Harmonic allocation following IEC guidelines using the voltage droop concept

Transcription

1 Unversty of Wollongong Researc Onlne Faculty of Informatcs - Papers (Arcve) Faculty of ngneerng and Informaton Scences 200 Harmonc allocaton followng IC gudelnes usng te voltage droop concept. J. Gosbell Unversty of Wollongong, vgosbell@uow.edu.au Robert A. Barr Unversty of Wollongong, rbarr@uow.edu.au Publcaton Detals Gosbell,. J. & Barr, R. A. (200). Harmonc allocaton followng IC gudelnes usng te voltage droop concept. 4t Internatonal Conference on Harmoncs and Qualty of Power, ICHQP 200 (pp. -6). Bergamo, Italy: I. Researc Onlne s te open access nsttutonal repostory for te Unversty of Wollongong. For furter nformaton contact te UOW Lbrary: researc-pubs@uow.edu.au

2 Harmonc allocaton followng IC gudelnes usng te voltage droop concept Abstract Present IC gudelnes are dffcult to apply to realstc cases because of te data load, te number of assumptons requred and te computatonal complety. A new approac s gven based on te concept of voltage droop, to be detaled n a companon paper. Te benefts of te approac are a smple calculaton wt mnmal data and no requred assumptons. It apples to radal or mesed dstrbuton systems were feeders are suffcently sort tat lne capactance can be gnored. Te approac can be appled at te nstallaton (M or L) and te equpment level and can be used to gve reference values for equpment emsson standards. Dscplnes Pyscal Scences and Matematcs Publcaton Detals Gosbell,. J. & Barr, R. A. (200). Harmonc allocaton followng IC gudelnes usng te voltage droop concept. 4t Internatonal Conference on Harmoncs and Qualty of Power, ICHQP 200 (pp. -6). Bergamo, Italy: I. Ts conference paper s avalable at Researc Onlne: ttp://ro.uow.edu.au/nfopapers/350

3 Harmonc Allocaton Followng IC Gudelnes Usng te oltage Droop Concept.J. Gosbell, Lfe Member, I and R.A. Barr, Member, I Abstract-- Present IC gudelnes are dffcult to apply to realstc cases because of te data load, te number of assumptons requred and te computatonal complety. A new approac s gven based on te concept of voltage droop, to be detaled n a companon paper. Te benefts of te approac are a smple calculaton wt mnmal data and no requred assumptons. It apples to radal or mesed dstrbuton systems were feeders are suffcently sort tat lne capactance can be gnored. Te approac can be appled at te nstallaton (M or L) and te equpment level and can be used to gve reference values for equpment emsson standards. Inde Terms-- dstrbuton systems, armoncs, IC standards, I standards, armonc allocaton, voltage drop. Symbol I U G M I k L L SCR S S t droop I. NOMNCLATUR Meanng Allocated armonc current at order to load "" Allocated armonc voltage at order to load "" Avalable armonc voltage at M level Harmonc order Subscrpt referrng to load "" Harmonc current drawn by load Harmonc allocaton constant Plannng level for armonc at L Sort crcut rato Mamum demand of load Sum of all substaton loads requrng a armonc allocaton System voltage droop Harmonc voltage caused by load at pont of connecton Harmonc reactance ponent representng dversty II. INTRODUCTION armoncs n power systems ave been an ssue over many Hdecades, wt Standards Australa publsng ts frst armonc standard AS n 979 []. cess armonc voltage levels can lead to addtonal losses and possble overeatng of nducton motors and sunt-connected capactors. Hg armonc currents from sngle pase equpment n tree pase nstallatons can lead to unepectedly g neutral currents [2]. Wt an empass on te benefts of power electroncs tecnology (small sze, effcency, better control), armonc dstorton of te power system s nevtable and specal procedures need to be put n place to lmt armoncs to allow networks and equpment to. J. Gosbell s wt te Unversty of Wollongong (e-mal: v.gosbell@uow.edu.au). R. A. Barr s a consultng engneer wt lectrc Power Consultng Pty Ltd (e-mal: rbarr@epc.com.au). operate as ntended. One of te man nternatonal documents addressng ts ssue s IC [3], a tecncal report developed and publsed by te Internatonal lectrotecncal Commsson. A major concept s te Compatblty Lmt for armonc voltage, ntended as te boundary between te mamum level to be allowed on networks (Plannng level) and te mnmum level at wc equpment wll malfuncton (Immunty level). Tese lmts reduce wt ncreasng armonc order. Altoug most power system armonc dstorton s caused by customer loads, [3] gves te major responsblty for controllng armoncs to te network owner snce tey are n te best poston to coordnate customer armonc emssons. Te IC report [3] recommends Plannng levels for dfferent parts of power systems. At M voltage levels and above, customers can be epected to be responsble for ter plant emssons. Network owners are requred to determne, for eac armonc, te mamum current wc eac customer can nject. Tese lmt values can form part of a network connecton agreement. Ts paper wll concentrate on te M allocaton process. Te IC document gves some general prncples, but tese can be very dffcult to mplement n practce. Anoter approac s gven n te I standard [2] wt armonc currents gven n a very smple tabular form. A dffculty wt ts s tat te detaled metodology of determnng te table s not well descrbed and t s not clear ow to etend t to networks based on uropean practces ncludng te meetng of te rater dfferent IC Plannng levels. Altoug gven te status of a tecncal report, [3] as been adopted as a full standard by te Australan natonal regulatory autortes and tey ave asked tat all network owners abde by t. Consequently tere as been ncentve n Australa to develop detaled approaces to M allocaton process. References [4] and [5] attempt to detal te allocaton process for dfferent stuatons. Standards Australa as publsed HB [6] as a gude to te use of bot te armonc and flcker standards n radal dstrbuton systems. Ts paper s a contnuaton of te above work and wll revew te IC approac and ten propose a new approac, amed at meetng te IC general prncples. Ts approac s based on te concept of te system "voltage droop" wc wll be dscussed below and leads to an allocaton dependent only on te mamum demand (called "agreed power" n IC standards) and fault level of te assessed nstallaton. Te approac s as smple as te I to mplement, but as a more rgorous teoretcal bass and can be adapted for /0/$ I

4 dfferent types of systems and dfferent armonc lmts. Te success of te metod depends on all sunt capactors beng detuned, but ts s an essental requrement for any armonc allocaton metod so far descrbed. Under tese condtons, te system armonc reactance s smply = () Secton III of te paper wll summarse te IC gudelnes and argue tat tere s not yet a satsfactory procedure for applyng tem to practcal stuatons. Te voltage droop concept, wc s te subject of a companon paper [7], wll be brefly descrbed n Secton I. It wll ten be sown ow t can smplfy armonc allocaton followng IC gudelnes ncludng an allowance for dversty. Te followng secton wll gve an alternatve form for te allocaton equaton usng Sort-crcut Raton (SCR) allowng te new approac to be related convenently to I-59 allocaton tables. Fnally we dscuss furter refnements wc could be made to ts armonc allocaton approac. III. SUMMARY OF IC APPROACH [3] A. Analyss prncples Normally armonc quanttes vary wt tme and are descrbed by ter 95% cumulatve probablty value. Wen we refer below to a armonc voltage, te 95% value s ntended unless oterwse stated. Dversty s represented by an eponental summaton law. For eample, f two ndependent sources gve armonc voltages of and 2 separately, te voltage due to ter combned effect s assumed to be.tot = + 2 (2) were as a value dependng on te armonc order, and n partcular as te value of.4 for 5 0. B. Allocaton prncples ac load s to be gven an equtable allocaton (ts dea wll be developed below). In a partcular M subsystem, wen te system s fully loaded, te mamum armonc voltage n te subsystem s to be equal to te Plannng level. Ts mples tat all avalable armonc voltage s allocated to all te customer loads wc are epected to be connected wt notng eld n reserve for contngences. Suppose te Plannng level for armonc at M s L M. Not all of ts s avalable for te locally connected M loads because of te contrbuton from upstream loads and from L loads connected to te local system. Te determnaton of te avalable voltage s gven n [3] and as te symbol G M. At armonc, te armonc current allocated to a load avng mamum demand S vares as S. Wen tere s dversty, t s found convenent to allocate a current ncreasng as S /. Te reason for ts can be seen by consderng te specal case of an M substaton wt all loads connected drectly to output bus. Addng te voltages taken to te power of s ten equvalent to addng S terms drectly. Ts leads to te allocaton law for ts case of U 2 / S = G M S (3) t were U s te armonc voltage allocated to load S and S t s te sum of all te M loads to be gven an allocaton. Te armonc current s ten allocated dependng on te armonc mpedance at te pont of load connecton. In te case were all nearby capactors are detuned, f te fundamental mpedance at te supply pont s, te allocated current wll be U I = (4) Ts allocaton procedure s unsatsfactory n te more usual case wen M loads are dstrbuted along M feeders were, typcally fault levels can vary by 0: or more. Consder te case of two loads A and B, avng dentcal mamum demand S, wt A connected very close to te M supply pont and B connected at te far end were te fault level s 0 tmes smaller. Applcaton of (3,4) would gve equal voltage and a current 0 tmes dfferent to te two loads. An alternatve strategy s to allocate equal armonc currents rater tan equal armonc voltages to two equal loads. Ts could be aceved by an allocaton law / I S (5) k s a constant called te "allocaton constant" for te partcular M power system and s determned by fndng te armonc voltage contrbuton for eac load from te nverse of (4), summng tem usng te summaton law and equatng te result to te avalable voltage G M. For te case of zerolengt feeders t s easy to see tat G M k = (6) / S t wle for te more general case, k s muc more dffcult to determne, snce combnng te voltages from all connected M loads now requres data for te magntude and connecton pont of all locally-connected loads to be accounted for, ncludng future loads wose detals mgt be unknown at te tme tat a specfc allocaton as to be determned. Te armonc current allocaton approac appears to be more equtable, owever anoter dffculty arses. Were te fault level at B s very low, ts load as to be allocated a small armonc current. Load A s restrcted to te same low allocaton, no matter ow strong s ts pont of supply. Te cost of acevng equtablty s to under-utlse te armonc absorpton capacty of te power system. Reference [3] sows an effectve compromse wc s md-way between voltage and current armonc allocaton te allocaton of armonc A. Ts can be epressed n te form / S I (7) were k s an allocaton constant dfferent n value to tat n (5). In te above case, load B wll be allocated a current only 0 smaller tan tat for load A, wle te armonc voltage at te pont of connecton wll be correspondngly 0 tmes

5 larger. Ts allocaton strategy s tus more equtable tan voltage allocaton, and allocates more armonc current tan does current allocaton. Agan, te determnaton of k requres a armonc loadflow of te system ncludng all future loads. C. Dffcultes wt present IC approac Weter armonc voltage, current or A allocaton s adopted, te dffcultes are smlar and ave been descrbed n detal n [5] Te data requrements are large, beng te magntude and mpedance at te pont of connecton for eac sgnfcant M load. Assumptons need to be made about te poston and pont of connecton of future loads. Assumptons need to be made of te mpact of L loads on te M system. Mesed systems cannot be solved easly by smple tools suc as spreadseets. A range of assumptons gves a range of allocated currents, and ts can create dffcultes n dealng wt customers. Utltes are responsble for controllng te system armonc voltage and would tend to be conservatve n allocatng armonc current. Customers ws to avod mtgaton costs and would prefer a scenaro gvng a large armonc current allocaton. A soluton to ts dlemma s one wc mnmzes te need to make assumptons about present and future loads. We sall sow tat te voltage droop concept provdes an allocaton strategy wt ts property, as well as beng applcable to any power system topology. I. PROPOSD APPROACH BASD ON OLTAG DROOP CONCPT [7] A. oltage droop Wen a large load s suddenly connected to a power system, tere s a relatvely large ntal voltage reducton related to te load current and te system fundamental mpedance. If te voltage cange s suffcently large, On Load Tap Cangng (OLTC) transformers wll operate to keep steady state voltages trougout te network wtn acceptable ranges. Te voltage cange between te load sde of te frst OLTC transformer above te load and te load tself s called oltage Drop. oltage Drop s related to te system mpedance between te load and te frst upstream OLTC transformer. Wt te ecepton of Lne Drop Compensaton scemes, oltage Drop cannot be corrected by OLTC operaton. In contrast to oltage Drop, oltage Droop s assocated wt te total ntal voltage reducton. oltage Droop s related to te total system Tevenn mpedance wc s larger tan tat assocated wt oltage Drop. Dependng on te confguraton of te network, a large part of te oltage Droop wll normally be counteracted by OLTC operaton. A dstortng load draws armonc current and creates a armonc voltage drop n te power system. Ts armonc voltage s related to te system Tevenn armonc 3 mpedance. If capactors are unmportant (eter tey are absent or detuned), ts mpedance s te fundamental Tevenn mpedance scaled up by te armonc order "". Ts dea gves te lnk between armonc allocaton and voltage droop. Several types of voltage droop can be dentfed. Te above dscusson concerned load voltage droop. Feeder voltage droop s te combnaton of te voltage droops of all te loads eter drectly connected to te feeder under revew or mpactng on t by means of spur connectons. Ts value s lmted by system planners ndrectly by voltage drop and network loss consderatons. Te value must be suc tat te combnaton of all upstream voltage regulators wll keep te voltage wtn te acceptable range. Ts lmtng value we sall call te System voltage droop wt symbol droop. For Australan dstrbuton systems, prelmnary work suggests tat a typcal value s 30-40% pu. Consder a load S connected to an unloaded M feeder at a pont were te fundamental Tevenn reactance s. Te load voltage droop seen at te pont of connecton troug to te end of te feeder s S. droop. = S (8) Te am of te new allocaton approac s to form an allocaton equaton related to (8) so tat te armonc voltage s related to te voltage droop. Te major dffculty n ts development s to allow for dversty. B. Case wt no dversty for armonc quanttes Let us assume tat every load s gven an allocated armonc current proportonal to ts fundamental current. In per unt I S (9) Ts load ten gves a armonc voltage drop contrbuton of S ( S ) (0) Tus for eac fundamental voltage drop n te system, tere wll be a correspondng armonc voltage drop k tmes larger. Hence we can wrte d () Ts wll lead to a mamum armonc voltage contrbuton to te network equal to k tmes te load mamum fundamental voltage droop contrbuton. Wen aggregated across all customers, te total armonc voltage at te etremtes of te power system becomes lmted by te mamum network voltage droop. In order to ensure tat te mamum armonc voltage s acceptable L L k d roop (2) To lmt te armonc voltage and allow te system to be fully loaded (n te armonc sense), we cose L L k = (3) d roop C. Dversty represented by te summaton law For reasons wc wll become apparent below, we modfy (9) to gve

6 I k / S = (4) Suppose tat eac load s takng up ts full armonc allocaton. Te mamum load armonc current I s ten gven by (4). Te correspondng armonc voltage contrbuton at te pont of connecton and at any pont downstream from tere to te network etremtes s ( ) / = I S (5) Frst consder te case were te M subsystem as only one feeder. Te armonc voltage at te end of te feeder s found by addng terms lke (5) taken to te power of, tat s terms lke = ( k ) S (6) We see tat te armonc voltages to te power of are now proportonal to te voltage droop contrbutons. Wen tese terms are all added = ( k ) d (7) In order to lmt te armonc voltage at te end of L feeders, k sould be cosen from L L k = (8) / d roop For eample, for = 5, L L = 5.5%, droop = 30%, k s taken as Wen tere are several feeders, t s not possble to derve (8) n a rgorous a manner. Te dffculty s due to te equaton for te armonc voltage due to one source actng troug several mpedances n seres. Tese voltages add drectly, not usng te summaton law. As a consequence, te armonc voltage drops trougout te network no longer eactly correspond to te fundamental voltage drops. We ave studed several cases to fnd te error due to te use of (8) n mult-feeder systems. Tere s only room ere to gve bref conclusons Te use of (8) always leads to armonc voltages beng less tan te desred lmt, so te systems absorpton capacty s not fully utlsed. For a gven source mpedance, as te feeder lengt ncreases, te error at frst grows and ten decreases. Te error s a mamum wen te feeder mpedance s about fve tmes te supply mpedance. Te error ncreases wt te number of feeders. In partcular, we ave studed te error for a typcal Australan suburban system were te zone substaton supples about ten feeders wose mpedance s about ten tmes te source mpedance. For ts case, te error s 20%, wc s acceptable for tese studes and gves some reserve aganst uncertantes suc as te future connecton of embedded generaton. Te metod gven n [5] mgt appear to be more accurate because of te detaled modellng requred, but n practce muc of te data as to be guessed. Anoter factor s tat te present metod requres a very smple calculaton and s very robust aganst computatonal error. 4 D. ample Wat 5 t armonc current sould be allocated to a 500kA nstallaton connected to an M power system were te fault level s 62.5 ka? Te L Plannng level s taken as 5.5% and dversty s assumed to be represented by =.4. Te mamum network voltage droop at te network etremtes s 30%. Soluton: Usng a base of MA, S = 0.5 pu, = 0.06 pu and / /.4 S 0.5 I = pu = gvng a 5 t armonc current of 0.3% of te fundamental current. Te form of (4) gves less percentage armonc current wt ncreased load sze, and we wll nvestgate ts n more detal later. Note te followng ssues Te mamum end of L feeder voltage droop s te correct fgure to use rrespectve of were te assessed load s connected. Te data requred for eac allocaton calculaton s just two numbers, te load's mamum demand and te fundamental reactance at te pont of connecton. Te result apples rrespectve of te power system topology smple radal, radal wt spurs or mes. Tere s a close relatonsp between te proposed new allocaton procedure and armonc A allocaton. It can be seen tat (4) s very smlar n form to (7), te dfference beng te eponent of wc s lsted n Table. For low frequency armoncs, were tere s no dversty, tere s no varaton wt fault level. For te common armonc range 5 0, ts power s 0.29, compare wt 0.5 for armonc A, gvng armonc allocatons slgtly less senstve fault level tan te armonc A polcy. At g frequences, ts power s eactly te same as for te armonc A approac, wt te allocaton constant now found mmedately rater tan from an etensve armonc loadflow calculaton. TABL I ARIATION OF DNOMINATOR XPONNT WITH HARMONIC RANG range - - < < DPNDNC ON SHORT-CIRCUIT RATIO A. Allocaton equaton Te SCR or sort-crcut rato of a load s defned as te rato of te fault level at te pont of connecton dvded by te load mamum demand. fault_level SCR = = (9) S S For te present study, t s mportant tat te SCR value s related to te reactance component of te total system mpedance. Ts relatonsp s not so smple n weak M and L systems were te resstance component of te mpedance

7 s sgnfcant. Here te fault level value n (9) mgt ave to be ncreased from te actual value to more truly reflect te value of. Substtuton of (9) nto (4) gves I SSCR (20) We now epress te allocated current as a fracton of te fundamental current by dvdng by S gvng I SCR (2) I Anoter useful equaton s te varaton of te armonc voltage at te pont of connecton wt te supply, gven by multplyng (4) by te armonc mpedance and ten elmnatng usng (9). U SCR (22) quaton(2) as been graped n Fg. usng a log/lnear grap for = 5 gvng a percentage armonc current ncreasng as SCR to te power of Ts slowly varyng functon appears to ncrease more quckly n te grap because of te logartmc abscssa scale to allow representaton of a wde range of SCR. We note tat te percentage armonc current approaces a mnmum value of 2.6% at low values of SCR. We ave added ponts correspondng to SCR values for typcal condtons of a weak M system (SCR = 8), a strong M system (SCR = 00), a personal computer n a suburban ouse (SCR = 800) and a compact fluorescent lamp (SCR = 30,000). Ts glgts tat ts concept apples for bot nstallatons and ndvdual tems of equpment. We see tat M allocatons sould le n te range of 4-0%, PCs sould epect to draw about 7% 5 t armonc current and CFLs about 43% 5 t armonc current. I5(%) CFL strong 20 weak M PC 0 M SCR Fg. araton of allocated current wt Note tat actual equpment standards for PCs and CFLs would not be epected to ave eactly tese values. Tese standards ave been determned based on assumptons tat may not eactly matc te summaton law wt =.4. Neverteless tey are a good reference pont n te absence of any oter nformaton. In partcular, ts approac may be wort consderng for te L nstallaton standards wc are at present beng developed by some autortes. B. Comparson wt I 59 allocaton procedure I 59 [2] drectly epresses te percentage current allocaton n terms of SCR n tabular form. Te I lmts 5 are dfferent (3% at te 5 t armonc) and k as been recalculated as We ave tentatvely assumed a voltage droop of 30%. A comparson between te two approaces s gven n Fg. 2. An eact matc between a tabular approac and a sngle equaton cannot be epected. Wt ts reservaton, we note tat te new approac gves an allocaton procedure varyng wt SCR n a very smlar way. In general, te I approac gves a ger allocaton. It s possble tat a smaller value of voltage droop s applcable n te USA, n wc case te smoot graped would be scaled up to gve even closer agreement. Alternatvely, t s possble tat te I approac assumes tat not all customers take ter full allocaton, n contrast wt IC gudelnes. I5(%) SCR Fg. 2 Comparson of I 59 and proposed new allocaton procedure. (I, Proposed ) On te wole, te consstency of te two approaces s very good consderng tat tey are compared for a range of SCR coverng almost tree decades. Ts confrms tat te new approac s broadly consstent wt present practces. I. DISCUSSION Te work reported s only part of our nvestgatons. We summarse some oter ssues tat we ave consdered and wc wll be detaled n future publcatons. A. Trplens Balanced trplen armonc currents do not flow n te same pat as te fundamental and non-trplen armonc currents. Te pat depends upon transformer vector groups, transformer connecton arrangements and eartng practces wc vary wt dfferent utltes. Neverteless t sould be possble to estmate te rato of te effectve fundamental reactance seen from te etremtes of te L system usng postve and zero sequence mpedances. B. Plannng levels Te proposed approac s based only on meetng a plannng level at L, unlke te IC approac wc gves recommended plannng levels to be appled across te power system, reducng towards te ger voltage parts of te network. Te new approac allows te epected armonc voltage varaton across te network to be determned so tat

8 te state of te system can be assessed followng a armonc survey campagn. Because of te form of te summaton law, armonc voltage levels fall slowly from L to M and ten more quckly as te ger voltage levels are approaced. Tus te armonc voltages wc would result are very smlar to te IC plannng levels and ts confrms tat te approac s close to te IC gudelnes. Tere are doubts tat te recommend IC Plannng levels can be used n all system types for eample some Australan SWR (Sngle Wre art Return) systems wc ave g M mpedances and low L mpedances. Te new approac apples ere snce te essental am s to meet a compatblty level at te end of te etremtes of te system, not to meet a specfed armonc voltage profle across dfferent voltage levels. C. Accountng for prevous story Due to te pror use of oter standards, or possbly no standards at all, te armonc levels n a power system mgt develop dfferently tan f every nstallaton met an allocaton followng (4). It may not be satsfactory to cange mmedately to a new metod of armonc allocaton f tere as been a sgnfcant over-allocaton or under-allocaton n te past. An approac needs to be developed were tere are pre-allocaton measurements to assess te mpact of prevous allocaton scemes and ten a correspondng correcton to (4). D. Flcker allocaton Fnally we dscuss te ramfcatons for flcker allocaton wc dffers from armonc allocaton n several ways Only a fracton of loads requre a flcker allocaton Flcker dversty s represented by an eponental summaton law usng an eponent m wose value s often taken as 3. Te determnaton of flcker voltages nvolves bot resstve and reactve mpedance components and canges n bot load P and Q. A flcker allocaton sceme could be developed followng (22) were U s replaced by Pst for sort term flcker allocaton (a smlar term for long term flcker allocaton), s replaced by a multpler to account for mpedance angle and power factor effects and s replaced by m. II. CONCLUSIONS Present IC gudelnes are dffcult to apply to realstc cases because of te data load, te number of assumptons and te computatonal complety. A new approac based on te voltage droop concept s proposed. Its mplementaton requres tat all sunt capactors are effectvely detuned. Te benefts of te approac are a smple calculaton wt mnmal data and very few assumptons. It apples to radal or mesed dstrbuton systems were feeders are suffcently sort tat lne capactance can be gnored. It also apples to non-standard power systems suc as rural SWR type systems. Te approac can be appled at te nstallaton (M or L) and te equpment level. Altoug equpment standards may be based on very specfc assumptons of dversty, te new 6 approac can be used to gve reference values. Te approac s sown to be closely related to te I 59 approac. It s suggested tat te concept could be appled to oter power qualty allocaton studes suc as flcker and unbalance, but muc work needs to be done n ts area before useful results can be found. III. RFRNCS [] AS "Dsturbances n mans supply networks. Part 2: Lmtatons of armoncs caused by ndustral equpment", Standards Australa, frst publsed 979. [2] I Std , "I Recommended practces and requrements for armonc control n electrcal power systems", I 992 [3] IC/TR "lectromagnetc compatblty (MC) Part 3-6: Lmts Assessment of emsson lmts for te connecton of dstortng nstallatons to M, H and H power systems", IC, d 2, 2008 [4].J. Gosbell and D Robnson, "Allocatng armonc emsson to M customers n long feeder systems", Proc. AUPC03, Sept-Oct, 2003, Crstcurc [5].J. Gosbell, "Harmonc Allocaton to M Customers n Rural Dstrbuton Systems", Aust Journal of lectrcal & lectroncs ngneerng, ol. 5, No. 3, 2009, pp [6].J. Gosbell, S. Perera,. Smt, D. Robnson and G. Sanders, "Power Qualty Recommendatons for te applcaton of AS/NZS and AS/NZS ", Standards Australa, HB , August 2003, ISBN [7] R.A. Barr and.j. Gosbell, "Introducng Power System oltage Droop as a New Concept for Harmonc Current Allocaton", I, Internatonal Conference on Harmoncs and Qualty of Power, Sept, 200, Bergamo, Italy. IX. BIOGRAPHIS c Gosbell (M'975) obtaned s BSc, B and PD degrees from te Unversty of Sydney. He as eld academc postons at te Unversty of Sydney and te Unversty of Wollongong were e became te foundaton Professor of Power ngneerng. He s now mertus Professor and Tecncal Advsor to te Integral nergy Power Qualty and Relablty Centre. He s currently workng on armonc management, power qualty montorng and standards. He s a member of Australan standards and CIGR sub-commttees and s a Fellow of te Insttuton of ngneers, Australa. Robert Barr (M'993) s a consultng engneer and drector of s company lectrc Power Consultng Pty Ltd. Robert olds an Honours degree n lectrcal ngneerng from Sydney Unversty, a Master of ngneerng degree from te Unversty of NSW and a PD n electrcal engneerng from te Unversty of Wollongong. Robert as over 36 years eperence n te feld of electrcty dstrbuton and s a fellow of te Insttuton of ngneers Australa, a member of Consult Australa and Natonal Presdent of te lectrc nergy Socety of Australa.