A Dual Operation of PV-Statcom as Active Power Filter and Active Power Injector in Grid Tie Wind- PV System

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1 L.Nak and K.Palansamy, ol.5, No.4, 215 A Dal Operaton of P-Statcom as Actve Power Flter and Actve Power Injector n Grd Te Wnd- P System Mr.Lakshman Nak Popavath, Dr. K.Palansamy School of Electrcal Engneerng, esearch IT- Unversty, ellore, Inda. School of Electrcal Engneerng, Assocate Professor, IT-Unversty, ellore, Inda. ( lakshman.help1@gmal.com, kpalansamy@vt.ac.n) Correspondng Athor: Mr.Lakshman Nak Popavath, Tel: , lakshman.help1@gmal.com eceved: , Accepted: Abstract- Ths paper presents the concept of tlzaton of P-solar farm as statc nchronos compensator (P-Statcom) to mtgate power qalty sses lke poor power factor, voltage varatons and crrent harmoncs n power stems. The proposed stem ncldes non lnear load, wnd generator and solar P- Statcom. The solar P Statcom compensatng harmoncs prodced by local load, spples reactve power reqred by the wnd genrator n addton to actve power njecton s demonstrated n ths reseach work. The P-Statcom control pattern for enhancng qalty of power s smlated n MATLAB / Smlnk n smpower stem block set. Keywords- Power Factor correcton;harmoncs; Solar P; P-Statcom; Wnd Energy; Power Qalty mprovement; Grd ntgrated Wnd-P stem; eactve power management. 1. Introdcton Explotaton of Green Energy esorces lke wnd and solar energy are the only way to reach the captal electrc power demand, becase these energy sorces are the cleanest and renewable n natre. Also the Dstrbton Generaton (DG) stem (Wnd and Solar) provdes a better voltage reglaton [1]. Modern power converters embloyed n sloar and wnd are capable of njectng or absorbng an varable reactve power nto the grd ntegrated stem for mprovng qalty of power [2-9]. The dstrbton network conssts almost all reactve components, whch always absorbs the reactve power. The ntegraton of dstrbted generators (DG) lke P Solar plant and Wnd farm nto the dstrbton network leads many advantages sch as redcton n losses, reachng local electrc power demand relef of transson congeston [7-9], [11-14]. These dstrbton generators can also spply the reactve power to the loads, bt earler IEEE 1547 ddn t permt to nject the reactve power nto the grd stem. De to the fast advancement n the technology the earler verson IEEE 1547 was revsed as IEEE , whch s expected to permt the njecton of reactve power nto the grd by dstrbton generaton stem for the enhancement of power qalty[15]. In ths paper the P Solar plant actng as Hysteress crrent control based statc nchronos compensator (P- Statcom) to mtgate the power qalty sses lke poor power factor, crrent harmoncs etc. And also for njecton and absorpton of actve and reactve power nto the grd ntegrated Wnd-P stem for power qalty mprovement drng Day and Nght tme applcatons. The present artcle remnds as follows, The sectons II, III, I, and secton I represents power qalıty ısses and ıts conseqences, proposed stem for power qalty mprovement, control scheme, reslts analyss and conclson respectvely. 2. Power Qalıty Isses and Its Conseqences The term Power Qalty s one of the most prolfc bzz words n the power concept. The tlzaton of non-lnear loads or senstve loads have been ncreasng exponentally whch may rases power qalty sses by drawng nonsnsodal crrents n the power stems. The major power qalty sses are poor power factor, voltage varatons, crrent harmoncs, reactve power demand, voltage flckerng, voltage nterrpton, power freqency varatons and etc.

2 L.Nak and K.Palansamy, ol.5, No.4, 215 The power qalty problems lke flckers, transents, voltage sag or swell, harmoncs and nterharmoncs may cases over heatng, satraton of transformers, overloadng, data loss, mall-operaton of eqpments lke logc controller and power meters. Partclarly on condctors the harmonc cases skn effect, proxmty effect and overheatng of the condctor whch may effect on the actve performance and lfe span of the eqpment. Man Sorce XS Conrtol Strategy PCC Wnd Farm Wnd Speed 3. Proposed System for Power Qalty Improvement Mtgaton of power qalty concerns lke crrent harmoncs, voltage varatons, low power factor etc. and also the actve power (P) and reactve power (Q) control or management can be stded n the proposed grd ntegrated Wnd-P stem as shown n Fg.1. The Photovoltac solar plant provdes the actve power drng day tme and t s actng as power qalty compensator drng nght tme and also drng less power generaton tme. Man Grd Sorce Xs s Dstrbted Generaton (DG) PCC L1 L2 L3 Solar Farm PCC P SF +jq SF Q WF L Wnd Farm P WF Non-Lnear Load Fg.1. Grd Integrated proposed stem: power Qalty The actve power generated by wnd farm s vared de to varatons n the wnd speed [1], whch absorb the reactve power so that the ndcton generator termnal voltage wll sgnfcantly affect. The solar plant actng as P-Stacom n the grd te stem wll compensate the reactve power (Ar) and njects the actve power (watt) to balance the load. By Mantanng the DC lnk capactor voltage constant n the proposed stem the harmoncs mtgaton and also for power factor correcton can be acheved [4]. The complete dal operaton of P Solar plant (P- Statcom) as reactve power compensator and actve power njector can be clearly analyzed wth the help of the proposed stem. The Fg.2 descrbes the complete 24 hors workng process of grd ntegrated proposed stem to ntensfy the qalty n electrc power. Solar Farm S S y S B Non-Lnear Load Fg.2. Complete operatonal scheme of proposed stem. 4. Control Scheme The control algorthm called Bang-Bang Crrent Controller s tlzed to generate the swtchng sgnals for the actve performance of P Solar plant as P-STATCOM wth help of the hysteress crrent control technqe [4, 1] for power qalty mprovement n grd te Wnd-P stem. The reference crrent sgnal can be generated for controller s as shown n Fg.3. The reference crrents are extracted wth the assst of nt vector templates as [4]. I. I. I. (3) sb sb Where, and sb are three phase nt vector templates derved from sampled peak voltage and respectve phase voltages as shown below. dc - dcref oltage Controller Unt ector U Sr, U Sy, U Sb Lmter From Sorce Sryb + - Sryb Crrent Controller Fg.3. eference crrent sgnal generaton for controller.,, sb Where s known as sampled peak voltage and t s compted as { ( sb )} 1 2 sb (1) (2). (4) (5) S S Y S B 979

3 L.Nak and K.Palansamy, ol.5, No.4, 215 The ON/OFF swtchng sgnals for IGBT based P- Statcom can be acqred from the proposed controller [4]. The S s the swtchng fncton for phase r s depcted as P-Statcom OFF Inverter Crrent(A) P-Statcom OFF ( HB) S (6) 2-2 (6) Here HB s the hysteress crrent band. Smlarly SY and SB are the swtchng fnctons for phase y and phase b respectvely. Table-1 represents the proposed stem parameters and ther ratngs. 5. eslt Analyss Table 1. System Parameters descrpton S.No atngs Parameters 1 3-phase, 415, 5 Hz Sorce oltage 2.5 mh Lne ndctance 3.65 mh Shnt ndctance 4 Power: 25kw Dstortng Load ka, 415, 5 Hz, N=15 rpm, P=4, Wnd Generator r=2ohm, Lr=.6H 6 Dc lnk oltage = 8, C=1 mf, Swtchng freqency = 2kHz Inverter Parameters ka Solar plant 8 Collector oltage=12, I=5A, Gate oltage=2 IGBT atngs The MATLAB / Smlaton reslts are stded for the proposed grd ntegrated stem n whch Photovoltac (P) Solar plant actng as statc nchronos compensator (P- Statcom) to nllfy the power qalty problems. The smlaton reslts also represent the dal operaton of P- Statcom as actve power njector and reactve power compensator for an enhancement of power qalty drng whole day and nght tme applcatons. The harmoncs generated by the non-lnear load can be completely cancelled ot by P-Statcom njected crrents (Fg 4). The sorce crrent now havng desred magntde and phase angle as shown n Fg.5. For the measrement of performance of grd te Wnd-P stem the P-Statcom s swtched ON from.1s to.2s, so that wth help of compensaton acton the crrent harmoncs are completely cancelled ot. From fg.5 t s clearly observed that de to lack of compensaton acton before.1s and after.2s the power s pollted de to harmonc contents P-Statcom ON tme(s) Fg.4. P-Statcom Injected Crrent for Qalty of Power P-Statcom Off Sorce crrent(a) Load crrent(a) Inverter crrent(a) P-Statcom ON Wnd generator crrent(a) P-Statcom Off tme(s) Fg-5. () Sorce Crrent () Load Crrent () Inverter njected Crrent (v) Wnd Generator Crrent (A). The Fgre.6 shows the reactve power compensaton and actve power njecton by P-statcom n varable wnd speed grd ntegrated Wnd-P stem. It s clearly observed that before.1s and after.2s the wnd speed s less compared to nomnal wnd speed 12 m/s as shown n Fg.7, whch ndcates the reactve power demand n the proposed stem. The reactve power demand whch s more than 4KAr s compensated to reqred level of sorce and load 98

4 L.Nak and K.Palansamy, ol.5, No.4, 215 by P-statcom from.1s to.2 s as shown n Fg.6 (a) and Fg.6 (b). By observng Fg.6 (a) from.1s to.2s both man sorce and wnd generator are spplyng less than 15KW to connected load, to make the load power constant the reqred actve power s njected by P-Statcom as shown n Fg.6 (b) P-Statcom OFF Sorce Power (P&Q) Load Power (P&Q) Inverter Power(P&Q) P-Statcom ON Wnd Generator Power (P&Q) Actve Power (P) eactve Power (Q) P-Statcom Off tme (s) Fg.6.(a) Sorce Power (P&Q) (b) Load Power (c) P- Statcom njected Power (d) Wnd Generator Power 25 Wnd Spped (m/s) Tme (sec) P-Statcom ot pt voltage Fg.8. P-STATCOM otpt oltage at gage pont P-Statcom OFF P-Statcom OFF P-Statcom ON tme(s) 2 Above ated speed Fg.9.Power Qalty mprovement at PCC. (Unty PF) 15 1 ated speed=12 m/s Below ated speed Cycle repeats tme (sec) Fg.7.arable Wnd Speed n proposed stem. The Fg.9 descrbes the dynamc operaton of P Solar plant as statc nchronos compensator for power qalty mprovement. It s clearly observed that the sorce voltage and sorce crrent have the desred phase relatonshp wth the help of actve compensaton acton of P-Statcom from.1sec to.2sec (P-STATCOM On tme), whch ndcates the mprovement n power factor and qalty of wave form (nty PF). The Fg.8 represents the P-Statcom otpt voltage at Gage pont (PCC) for power qalty mprovement. 981

5 L.Nak and K.Palansamy, ol.5, No.4, Conclson Ths paper represents the dal operaton of P solar plant (P-Statcom) as actve power njector and reactve power compensator for the enhancement of qalty of power n the varable wnd speed grd te Wnd-P stem. It also remnds power qalty sses and ts conseqences and need for reactve power compensaton. Wth actve performance of P Solar farm as P-Statcom the crrent harmoncs are completely nllfed and power factor s mproved. The actve power njecton and reactve power compensaton reslts are smlated n MATLAB/Smlnk n smpower stem block set wth the help of the proposed control scheme to mprove the tlzaton factor of the stem and for power qalty mprovement n grd ntegrated power stem. eferences [1] S. Heer, Grd Integraton of Wnd Energy Conversons. Hoboken, NJ: Wley, 27, pp [2] Nma Saadat, S. S. Cho,, and D. Mahnda lathgamwa A Seres-Connected Photovoltac Dstrbted Generator Capable of Enhancng Power Qalty, IEEE Ttransactons on Energy Converson, vol. 28, no. 4, december 213. [3] X She, Alex Q. Hang, Fe Wang, and olando Brgos, Wnd Energy System Wth Integrated Fnctons of Actve Power Transfer, eactve Power Compensaton, and oltage Converson, IEEE Transactıons on Indstrıal Electronıcs, vol. 6, no. 1, Oct 213. [4] Sharad w. mohod, and mohan v. aware A statcomcontrol scheme for grd connected wnd energy stem for power qalty mprovement. IEEE stems jornal, vol. 4, no. 3, SEPTEMBE 21. [5] ajvk.arma, ShahArfrahman, and Tm anderhede, New Control of P Solar Farm as STATCOM (P-STATCOM) for Increasng Grd PowerTranssonLmtsDrngNghtandDay IEEEtra nsactonsonpowerdelvery,vol.3,no.2,aprl215 [8] G.pyo,H.Kang and S.Moon, A New Operaton Method for Grd-connected P System consderng oltage eglaton n Dstrbton System.n Conf.proc.IEEE PES GM 2-24 jly 28,pp-1-7. [9] ajv K. arma, nod Khadkkar, and av Seethapathy Nghttme Applcaton of P Solar Farm as STATCOM to eglate Grd oltage, Power Engneerng Letters, IEEE Ttransactons on Energy Converson, vol. 24, no. 4, december 29. [1] N M. I. Mlands, E.. Cadava, and F. B. Gonzalez, Comparson of control strateges forshnt actve powerflters nthreephase for wre stem, IEEETrans.PowerElectron.,vol.22,no.1,pp.236,J an. 27. [11] C.Han, A.Q.Hang,M.Baran, S.Bhattacharya, and W.Ltzenberger, STATCOM mpact stdy on the ntegraton of a large wnd farm nto a weak loop power stem, IEEE Trans. Energy Conv., vol. 23, no. 1, pp , Mar. 28. [12] ajve. K.arma, Shrram, S.angarajan Novel Applcaton of a P Solar plant as STATCOM drng Nght and Day n a Dstrbton Utlty network. - Conf.IEEE-211. [13] Sreejth.S, Upama Bose, K. Mn Dvya Sree achana, allathr Jyoth Applcaton of D- STATCOM as Load Compensator for Power Factor Correcton, 214 Internatonal Conference on Control, Instrmentaton,Commncaton and Comptatonal Technologes (ICCICCT)-214. [14] Sanheza, Sérgo M..; az, Alexandre., Photovoltac solar stem connected to the electrc power grd operatng as actve power generator and reactve power compensator, Solar Energy, v 84, n 7, p , Jly 21. [15] IEEE P1547 Standard for dstrbted esorces nterconnected wth electrc power stems, IEEE P1547 std. Sep.22. [6] angarajan, S.S.; Sreejth, S.; Ngam, S., "Effect of dstrbted generaton on lne losses and Network esonances," n Advances n Electrcal Engneerng (ICAEE), 214 Internatonal Conference on, vol., no., pp.1-6, 9-11 Jan. 214 [7] ajv. K. arma, Ehsan M. Savash, Byomakesh Das, and nay Sharma, eal-tme Dgtal Smlaton of a P Solar System as STATCOM (P-STATCOM) for oltage eglaton and Power Factor Correcton 212 IEEE Electrcal Power and Energy Conference. 982