International Journal of Engineering and dvaned Tehnology (IJET) ISSN: 49 8958, Volume3 Issue6, ugust 04 Modeling and Simulation of Unified Power Quality onditioner (UPQ) Manoj D. Kharad, Naveen Kumar strat:this paper presents design, modeling and simulation of Unified power quality onditioner system to improve the power quality. Unified power quality onditioner onsists of omined series and shunt ative power filters for simultaneous ompensation of voltage and urrent. The Unified power quality onditioner system is modeled using the elements of Simulink and it is simulated using matla. new synhronousrefereneframe ased ontrol method and dq0 theory is used to improve the power quality at the point of ommon oupling on power distriution systems under unalaned and distorted load onditions. The results are analyzed and presented using matla/simulink software. One inverter is ontrolled as a variale voltage soure in the series PF, and the other as a variale urrent soure in the shunt PF Keywords tive power filter (PF), phaselokedloop (PLL), power quality (PQ), synhronous refereneframe (SRF), unified powerquality (PQ) onditioner (UPQ). I. INTRODUTION UNIFIED POWERQULITY ONDITIONER (UPQ) systems were widely studied y many researhers as an eventual method to improve the PQ in eletrial distriution systems [3]. The term power quality (PQ) has gained signifiant attention in the past few years. The advanement in the semiondutor devie tehnology has made it possile to realize most of the power eletronis ased devies/prototypes at ommerial platform. s a rule of thum in all areas of engineering, the proper utilization of the resoures that we have in the most effiient way has lead to great development and is the major onern for most engineers in their respetive fields. Reative power ompensation is one of the ommon yet very important issues for power system engineers at transmission as well as at distriution level. It is a wellknown fat that a typial distriution network onsist of distriution transformer, motor loads, et., demands reative power. This loadreative power demand level is mainly affeted y the type of loads present on the network. The apaitor anks have een used to ompensate the loadreative power demand. It is the Simplest and under ertain onditions, is a very effetive way to ompensate the loadreative power demand. This traditional way has ertain major disadvantages, suh as fixed ompensation, possile Ourrene of resonane ondition with neary loads, swithing transient, ulky size, aging effet, et [6]. II. UNIFIED POWERQULITY ONDITIONER (UPQ) The UPQ onsists of two voltage soure inverters onneted ak to ak with eah other sharing a ommon d link. Manusript Reeived on ugust 04. Manoj D. Kharad, Department of eletrial engineering MSS s ollege Of Engineering nd Tehnology, Jalna,Maharashtra, India. Naveen Kumar, Department of eletrial engineering MSS s ollege Of Engineering nd Tehnology, Jalna,Maharashtra, India. Fig. onfiguration of the UPQ Fig shows the asi onfiguration of the unified power quality onditioner. The shunt onverter Of the UPQ must e onneted as lose as possile to the nonlinear load, instead of the network side. The UPQ approah is the most powerful ompensator for a senario as depited in Fig, where the supply voltage Vs is itself already unalaned & distorted &is applied ritial load that require high power quality.on the other hand, part of the total load inlude nonlinear loads that injet a large amount of harmoni urrent into the network, whih should e filtered []. In fig, urrent i L represents all nonlinear loads that should e ompensated. The shunt ative filter of the UPQ an ompensate all undesirale urrent omponents, inluding harmonis, imalanes due to negative and zero sequene omponents at fundamental frequeny, and the load reative power as well. The same kind of ompensation an e performed y the series ative filter for the supply voltage, hene, the simultaneous ompensation performed y the UPQ guarantees that oth the ompensated voltage V L at load terminal and ompensated urrent i s that is drawn from the power system eome alaned, so that they ontains no unalane from negative and zero sequene omponents at fundamental frequeny. Moreover, they are sinusoidal and in phase, if the load reative power is also ompensated. dditionally, the shunt ative filter has to provide d link voltage regulation, asoring or injeting energy from or into the power distriution system, to over losses in onverters, and orret eventual transient ompensation errors that lead to undesirale transient power flows into the UPQ. It might e interesting to design UPQ ontrollers that allow different seletions of the ompensating funtionalities []. 33 Pulished y: lue Eyes Intelligene Engineering
Modeling and Simulation of Unified Power Quality onditioner (UPQ) III. THE UPQ ONTROL STRTEGY. Shunt ontrol Strategy: The shunt ative power filter is provided the urrent and the reative power (if the system need) ompensation. It ats as a ontrolled urrent generator that ompensated the load urrent to fore the soure urrents drained from the network to e sinusoidal, alaned and in phase with the positivesequene system voltages. The onventional SRF method an e used to extrat the harmonis ontained in the supply voltages or urrents. For urrent harmoni ompensation, the distorted urrents are first transferred into twophase stationary oordinates using α β transformation (same as in p q theory). fter that, the stationaryframe quantities are transferred into synhronous rotatingframes using osine and sinus funtions from the phaselokedloop (PLL). The sinus and osine funtions help to maintain thesynhronization with supply voltage and urrent. Similar to the p q theory, using filters, the harmonis and fundamental omponentsare separated easily and transferred ak to the a frame as referene signals for the filter. The onventional SRFalgorithm is also known as d q method, and it is ased on a to d q 0 transformation (park transformation), whihis proposed for ative filter ompensation [3]. The instantaneous threephase urrents and voltages are transformed to α β oordinates as shown in equation to6. I so= 3 [i sa i s i s ].....eq I sα= 3 [i sa i s i s]..eq I sβ= [ i s i s ]... eq3 V so= 3 [v sa v s v s ]... eq4 Vsα= 3 [v sa v s v s]..eq5 V sβ= [ v s v s ]..eq6 The soure side instantaneous real and imaginary power omponents are alulated y using soure urrents and phaseneutral voltages as given in eq7 and eq8. P= Vsα I sα V sβ I sβ...eq7 Q= V sβ I sα Vsα I sβ..eq8 The instantaneous real and imaginary powers inlude oth osillating and average omponents. verage omponents of p and q onsist of positive sequene omponents of soure urrent. The osillating omponents of p and q inlude harmoni and negative sequene omponents of soure urrents []. In order to redue neutral urrent, p is alulated y using average and osillating omponents of imaginary power and osillating omponent of the real power. These urrents are transformed to threephase system as shown in The referene urrents are alulated in order to ompensate neutral, harmoni and reative urrents in the load. These referene soure urrent signals are then ompared with sensed threephase soure urrents, and the errors are proessed y hysteresis and PWM ontroller to generate the required swithing signals for the shunt PF. Vsa V Veta i0 P Veta Isalpha* In In I P ILa Q In Susystem 3 Id Veta iseta* In is* In3 Fo=50Hz p 4 Vd Produt In In is* In3 Fig. P Qtheory Simulation 34 Pulished y: lue Eyes Intelligene Engineering
International Journal of Engineering and dvaned Tehnology (IJET) ISSN: 49 8958, Volume3 Issue6, ugust 04 N ThreePhase Soure Disrete, Ts = 5e006 s. pow ergui v a a a ThreePhase VI Measurement Sope Sope a ThreePhase VI Measurement Sope Diode ridge Sope3 Diode ridge Series tive Filter Shunt tive Filter G G Vd Idref 700 Vdref Vsa _ Vf Pulses Referene Vtg. PI ontroller dq0 Theory PWM Referene Generation Hysteresis and PWM PQ Theory Vsa Isa* ILa Pulses IL Id If Vd Fig. 3 Simulation iruit of UPQ. Series ontrol Strategy: The series ative power filter is provided the voltage ompensation. It generates the ompensation voltage that synthesized y the PWM onverter and inserted in series with the supply voltage, to fore the voltage of P to eome sinusoidal and alaned. supply voltages vsa are transformed to dq0 oordinates. Vd=/3[Va*sinwtV*sin(wt π/3)v*sin(wtπ/3)]vq=/3[va*oswtv*os(wtπ/3) V*os(wtπ/3)]V0= /3 (Va V V ) The voltage in d axes onsists of average and osillating omponents of soure voltages. The average voltage is alulated y using seond order LPF (low pass filter).the load side referene voltages are alulated. The swithing signals are assessed y omparing referene voltages and the load voltages and via sinusoidal PWM ontroller. Then dq0 are transformed to Vsa oordinates Va = [Vd*sin(wt) Vq*os(wt) Vo ] V = [Vd*sin(wtpi/3) Vq*os(wtpi/3) Vo)] V = [Vd*sin(wtpi/3) Vq*os(wtpi/3) Vo)] These produed threephase load referene voltages are ompared with load line voltages and errors are then proessed y sinusoidal PWM ontroller to generate the required swithing signals for series PF IGT swithes. Vsa a sin_os dq0 Vd a_to_dq0 Transformation (pu) Freq Fig. 4 DQ0 Theory Simulation IV. wt Sin_os Disrete 3phase PLL Fo=50Hz Disrete ndorder Filter SIMULTION RESULTS The harmonis and unalaned omponents are ompensated in ase of unalaned and distorted urrent and voltage at the P. Simulation results show that the proposed ontrol strategy ompensates harmoni omponents as well as most of the other unalaned loadurrent distortions. It is shown that the UPQ an dq0 sin_os a dq0_to_a Transformation _ 35 Pulished y: lue Eyes Intelligene Engineering
Modeling and Simulation of Unified Power Quality onditioner (UPQ) ompensate the voltage and urrent prolems simultaneously. In this study, the proposed SRFased ontrol algorithm for the UPQ is evaluated y Matla/Simulink software under Unalaned and distorted loadurrent and sourevoltage onditions. The UPQ system parameters used in this study are given in Tale I. TLE I UPQ SIMULTION PRMETERS Parameters values Soure Voltage Vsa 400Vrms Frequeny f 50 Hz 3 phase line L L a 5mH Indutane phase line L L a 5mH Load Indutane 3 phase D Indutane Ld3 0mH 3 phase D Resistane Rd3 30 Ω phase D d 0.4µF apaitane phase D Resistane Rd 90Ω D Voltage V D 700V link Twoseries apaitor, 00µF Shunt line Indutane La 3mH tive Filter Resistane Ra 5Ω Filter Filter apaitor a 0µF Series tive Filter line Indutane Lta 3mH Filter Resistane Rta 5Ω Filter apaitor ta 0µF Two Transformer series S KV (D) (E) Fig. 5 Simulation Results for Operational Performane of the UPQ System (a) Soure voltage (), () Load urrent (I L a), () Soure urrent (), (d) Load voltage (V L a), (e) D link Voltage (V D ) efore harmoni ompensation, the THD of the supply urrent is 9.33%. The otained results show that the proposed ontrol tehnique allows the 4.8% mitigation of all harmoni omponents as shown in fig. efore ompensation, the THD level of the load voltage in phase a was 3.7% and the soure urrent was 9.33%; after ompensation, the THD level of the load voltage is approximately 0.99% and the soure urrent is approximately 0.93%. In the simulation studies, the results are speified efore and after the operation of the UPQ system. In addition, when the UPQ system was operated, the load 0 0 FFT window: 5 of 50 yles of seleted signal 0 0.5 0.5 0.5 0.53 0.54 0.55 0.56 0.57 0.58 0.59 Time (s) () () FFT window: 5 of 50 yles of seleted signal 00 0 00 0.5 0.5 0.5 0.53 0.54 0.55 0.56 0.57 0.58 0.59 Time (s) () () () Fig. 6 Simulation Results for FFT nalysis of the UPQ System (a) Soure urrent (), () Load voltage (V L a), 36 Pulished y: lue Eyes Intelligene Engineering
V. ONLUSION The UPQ system is suessfully designed and modeled using the iruit elements of simulink. The simulation results show that, when unalaned and nonlinear load urrent or unalaned and distorted mains voltage onditions, the aove ontrol algorithms eliminate the impat of distortion and unalane of load urrent on the power line, making the power fator unity. Meanwhile, the series PF isolates the loads voltages and soure voltage, the shunt PF provides threephase alaned and rated urrents for the loads. The THD in the output is redued y using UPQ. The sope of this work is the modeling and simulation of UPQ system. The hardware implementation is yet to e done. The simulation an e extended to multi us system. REFERENES [] H. kagi, E. H. Watanae, and M. redes, Instantaneous Power Theory and ppliations to Power onditioning. Hooken, NJ: WileyIEEEPress, pr. 007. [] MetinKesler, EnginOzdemir, Novel ontrol Method for Unified Power Quality onditioner (UPQ) Under NonIdeal Mains Voltage and Unalaned Load onditions,9784444783/0/00 IEEE. [3] MetinKesler and EnginOzdemir, SynhronousRefereneFrame ased ontrol Method for UPQ Under Unalaned and Distorted Load onditions, IEEE Trans. Industrial eletronis, vol. 58, no. 9, septemer 0. [4] VinodKhadkikar,mrish handra, New ontrol Philosophy for a Unified Power Quality onditioner (UPQ) to oordinate Load Reative Power Demand etween Shunt and Series Inverters, IEEE trans. on power delivery, vol. 3, no. 4, otoer 008. [6] P. Kannan, V.Rajamani, Design, Modeling and Simulation of UPQ system with PV array, International Journal of Engineering Researh & Tehnology (IJERT)Vol. Issue 6, ugust 0 ISSN: 78 08. International Journal of Engineering and dvaned Tehnology (IJET) ISSN: 49 8958, Volume3 Issue6, ugust 04 Mr. Manoj D. Kharad, was orn in urangaad, India,in987. He reeived the.e. degree in eletrial engineering from the PES ollege ofengineering, Dr. aasahe medkar Marathwada University, urangaad, in 0 and He is urrently pursuing Master of Engineering degree in power system from themss s ollege of engineering and tehnology, jalna, Maharashtra, India. Mr. Naveen Kumar, was reeived.teh. degree in The Streem eletrial & eletronis engineering(eee) from sreekavitha engineering ollege, J.N.T.University, Hyderaad, and M.Teh degree in Power System ontrolling and utomation(ps) from the JITS ollege of engineering Warangal J.N.T.University, Hyderaad.presently working as sst.professor in the Dept. of Eletrial Enginering, From MSS's engineering ollege, jalnamaharastra. 37 Pulished y: lue Eyes Intelligene Engineering