Adaptive Droop Control Shunt Active Filter and Series AC Capacitor Filter for Power Quality Improvement in Power System

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1 ville online t: Speil Issue from nd Ntionl onferene on omputing, Eletril, Eletronis nd Sustinle Energy Systems, 6 th 7 th July 17, Rjhmundry, Indi dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for Power Qulity Improvement in Power System G.nil Kumr 1 M.V.Rghvendr Reddy 1PG Sholr, Deprtment of EEE, Godvri Institute of Engineering nd Tehnology, Rjhmundry, ndhr Prdesh, Indi. sssitnt Professor, Deprtment of EEE, Godvri Institute of Engineering nd Tehnology, Rjhmundry, ndhr Prdesh, Indi. To ite this rtile G.nil Kumr nd M.V.Rghvendr Reddy, dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for, Interntionl Journl for Modern Trends in Siene nd Tehnology, Vol. 3, Speil Issue 4, July 17, pp STRT Most of the pollution issues reted in power systems re due to the nonliner hrteristis nd fst swithing of power eletroni equipment. Power qulity issues re eoming stronger euse sensitive equipment will e more sensitive for mrket ompetition resons, equipment will ontinue polluting the system more nd more due to ost inrese used y the uiltin ompenstion nd sometimes for the lk of enfored regultions. Effiieny nd ost re onsidered tody lmost t the sme level. tive power filters hve een developed over the yers to solve these prolems to improve power qulity. mong whih shunt tive power filter is used to eliminte nd lod urrent hrmonis nd retive power ompenstion. In this pper the study is rried out on oth PI ontroller sed nd rtifiil Neurl Network (NN) ontrolled, threephse shunt tive power filter to ompenste hrmonis nd retive power y nonliner lod to improve power qulity is implemented for threephse three wire systems. Keywords tive Power Filter, Hrmoni, Instntneous P Q Theory, lned, Unlned Lods, D Link Voltge ontroller, Voltge Soure Inverter (VS) opyright 17 Interntionl Journl for Modern Trends in Siene nd Tehnology ll rights reserved. I. INTRODUTION Eletri utilities nd end users of eletri power re eoming inresingly onerned out meeting the growing energy demnd. Seventy five perent of totl glol energy demnd is supplied y the urning of fossil fuels. ut inresing ir pollution, glol wrming onerns, diminishing fossil fuels nd their inresing ost hve mde it neessry to look towrds renewle soures s future energy solution. Sine the pst dede, there hs een n enormous interest in mny ountries on renewle energy for power genertion. The mrket lierliztion nd government s inentives hve further elerted the renewle energy setor growth. Renewle Energy Soure (RES) integrted t distriution level is termed s Distriuted Genertion (DG). The utility is onerned due to the high penetrtion level of intermittent RES in distriution systems s it my pose thret to network in terms of stility, voltge regultion nd PowerQulity (PQ) issues. Therefore, the DG systems re required to omply with strit tehnil nd regultory frmeworks to ensure sfe, relile nd effiient opertion of overll network. With the dvnement in power eletronis nd digitl ontrol tehnology, the DG systems n now e tively ontrolled to enhne 9 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

2 G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for the system opertion with improved PQ t Point of ommon oupling (P). However, the extensive use of power eletronis sed equipment nd nonliner lods t P generte hrmoni urrents, whih my deteriorte the qulity of power. Generlly, urrent ontrolled voltge soure inverters re used to interfe the intermittent RES in distriuted system. Reently, few ontrol strtegies for grid onneted inverters inorporting PQ solution hve een proposed. In n inverter opertes s tive indutor t ertin frequeny to sor the hrmoni urrent. ut the ext lultion of network indutne in reltime is diffiult nd my deteriorte the ontrol performne. similr pproh in whih shunt tive filter ts s tive ondutne to dmp out the hrmonis in distriution network is proposed. ontrol strtegy for renewle interfing inverter sed on theory is proposed. In this strtegy oth lod nd inverter urrent sensing is required to ompenste the lod urrent hrmonis. The nonliner lod urrent hrmonis my result in voltge hrmonis nd n rete serious PQ prolem in the power system network [3]. tive Power Filter (PF) is extensively used to ompenste the lod urrent hrmonis nd lod unlne t distriution level. This results in n dditionl hrdwre ost. nother solution is to inorporte the fetures of PF in the, onventionl inverter interfing renewle with the grid, without ny dditionl hrdwre ost. Here, the min ide is the mximum utiliztion of inverter rting whih is most of the time underutilized due to intermittent nture of RES. The gridinterfing inverter n effetively e utilized to perform funtions s trnsfer of tive power hrvested from the renewle resoures (wind, solr, et.), lod retive power demnd support, urrent hrmonis ompenstion t P, urrent unlne nd neutrl urrent ompenstion in se of 3phse 4wire system. Moreover, with dequte ontrol of gridinterfing inverter, ll the four ojetives n e omplished either individully or simultneously. The PQ onstrints t the P n therefore e stritly mintined within the utility stndrds without dditionl hrdwre ost. Figure 1: si Prinipl of Shunt urrent ompenstion in tive Filter The ontrol strtegy for shunt tive power filter genertes the referene urrent, tht must e provided y the power filter to ompenste retive power nd hrmoni urrents demnded y the lod. This involves set of urrents in the phse domin, whih will e trked generting the swithing signls pplied to the eletroni onverter y mens of the pproprite losedloop swithing ontrol tehnique suh s hysteresis or dedet ontrol. Severl methods inluding instntneous rel nd retive power theory hve een proposed for extrting the hrmoni ontent [5]. With the development of power eletroni tehnology, low voltge nd high urrent swithing power supply hs een pplied widely in prodution nd life. ut hrmoni pollution eomes severe inresingly in swithing power supply. Generlly, there re two methods to eliminte hrmonis, whih re minly pssive power filter nd tive power filter. The former is reltively low ost, ut filtering effet is fr from desirility. y ontrst, the ltter n suppress the hrmonis instntly nd ompenste retive power, nd it eomes n effetive pproh to inhiit hrmonis. Thus, this pper employs tive power filter to suppress hrmoni urrent of low voltge nd high urrent swithing power supply II. DESIGN OF PF Priniple of PF PF, whih is shemtilly depited in Figure, onsists of twolevel Voltge Soure onverter (VS), d energy storge devie, oupling trnsformer onneted in shunt to the distriution network through oupling trnsformer. The VS onverts the d voltge ross the storge devie into set of threephse 3 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

3 G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for output voltges. These voltges re in phse nd oupled with the system through the retne of the oupling trnsformer. Suitle djustment of the phse nd mgnitude of the PF output voltges llows effetive ontrol of tive nd retive power exhnges etween the PF nd the system. Suh onfigurtion llows the devie to sor or generte ontrollle tive nd retive power. e hieved with minimum pprent power injetion into the system. Priniple of PF pplied to Drive Figure 3: Shemti Digrm of PF Figure : Shemti Digrm of PF The VS onneted in shunt with the system provides multifuntionl topology whih n e used for up to three quite distint purposes: Voltge regultion nd ompenstion of retive power orretion of power ftor Elimintion of urrent hrmonis. Here, suh devie is employed to provide ontinuous voltge regultion using n indiretly ontrolled onverter. s shown in Figure.1 the shunt injeted urrent Ish orrets the voltge sg y djusting the voltge drop ross the system impedne Zth. The vlue of Ish n e ontrolled y djusting the output voltge of the onverter. The shunt injeted urrent Ish n e written s, Ish = IL IS = IL ( Vth VL ) / Zth (1) Ish /_η = IL /_ θ () It my e mentioned tht the effetiveness of the PF in orreting voltge sg depends on the vlue of Zth or fult level of the lod us. When the shunt injeted urrent Ish is kept in qudrture with VL, the desired voltge orretion n e hieved without injeting ny tive power into the system. On the other hnd, when the vlue of Ish is minimized, the sme voltge orretion n n tive power filter, PF, typilly onsists of three phse pulse width modultion (PWM) voltge soure inverter [5]. When this equipment is onneted in series to the soure impedne it is possile to improve the ompenstion hrteristis of the pssive filters in prllel onnetion [6], [7]. This topology is shown in Figure 3, where the tive filter is represented y ontrolled soure, where is the voltge tht the inverter should generte to hieve the ojetive of the proposed ontrol lgorithm. Instnteous Power Theory The ontrol sheme of the shunt tive power filter must lulte the urrent referene signls from eh phse of the inverter using instntneous relpower ompenstor. The lok digrm s shown in Figure.4, tht ontrol sheme genertes the referene urrent required to ompenste the lod urrent hrmonis nd retive power. The PI ontroller is tried to mintin the dus voltge ross the pitor onstnt of the sded inverter. This instntneous rel power ompenstor with PIontroller is used to extrts referene vlue of urrent to e ompensted. 31 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

4 G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for orthogonl referene system of oordintes α, β. In oordintes xes re fixed on the sme plne, prt from eh other y 1o tht s shown in Figure 5. The instntneous spe vetors voltge nd urrent V, i re set on the xis, V, i re on the xis, nd V, i re on the xis. These spe vetors re esily trnsformed into α, β oordintes. The instntneous soure voltges vs, vs, vs re trnsformed into the α, β oordinte s voltge vy lrke trnsformtion s follows: Figure 4: Referene urrent Genertor Using Instntneous RelPower Theory The referene urrents (is*, is * nd is *)re ompred with tul soure urrent (is)is, is nd is tht filittes generting sded multilevel inverter swithing signls using the proposed tringulrsmpling urrent modultor. The smll mount of relpower is djusted y hnging the mplitude of fundmentl omponent of referene urrents nd the ojetive of this lgorithm is to ompenste ll undesirle omponents. When the power system voltges re lned nd sinusoidl, it leds to onstnt power t the d us pitor nd lned sinusoidl urrents t mins simultneously. III. PROPOSED INSTNTNEOUS PROPOSED ONEPT The proposed instntneous relpower (p) theory derives from the onventionl pq theory or instntneous power theory onept nd uses simple lgeri lultions. It opertes in stedystte or trnsient s well s for generi voltge nd urrent power systems tht llowing to ontrol the tive power filters in reltime. The tive filter should supply the osillting portion of the instntneous tive urrent of the lod nd hene mkes soure urrent sinusoidl Similrly, the instntneous soure urrent is, is, is lso trnsformed into the oordinte s urrent i i y lrke trnsformtion tht is given s; Where α nd β xes re the orthogonl oordintes. They Vα, iα re on the αxis, nd Vβ, iβ re on the βxis. RelPower (p) lultion The orthogonl oordintes of voltge nd urrent Vα, iα re on the αxis nd Vβ, iβ re on theβxis. Let the instntneous relpower lulted from the αxis nd β xis of the urrent nd voltge respetively. These re given y the onventionl definition of relpower s : This instntneous relpower p is pssed to first order utterworth design sed 5 Hz low pss filter (LPF) for eliminting the higher order omponents; it llows the fundmentl omponent only. These LPF indites omponents of the relpower losses nd it s denoted s p The D power loss is lulted from the omprison of the dus pitor voltge of the sded inverter nd desired referene voltge. The proportionl nd integrl gins (PI ontroller) re determining the dynmi response nd settling time of the dus pitor voltge. The D omponent power losses n e written s Figure 5: αβ oordintes Trnsformtion The pq theory performs lrke trnsformtion of sttionry system of oordintes to n 3 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

5 MESUREMENTS onverter 1 ontroller Grid onneted onverter 1 Disrete, Ts = 5e5 s. powergui Susystem G Step1 TIVE FILTER TIVE FILTER d G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for The instntneous relpower ( p) is lulted from the omponent of the relpower loss p nd the D power loss pd(loss) ) ; it n e defined s follows; IV. SIMULTION RESULTS The instntneous urrent on the α,β oordintes of Iα nd iβ re divided into two kinds of instntneous urrent omponents; first is relpower losses nd seond is retive power losses, ut this proposed ontroller omputes only the relpower losses. So the α,β oordinte urrents Iα nd iβ re lulted from the v,v voltges with instntneous rel power p only nd the retive power q is ssumed to e zero. This pproh redues the lultions nd shows etter performne thn the onventionl methods. The oordinte urrents n e lulted s Fig: 6 Simultion Digrm Fig: 7 Soure Voltge nd urrent From this eqution, we n lulte the orthogonl oordinte s tivepower urrent. The xis of the instntneous tive urrent is written s: Similrly, the xis of the instntneous tive urrent is Written s: Fig:8 Power Ftor of the supply Let the instntneous powers p(t) in the xis nd the xis is represented s p nd p respetively. They re given y the definition of relpower s follows: Fig:9 tive Power nd Retive Power from the supply Fig:1 D Link Voltge 33 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

6 Mg (% of Fundmentl) Mg (% of Fundmentl) Disrete, s = 5e5 s powergui T Isf From6 From1 I From3 Isf From Irefsf From7 Voltge Soure Voltge Soure1 Voltge Soure dd Series RL rnh1 Series RL rnh Series RL rnh Sope V From8 I From9 VI Mesurement V I power ftor tive & Retive Power Sope4 VI Mesurement1 Susystem Universl ridge Timer1 VI Mesurement Series RL rnh3 om Series RL rnh1 reker1universl ridge1 Trnsformer (Two Windings) Susystem1 Mg (% of Fundmentl) Mg (% of Fundmentl) G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for Seleted signl: 4 yles. FFT window (in red): yles Seleted signl: 5 yles. FFT window (in red): yles Fundmentl (6Hz) = 151, THD= 36.99% Fundmentl (5Hz) = 333.3, THD=.78% Frequeny (Hz) Frequeny (Hz) Fig:11 THD nlysis of for urrent efore filters (36.99%) Fig:16 THD nlysis for Soure urrent (.78%) Seleted signl: 4 yles. FFT window (in red): yles Seleted signl: 5 yles. FFT window (in red): yles Fundmentl (6Hz) = 146.5, THD= 17.6% 5 1 Fundmentl (5Hz) = 5, THD= 9.41% Frequeny (Hz) Fig: 1 THD nlysis of for urrent with filters (17.6%) Frequeny (Hz) Fig: 17 THD nlysis for Lod urrent (9.41%) Fig:13 Proposed Simultion iruit with fyzzy logi Fig:14 Lod urrent, Soure urrent nd Filter urrent Fig:15 Proposed iruit Power Ftor V. ONLUSION This pper presents novel method to improve the power qulity t point of ommon oupling for 3phse 4wire DG system using PI ontroller for grid interfing inverter. The grid interfing inverter is effetively utilized for power onditioning. This pproh elimintes the dditionl power onditioning equipment to improve power qulity t P. The gridinterfing inverter with the proposed pproh n e utilized to injet rel power genertion from RES to the grid, nd operte s shunt tive Power Filter (PF). The urrent unlne, urrent hrmonis nd lod retive power, due to unlned nd nonliner lod onneted to the P, re ompensted effetively suh tht the grid side urrents re lwys mintined s lned nd sinusoidl t unity power ftor. Moreover, the lod neutrl urrent is prevented from flowing into the grid side y ompensting it lolly from the fourth leg of inverter. When the power generted from RES is more thn the totl lod power demnd, the gridinterfing inverter with the proposed ontrol pproh not only fulfills the totl lod tive nd retive power demnd (with hrmoni ompenstion) ut lso delivers the exess generted sinusoidl tive power to the grid t unity power ftor. 34 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17

7 G.nil Kumr nd M.V.Rghvendr Reddy : dptive Droop ontrol Shunt tive Filter nd Series pitor Filter for REFERENES [1] S.K.Khden, M.su,M.F.onlon," Power qulity in grid onneted renewle energy systems: Role of ustom power devies". IERPQ, Grnd,spin, Mr1. [] Dr.Jzeri, Dr..Mozfri," Novel DG grid interfe ontrol strtegy for tive power injetion mngement nd power qulity improvement" IPS,Thrn,Iron, Nov11. [3].rulmplm, M.rnes,.Engler, " ontrol of power eletronis iinterfes in distriuted genertion miro grids" IJE,vol.5,4.,pge no.11. [4] IonelVEHIU, GeluGURGUITU, Emil ROSU,"dvned tive Power onditioner to Improve Power Qulity in Mirogrids" IPE.,IEEE onf.,1. [5] Shym ll vrm, jy ngr, nkit soni, Shrm Gjendrgdkr, " Renewle nd nonoonventionl energy soures ndengineering system" Interntionl journl of mehnil nd indusril engineering, IJMIE, Vol.,1,issue.,3,1. [6] K.S.Sidhu, " Non onventionl energy resoures". [7] Gyn reserh nd nlyti.ltd," The potentil for renewle energy in Indi1". jn.,1. [8] Peter Meisen," Overview of renewle energy potentil of Indi" Glol energy network institute GENI., ot.,6. [9] Energy lterntive Indi," Indi renewle energy dvisor" 5 th renewle energy Indi 11 expo., New delhi., ug11. [1] Sutn Guru," Renewle energy soures in Indi is it vile" Julin simon entre for poliy reserh.,ot. [11] "lterntive energy soures", Ministry of non onventionl energy soures, Govt.of.Indi. ug5. [1] Thomos kermn, Gorn ndersson, Lennrt Soder," Distriuted genertion definition".,epsr.,1. [13]..yod Rejul,J.Mur md,j.l ernl,j.m.yust, Loyo,J.. Dominguez," Definitions for distriuted genertion: revision". [14] N.Rihrd friedmon," Distriuted genertion, Tehnology hllenges nd needs" merin power onferene, higo,pril1999. [15] Roert H. Lsseter, Polo pigi," Miro grid: oneptul solution"., PES,Germeny.,jun4. 35 Interntionl Journl for Modern Trends in Siene nd Tehnology, Volume 3, Speil Issue 4, July 17