Mitigation of Harmonics in Micro Grid using Photo Voltaic cell interfaced Shunt Active Power Filter

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Irene Quinn
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1 Mtgaton of Harmoncs n Mcro Grd usng hoto Voltac cell nterfaced Shunt Acte ower Flter Selakumar.S 1, Aruna.V 2, Jagan.R 3, UG scholar, Department of EEE, SMVEC 1, 2, 3. ondcherry, Inda. Abstract: - Ths paper proposes a technque to mtgate the harmonc dstorton n mcro grd system. In conentonal system capactors and oltage source nerter (VSI) are used to generate reacte power and to nject the compensaton current nto the grd [2],[3],[4]. The performance of SAF s manly depends on controllablty of DC lnk oltage [6]. The man objecte of ths paper s to mproe the performance of the Shunt Acte ower Flters (SAF) by addng RE source n the DC lnk sde. In proposed technque the capactor banks are replaced by clean renewable energy sources lke photooltac cell, wnd mll, bo gas generator etc. Among ths we prefer V panels for effecte compensaton due to ts system controllablty and the preferable output characterstcs. Due to the addton of ths Shunt Acte ower Flters (SAF) the power carryng capablty of the grd lnes must be mproed and the effcency of transmsson can be mproed. The addtonal real power demand n the mcro grd has been meetng out wth the help of ths topology. The output results are obsered from MATLAB/Smulnk enronment. Keywords V pannel, Shunt Acte ower Flter(SAF), conductance type MT, Mcro grd system. I. INTRODUCTION On current stuaton power demand became tal role. In that occason losng of power durng transmsson made some major ssues. On referrng ancent days the electrcal power demand s meetng out by centralzed power generaton unts whch are located near to the energy resources. Then the generated power s transmtted to the load through the long transmsson lnes. As the populaton ncreases the aboe mentoned transmsson lnes became faulty. Due to eoluton of Mcro Grd Technology Renewable energy sources lke hoto oltac system, Wnd energy, Bo mass generaton etc,. Major researches are gong n the feld of Mcro Grd technology n order to manage the power demand. Mcro grd s nothng but an nterconnecton of more than one RE or Non- RE source of capacty less than 50MVA to supply the ndustral or resdental load s called Mcro Grd [4]. The major concern n mcro grd technology s harmoncs ejecton by the nonlnear load [5], [8]. Harmoncs s nothng but a seere ower qualty ssue whch s the effect of addton of more than one frequency wth the fundamental frequency. A load s consdered to be non-lnear f the current drawn by load wll be non-snusodal een f t s connected to a snusodal oltage. Now a day s ndustres prefer seeral nonlnear loads, among them we selected 3 phase controlled rectfer for our analyss. In consdered load a seere power qualty ssue s caused when t s operated at RL Loaded condton. The only control arable n ths system s trggerng angle (α). Trggerng angle s nothng but the nstant at whch gate s gen to the swtches the rectfer. Due to ths delayed turn on/off of load the current consumed by the load s also nonlnear.e., non-snusodal n nature t looks lke almost square waeform. Ths wll result n seere power qualty ssue n the Mcro Grd System. These problems are pre-defned n IEEE 519 and EN Accordng to the IEEE standard Grd system operated less than 69kV should mantan Total Harmonc Dstorton (THD) alue less than 5% and nddual oltage dstorton must be less than 3% [1]. To satsfy those constrants compensaton s done by arous methods. In normal topology the Harmonc mtgaton s encountered by usng Acte ower Flter. They are connectng seres, parallel, seres-shunt and hybrd confguraton wth the Grd lnes [9]. In our topology current harmonc s compensated by couplng SAF parallel wth mantanng some external power supply (photooltac cell). The performance of proposed system s ealuated under two operaton condton. One s under fxed trggerng angle (Statc performance) another one s under arous trggerng angle (Dynamc performance). For edent these compensaton, the performance of the proposed system s seen through MATLAB/SIMULINK enronment and we conclude the results. SSN: age 176

II. CONFIGURATION OF V-SAF A. Operatng prncple of SAF Shunt Acte ower Flter (SAF) s a power electronc crcut whch s used to meet out the power qualty ssues n a grd lne.

It consumes power from the grd to mantan the constant oltage wth small deaton. The effcency of compensaton s manly dependng on controllablty of DC lnk oltage.

So, we proposed a system to replace the place of capactor by renewable energy source.

In order to ncrease the power ratng of V Cell more than one cell s connected ether n seres/parallel depends on our requrement. Whch s also be desgned n MATLAB/SIMULINK enronment.

The data for ths calculaton s obtaned from current sensors attached n transmsson lne of Mcro grd. B.

2 II. CONFIGURATION OF V-SAF A. Operatng prncple of SAF Shunt Acte ower Flter (SAF) s a power electronc crcut whch s used to meet out the power qualty ssues n a grd lne. It s coupled wth external DC source to mantan the nput oltages called DC lnk oltage. In ancent days these can be acheed by couplng a capactor of large alues [7]. It consumes power from the grd to mantan the constant oltage wth small deaton. The effcency of compensaton s manly dependng on controllablty of DC lnk oltage. But the capactor prodes short range of controllablty. Addtonal to that the magntude of some ntermedate frequency s domnant n nature. So, we proposed a system to replace the place of capactor by renewable energy source. Here, we prefer photooltac system to prode fner controllablty, whch works under the prncple of hoto-electrc effect. In order to ncrease the power ratng of V Cell more than one cell s connected ether n seres/parallel depends on our requrement. Whch s also be desgned n MATLAB/SIMULINK enronment. reference current for these controller s calculated by Fast Acton Reference Current generator method. Here we preferred Instantaneous ower Theory method for reference current generaton. The data for ths calculaton s obtaned from current sensors attached n transmsson lne of Mcro grd. B. Desngng of DC source In these paper we are proposed a new topology to mantan a dc source generated from hotooltac panel (V). The equalent crcut of V s shown n the fgure. The desgn parameters that hae been consder from IEEE Standards. Fg.2 Equalent crcut of V panel I (2) I p I 0 e ( V R I ) / V ta V R s I s 1 / R p Fg.1 Block Dagram of V-SAF As mentoned n the block dagram, nonlnear load s drectly connected to the Mcro grd means there wll be more power qualty ssues must be happened. To meet out these problems we hae proposed a new topology called V based Shunt Acte power flter. In ths system, compensaton current s generated from hotooltac panel and njected through SAF at out of phase wth Mcro grd at the pont of common couple (CC) whch s nearer to load. Ths compensaton current mtgates the harmoncs current and make the source or grd current as pure snusodal. I l =I c + I s (1) Ths compensaton current can be controlled by Hysteress current controller. The Where I p and I 0 are the photooltac (V) and saturaton currents, respectely wth the array and V T = N s kt/q s the thermal. arameters Range I mp 76.1A V mp 26.3 max, m W I sc 8.21A V oc 32.9V I o, n A I p 8.214A A 1.3 R p Ω R s Ω N sc 1 N pc W Tab.1 Desgn parameters of V panel The photooltac panel s connected to the SAF s desgned from the aboe mentoned parameters and equatons. Voltage from the desgned V panel s feed nto the DC lnk sde of the SAF. In order to mantan the coupled DC oltage as constant a I controller s desgned. The performance of desgned V panel at dfferent enronment condton s projected n Fg. 5(b&c). SSN: age 177

III. CONTROL STRAGIES A. Reference curent generaton by Clarke s transform method There are dfferent methods for generatng a reference current for SAF.

For Clarke transform the formula s gen n Equaton (3) - (11).

3 III. CONTROL STRAGIES A. Reference curent generaton by Clarke s transform method There are dfferent methods for generatng a reference current for SAF. Here, the reference current s generated by usng Clarke transformaton. Durng ths conerson the reolng phase current abc nto statonary reference frame αβ. For Clarke transform the formula s gen n Equaton (3) - (11). Then t s gen to the Hysteress controller n order to control the current njected by the V-SAF nto the MG by controllng Gate pulse gen to VSI n the SAF Q a b c (3) a b c (4) (5) (6) Fg.3a Reference current calculaton by Clarke transform Fg 3a shows the sequence of reference current calculaton Clarke transformaton method. The estmated reference current s gen to the hysteress current controller to generate gatng pulse for VSI. osc (7) loss Q c1 2 2 osc 1 (8) Q c osc ca cb cc 2 1 c 3 (9) (10) (11) c1 c 2 c3 From equaton (3) & (4) we can easly conert the lne current and oltage from reolng frame to statonary reference frame. Usng these alues, the nstantaneous real and reacte power (&Q) has been calculated from (5) & (6). Then reference current c1, c2, c3 has been calculated from (8) - (10) n statonary frame. From ths fnally the alues are conerted to reolng frame usng (11). Fg.3b Block dagram of Hysteress current controller Fg. 3b shows the gate pulse generaton for VSI from Hysteress current controller. Ths pulse s gen to the swtches n SAF. B. MT codng for proposed V panel The Maxmum power s obtaned from the V panel by usng an algorthm called Maxmum ower ont Trackng (MT). There are many power pont trackng technques are proposed by conentonal authors. Among them we are stepped to Incremental Conductance method. It based on the property of M: Where the change n power to change n oltage s Zero,.e., (d/dv) = 0. So, the IC method uses a repettous algorthm based on the eoluton of the derate of conductance G,.e., dg+g=0. The algorthm for ths IC method s followed back. SSN: age 178

4 Fg. 5a Desgned V system n Smulnk enronment Fg 5a shows the V panel desgned n MATLAB whch s used as source n mcro grd and coupled n DC lnk sde wth some correctons. Fg.4 Conductance type MT algorthm C. DC lnk oltage regulaton The DC lnk oltage s mantaned as constant wth the help of DC-DC conerter. Here we use two control loops one s to obtan maxmum power from the V panel. Another one s to mantan constant oltage from at the DC lnk sde t s done by a normal I controller. The output of Boost conerter s shown n Fg. 5c. arameters Values K op 0.5 K 10 C 1000µF L 66mH Tab. 2 Desgn parameter of Boost conerter IV. SIMULATION RESULTS Fg.5b V power s oltage at constant temp A. Results for pannel wth plots The performance of the photooltac panel (V) s smulated wth the aboe parameters and shown n fg 5(b&c). Fg.5c V oltage s. current at constant temp As aboe fg shows that plot between Voltage and ower obtaned from the V panel. It ndcates at constant temperature 25 0 C. The V exhbts non-lnear /V and I/V characterstcs, there wll be one unque pont where the maxmum power s obtaned under partcular enronmental condton (fg5c&b). The /V and V/I characterstcs alters accordng to the temperature and rradatons. SSN: age 179

Fg.5d Constant V oltage at DC Lnk sde of V-SAF Fg. 5d shows the constant DC Lnk oltage mantaned at SAF wth the help of I controller. From the plot s obsered that the settlng tme of V oltage s 0.

5 Fg.5d Constant V oltage at DC Lnk sde of V-SAF Fg. 5d shows the constant DC Lnk oltage mantaned at SAF wth the help of I controller. From the plot s obsered that the settlng tme of V oltage s 0.1 sec up to whch the SAF s separated wth the help of electromechancal relay whch s permanently turned on after the settlng down of V panel. B. Capactor based SAF s V-SAF The result of proposed and conentonal system s compared wth ther dfferent operatng condton are shown below. To obtan these results a non-lnear load of 3phase control rectfer s desgned wth the followng parameters. arameters Vab fg Rs Ls Lcouplng Vdc Fg.6 Load current at α=0o The output waeform of load current wthout flter s shown n fg.6. It conssts of hgh harmonc content whch affects the transmsson effcency of the Mcro grd and loads connected n the same grd. Values 400V 50Hz 10µΩ 1µH 2mH 1200V Tab. 3 Desgn parameters of SAF arameters Rl Ll Vab α Range 100Ω 500 mh 400V Fg.7 Compensaton current at α=0o Tab.4 Desgn parameters of Non-Lnear load To obtan the dynamc performance of the proposed V-SAF the trggerng angle α should ary from 0-90 degree when t s connected wth RL load. Statc performance s obsered by fxng α as constant at 0 degree whch s projected n followng plots. Fg.8 Source current at α=0o The compensaton current generated from proposed system s shown (fg.7). After the njecton of these SSN: age 180

current nto the Mcro grd, the source current wll become lookng lke snusodal as shown n (fg.8).

Comparson of Conentonal wth V-SAF System The THD results of dfferent systems such as Wthout any Flter. Wth Capactor based SAF. Wth V based SAF. Fg.

Dynamc performance of V-SAF The Dynamc performance of V-SAF s obtaned by obserng the source and load current for dfferent trggerng angle at the Non-lnear load, whch means dynamc characterstcs of load

In spte of ths the performance of mcro grd wll be reduced and major ssues hae been obsered n load connected n the MG system. Fg.12 Dynamc characterstcs of load current Fg.

6 current nto the Mcro grd, the source current wll become lookng lke snusodal as shown n (fg.8). The Harmonc content n the source current wll be elmnated by njected compensaton current s nferred from fg.8. C. Comparson of Conentonal wth V-SAF System The THD results of dfferent systems such as Wthout any Flter. Wth Capactor based SAF. Wth V based SAF. Fg.11 THD Result of V-SAF The V-SAF prodes a satsfactory performance on the bass of THD reducton and other problems n preous system. And the system s fully based on renewable energy sources. D. Dynamc performance of V-SAF The Dynamc performance of V-SAF s obtaned by obserng the source and load current for dfferent trggerng angle at the Non-lnear load, whch means dynamc characterstcs of load and source current. Fg.9 THD result of Wthout Flter The aboe fg.9 mples the THD alue of source current wll be ery hgh at absence of flter. In spte of ths the performance of mcro grd wll be reduced and major ssues hae been obsered n load connected n the MG system. Fg.12 Dynamc characterstcs of load current Fg.10 THD result of Capactor-SAF On comparng wth Fg. 9, een though the THD alue s reduced the magntude of ntermedate frequences are domnant n nature. It s due to partal partcpaton of capactor nto the crcut and so the resonance frequency of LC component n the crcut wll be permutated, whch results n domnant nature of ntermedate frequency. SSN: Fg.13 Dynamc characterstcs of source current The followng plot shows that the relatonshp between THD n source current ncreases exponentally wth ncrease n trggerng angle (α) at the Non-Lnear load consdered n the system. age 181

Trggerng angle(α) THD alue of proposed system THD alue of conentonal system THD alue of Wthout any flter 0 5.72 6.1 31.06 10 25.16 27.12 32.87 20 31.34 33.1 36.68 30 33.18 35.16 40.

3 Comparson between wthout flter, conentonal flter and proposed flter V.

From these analyses t s concluded that V-SAF s superor to other Conentonal topologes. The purpose of flter s to put off the harmoncs mposed by the nonlnear loads.

In addton to that compensaton s also enhanced by absolute controllablty of V system whch concluded at low THD alue of 5.72% at α=0 0.

The explot and analyss of both AC sde and DC sde are nqured and dfference s shown before and after compensaton by usng MATLAB/SIMULINK.

. Stratford Update of Harmonc Standard IEEE-519: IEEE Recommended ractces and Requrements for Harmonc Control n Electrc ower Systems IEEE Trans on Industral Applcatons, ol.25, No.6, pp.

S, erformance Ealuaton Shunt Acte Flter For hotooltatc Generaton System For Improng ower Qualty, Internatonal Journal of Emergng Technology n Computer Scence & Electroncs IJETCSE) ISSN:

Hatt,Shunt acte power flter connected to a photooltac array for compensatng harmoncs and reacte power smultaneously, 4th Internatonal Conference on ower Engneerng, Energy and Electrcal

Neznansk, Comprehense compensaton of grd current dstorton by shunt acte power flters, XII Internatonal School on Nonsnusodal Currents and Compensaton, ISNCC 2015, Lagow, oland.

7 Trggerng angle(α) THD alue of proposed system THD alue of conentonal system THD alue of Wthout any flter Tab. 3 Comparson between wthout flter, conentonal flter and proposed flter V. CONCLUSION From ths paper, the role of a V- SAF to meet out power qualty ssues on mcro grd due to non-lnear s analyzed. From these analyses t s concluded that V-SAF s superor to other Conentonal topologes. The purpose of flter s to put off the harmoncs mposed by the nonlnear loads. To enhance the compensaton V panel wth hgh performance s coupled at DC lnk sde of SAF. It beaten the resonance frequency effect arses n Conentonal Capactor coupled system. In addton to that compensaton s also enhanced by absolute controllablty of V system whch concluded at low THD alue of 5.72% at α=0 0. Addton to that the effect of contrast n load sde parameters lke trggerng angle s also analyzed. The explot and analyss of both AC sde and DC sde are nqured and dfference s shown before and after compensaton by usng MATLAB/SIMULINK. The results attached n the paper also prode an edent the same concluson. VI. REFERENCE [1] Chrstopher K. Duffey and Ray.. Stratford Update of Harmonc Standard IEEE-519: IEEE Recommended ractces and Requrements for Harmonc Control n Electrc ower Systems IEEE Trans on Industral Applcatons, ol.25, No.6, pp , No/Dec [2] SUJATA.M.BAGI and VINOD.S.ATILI.S, erformance Ealuaton Shunt Acte Flter For hotooltatc Generaton System For Improng ower Qualty, Internatonal Journal of Emergng Technology n Computer Scence & Electroncs IJETCSE) ISSN: Volume 14 Issue 2 ARIL [3] Rachd Belad, A.Haddouche,M.Mghezz Laraf and M.Hatt,Shunt acte power flter connected to a photooltac array for compensatng harmoncs and reacte power smultaneously, 4th Internatonal Conference on ower Engneerng, Energy and Electrcal Dres, May 2013,pp [4] A. Cchowsk, W. Sleszynsk and J. Neznansk, Comprehense compensaton of grd current dstorton by shunt acte power flters, XII Internatonal School on Nonsnusodal Currents and Compensaton, ISNCC 2015, Lagow, oland. [5] Jeeananthan.K.S,Desgnng of Sngle hase Shunt Acte Flter Usng Instantaneous ower Theory, Internatonal Journal of Electrcal and Electroncs Research Vol. 2, Issue 2, pp: (1-10), Month: Aprl - June [6] K.Sarasath and R.Rajalakshm, Member, IEEE, erformance Analyss Of Shunt Acte Flter Usng Dfferent Controllers, Internatonal Journal of Engneerng Trends and Technology (IJETT) - Volume4Issue5- May [7] Y. He, J. Lu, J. Tang, Z. Wang, Yunpng Zou, Research on control system of DC oltage for acte power flters wth three-leel NC nerter, IEEE, pp , [8] A. Luman and G. Srkanth, A Technque for Shunt Acte Flter meld mcro grd System, A. Luman Int. Journal of Engneerng Research and Applcatons ISSN: , Vol. 5, Issue 8, (art - 3) August 2015, pp [9] Hrofum Akag, Edson hrokazu watanabe and Maurco Aredes Instantaneus power theory and applcatons to power condtonng IEEE-press chapter 3-4,pp , C C Fg.14a Smulaton fle of proposed Mcro Grd system n MATLAB/Smulnk enronment SSN: age 182

8 Fg.14 b Smulaton fle of proposed V-SAF n MATLAB/Smulnk enronment SSN: age 183

Design of Shunt Active Filter for Harmonic Compensation in a 3 Phase 3 Wire Distribution Network

Design of Shunt Active Filter for Harmonic Compensation in a 3 Phase 3 Wire Distribution Network Internatonal Journal of Research n Electrcal & Electroncs Engneerng olume 1, Issue 1, July-September, 2013, pp. 85-92, IASTER 2013 www.aster.com, Onlne: 2347-5439, Prnt: 2348-0025 Desgn of Shunt Actve