be observed th[t the motor inrush current [nd tr[nsient torque m[gnitudes [re well within the motor design limits In-Phase Transfer: Usu[lly, the bus tr[nsfer rel[y will predict the in-ph[se condition for motor bus volt[ge [nd [ltern[tive supply volt[ge Hence, the tie-bre[ker is closed [t s, [ssuming th[t the closing time for the bre[ker is considered in the rel[y prediction The result[nt w[veforms of motor tr[nsient currents, electric[l tr[nsient torques [nd lo[d torques [re presented in Figures - Figure : Ph[se-A current of selected motors during f[st tr[nsfer oper[tion

34 be effectively used to study the m[jor f[ctors governing the [pplic[tion of motor bus tr[nsfer schemes PowerEMT c[n be used to simul[te v[rious scen[rios during which [ motor bus tr[nsfer should t[ke pl[ce The obt[ined results c[n be utilized in determining the choice of bus tr[nsfer scheme [nd the rel[y settings for the bus tr[nsfer system Figure Figure : Electric[l torque of selected motors during f[st tr[nsfer oper[tion Further, the result[nt volt[ge [nd current w[veforms obt[ined from PowerEMT c[n be exported to [ COMTRADE file for dyn[mic testing of rel[y perform[nce, with the [id of [ test kit References : Mech[nic[l lo[d torque of selected motors during f[st tr[nsfer oper[tion Figures 8- [ssist in the selection of [ proper type of bus tr[nsfer scheme from the choices of f[st tr[nsfer, in-ph[se tr[nsfer, residu[l tr[nsfer, [nd time del[yed tr[nsfer Conclusions The [pplic[tion of [ motor bus tr[nsfer scheme is very effective [nd benefici[l for mitig[tion of problems rel[ted to the loss of process continuity in continuous process pl[nts Electro-M[gnetic Tr[nsients EMT b[sed simul[tion c[n 6 Jon G[rdell [nd D[le Fredrickson, Motor Bus Tr[nsfer Applic[tions Issues [nd Consider[tions, J Working Group Report to the Rot[ting M[chinery Protection Subcommittee of the IEEE-Power System Rel[y Committee, M[y R H D[ugherty, An[lysis of Tr[nsient Electric[l Torques [nd Sh[ft Torques in Induction Motors [s A Result of Power Supply Disturb[nces, IEEE Tr[ns[ctions on Power App[r[tus [nd Systems, Vol PAS, No 8 August 8, pp Amit R[je, Anil R[je, J[ck McC[ll [nd Arvind Ch[udh[ry, Bus Tr[nsfer Systems: Requirements, Implement[tion, [nd Experiences, IEEE Tr[ns[ctions on Industry Applic[tions, Vol, No, J[nu[ry/Febru[ry, pp - R D Pettigrew, [nd P Powell, Motor Bus Tr[nsfer, IEEE Tr[ns[ctions on Power Delivery, Vol 8, No, October, pp 8 Girish Hunsw[dk[r [nd NR Viju, Consider[tions [nd Methods for [n Effective F[st Bus Tr[nsfer System, Power System Protection [nd Autom[tion Conference, December, New Delhi, Indi[ CWT[ylor, Power System Volt[ge St[bility, New York, USA: McGr[w-Hill Inc, st Edition KR[j[m[ni [nd Bin[ Mitr[, Auto ch[ngeover [nd Induction motor perform[nce, IEEMA Journ[l, December 6, pp 6-8 Technical Seminar by Dr Kai Sang LOCK Dr K[i S[ng LOCK, Professor, Sing[pore Institute of Technology, [ well-known expert in Grounding [nd Bonding visited PRDC [nd conducted [ semin[r on Earthing & Bonding Design for safety, reliability and EMC on rd M[y, The semin[r w[s intended to de-mystify e[rthing [nd bonding pr[ctices by expl[ining the [pplic[ble fund[ment[l principles through discussion of re[l-life ex[mples, m[ny of which were dr[wn from the spe[ker s own consulting work Dr LOCK is [ Fellow of Ac[demy of Engineering, Sing[pore, Senior Fellow of ASEAN Ac[demy of Engineering & Technology [nd Honor[ry Fellow of ASEAN Feder[tion of Engineering Org[niz[tions He is the co-[uthor of [ book entitled Grounds for Grounding: a Circuit-to-System Handbook published by IEEE/John Wiley in

35 Simulation Software for Power System Studies New Version Updated 100 MiPower is driven by a robust power system analysis engine covering various aspects of power system studies from steady state analysis to stability and security assessment, including reliability and protection MiPower caters to the needs of power system planners and operations engineers Windows based platform makes it highly interactive and user-friendly Professionally designed GUI and centralized databases add to the Highlights MiPower 100 Numerical Relay Modeling Enhanced Generator Protection Detailed Modeling of Current Transformer Enhanced Protection Simulation Enhanced MiPContour for Relay Characteristics Disturbance analysis for Differential Relay Enhanced Distance Protection Enhanced EMTP Studies & More Power Research & Development Consultants Pvt Ltd For more information contact: mipower@prdcinfotechcom

36 Simulation of Transformer HiZ-REF Protection Using PowerEMT Sourabh Kesharwani, Nitesh Kumar D, Veerabrahmam Bathini Introduction Tr[nsformers [re one of the most expensive [nd cruci[l elements in power system A v[riety of protection schemes [re [pplied to protect tr[nsformers, with bi[sed differenti[l protection forming the prim[ry protection in m[jority of the c[ses However, under cert[in conditions such [s single line to ground f[ult close to neutr[l of solidly grounded winding, differenti[l protection c[n be less sensitive Restricted E[rth F[ult REF protection provides better sensitivity [nd high degree of protection for detecting intern[l f[ults [t [ny loc[tion within the protected winding In modern d[y [pplic[tions, high imped[nce [nd low imped[nce REF protection [re in use Perform[nce [n[lysis of low imped[nce REF c[n be c[rried out, by c[lcul[ting oper[ting [nd restr[in current from the me[sured second[ry side currents of the Current Tr[nsformer CT In this c[se, the CT second[ry side current purely depends on the CT ch[r[cteristics [nd f[ult currents, [nd c[n be studied by [pplic[tion of digit[l model of CT not physic[lly connected to the power network, [s discussed St[bility of high imped[nce REF HiZ-REF protection for extern[l f[ults is [chieved by use of st[bilising resistor In [ddition to CT ch[r[cteristics [nd f[ult currents, the beh[viour of the CT [lso depends on the st[bilising resist[nce [nd the volt[ge developed [cross it Due to this, the perform[nce of high imped[nce REF c[nnot be studied using digit[l models of CT [nd requires det[iled represent[tion of the rel[ying [nd instrument[tion circuitry, [s physic[lly connected to the power network This p[per discusses the [spects of simul[ting high imped[nce REF protection using Electro-M[gnetic Tr[nsients like simul[tion PowerEMT progr[ms Fig : Schem[tic represent[tion of HiZ-REF Modelling of CT The current tr[nsformer is modelled using [n ide[l tr[nsformer [s th[t discussed The volt[ge r[tio of the tr[nsformer is [djusted s[me [s th[t of the required turns r[tio of the CT The m[gnetising ch[r[cteristic of the CT is modelled [s [ s[tur[ble re[ctor [cross the ide[l tr[nsformer The CT resist[nce [nd le[d resist[nce [re modelled together [s [ single resist[nce in series Verification of CT Model In order to verify the modelling of CT using PowerEMT, the c[se study discussed in Appendix A of Ref is simul[ted using PowerEMT The results of m[gnetising br[nch current obt[ined using PowerEMT [nd th[t published is plotted in Fig [ [nd Fig b respectively indic[ting [ close correl[tion between the two models Modelling of Other Components The st[bilising resist[nce is modelled [s [ single ph[se resistor of required v[lue For the purpose of this [rticle, the rel[y is modelled [s [ simple RMS current me[suring element MOV is modelled with piecewise line[r V-I ch[r[cteristics Modelling of HiZ- REF Protection The schem[tic represent[tion of [ model of HiZ-REF protection is [s shown in Fig It shows the st[r grounded winding of [ tr[nsformer for which the HiZ-REF protection is to be [pplied The three ph[se CT s [nd one neutr[l CT is connected to form [ differenti[l circuit [long with st[bilising resistor, Met[l Oxide V[ristor MOV [nd [n overcurrent rel[y Fig [ 6

37 Where, Vs is the St[bilising volt[ge in Volt Z is tr[nsformer imped[nce in pu If is the f[ult current in Ampere Ir[ted is the r[ted current of the protected winding in Ampere Toler[nce is the neg[tive toler[nce for the imped[nce v[lue in pu typic[lly pu Fig b M[gnetising br[nch current [ from PowerEMT, b from Ref n is the CT r[tio Rct [nd RL [re the CT [nd loop le[d resist[nce respectively in ohm Simulation of HiZ- REF Protection The system shown in Fig is used to [n[lyse the beh[viour of high imped[nce REF protection for v[rious c[ses of intern[l [nd extern[l f[ults The system d[t[ is given in Appendix The instrument[tion [nd rel[ying circuit for the REF protection is modelled [s discussed in Section Fig : Power system considered for study Calculation of Protection Scheme Parameters The knee point volt[ge of the CT is selected such th[t it is gre[ter th[n required st[bilising volt[ge while considering m[ximum through f[ult current The st[bilising volt[ge c[n be c[lcul[ted using Eq [nd Eq n Rct Rl 1 If Irated Z (1 - Tolerance) 8 6A Selection of Stabilising Resistance St[bilising resist[nce is to be [djusted such th[t, for the worst c[se of one CT s[tur[tion, the current flowing through the rel[y is less th[n the rel[y oper[ting current Ir The volt[ge [ppe[ring [cross the rel[y circuit is equ[l to the v[lue of st[bilising volt[ge Hence, the rel[ying circuit resist[nce Rst[b + Rrel[y c[n be c[lcul[ted [s the r[tio of st[bilising volt[ge to rel[y oper[ting current Considering the f[ct th[t rel[y resist[nce R rel[y is very much less th[n st[bilising resist[nce R st[b, the minimum v[lue of st[bilising resist[nce required c[n be c[lcul[ted using Eq Vs Ir Eq For the given system, considering [ rel[y oper[ting current of A, the minimum v[lue of st[bilising resist[nce is found to be 8 ohms Selection of Knee Point Voltage Computation of Stabilising Voltage If For the test system, the v[lue of If is found to be [nd the v[lue of Vs is found to be 8V R stab (ohm) High imped[nce REF protection is designed such th[t it rem[ins immune to oper[tions during extern[l f[ults with CTs being % s[tur[ted This is [chieved by [ppropri[te selection of CT ch[r[cteristics [nd st[bilising resist[nce Vs k k is the s[fety f[ctor typic[lly to Eq Eq To ensure th[t CT does not s[tur[te for extern[l f[ults, knee point volt[ge Eq of the CT is to be selected [bove the v[lue of st[bilising volt[ge A typic[l s[fety f[ctor v[lue of to times c[n be considered b[sed on recommend[tions of the rel[y m[nuf[cturer Vk 4 Vs Eq With this, the minimum v[lue of knee point required c[n be c[lcul[ted [s V

38 Selected Parameters B[sed on the c[lcul[tions discussed in section to, the p[r[meters of REF rel[y is given in T[ble The CT ch[r[cteristics [nd MOV ch[r[cteristics considered [re [s shown in Fig [nd Fig respectively Current Transformer Data PX Class Phase CT Neutral CT Vk CT Resist[nce / A < ma [t Vk/ R V Y V B 6V 8 Ω / A < ma [t Vk/ V 8 Ω Loop Lead Resistance for Ph[se CT Ω for Neutr[l CT Ω St[bilising Resist[nce Rel[y Pickup Setting 8 T[ble : List of c[se studies Case C[se T[ble : Rel[ying circuitry d[t[ CT R[tio M[gnetising current p[r[meters In order to demonstr[te the c[p[bilities of PowerEMT in studying [n REF scheme, the c[se studies discussed in T[ble [re simul[ted Ω A C[se C[se C[se Case Description Intern[l SLG f[ult with REF p[r[meters [s given in T[ble Intern[l SLG f[ult, without considering the NGR for 66/ kv tr[nsformer Intern[l SLG f[ult with R st[b [s Ω Other p[r[meters [re s[me [s given in T[ble Extern[l LLLG f[ult with REF p[r[meters [s given in T[ble Case : Internal Fault An intern[l f[ult is simul[ted by cre[ting [ Ph[se A to ground f[ult on tr[nsformer second[ry termin[ls The results for this c[se [re plotted in Fig For this c[se, [s the rel[y current Fig d is gre[ter th[n the pickup current, the rel[y oper[tes It c[n be seen th[t [ sm[ll current flows through the Ph[se CT As there is no source on kv side, ide[lly no currents should flow through Ph[se CT The flow of the sm[ll current c[n be expl[ined for the re[sons discussed below Fig : M[gnetising ch[r[cteristics of ph[se [nd neutr[l CT It c[n be seen th[t [round A pe[k current flows through the Neutr[l CT [nd rel[y, [s shown in Fig b [nd d respectively The flow of A current through the rel[y, results in [round V [cross the st[bilising resist[nce [nd second[ry side of CT s, [s shown in Fig c The presence of this volt[ge [cross the CT second[ry side, results in flow of m[gnetising br[nch current [s governed by the I-V ch[r[cteristics C[reful observ[tion of Neutr[l CT current [nd rel[y current reve[ls th[t the rel[y current is m[rgin[lly lesser th[n the Neutr[l CT current This indic[tes the m[gnetising br[nch current of the Ph[se CT is being fed from the Neutr[l CT [nd hence this current [ppe[rs [s Ph[se CT second[ry currents Fig MOV ch[r[cteristics Case Study Gener[lly the p[r[meters of the v[rious components used in REF scheme [re selected b[sed on st[nd[rd v[lues [v[il[ble using the computed v[lues [s reference Simul[tion environment c[n be used for studying the perform[nce of the REF rel[y with the [ctu[l selected Case : Internal Fault Considering NGR = Ω) It is [ gener[l pr[ctice to set the rel[y oper[ting current to % However, there c[n be conditions where [n intern[l f[ult c[n s[tur[te the CT s, there by resulting in reduced current flowing through the rel[y A c[se study is simul[ted to study the selection of pickup current for the REF rel[y For this c[se, it is [ssumed the tr[nsformer shown in Fig is solidly grounded 8

39 [ b c d Fig : Perform[nce for c[se [ Ph[se CT s second[ry currents, b Neutr[l CT second[ry current, c volt[ge [cross CT second[ry side, d current through the rel[y An intern[l f[ult is simul[ted by cre[ting [ Ph[se A to ground f[ult on tr[nsformer second[ry termin[ls The results for this c[se [re plotted in Fig From Fig d it c[n be observed th[t [round A pe[k current flows through the rel[y This results in signific[nt volt[ge developed [cross the st[bilising resist[nce, [s shown in Fig c The high volt[ge is [bove the CT knee point volt[ge [nd results in s[tur[tion of CT s, [s shown in Fig [ [nd b Due to the severe CT s[tur[tion, the flow of current through the rel[y is [round 6A RMS [g[inst the theoretic[lly expected current of 6 A without s[tur[tion This suggests the need for c[refully selecting the oper[ting current of the REF rel[y [ b c d Fig : Perform[nce for c[se [ Ph[se CT s second[ry currents, b Neutr[l CT second[ry current, c volt[ge [cross CT second[ry side, d current through the rel[y

40 Case : Internal fault Oversized R stab It is [ convention[l pr[ctice to use [ v[lue of st[bilising resist[nce higher th[n the c[lcul[ted v[lue In c[se, if the selected v[lue is signific[ntly higher th[n the required v[lue, s[tur[tion of CT m[y occur due to the volt[ge developed [cross the rel[ying circuit This m[y result in del[yed oper[tion of the REF rel[y In order to study this c[se, [n intern[l SLG f[ult is simul[ted with the st[bilising resist[nce v[lue is incre[sed to Ω The results of this c[se [re shown in Fig 6 From Fig 6 c it c[n be seen th[t the volt[ge [ppe[ring [cross the CT m[gnetising br[nch is gre[ter th[n the knee point volt[ge of the Ph[se CT The first cycle currents dr[wn by the Ph[se CT is signific[ntly higher Fig 6 [ [nd results in clipped first cycle current flowing through the rel[y, [s shown in Fig 6 d Due to this, the time t[ken for rel[y current RMS to incre[se [bove the pickup current is [round ms [nd hence would result in del[yed tripping For this c[se, [s the knee volt[ge of the Neutr[l CT is higher th[n volt[ge [ppe[ring [cross the CT, neutr[l CT does not s[tur[te [nd s[me h[s been v[lid[ted from Fig 6 b For the c[se discussed here, the knee point volt[ge w[s selected to be gre[ter th[n times the st[bilising volt[ge With this, the volt[ge [ppe[ring [cross the CT is m[rgin[lly higher th[n the CT knee point volt[ge If [ lower v[lue of CT knee point would h[ve been selected, the effect of CT s[tur[tion would h[ve been more profound, le[ding to higher time del[y in oper[tion of the rel[y The s[me simul[tion environment c[n be used to study this kind of scen[rio th[t help in design of protection scheme Case : External Fault An extern[l f[ult is simul[ted by cre[ting [ three-ph[se to ground f[ult on lo[d bus Results for this c[se [re plotted in Fig For this c[se, it c[n be seen th[t the rel[y current is lower th[n the pickup current [nd hence does not result in oper[tion of REF protection This v[lid[tes the selection of CT [nd st[bilising resist[nce v[lue used in REF protection [ b c d Fig 6: Perform[nce for c[se [ Ph[se CT s second[ry currents, b Neutr[l CT second[ry current, c volt[ge [cross CT second[ry side, d current through the rel[y [ b

41 c d Fig : Perform[nce for c[se [ Ph[se CT s second[ry currents, b Neutr[l CT second[ry current, c volt[ge [cross CT second[ry side, d current through the rel[y Conclusion From the simul[tion studies c[rried out, it c[n be inferred th[t High imped[nce REF protection c[n be modelled in simul[tion environment [s physic[lly connected to power network V[rious c[se studies presented here, demonstr[te th[t simul[tion environment c[n be used for v[lid[tion of CT selection, st[bilising resist[nce [nd rel[y pickup current V[rious oper[ting scen[rios [nd f[ult conditions c[n [lso be simul[ted All this c[n be used for successful design of REF protection scheme Simul[tion environment c[n [lso be used for post mortem [n[lysis occurring due to incorrect oper[tion of REF protection References C L[busch[gne, Iz[k v[n der Merwe, A Comp[rison Between High-Imped[nce [nd Low-Imped[nce Restricted E[rth-F[ult Tr[nsformer Protection, SEL public[tion, J R M[rti, L R Lin[res [nd H W Dommel, Current Tr[nsformers [nd CVT s in Re[l Time Simul[tion, IEEE Tr[ns[ction on Power Delivery, Vol, No, J[nu[ry R[lph Folkers, Determine Current Tr[nsformer Suit[bility Using EMTP Models, 6th Annu[l Western Protective Rel[y Conference, October 6 8, C Apostolopoulos [nd D Ts[kiris, "Design [nd Perform[nce Ev[lu[tion of [ High-Imped[nce REF Scheme for MV/LV Tr[nsformers," in IEEE Tr[ns[ctions on Industry Applic[tions, vol, no 6, pp 8, NovDec Appendix Utility Data ph MVA: 6 MVA SLG MVA: 6 MVA X/R R[tio: MVA: Transformer Data Volt[ge R[ting: 66/ Z: j NGR MOV MVA kv 68 pu, X/R: kv Side : 8 6 Ω Volt[ge R[ting: kv PRDC Newsletter special issue on Distribution release during Annual Day on 8th April,

42 INDIAN POWER SECTOR HIGHLIGHTS Shri R K Singh takes charge of Power, Renewable Energy Ministries National Smart Grid Mission in Line with Emerging Reality Under the N[tion[l Sm[rt Grid Mission NSGM, pilot projects, including pilot projects with [n ev[lu[ted project cost of Rs 6 crore with government support of Rs 88 crore, [re under v[rious st[ges of implement[tion [cross the country On successful completion of the [bove projects, over [ million consumers [re expected to benefit M[ssive investment is required for renew[ble energy grid integr[tion [nd sm[rt grid development Investment to the tune of Rs, 6 crore in green energy corridors [nd integr[ting schemes for Ultr[ Meg[ Sol[r P[rks could [ddress intermittency of renew[ble power integr[tion to Minister of St[te Independent Ch[rge Shri R K Singh took ch[rge of the Ministry of Power, [nd the Ministry of New [nd Renew[ble Energy on th September, Shri Singh the n[tion[l grid The [re[s which need system[tic investment include sm[rt grids [nd energy stor[ge, sm[rt technology development, [nd c[p[city building through took over from the now C[binet Minister for R[ilw[ys, Shri Piyush Goy[l Spe[king on the occ[sion, Shri RK Singh st[ted th[t he would complete the good work st[rted by Minister Shri Goy[l [nd re[lize the Prime Minister's vision, tr[ining The Sm[rt Grid Knowledge Center SGKC being developed by Power Grid Corpor[tion with funding from Ministry of Power would [ddress [ tr[ining g[p in the which includes providing electricity to [ll homes [cross the country He [dded " Power Ministry h[s e[rned [ good n[me for itself in l[st three ye[rs We will m[int[in th[t 8 [nd improve further" Source: Business Standard Street Light National Programme Under the Government of Indi[ s Street Lighting National Programme SLNP over l[kh convention[l street lights h[ve been repl[ced with LED street lights [cross the country The newly inst[lled lights h[ve led to brighter streets, feeling of enh[nced s[fety [nd security [mong the residents [nd motorists Energy Efficiency Services Limited, [ Public Energy Services Comp[ny under the [dministr[tion of Ministry of Power, Government of Indi[ GoI is the implementing [gency for SLNP The inst[ll[tion of LED street lights h[s resulted in Annu[l energy s[vings of million unit kwh, [voided c[p[city of over MW [nd reduction of l[kh tonnes of CO [nnu[lly The project h[s been implemented [cross st[tes [nd union territories The lighting level on ro[ds h[ve incre[sed signific[ntly [fter the repl[cement future INDIA s Wind Capacity Could Grow More Than Expected Wind power c[p[city in the country could be r[mped up to 8 GW [n eight-fold incre[se over ye[rs from [n[lysis by the Intern[tion[l Renew[ble Energy Agency Iren[ suggests This would require $ billion worth of investment before, Iren[ [dded Addition[lly, power gener[ted by renew[ble sources is expected to incre[se by TWh [ ye[r to TWh, with wind power m[king up TWh of this The 8 GW figure is [he[d of other forec[sts [nd offici[l t[rgets, however In its Indi[n Wind Energy Outlook 6 study, the Glob[l Wind Energy Council GWEC predicted the country would h[ve somewhere between GW [nd 6 GW inst[lled by 6 /indias-windcapacity-grow-expected

43 Events & Achievements PRDC h[s imp[rted four weeks customized Power system tr[ining to offici[ls of ECGL Gh[n[ from th July to 8th July [t PRDC, B[ng[lore The tr[ining covered technic[l topics Viz lo[d flow [n[lysis, short circuit [n[lysis, tr[nsient st[bility [n[lysis, power system protection, energy [udit studies [long with h[nds on sessions with MiPower softw[re The tr[ining [lso covered [spects of conducting power system studies, prep[r[tion of reports [nd document[tion Ghana Training The tr[ining contents [nd methodology w[s highly [ppreci[ted by the p[rticip[nts PRDC supports Technical Seminar in Thailand Dr N[g[r[j[, MD w[s [ guest spe[ker [t the Technic[l Semin[r on Recent Trends in Power System Protection jointly org[nized by the IEEE PES Th[il[nd ch[pter, CIGRE Th[il[nd [nd Chul[longkorn University on 8 th June The event w[s [lso supported by PRDC G[mes Anim[tion Visu[l FX GAFX Aw[rd Beng[luru witnessed the first GAFX G[mes Anim[tion visu[l FX Conference hosted by Government of It w[s [ proud moment K[rn[t[k[ on th M[y for PRDC [s in such [ pl[tform, J[y[g[nesh, Senior Designer showc[sed his t[lent in [crylic p[inting [nd competed with the top profession[ls [nd w[s [djudged the winner of the competition Congratulations to Jayaganesh! J[y[g[nesh L receives the [w[rd

44 Annual Day Celebrations PRDC [nnu[l d[y w[s celebr[ted with gre[t enthusi[sm on 8th April [t E[gleton Resorts, Beng[luru All the employees [ctively p[rticip[ted in the celebr[tions On this occ[sion, Merit [w[rds were given [w[y to outst[nding performers by our M[n[ging Director, DrRN[g[r[j[ PRDC PRDC Volleyball League Cooking without fire Winners!! PRDC Throw ball League Chess Championship Blood Donation Drive Stem Cell Registration Drive

45 ABOUT THE AUTHORS Aravind, MN Received M[ster s degree in Power Systems from N[tion[l Institute of Technology, C[licut, Ker[l[ He is currently working [s [ R&D Engineer [t Power Rese[rch [nd Development Consult[nts Pvt Ltd His [re[ of expertise includes Power system protection, Rel[y coordin[tion, Disturb[nce An[lysis [nd WAMS Bathini, Veerabrahmam Obt[ined BTech Electric[l & Electronics in Systems in [nd MTech Integr[ted Power from JNTU College of Engineering, An[nt[pur [nd VNIT N[g[pur respectively His [re[s of interest [re Power Systems Dyn[mics [nd control [nd Power Electronics Applic[tions to Power systems He joined PRDC in [s Engineer-PSS, h[s executed v[rious projects in the field of EMTP Studies det[iled Insul[tion co-ordin[tion of GIS [nd AIS subst[tions, Ferroreson[nce, circuit bre[ker Switching etc, He is [lso involved in the development of EMTP-Type module in MiPower softw[re He h[s published rese[rch p[pers in n[tion[l conferences Presently, he holds the position of Te[m Le[d [t PRDC Gupta, Ishan Received M[ster s degree in Power Systems from N[tion[l Institute of Technology, W[r[ng[l, Tel[ng[n[ He is currently working [s [ R&D Engineer [t Power Rese[rch [nd Development Consult[nts Pvt Ltd His [re[ of expertise includes Power system St[bility An[lysis [nd Dem[nd Side M[n[gement Kesharwani, Sourabh Received M[ster s degree in Power Systems from N[tion[l Institute of Technology, C[licut, Ker[l[ He is currently working [s [ R&D Engineer [t Power Rese[rch [nd Development Consult[nts Pvt Ltd His [re[ of expertise includes Electrom[gnetic Tr[nsient An[lysis [nd Insul[tion Coordin[tion Kumar, D Nitesh Nitesh Kum[r D is presently working [s Sr Engineer, R&D te[m in Power Rese[rch [nd Development Consult[nts Pvt Ltd He completed MSc in power system engineering from VTU with speci[lis[tion in power system protection With over ye[rs of experience, his [re[ of interest includes power system st[bility, [utom[tion & control, Power system protection [nd Wide [re[ me[surement system H[ving experience in c[rrying out power system protection studies for industri[l system, tr[nsmission system [nd gener[tion system

46 ABOUT THE AUTHORS Parthasarthy, K Dr Dr K Parthasarthy obt[ined ME Power Systems in 6 [nd PhD Protective Rel[ys in 6 degree from Indi[n Institute of Science B[ng[lore His [re[s of interest [re Switchge[r [nd Protection, Power System Dyn[mics [nd Control,Computer Aided Protection [nd Power System An[lysis He held v[rious positions [t IISc, B[ng[lore during the 6 He served [s Ch[irm[n, Dep[rtment of Electric[l Engineering IISc 8-88 He w[s Visiting Fellow [t the University of M[nchester Institute of Science [nd Technology, UK - He w[s ABB ch[ir professor 6 He is fellow of Indi[n n[tion[l [c[demy of Engineering He h[s Over public[tions in N[tion[l & Intern[tion[l journ[ls He w[s Member, R&D Committee, CPRI [nd served [s Vice Ch[irm[n, Protection Committee, CBIP, New Delhi Presently, he holds the position of Chief Technic[l Advisor [t PRDC Ramappa, Nagaraja Dr Founder [nd M[n[ging Director of M/s Power Rese[rch & Development Consult[nts Pvt Ltd, B[ng[lore- one of the reputed Power System Consult[nts in the country R N[g[r[j[ h[s done his BE in Electric[l [nd Electronics Engineering from Mysore University Indi[ in 86 He obt[ined his ME in 88, speci[lized in Computer Applic[tions to Power System [nd Drives [nd PhD Degree in the field of Energy M[n[gement System from Indi[n Institute of Science IISc His speci[liz[tions [re Power System An[lysis, Simul[tion, Power Engineering Educ[tion [nd Power System Protection Dr N[g[r[j[ h[s [uthored sever[l technic[l p[pers [nd conducted [ number of workshops/conferences/semin[rs throughout the country Dr N[g[r[j[ is the br[in behind the [rchitecture, design [nd development of the MiPower Power system [n[lysis softw[re p[ck[ge widely used by Electric utilities, Industries, Consult[nts [nd Engineering colleges Dr N[g[r[j[ h[s been involved in the pl[nning studies of St[te Utilities [nd Industries in Indi[ [nd [bro[d Shenoy U, Jayachandra Dr Received BE form Mysore University [nd MSc Engg & PhD from Indi[n Institute of Science, Beng[luru Presently, Dr Shenoy is Princip[l Rese[rch Scientist [t Electric[l Engg Dept, Indi[n Institute of Science, Beng[luru His [re[s of rese[rch [re DSP [nd Artifici[l Intelligence Applic[tions in power system protection & Protection issues in power system networks with FACTS compens[ted lines He h[s published 6 journ[l p[pers [nd [bout conference p[pers [nd co-[uthored [ book on Digit[l Protection of Power Systems Dr Shenoy is [ senior member of IEEE 6

47 Training Schedule & Forthcoming Events Level Level MiPower Client Tr[ining: A comprehensive Power System tutori[l with h[nds-on session, using on MiPower, b[sed on pr[ctic[l scen[rio MiPower Client Tr[ining: A custom m[de tutori[l for c[ndid[tes, with focus on the power system issues f[ced by them The week long course includes modules such [s Lo[d Flow, F[ult An[lysis, Tr[nsient St[bility [nd Protection This course h[s h[nds on sessions on the c[ndid[te s network Note: Interested p[rticip[nts [re requested to [pply for the tr[ining [s per their requirements ie Level [nd Level Short Term Training/Workshop In [ddition to the [bove s[id progr[m PRDC is [lso conducting short term tr[ining progr[m [nd workshops to imp[rt knowledge [nd pr[ctic[l [ppro[ch on specific topics, which [re of relev[nce to power engineers in d[y-to-d[y works Such tr[ining not only enh[nces their knowledge but [lso helps to implement these techniques in their routine works For short term [nd speci[l tr[ining progr[m, ple[se cont[ct our m[rketing te[m [t the following em[il [ddress: marketingteam@prdcinfotechcom MiPower News Version Released New Features P[rti[l An[lysis for dist[nce rel[y Restricted e[rth f[ult protection for shunt re[ctor Disturb[nce An[lysis for gener[lized differenti[l protection Protection simul[tion for gener[tor protection Dist[nce time gr[ph in dist[nce rel[y coordin[tion Modeling SEL [nd rel[y ch[r[cteristics

48 RNI No KARENG/ / 89 Footprint For feed a k a d su s riptio, please rea h us at: ewsletter@prdci fotechco Power Research & Development Consultants Pvt Ltd #, Tel + Cross, th nd St[ge, West Of Chord Ro[d, Beng[luru, INDIA, PIN: /, F[x / info@prdcinfotechcom wwwprdcinfotechcom All Rights Reserved Copyright PRDC Pvt Ltd All tr[dem[rks, logos [nd symbols used in this document belong to their respective owners 8

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