Standardization of Power Quality Indices Related to Non-Sinusoidality in the Networks with a Voltage of 220 kv and Higher

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1 Stadardizatio of Power Quality dices Related to No-Siusoidality i the Networks with a Voltage of kv ad Higher L.. overikova, ad S.S. Smirov Abstract- The suggested paper deals with the stadards of : why are the stadards of established oly up to 33 kv, differet stadards established for differet harmoics, lower admissible values established as the harmoic umber icreases, startig with the 17-th harmoic, the reasos for stadard values. ad.4%, the stadards for harmoics divisible by 3, startig with the 9-th harmoic, more rigid tha for harmoics odivisible by 3? the paper proofs to remarks o State Stadard are give. dex Terms-- Power quality, harmoics, power quality idices, admissible values. NTRODCTON The Russia power quality stadard [4] employs two idices to estimate a extet to which the voltage waveform is distorted: - total harmoic distortio ad - a harmoic factor, where is the umber of harmoic. There are stadards for these idices. The stadards of will be discussed later. dex is calculated as follows ( ) = *1%, (1) where is a rsm voltage value of the -th harmoic, (1) is a rsm value of positive-sequece voltage of the fudametal frequecy istead of which we ca use. om This study was performed with support from grat of the leadig scietific school of Russia Federatio НШ TABLE 1 NORMALLY ADMSSBLE VALES of, % eve harmoics, o-divisible by eve harmoics, divisible by The stadards of are established for the etworks with a voltage up to 33 kv iclusive [4]. Table 1 presets the stadard values of for the voltages of ueve harmoics i the kv etworks. Harmoic compoets of distorted voltages most ofte exceed the stadard values o the harmoics preseted i Table 1. The maximal admissible values (MAV) more the ormally admissible values (NAV) i 1.5 times. The preseted stadards, as follows from [4], meet the iteratioal stadards ad directives of the teratioal Electrotechical Commissio cocerig electromagetic compatibility i power supply systems ad methods for measuremets of electromagetic disturbaces. The aalysis of the stadard values raises the questios: Why are the stadards of established oly up to 33 kv? Why are differet stadards established for differet harmoics? Why are lower admissible values established as the harmoic umber icreases, startig with the 17-th harmoic? What are the reasos for stadard values. ad.4%? Why are the stadards for harmoics divisible by 3, startig with the 9-th harmoic, more rigid tha for harmoics o-divisible by 3? 166

2 The questios arise first of all i coectio with the fact that uder the law o Electric power idustry [8] power quality should meet the requiremets of techical regulatios ad other madatory requiremets laid dow by other ormative acts. accordace with the law O techical regulatio [9] a draft of Techical Regulatios O electromagetic compatibility [1] has bee elaborated which is also valid for electric eergy i public electric etworks. The documet establishes madatory essetial requiremets for limitig electromagetic disturbaces i public electric etworks (esurig power quality)". "Electromagetic disturbaces i public electric etworks (power quality) shall ot exceed the levels providig operatio i accordace with the purposes of techical facilities that are fed by these etworks. To meet the essetial requiremets of the Techical regulatios the level of electromagetic disturbaces (power quality) should meet the requiremets of atioal electromagetic compatibility stadards. Electric eergy i public electrical etworks ca be supplied to cosumers oly if it is cofirmed that it meets the essetial requiremets of the Techical regulatios. t follows from the preseted provisios of the two laws ad the draft of the Techical Regulatios that power quality i terms of ad should be provided i accordace with the requiremets i [4]. Secodly, the requiremets of idex for some harmoics i [4], i the opiio of the authors, seem ujustified both techically ad ecoomically ad urealizable i real electric etworks, particularly, i Siberia. The specific features of electrical etworks affect the values of. The mai features of electric etworks ad loads i Siberia are: exteded electric etworks which were desiged igorig the power quality issues related to osiusoidality; most of the large oliear loads that cause distortios i the etwork were coected to the etworks without solvig the problems of limitig the disturbaces caused by them ad meetig the requiremets [4] at a coectio poit; most of the loads are cocetrated i cities that are located at large distaces from each other but coected through a commo electric etwork. High harmoics i the exteded electric etworks i Siberia result i a ripple effect. The legths of trasmissio lies are commesurable with the wave legths of harmoic compoets. As the harmoic umber icreases, the wave legths become shorter ad more commesurable with the legths of real trasmissio lies. The wave legth of propagatig electric eergy is about 6 km at a fudametal frequecy of 5 Hz. With a -fold frequecy rise the wave legth decreases times. For example, the wave legth o the 15 th harmoic is about 4 km, o the 19 th 316 km, o the 3d 6 km, o the 5 th 4 km. The ed of the trasmissio lie (ode) may coicide with a amplitude value of the voltage wave of the -th harmoic. Thus the voltage level of the -th harmoic i cosumer may exceed the stadard value. Fig. 1 shows the values ad i the odes of a kv etwork feedig tractio substatios of the East-Siberia railway o the sectio Lea- Taximo. The railway from Lea to Taximo is 75 km log, the total legth of kv lies is almost the same. The curves show very well the ripple effect for differet harmoics. The etwork i this area has log trasmissio lies, the capacities of loads coected i the etwork odes are isigificat ad do ot have a cosiderable impact o the wave character of harmoic voltage propagatio. The Figure shows that the higher the harmoic umber the greater umber of maximums ad miimums the harmoic voltage waveforms have. 167

3 4 3,5 3,5 1,5 1,5 Lea Yakurim Якурим Таyura Niya irega lka uerma Dava Severobaikalsk ichera Agoya Novy oya Yachuka Agaraka Pereval Okusika Taximo u, u() (%) u u(3) u(5) u(7) u(11) u(13) Fig. 1. Chages i ad i the coectio odes of tractio substatios o the sectio Lea-Taximo. Owig to exteded lies ad ripple effect i them the higher harmoics propagate over large distaces ad maifest themselves i the etwork odes i the viciity of which there are o oliear loads that geerate higher harmoics. Fig. 1 ad exceed the stadard values i some coectio odes of tractio substatios, however, it is kow that tractio loads do ot geerate harmoics. Power system ca absorb higher harmoics without exceedig the stadard distortios uder certai coditios, for example where the odes i the etwork have large odistortig loads. the idustrial cities that do ot have cosiderable distortig loads the idices ad are ormal. However, i Siberia large populated settlemets, ad hece loads, are located at large distaces from each other. The large populated settlemets have a more developed etwork, which facilitates the absorptio of higher harmoics without cosiderable voltage distortios. Therefore, i the odes i the etwork betwee cities with large loads the values of do ot meet the stadard requiremets [4]. Below we will try to substatiate the remarks o GOST (State Stadard) THE VALES OF STANDARD VALES N GOST The state power quality stadard adopted i 1997 [4] lays dow more rigid requiremets to idices ad (Table 1) tha the stadard of 1987 [5]. For the etworks of 11 kv ad higher the ormal value for was established equal to % ad the maximum value - to 4%. The maximum value for of all ueve harmoics was established equal to %. The questio arises if more rigid orms are justified i the stadard curretly i force [4]. f after eactig the Techical regulatios O electromagetic compatibility the orms for the idices of remai uchaged, eormous fuds will be ecessary to meet the requiremets of the regulatios. Measuremets i the real electric etworks show that for harmoics 9,15, 1, 3, 5 ad others, for which the stadards are very low, are very ofte violated. This is cofirmed by the measuremets (Table ) obtaied i differet odes i the etwork of rkutsk power system ad i the coectio odes of tractio substatios of the East-Siberia railway. The values exceedig the stadards are highlighted i bold i Table. 168

4 TABLE MEASRED VALES OF ON BSES OF V SBSTATONS, % Substatio dices u(9) u(15) u(1) u(3) u(5) Dava Novoiljisky Severobaikalsk Tataurovo Zaigraevo Baikalsk Novy oya Cheremkhovo Tulu Zima MAV NAV (9), % hilok haragu Mogzo Chita rulga Bushulei Zilovo seievskaya Pekovaya Mogocha Semiozeray Amazar Chichatka Erofei Pavlovich Gozha Zavitaya Substatio Fig.. Measured (9) o the buses at kv tractio substatios of the Zabaikalskaya Railway. (), % 1, 1,,8,6,4, hilok haragu Mogzo Chita rulga Bushulei Zilovo seievskaya Pekovaya Mogocha Semiozeray Amazar Chichatka Erofei Pavlovich Gozha Zavitaya se P u(19) u(3) u(5) Fig.3. Measured (19), (3), (5) o the buses at kv tractio substatios of the Zabaikalskaya Railway. Similar situatio is observed i the coectio odes of tractio substatios of the Zabaikalskaya railway. Fig. ad Fig.3 show the measured values of for harmoics 9, 19, 3 ad 5. The diagrams show the values with a probability of.95. The value of (9) exceeds the ormally admissible value of.4% at all substatios. The value of (19) exceeds the stadard value of.4% at most substatios. The value of (3) exceeds or close to exceedig the admissible value of.%. additio to the data give here the voltages of cosidered substatios cotai harmoic compoets of the voltage that exceed ormally ad maximum permissible values idicated i Table 1. Their ormalizatio will call for cosiderable fuds ad if to add the costs of ormalizatio of voltage harmoics 9, 19, 3, 5 the size of required fuds will be so huge that it will be difficult to imagie. Thus, we arrive at the coclusio that maybe first of all it is ecessary to try to coduct a feasibility study o the stadard values of for harmoics 9, 19, 3, 5. The h 169

5 stadards for high ad ultra high voltage etworks that are established i EEE Std [6] ca be take as a example of less rigid orms for. [6] for the voltages of 161 kv ad higher uder ormal operatig coditios, that are characterized by uchageable coditios for more tha 1 hour, the stadard for is established at the level of 1.% ad for 1.5%. der uchageable operatig coditios lastig for a shorter time period ad uder uusual coditios the stadards for the idices icrease 5%.. THE NEED OF STANDARDZNG () N THE NETWORS OF 55 V AND HGHER [4] there are o stadards for ad for the voltages of 5 kv ad higher. Table 3 presets the results of measuremets o the buses at 5 kv substatio Taishet ad Bratsk HPP (BHPP) [3]. This table also shows the stadards for idices ad for the voltage of 33 kv: the upper value is a maximum permissible value, the lower is a ormally permissible value. For the measured idices there are also two values: the upper is the largest measured value, the lower is the value with a probability of.95. TABLE 3 AND MEASRED ON 5 V BSES, % dex (3) (5) (7) (11) (13) Stadards for 33 kv BHPP Taishet Phase Phase А В С А В С Р (MW) Number of меasuremet P u Fig.4. Chage i ad P i phase A of Taishet substatio u ( %) The table shows that the voltages of the 11-th harmoic have the values exceedig the voltages of the other harmoics ad the stadards established for 33 kv. The distorted voltage has more sigificat third ad fifth harmoic compoets. Fig. 4 shows the values of active power (P) i the 5 kv lie ad o the 5 kv buses at Taishet substatio. The values were measured for 4 hours. t is see from the curves that durig the 4 hours power was trasmitted alterately to rasoyarsk ad rkutsk power system. both cases voltage waveform was distorted. Power was trasmitted from a 5 kv etwork to the etworks of lower voltages, thus, the 5 kv etwork is the source of distortios ad disturbaces with all the cosequeces to follow (accelerated agig of isulatio ad decrease of equipmet service life, icrease i power losses). Measuremets of higher harmoic state variables i the 5 kv etwork were used to simulate the 5 kv trasmissio lie from the Bratsk Hydropower Plat to the rasoyarsk power system. The, calculatios were carried out to estimate its impact o the harmoic state variables o the kv buses of the Bratsk Hydropower Plat. The calculatios show that the higher harmoics trasmitted alog the 5 kv lie have the largest impact o the voltage levels of the 3 rd ad 11 th harmoics o the kv buses at the Bratsk 17

6 u() (%) u() (%) Fhase agle (degrees) u(11).95 u(13).95 u(11)aver. u(13)aver. Fig. 5. A chage i ad o the 1 st system of buses at the Bratsk Hydropower plat with a chage i the phase agle of voltage of the fudametal frequecy Fhase agle (degrees) u(11)aver. u(13).95 u(11).95 u(13) aver. Fig. 6. A chage i ad o the d system of buses at the Bratsk Hydropower plat with a chage i the phase agle of voltage of the fudametal frequecy. Hydropower plat. Phase agle of voltage of the fudametal frequecy i the coectio ode of the lie iflueces the magitude of the impact. Fig. 5 shows how the voltage values of the 11 th ad 13 th harmoics o the first system of the kv buses at the Bratsk Hydropower plat chage with the chages i the phase agle of voltage of the fudametal frequecy i the coectio ode of the lie. The values of (11) ad (13) chage greatly whe the phase agle of the voltage of the fudametal frequecy i the coectio ode of the 5 kv lie chages i the rage from 31.9 to 41.9 degrees. Thus, the value of (11) decreases by 1%. The 5 kv lie iflueces similarly the harmoic state of the d system of the kv buses (Fig. 6). Based o the examples we ca coclude that the stadards for the values of idices ad should be established i the etwork of 5 kv ad higher. V. PROPOSALS ON NORMALZATON OF THE VOLTAGE WAVEFORM DSTORTON accordace with [4] the most probable iitiator of voltage waveform distortio is cosumer with oliear load. The oliear load cosumes o-siusoidal curret which is draw from the power source alog the etwork elemets (lies, trasformers). The source has effective resistace ad reactace ad causes o-siusoidal voltage sags i the etwork elemets. As a result, voltage i the odes becomes o-siusoidal. Voltage of the -th harmoic i ay i-th ode is determied from the expressio M & ji j= i = 1 Yii &, (1) where & ji is a curret to ode i from the j-th oliear load coected to the etwork; Y ii is iput admittace of ode i of the -th harmoic. f there were oly oe cosumer with oliear load i the etwork, as it follows from (1), he would be the iitiator of voltage distortio. t is geerally agreed that the equipmet that cotais ferromagetic cores is ot a source of higher harmoics. This equipmet coverts oly 1% of eergy received at the frequecy of 5 Hz ito the eergy of higher harmoics ulike electroic ad arc equipmet. The latter coverts 1%- 3% of eergy produced at the frequecy of 5 Hz ito the eergy of higher harmoics. This equipmet relates to oliear loads. f there are several cosumers with oliear load, the curret value i the etwork ode is determied by the vector sum of currets i the umerator (1). The vector sum of currets depeds o the value ad phase of each 171

7 (), % Number of measuremet u(3) u(5) u(7) u(11) u(13) Fig. 7. Chage i after switchig a capacitor bak for reactive power compesatio. curret. The curret phase is determied by the curret phase of oliear load ad a distace betwee the oliear load ad the aalyzed ode. A ripple effect iflueces the curret of higher harmoics i the etworks of kv ad higher that have lies that are commesurable i legth with the higher harmoic waves. Thus, the resultat curret value i the umerator of expressio (1) may vary from the maximum value, whe curret phases coicide, to the miimum oe, whe the phases are opposite. The studies show that i the etworks with several oliear loads the resultat value of curret is, as a rule, smaller tha idividual cotributios from each oliear load. However, it also follows from expressio (1) that the voltage value will deped o the value of iput admittace of the ode. The admittace value is determied by the etwork. Chage i the etwork scheme ad its structure will chage the admittace, though i this case the curret value will chage as well. Calculatios show that the curret ad admittace chages may occur i oe directio, i.e. either both icrease or both decrease, ad these chages do ot lead to sigificat chages i the voltage value. But sometimes there ca be chages that may result i a more cosiderable decrease of the admittace as compared to the chage i the curret value, ad the the voltage rises sharply. Most ofte this occurs if the admittace value declies as a result of resoat circuit formatio. The curves built o the basis of measuremets illustrate this situatio very well (Fig. 7). As is see from the curves, switchig of a capacitor bak at substatio Tataurovo, that belogs to the Buryat power system, caused a sharp icrease i the voltages of the third ad fifth harmoics, their ormally admissible value is 1.5% Y(3).3 Y(5) Y(), Sm Y(7).1.5. Fig. 8. put admittaces of the kv etwork odes o the sectio Lea- Taximo of the ESR. Lea Yakurim Tayura Niya irega lka uerma Dava Severobaikalsk ichera Agoya oya Yacuka Agaraka Pereval Okusika Taximo 17

8 The ifluece of the etwork o the value of is also show i Fig. 8. Fig. 8 shows admittaces Y i the coectio odes of tractio substatios to the kv etwork. There is several time differece i the iput admittace values i the odes with the same harmoics. Accordig to expressio (1) values could be differet at the same currets i odes. other words equal loads i differet odes could cause differet voltage distortios. Thus, the harmoic voltage level is determied ot oly by oliear load but also by the etwork with oliear load. Therefore, resposibility for power quality related to higher harmoics should be divided betwee cosumers with oliear load ad power supply compay that ows the electric etwork. Cosumer should be resposible for harmoic currets, which are geerated ito the etwork by his load, because oly he ca cotrol his load. This proposal coforms to the draft Techical Regulatios o limitatio of electromagetic disturbaces i the etwork [1]. The stadards (Table 4 ad Table 5) i [3] ca be preseted as a example of stadards for distortio currets. Power supply compay should be resposible for the harmoic voltage levels because it cotrols impedaces (admittaces) of the whole etwork. t is said i [7] that the etwork is resposible for possible resoat modes at higher harmoics. We ca do more ad establish the stadards for the value of iput admittace of the etwork odes at higher harmoics. Both coductace ad susceptace ifluece harmoic voltage values. Therefore the stadards should be established for admittace. t is possible to cosider distortio harmoic powers istead of admittace as proposed i []. Based o the distortio powers, expressio (1) ca be writte i the form M D & =, Г ( ) ji j = 1 ( ) ( ) orm D& П ( ) ii where D & = Г ji i & is geeratio of ( ) (1) ( ) ji distortio power of the -th harmoic to the i-th ode by the oliear load of the j-th ode, D & П ( ) ii = ( ) orm(1) iy is absorptio ( ) ii of distortio power of the -th harmoic of the i-th ode, ( 1) i is a rms value of voltage of the fudametal frequecy i the i-th ode, ( ) orm is a stadard value established i [4]. TABLE 4 STANDARDS FOR DSTORTON CRRENTS N PBLC POWER SPPLY SYSTEMS OF V КЗ H <11 11 < 17 (%) () 17 < 3 3 < (%) < > TABLE 5 STANDARDS FOR DSTORTON CRRENTS N PBLC POWER SPPLY SYSTEMS HGHER THAN 161 V КЗ H <11 11 < 17 (%) () 17 < 3 3 < (%) < >

9 The stadards for admittace values may be established as a stadard value of distortio power absorptio D & П ( ) orm. Aother approach is also possible. To meet the requiremets i [4] with respect to it is ecessary to meet the coditio & D i each ode. D & П ( ) ii Г ( ) ji Resoat filters ca be employed as additioal techical measures to meet the coditio. The filters, i this case, should be chose based o the priciple of cetralized ormalizatio of harmoic voltages i the etwork, by icreasig the capabilities of absorbig harmoic currets i the whole etwork. V. CONCLSONS As coclusios to the paper we preset the high-priority goals to be implemeted i the area of ormalizatio of higher harmoics: 1. to coduct a feasibility study o the stadard values of ad ;. to establish stadards for the values ad for the voltages of 5 kv ad higher; 3. to establish stadards for the values of harmoic currets of cosumers; 4. to establish stadards for the values of iput admittaces of etwork odes. V. REFERENCES Periodicals: [1] Bratukhi P.., armashev V.S., Protasov S.N. Techical Regulatios O Electromagetic Compatibility Prelimiarily Approved// Novosti electrotehiki, 4, 4(8). [] Smirov S.S., overikova L.. Normalizatio of Voltage Levels of Higher Harmoics i High Voltage Networks // Electrichestvo,, 11. Papers from Coferece Proceedigs (Published): [3] overikova L.., Smirov S.S., Voroov Yu.N., yu V.A. Higher Harmoics i the Nodes of 5 kv Trasmissio Lies Coectio. Eergy Cooperatio i Northeast Asia: prerequisites, coditios, ways // Proceedigs of the teratioal Coferece. September 9-13,, rkutsk, Russia. Stadards: [4] State stadard Power quality. Electromagetic compatibility of techical equipmet. Power quality limits i electrical systems. - M., [5] State Stadard GOST Electric Power. Requiremets to Electric Power Quality i Public Electrical Networks. Moscow. Publishig Compay of Stadards [6] EEE Recommeded Practices ad Requiremet for Harmoic Cotrol i Electra Power Systems. EEE Stadard , EEE, New York, 199. structios: [7] RD Methodical Guidelies o Cotrol ad Aalysis of Power Quality i the Public Power Supply Systems. Part. Power Quality Aalysis. Laws: [8] A Federal Law of the Russia Federatio of March 6, 3 35-FL O Electric Power dustry. Rossiiskaya Gazeta, 3, April 1 ( 6 (3174)). [9] A Federal Law of December 7, ФЗ O Techical Regulatio. Rossiiskaya Gazeta,, December 31 ( 45 (3113)). V. BOGRAPHES Lidia. OVERNOVA was bor i Russia. She graduated from the Novosibirsk Power Egieerig stitute. She defeded the thesis of Cadidate of Techical Scieces ad received the scietific degree. At preset she is a Researcher at the Eergy Systems stitute of the Russia Academy of Scieces. She is also a Doctor of the Power Supply Departmet of the rkutsk stitute of Egieers of Railway Trasport. Her fields of iterest are power quality ad harmoics. Sergei S. SMRNOV was bor i 1936 i Russia. He graduated from the Moscow Power Egieerig stitute. He defeded the theses of Cadidate ad Doctor of Techical Scieces ad received the scietific degrees. At preset he is a Researcher at the Eergy Systems stitute of the Russia Academy of Scieces. His field of iterest is harmoics. 174

International Journal of Emerging Technologies in Computational and Applied Sciences (IJETCAS)

International Journal of Emerging Technologies in Computational and Applied Sciences (IJETCAS) teratioal Associatio of Scietific ovatio ad Research (ASR) (A Associatio Uifyig the Scieces, Egieerig, ad Applied Research) teratioal Joural of Emergig Techologies i Computatioal ad Applied Scieces (JETCAS)