The amended standard C a and its implications for frequency-tracking M-class Phasor Measurement Units (PMUs)

Transcription

1 Rosco, Andrw and Dickrson, Bill and artin, Knnth (014) h amndd standard C a and its implications or rquncytracking -class phasor masurmnt units (PUs). In: IEEE Applid asurmnts or Powr Systms (APS 014), , his vrsion is availabl at Strathprints is dsignd to allow usrs to accss th rsarch output o th Univrsity o Strathclyd. Unlss othrwis xplicitly statd on th manuscript, Copyright and oral Rights or th paprs on this sit ar rtaind by th individual authors and/or othr copyright ownrs. Plas chck th manuscript or dtails o any othr licncs that may hav bn applid. You may not ngag in urthr distribution o th matrial or any proitmaking activitis or any commrcial gain. You may rly distribut both th url ( and th contnt o this papr or rsarch or privat study, ducational, or not-or-proit purposs without prior prmission or charg. Any corrspondnc concrning this srvic should b snt to th Strathprints administrator: strathprints@strath.ac.uk h Strathprints institutional rpository ( is a digital archiv o Univrsity o Strathclyd rsarch outputs. It has bn dvlopd to dissminat opn accss rsarch outputs, xpos data about thos outputs, and nabl th managmnt and prsistnt accss to Strathclyd's intllctual output.

2 h amndd standard C a and its implications or rquncy-tracking -class Phasor asurmnt Units (PUs) Andrw J. Rosco Dpartmnt o Elctronic and Elctrical Enginring Univrsity o Strathclyd Glasgow, UK Andrw.J.Rosco@strath.ac.uk Bill Dickrson Arbitr Systms Paso Robls, CA, USA Knnth E. artin Elctric Powr Group Portland, OR, USA Abstract h nw amndmnt to th Phasor asurmnt Unit (PU) standard C a maks svral signiicant changs, compard to th standard C (011). his papr highlights som o th most important changs, with a particular mphasis applid to how thos changs rlat to th way that a rquncy-tracking PU (Phasor asurmnt Unit) algorithm nds to b dsignd. In particular, thr is a dlicat trad-o btwn passband latnss (th bandwidth tst) and stopband rjction in th Out-O-Band (OOB) tst. or a PU algorithm using rquncy-tracking and adaptiv iltrs, it is shown that passband latnss can b rlaxd to about.5db, but that th stopband nds to bgin up to 14.8% closr to 0 Hz than or a ixd-iltr PU. his is partly du to th xact procdurs o th C a OOB tsting, and partly du to th adaptiv natur o a rquncy-tracking PU iltr sction. Kywords Powr systm masurmnts, ourir transorms, rquncy masurmnt, Powr systm aults, Phas stimation, Powr systm stat stimation, Powr systm paramtr stimation A () r S 0 H I. ABLE O NOENCLAURE Amplitud o intrharmonic (pu) Basband iltr rspons Bandwidth rquird Rporting Rat (Hz) undamntal rquncy (Hz) Nominal rquncy (Hz) Intrharmonic rquncy (Hz) odulation rquncy (Hz) und rquncy or a tracking PU (Hz) Pr-unit inrtia (s) odulation dpth (pu) II. INRODUCION h prsnt standard IEEE C was issud in 011 [1] and prsntd a signiicant chang rlativ to th 005 standard. Spciically, dynamic rquirmnts such as bandwidth, rspons tim, dlay tim, latncy, and rquncy ramps wr addd. hs ar tstd by applying amplitud and phas modulatd signals, amplitud and phas stps, and rquncy ramps. Howvr, ovr th past yars som issus hav bn idntiid with th C (011) standard. hs ar addrssd with a nw amndmnt C a. In sction III, som obsrvations concrning rquirmnts/limits in C a ar mad, rom an application standpoint. Howvr, th main ocus o this papr is on th updatd rquirmnts or th bandwidth and Out-O-Band intrrnc (OOB) tsts, and th implications or -class Phasor asurmnt Unit (PU) dsign. h xact way ths tsts ar carrid out, and thir statd limits, dins th way that iltring must b dsignd and implmntd. In particular, it is shown in this papr that rquird iltr masks ar dirnt or ixd-iltr and rquncy-tracking dvics. In both implmntations a quadratur oscillator is usd to dcod th phasor componnts rom th AC signal using a htrodyn procss. h ixd iltr dsign kps th quadratur oscillator at th nominal systm rquncy, 0 whr th rquncy tracking iltr adjusts th quadratur oscillator to th actual systm rquncy. Whil a viabl mask or ixd-iltr dvics is givn in [], a rquncy-tracking PU with adaptiv iltring rquirs a dirnt iltr mask to comply with th standard. Equations dvlopd in this papr allow such a mask to b cratd. III. HE REERENCE ALGORIH AND APPLICAION REQUIREENS Within C , and C a, a Rrnc PU algorithm dsign is prsntd. It is important to not that th standard stats It is givn or inormation purposs only, and dos not imply bing th only (or rcommndd) mthod or stimating synchrophasors. Its purpos is to stablish common ground or undrstanding prormanc rquirmnts and conirming thir achivability. h rrnc modl achivs his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.

3 what it stats abov, but is not usd in any commrcial PUs to our knowldg. Prsntly, C a contains a sris o tsts with limits that can b complid with by th major PU manuacturrs, and also th Rrnc algorithm. his has rquird a crtain dgr o compromis in som aras. h tsts and limits rlct prormanc achivabl by both th Rrnc algorithm and all o th prsnt major manuacturr s dvics. h tsts and limits do not ncssarily rlct prsnt o utur application rquirmnts, partly bcaus ths ar not yt wll quantiid by th industry. I. CANDIDAE ALGORIH DESIGNS A myriad o compting PU algorithms hav bn proposd in litratur and ar apparing within actual PUs. Som usd ixd iltrs which rmain cntrd on th nominal rquncy. Such algorithms includ th C a Rrnc, Last Squars [3] or aylor ourir ransorm [4], and th Intrpolatd D [5] approachs. hs approachs gnrally sur rom dgradd prormanc as rquncy dviats rom nominal. Othr algorithms us rquncy-tracking, so that th algorithm tuns itsl to constantly track th moving undamntal [6] [7] [8] [9]. his tnds to dcras rrors whn rquncy is o-nominal. I th iltrs ar carully dsignd, th iltr notchs (zros) can also b movd to track harmonics, and vn intr-harmonics i thir rquncy is known [9]. ost proposd algorithms us symmtric IR windows sinc ths most asily mt th C a rspons and dlay tims. Howvr, [9] proposs th us o Kalman iltring which is ssntially an IIR tchniqu. any modrn PUs actually prorm signiicantly bttr than th C a limits.. -CLASS ILER LANESS AND BANDWIDH h bandwidth tst is changd undr C a. Prviously thr wr two tsts: on with amplitud modulation only, and on with amplitud and phas modulation coincidntally. h combination o amplitud and phas modulation in C mad it diicult to idntiy problms du to signal procssing in this tst, as th cts could somtims occur dstructivly or constructivly and in complx non-linar mannrs [10]. So, th amplitud and phas modulations ar now applid sparatly in two squntial tsts: with 0.1 pu amplitud and thn 0.1 rad modulation applid. h rquird bandwidth o th PU is st by a valu r, calculatd as r = S /5 ( S =rporting rat), but clippd to a maximum valu o 5 Hz. h maximum allowabl E (otal ctor Error) during this tst is st at 3% and it is intrsting to analys what this actually mans. Whn th 0.1 pu amplitud or 0.1 rad phas modulation is applid to a 1 pu undamntal at nominal rquncy 0, th tru phasor should oscillat about th nominal (1+0j) point as shown in ig. 1. h lngth o trajctory or a 0.1 rad disturbanc is almost idntical to th lngth or a 0.1 pu amplitud disturbanc sinc sin() whn is small. A small phas modulation can thror b analysd in th sam way as an amplitud modulation. ig. 1 Phasor oscillation during th bandwidth tst So, ignoring th ixd undamntal componnt at (1+0j) which is assumd to b accuratly masurd, th actual vctor dviation xpctd in th prsnc o ithr amplitud or phas modulation can b valuatd by th ollowing procss: h vctor dviation rom (1+0j) will hav a orm: j t j t (1) whr =0.1 is th modulation dpth, and is th modulation rquncy, which can b a maximum o r. h two conjugat phasors rprsnt phasors which add togthr to giv th straight-lin trajctoris o ig. 1. Whn th wavorm is masurd, ths dviations will b attnuatd by th iltr. h masurd vctor will appar as: j t j t as () whr ( ) rprsnts th basband IR iltr rspons. h dirnc btwn ths last two quations rvals th xpctd masurmnt rror: E j t j t 1 1 as Now, or any IR iltr having only ral wights: * (4) and also by stting a as a unit phasor: t j E 1 a * 1 a * (5) so: E a 1 a * (3) 1 (6) and it can b rcognisd that th sum o ths conjugats quals th ral part o thir sum, and will orm an oscillating E btwn zro and a maximum valu. E R 1 a (7) inally, assuming that th iltr is symmtric about th timstamp (t=0) in th tim domain, th phas o th rspons his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.

4 o ( ) is zro or all and so ( ) can b rgardd as ral, not complx. h maximum rror at any instant in (7) will b: E 1 (8) ax hror, th constraints on th gain ( ) can b drivd, E Limit 1 (9) inally, r-ordring and substituting or =0.1, E Limit =0.03 (3%), this rvals: ,i (10) his mans that th gain o th iltr at th dg o th PU bandwidth ( = r ) must b no lowr than dB. his 3dB igur is not xplicitly statd in th C txt, but a rcnt NIS prsntation alluds to this igur [10], as dos [11], and th 3dB point is a convntional way to dscrib bandwidth. Knowldg o this rlationship is vry usul or PU dsign. or a givn iltr window lngth, a rlaxd latnss rquirmnt can allow an nhancd attnuation dpth outsid th passband, and this has clar bnits or broadband harmonic, intr-harmonic and nois rjction. An asymmtric iltr, such as a Kalman iltr as proposd in [9], will hav a non-zro phas ( ) and so th gain at th band dg may nd to b highr than -3dB or such a iltr, to satisy (9)-(10). In othr scnarios whr amplitud and phas modulation occurs togthr, th vctor dviation may b xtrmly complx du to non-linar intrations causd by non-uniorm iltr window wights. I by som chanc th dviation occurs in a in a prct circular trajctory, thn th analysis is simplr: j t (11) as j t (1) as j t 1 E (13) E 1a (14) In this cas th E will b constant at th sam maximum valu as ound in (7). A. Bandwidth in th Rrnc algorithm h Rrnc algorithm in C a uss a latnss mask in th passband o ±0.043dB as part o its iltr dsign procss (ig. 3). his valu coincids with an rror o 0.5% in absolut amplitud calibration. By using such a lat iltr, as th undamntal rquncy varis ovr th passband, no xtra amplitud calibration nds to b calculatd or th digital iltr rspons, in ordr to mt a E o 1%. his maks ral-tim computation asir within th Rrnc algorithm, but, as was shown abov, a latnss o ±0.043dB is ar tightr than is rquird to pass th bandwidth tst, in trms o E. B. Bandwidth in a rquncy-tracking or rquncycompnsatd algorithm. I th iltr amplitud rspons is known and can b xprssd mathmatically using a ittd unction or a lookup tabl, thn th o-nominal iltr gain can b accountd or, using th masurd rquncy valu. his could b calld a rquncy-compnsatd PU. Altrnativly, and additionally, i th quadratur oscillator [1] [7] tracks th masurd undamntal rquncy, so that th undamntal input rquncy to th IR iltrs is always movd towards 0 Hz, thn th dviation o th iltr gain rom unity is minimisd, vn during o-nominal rquncy. his is a rquncy-tracking PU [7] [8]. Combining both approachs can lad to vry low valus o stady-stat E as th undamntal rquncy changs, but allows a rlaxation o th latnss rom ±0.043dB to narly th 3dB igur drivd abov. In practic, it is ound that stting a targt iltr gain o about -.5dB lads to accptabl rsults in th bandwidth tst, with highst E rsults in th rgion o.3-.75%. his margin givs a vry low risk o unxpctd complianc ailurs du to ADC rsolution or nois sinc ths tsts ar don with 1pu signals and all th modulatd signal is in th passband. C. rquncy and ROCO during bandwidth tsts h original E (rquncy Error) and RE (Rat o chang o rquncy Error) limits during bandwidth tsting, or C (011) wr as shown in ABLE I. hs prsntd a highly quantisd E and RE prormanc which jumpd suddnly at th S =0 Hz boundary. ABLE I. Bandwidth rror limits - C (011) [1] h problm with that quantisation was that an -class PU with a rporting rat ( S ) o 15-0 Hz has quit a long window to mt OOB rquirmnts, with high attnuation at th stop-band which bgins at S /. But th bandwidth o such low-rporting-rat PU s riss proportionatly with r = S /5 (ig. ). By contrast, PUs with S 5 hav thir bandwidth cappd at r =5 Hz (ig. ). So, as rporting rat riss rom S =10 Hz towards S =5, initially E and RE tnd to incras as th bandwidth r incrass. But, as S riss byond 5 Hz, th dominant ct is or a dcras in E and a stady-stat or slightly dcrasing RE, bcaus r is cappd at 5 Hz and th iltr gain can b incrasd towards 0 db at r. ig. shows th rquird bandwidth r (lt-hand Y axis) and xampl E rsults (right-hand Y axis) rom a C a-compliant rquncy-tracking algorithm, or all valid S suitabl or 50 or 60 Hz systms. his highlights th problm with th C limits, or S =10 to S =0 Hz PUs. his issu has bn rsolvd in C a, by a nw tabl (ABLE II) which allows E and RE to ris proportionatly or low valus o S, as bandwidth riss, but thn E and RE ar cappd at uppr valus. By xtnding th mathmatical analysis o (1)-(10) it would b possibl to mathmatically his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.

5 justiy th nw valus, but ig. shows that th nw C a E valus ar crtainly achivabl with iltr gain at th band dg st clos to th limit at -.5dB. Exampl rsults rom tsting both a rquncy-tracking and ixd-iltr (Rrnc) PU ar shown. Corrsponding RE rsults tll a similar story. ABLE II. Bandwidth rror limits - C a [] th tund rquncy. (or a ixd-iltr PU = 0, and or a tracking PU ). ig. 3 iltr mask or th C a Rrnc algorithm [] I an intrharmonic o amplitud A applid at rquncy, whil th undamntal signal has amplitud 1pu at rquncy. ig.. rquncy Error (E) xampl undr bandwidth tsts I. OU O BAND (OOB); SOP-BAND REJECION h othr major chang in C a is within th OOB tst, and rquirs grat car in th iltr dsign. In th original C , th mphasis was on achiving a 1.3% E rsult whn th 10% OOB intrharmonics wr applid. his corrspondd to a 0dB stop-band rjction, which dind th original Rrnc algorithm mask. Howvr, C also containd OOB E and RE limits which could not mt by its Rrnc algorithm, with just 0dB stopband rjction. In C a, th OOB RE limit has bn suspndd. But, th OOB E limit o 0.01 Hz has bn rtaind. his is signiicant bcaus it rquirs >0 db o stopband rjction. It is now th OOB E limit, not th 1.3% E limit, which dins th iltr mask. h nw mask or th Rrnc algorithm is shown in ig. 3. o achiv th incrasd stopband rjction, using th Rrnc algorithm, rquirs longr tim windows and slightly adjustd iltrs compard to thos givn in C his has, in turn, rquird longr (rlaxd) rspons and latncy limits to b applid in C a. any PUs may xhibit signiicantly shortr rsponss and latncis than th C a limits. A. Dtrmining th rquird OOB iltr rjction It is possibl to calculat th rquird basband iltr rjction (), which is a unction o rquncy sparation rom A jt j t in (15) Whn th htrodyning with th quadratur oscillator and thn iltring () ar applid, with both tund to xpct an undamntal rquncy, th prcivd masurmnt vctor at th iltr output will consist o th dominant undamntal with a magnitud 1pu, upon which is suprimposd anothr trajctory, which will in th worst cas will b circular, similarly to (11). j t jt j t Htrodyn d A (16) Htrodyn d as as t j t j A j t j t A j t j t A (17) (18) (19) Assuming that iltr gain (- ) is almost unity, th masurmnt rror is du to th scond trm. rquncy rror can b valuatd by xamining th worst-cas ct o this on th phas o th (othrwis stady) phasor as whr: as as j as t j t (0) 1 A (1) It can b sn that as consists o a small circular rror trajctory cntrd on th point (1+0j). h ct on rquncy masurmnt is dtrmind by th maximum rat o chang o phas rror : as () h biggst rat o chang o will occur whn at th closst approach o as to th origin (0+0j), whn ( -)t =. At this instant as has its lowst magnitud, with a valu o ((1-A( -))+0j) but also has its maximum vlocity paralll to th j axis: -( -)A( - ) s -1. hror, his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.

6 th maximum magnitud o th rat o chang o phas rror is: d A dt ax 1 A d 1 E ax and thror: dt ax E (3) (4) ax (5) A E ax Sinc E ax = 0.01 Hz, and th closst OOB rquncy or th S =10 Hz PU is 5 Hz, E ax << - and so th ollowing approximation is valid: E ax (6) A his dins th highst iltr gain which can possibly satisy th OOB tst. In practic, to allow a saty margin or nois, Ectiv Numbr o Bits (ENOB) o ADC rsolution tc., it is snsibl to allow rduc this igur by 3dB. 3 E ax 0 10 (7) A Howvr, th way that (7) nds to b valuatd is dirnt or ixd-iltr and rquncy-tracking PUs, as is th rang o valus o which should in thory b applid to validat th prormanc. B. ixd-iltr algorithms or any intrharmonic such as lickr at rquncy, th rippl rquncy o rror at th PU output, du to th htrodyning procss, is givn by: rippl (8) h aim o th C a OOB tst is to vriy a iltr stopband which limits any masurmnt rippls with rquncis >= S /. hror: S (9) or ixd-iltr PUs such as th Rrnc algorithm, = 0 always, and so: S ixd iltr stopband : 0 (30) his matchs xactly with th C a OOB tst, whr th stopband is dind xactly as (30). C a tsting applis (30) but only varis undamntal rquncy ovr a rducd rang compard to th whol valid rang ( 0 ± r ): S rang : 0 0 S (31) 0 0 or ixd-iltr dvics, on th lt hand sid (LHS) o (7), th mask always rrs to ( - 0 ). But, on th right hand sid (RHS), thr is a worst cas during C a tsting whr ( -) rachs ( S /+ S /0) = 11 S /0, i.. a 10% incras rom S /. his 10% incras mans that th gain () nds to b 0*log(1.1)=0.83dB rducd rom a valu obtaind via a mor naïv analysis by (or xampl, and incorrctly): 3 E ax (3) A 0 Carul valuation o (7), in th abov coniguration, lads to th mask givn or th C a Rrnc algorithm. C. rquncy-tracking algorithms h ct and analysis o intrharmonics within a rquncy-tracking dvic is dirnt. In such a dvic, = i th algorithm is tracking corrctly. hror, to din th rquird stopband rom (8) and (9): racking stopband : S (33) Equation (33) implis that a dirnt rgim rom (30) should idally b usd to tst a rquncy-tracking dvic. h dirnc btwn (30) and (33) is small whn 0 but bcoms signiicant as th undamntal rquncy dviats rom nominal. h actual C a tst applis th rgim in (30) and (31). h issu hr is that th lowst rippl rquncy apparing atr th htrodyning during th tst rgim is givn by (8) with (as a worst-cas xampl) = = ( 0 + S /0) Hz and = ( 0 + S /) Hz. his rquirs a stopband width o only 9 S /0 Hz, which is 10% narrowr than th stopband rquird using a ixd-iltr dvic to pass th sam tst. hror, it is hardr or a rquncy-tracking algorithm to pass th C a OOB tst than or a ixd-iltr algorithm to. h iltr has to b mor aggrssivly dsignd to achiv stopband cuto at a basband iltr rquncy which is 10% lowr than th quivalnt ixd-iltr dsign. aking us o th availabl ~.5 db iltr latnss rlaxation is on way to try and achiv this mor aggrssiv cuto. Notic that i th tsting rgim was changd to (33) or th rquncy-tracking dvic, this 10% narrowing would no longr b rquird. Also, in that cas, th ull valid undamntal input rquncy rang ( 0 ± r ) (and potntially much widr) could b tstd, using th sam basband iltr dsign, and th sam 0.01 Hz E might still b attaind, or narly attaind (but s sction D blow). h rquird attnuation can again b valuatd by (7). or a rquncy-tracking PU, = i th algorithm is tracking corrctly. his mans thr is no dviation btwn th rquncis on th LHS and RHS o (7) and th 0.83 db actor is not rquird. In act, th gain o th iltr can b 0.9 db highr at th lowst rquird rquncy ( - ), than th simplistic analysis o (3) suggsts, sinc ( -) is also rducd by a actor 0.9 at th sam critical point. his works slightly in avour o th tracking PU during th OOB tst, but his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.

7 not nough to balanc th diiculty introducd by th 10% stopband rduction. D. Accounting or adaptiv iltr shortning hr is a urthr complication or tracking algorithms, which is that th ntir iltr window dsign may adapt linarly to bcom shortr as th masurd undamntal rquncy incrass (to track th iltr notchs with th harmonics). racking algorithms such as [7] [8] all into this catgory. his will xpand th iltr rquncy rspons proportionatly. hror, whn dsigning such an adaptiv iltr or th baslin 0 cas, th mask window width in rquncy may nd to b urthr rducd by a proportional actor o: Adaptiv askwidth actor 0 0 (34) 0 Othrwis, a tracking PU will likly ail an OOB tst whn = ( 0 + S /0). Exampls o th actor in (34) ar 0.99 (a 1% rduction) or S =10 Hz and 0.95 (a 4.8% rduction) or S =50 Hz, with 0 =50 Hz. his rduction is not du to th C a tst procss rgim, but is inhrnt in a rquncytracking dvic with such adaptiv iltrs. II. OERALL EECS ON HE ILER ASK OR REQUENCY-RACKING ALGORIHS h total ct is that th width o th stopband mask or a rquncy-tracking algorithm is rducd by btwn 11% and 14.8% compard to th mask or a ixd iltr, whn th iltr is dsignd at 0 and th C a OOB tst procdur is to b applid. As an xampl, ig. 4 shows th masks and iltr nvlops or th C a Rrnc algorithm, and a C a-compliant tracking algorithm, in th = 0 = S = 50 Hz cas. h mask rquncy-width rductions rquird or th tracking iltr (10%+4.8%) hav bn indicatd, showing how th mask stopband bgins almost 15% closr to th passband than S /. Both masks ar calculatd using (7) and th procdurs o sction I B and I C. ig. 4 Exampl o iltr nvlops and masks or th Rrnc algorithm, and a C a-compliant tracking algorithm. = 0 = S = 50 Hz. S III. CONCLUSIONS h nw standard C a-014 is a usul amndmnt to C h Rrnc algorithm within C a is now compliant, as wll as PUs rom most (i not all) major PU manuacturrs. hr ar som aras whr, rom an application prspctiv, limits (particularly RE) would idally b tightnd or additional scnarios tstd, but this rally rquirs a gratr ngagmnt btwn th PU usr community and th C a standard committ, to agr on ralistic conditions, vidnc, xpctations and limits. Implmnting a good iltr and algorithm rquirs a carul balanc btwn, in particular, th bandwidth and OOB tsts. hs tsts hav both altrd undr C a. hortical drivations in this papr, backd up with C a tsts in a simulatd nvironmnt, show that th passband latnss can b rlaxd to about.5db or a rquncy-compnsatd or rquncy-tracking PU. In ths PUs, th rducd latnss can b tradd o, in ordr to provid a astr cuto to th stopband and a dpr broadband stopband rjction. iltr masks or both ixd-iltr and rquncy-tracking dvics hav bn drivd. h mask dining th bginning o th stopband nds to b up to 14.8% narrowr or a rquncytracking PU than or a ixd-iltr PU. his is partly du to th xact way that th prsnt OOB tst is conductd, and partly du to th inhrnt rquncy-tracking proprty. REERENCES [1] IEEE, "IEEE Standard or Synchrophasor asurmnts or Powr Systms," C , 011. [] IEEE, "IEEE Standard or Synchrophasor asurmnts or Powr Systms -- Amndmnt 1: odiication o Slctd Prormanc Rquirmnts " C a-014, 014. [3] D. Blga and D. Ptri, "Prormanc o Synchrophasor asurmnts Providd by th Wightd Last Squars Approach," in IEEE IC 013, innapolis, 013, pp [4] P. Castllo,. Lixia, C. uscas, and P. A. Pgoraro, "Adaptiv aylor- ourir synchrophasor stimation or ast rspons to changing conditions," 01 IEEE Intrnational Instrumntation and asurmnt chnology Conrnc (Imtc), pp , 01. [5] D. Blga and D. Ptri, "Accuracy Analysis o th ulticycl Synchrophasor Estimator Providd by th Intrpolatd D Algorithm," IEEE ransactions on Instrumntation and asurmnt, vol. 6, pp , ay 013. [6] J. A. D. Srna, "Synchrophasor Estimation using Prony s thod," IEEE ransactions on Instrumntation and asurmnt, vol. 6, 013. [7] A. J. Rosco, I.. Abdulhadi, and G.. Burt, "P and Class Phasor asurmnt Unit Algorithms using Adaptiv Cascadd iltrs," IEEE ransactions on Powr Dlivry, vol. 8, pp , 013. [8] A. J. Rosco, "Exploring th rlativ prormanc o rquncy-tracking and ixd-iltr Phasor asurmnt Unit algorithms undr C tst procdurs, th cts o intrharmonics, and initial attmpts at mrging P class rspons with class iltring," IEEE ransactions on Instrumntation and asurmnt, vol. 6, pp , 013. [9] I. Kamwa, S. R. Samantaray, and G. Joos, "Wid rquncy Rang Adaptiv Phasor and rquncy PU Algorithms," IEEE ransactions on Smart Grid, vol. 5, 014. [10] National Institut o Standards and chnology (NIS), "Lssons larnd rom th NIS assssmnt o PUs," 014 Availabl: accssd ay 014. [11] K. E. artin, B. Kasztnny,. G. Adamiak, G. Antonova,. Bgovic, t al., "Synchrophasor asurmnts undr th IEEE Standard C with amndmnt C a," IEEE ransactions on Powr Dlivry, In Rviw. his is a postprint o a papr submittd to and prsntd at th IEEE Intrnational workshop on Applid asurmnts or Powr Systms (APS), 014 [ and is subjct to IEEE copyright.