Power Quality Enhancement By Current Controlled Voltage Source Inverter .
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)Power Quality Enhancement by Current Controlled Voltage Source Inverter BasedDSTATCOM for Load VariationsHareesh MyneniG. Siva KumarD. SreenivasaraoPhD scholar, EEDNIT WarangalTelangana - 506 004, IndiaEmail: hari247.sol@gmail.comMember, IEEEAsst. Professor, EEDNIT WarangalTelangana – 506 004, IndiaEmail: gsivakumar@nitw.ac.inAsst. Professor, EEDNIT WarangalTelangana - 506 004, IndiaEmail: srinudee@nitw.ac.in compensation, no requirement of transformer, less number ofswitching devices. In comparison to normal open loopvoltage Pulse Width Modulation (PWM) inverter, the currentcontrolled PWM inverter having more advantages: control ofinstantaneous current waveform and high accuracy,extremely good dynamics, compensation of dc side and acside voltage changes, peak current protection [8], [9]. Moreover the performance of current controlled voltage sourceinverter system largely depends on quality of applied currentcontrol technique.Different theories are presented in literature for referencecompensating current generation. Some of them are p-qtheory based extraction of fundamental active and reactivecomponents of currents [7], Synchronous Reference Frame(SRF) theory based transformation of a-b-c frame tosynchronous rotating frame [10], [11], instantaneoussymmetrical component theory [12], and neural networktheory.PI controllers or closed loop regulators are used tocalculate the power loss term (Ploss) of VSI, which is useful inthe reference current generation [13], [14], [15]. However thepower loss (Ploss) of VSI is fraction of average load power, soit will not affect transient response of the system [16].In this paper, without voltage regulation loop ( i.e. withoutconsidering Ploss term) dc-link voltage maintained constant bydesigning dc-link capacitor in new approach which also givescapacitor value low compare to existing design value. Themain advantage of this proposed method is number of voltagesensing elements are reduced without compromising theDSTATCOM performance. Here the reference currents aregenerated by using instantaneous symmetrical componenttheory because of simplicity and good dynamic response. Forload variations also the proposed DSTATCOM topology isable to compensate without dc-link voltage regulation.Abstract -- In this paper, Distribution Static Compensator(DSTATCOM) is used for power factor correction, harmonicsmitigation, and balancing of source currents in distributionsystem. In existing DSTATCOM control algorithms, dc-linkvoltage is maintained constant by dc voltage regulation loop (orPI controller), which give Ploss term of Voltage Source Inverter(VSI). In the proposed method, power quality improvement isachieved by DSTATCOM without dc-link voltage regulationloop. For that, the DSTATCOM parameters are designed in newapproach. The main advantage of the proposed scheme is that, itwill reduce the voltage sensing elements without affecting thecompensation capability of DSTATCOM. Its performance isvalidated through matlab - simulink platform under variousload conditions.Index Terms--DSTATCOM, dc-link voltage, harmonicmitigation, PI controller, voltage source inverter (VSI).I.INTRODUCTIONIn distribution power system most of the loads are typicalloads, such as adjustable speed drives, computer loads,electronic ballasts, refrigerators, air conditioners and otherdomestic, commercial appliances. Switch Mode PowerSupply (SMPS) is used almost in all these appliances, itdraws excessive harmonic currents and causing severe powerquality problems such as poor voltage regulation, lowefficiency, reactive power burden, current harmonics, high%THD and current unbalancing etc. The power qualityproblems and its mitigation techniques are reported in theliterature [1], [2]. There are many standards proposed tocontrol the power quality of supply system in the distributionsystem [3]. The power quality is improved by using thecustom power devices, such as DSTATCOM, DynamicVoltage Regulator (DVR) and Unified Power QualityConditioner (UPQC). Among the different custom powerdevices, DSTATCOM is more generally used to mitigatecurrent related power quality problems in distribution system[4]. Many DSTATCOM topologies are there for powerquality improvement, some of them are, three-leg VoltageSource Inverter (VSI) with zig-zag transformer [5], [6], fourleg VSI [7], three single phase VSI and three-leg VSI withsplit capacitor. The three-leg VSI with split capacitor ishaving its own advantages such as neutral current978-1-5090-3892-3/15/ 31.00 2015 IEEEII.DSTATCOM TOPOLOGY IN DISTRIBUTION SYSTEMDSTATCOM topology in distribution power system isshown in Fig. 1. It consists of interfacing inductance ( Lf ),resistance ( Rf ), two equal dc link capacitor ( Cdc1, Cdc2 ) andVSI. The three-phase distribution system is connected to nonlinear diode rectifier load or controlled bridge rectifier load182
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)B.Proposed DC-link capacitor (Cdc)In existing methods, dc-link capacitor value is calculatedfrom the equation given below.2 pST(2)Cdc (1.8V )2 (1.2V )2mmwhere, Cdc is dc link capacitor, S is kVA required by load, p isnumber of cycles required to control the dc voltage and T issystem period. The design of dc capacitor value with thismethod gives better compensation but, the dc link capacitorvalue is high, leads to slow transient response [18].In proposed topology without dc voltage regulation, forproper compensation and to improve transient response, thereshould be special focus on the designing of dc capacitorvalue. For that, Unit Capacitor Constant (UCC) is introducedin the design of capacitors, it is similar to the unit inertiaconstant in synchronous rotary condensers [18].1(3)UCCC V /Q2 dc dcand unbalanced RL-load. The source neutral point (N) is connected to load common point (n), in order to provide path forunbalanced current. In Fig. 1, the source connected to theload and DSTATCOM is connected in shunt with the load tomitigate current harmonics and load reactive power compensation. Here, vsa, vsb, vsc are the source voltages, isa, isb, isc arecurrents drawn from source, ila, ilb, ilc are load currents and ifa,ifb, ifc are filter currents injected by DSTATCOM at the Pointof Common Coupling (PCC). The capacitance values of twodc-link capacitors are equal. These two dc-link capacitors arecharged to equal value through an anti-parallel diodes of anIGBT switches without applying gate signals. Designing ofDSTATCOM parameters like dc-link voltage, interfacinginductor and dc-link capacitors are required for proper tracking of reference filter currents. The design process ofDSTATCOM is explained in section-III.vsaNPCCisailbvsc iscilcifcifbUnbalanced Loadilavsb isbnwhere, Q reactive power required by load, C dc-linkcapacitor.ifaLfRLRfS1S2S3Cdc1Interfacing Inductor (Lf)The value of the interfacing inductance is selected on thebasis of proper shaping of compensating current. With highervalue of inductance, compensating current will not follow thereference currents, with the lower value of inductance thereare large ripple in the compensating current. In designing ofinterface inductance, hysteresis band width and maximumswitching frequency of compensator plays an important role.The maximum switching frequency occur when theinstantaneous supply voltage is around its peak value [14].The value of interface inductance (Lf) is obtained frommVdc ,(4)Lf 4hfswmaxwhere, m is modulation index, h is hysteresis band width andfswmax is maximum switching frequency.C.Diode BridgeLoadnlS1lS2lS3lCdc2Voltage SourceInverter (VSI)Fig. 1. Topology of DSTATCOM in three-phase four-wire distributionsystemIII. DESIGN OF DSTATCOM PARAMETERS FOR PROPOSEDMETHODDesign of DSTATCOM parameters: dc-link voltage, dclink capacitor, interfacing inductor is discussed below.A.Proposed DC-link voltage (Vdc)In literature, dc-link voltage is maintained constant toreference dc voltage with voltage regulation loop. Herereference dc voltage is taken as 2 times of peak of the phasevoltage of source [17].In the proposed method of compensation, dc-link voltageis maintained constant without dc voltage regulation, but itrequires a proper design of DSTATCOM parameters. In orderto supply compensating filter current, the current controllerautomatically forces the compensating current in such a waythat to maintain the dc-link voltage constant. In general thedc-link capacitors are charged through anti-parallel diodes ofIGBT switches of VSI to the voltage Vdc. In three-phase fourwire system, each dc-link capacitor is charged to peak ofphase voltage, i.e.,(1)Vdc1 Vdc 22Vph rms ,D.Hysteresis bandHysteresis controller is a non-linear current controller [8].The hysteresis control scheme is based on non-linearfeedback loop with two level hysteresis comparators. Whenerror exceeds given tolerance band (h), switching pulses areproduced. In this paper, variable switching frequencyhysteresis current controller is used. The controlling ofswitching frequency results in complex control of voltagesource inverter [19]. The main advantages of hysteresiscurrent controller are simplicity, outstanding robustness, andno tracking errors.IV.The DSTATCOM performance in current control modemainly depends on generation of reference filter currents.where, Vdc1 and Vdc2 are dc-link voltages and Vph-rms is phaserms voltage.978-1-5090-3892-3/15/ 31.00 2015 IEEEREFERENCE CURRENTS GENERATION AND CONTROLSTRATEGY183
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)where, ifa*,ifb*,ifc* are reference filter currents, ila, ilb, ilc are load currents, vs0 is zero sequence voltage and 3 .It is observed from Fig. 2, after getting the reference filtercurrents from instantaneous symmetrical component theory,error is calculated between reference filter currents and actualfilter currents injected at PCC. The error is given to hysteresiscontroller, having inherent hysteresis band to generate theswitching signal. If error is positive, top switch S1 or S2 or S3of the leg is ON. If error is negative, bottom switch S11or S21or S31 of the leg is ON.The current control forces the filter currents to follow thereference current signals produced by instantaneoussymmetrical component theory.Many control strategies are there to generate reference filtercurrents and each having its own advantages anddisadvantage [7], [8], [19]. The reference filter currents aregenerated by using instantaneous symmetrical componenttheory is used in this paper. The positive sequence currentsand voltages are,ªia º«»«ia »«»«i » a0 ¼ªvsa º«»«vsa »«»«v » sa 0 ¼ª1«1««13««1« ª1«1««13««1 «aa21aa21a 2 º ªi º» sa»« »a » «isb »»« »1 » « isc »¼»¼,a 2 º ªv º» sa»« »a » «vsb »»« »1 » « vsc »¼¼».(5)PlavgvsaThe first objective is, in either three-phase three-wire orfour-wire unbalanced and nonlinear load system, is to providebalanced supply currents such that zero sequence componentin the system becomes zero.isa isb isc 0(6)where, isa, isb, isc are the source currents.The second objective is, for a predefined power factor, therelation between instantaneous positive sequence voltage(vsa ) and current (isa ) is given below. vsa isa T (7)where, θ is angle between fundamental positive sequencesource voltage and current and it is consider zero because ofunity power factor constraint.The third objective of compensation is, three-phase sourcesupply only active power Plavg to the load, that means thereactive power required by load is supplied by compensator(DSTATCOM). The VSI also draws real power from thethree-phase supply which in termed as losses in the inverter.The power loss in inverter is very less when compare to realpower drawn from source so losses are neglected.(8)vsa isa vsbisb vsc isc Plavg§ v v ·*i sa s0 Pfa la ' ¹ lavgvsbvscilaiilbilci§ v v ·*i sb s0 Pfb lb ' ¹ lavg§ v v ·*i sc s0 Pfc lc ' ¹ s CurrentControllerS11S2-ifcS21S3NOTS31Fig. 2. Switching pulses generation for VSI of DSTATCOM.V.SIMULATION STUDIESIn order to validate the proposed method, simulationstudies are carried out in MATLAB Simulink. The systemparameters used for simulation studies are given in Table.1.The simulation results for the proposed method are presentedin this section for three cases.Case A: Performance of DSTATCOM with Unbalanced andThree-Phase Diode Bridge LoadThe source voltages, source currents, phase-a sourcevoltage and source current are shown in Fig. 3 withoutDSTATCOM. From Fig. 3(b) and 3(c), it is observed thatthree-phase source currents are non-sinusoidal andunbalanced, and phase-a current lags phase-a voltagerespectively. The phase-a source current %THD is 20.04%and harmonic spectrum are shown in Fig. 4. The loadcurrents, filter currents, source currents and phase-a sourcecurrent and source voltage with DSTATCOM are shown inFig. 5. It is observed from Fig. 5(c), source currents arebalanced and sinusoidal, and from Fig. 5(d) phase-a sourcecurrent is in-phase with source voltage.The voltages across the dc-link capacitors Vdc1 and Vdc2 arecharged through anti-parallel diodes of IGBT switches andmaintained constant as shown in Fig. 6(a) and Fig. 6(b). It isobserved from Fig. 7, the %THD of phase-a source current isreduced to 1.76%, which is less than 5% recommended byIEEE 519-1992 standard.where, vsa, vsb, vsc are source voltages, isa, isb, isc are sourcecurrents and Plavg is average active power drawn by load.From equations (6), (7), (8), the solution for referencecurrents isi*fa ila isa ½ i*fb ilb isb ¾(9) i*fc ilc isc ¿i*fa ila § vsa vs 0 · Plavg ½' ¹ § vsb vs 0 ·*i fb isb (10) Plavg ¾' ¹ i*fc isc § vsc vs 0 · Plavg ' ¹¿978-1-5090-3892-3/15/ 31.00 2015 IEEEi184
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)DC link Voltage (Vdc1)TABLE ISIMULATION PARAMETERSSystem ParametersValuesSystem voltage200 V (Phase)Supply frequency50 HzSource Rs and Ls1 Ω, 0.1 mHInterfacing inductor16 mHdc-link capacitor600 μFCase:A Three phase diode120 ϳ63 Ω,bridge rectifier loadUnbalanced load200 j103 Ω, 160 ϳ63 Ω,100 ϳ110 Ω.Case:B Three phase controlled θ 450,rectifier load55 ϳ62 ΩUnbalanced load84 ϳ60 Ω, 70 ϳ121 Ω,95 ϳ48 Ω.Case:C Load varied at t 0.6sec of three phase56 ϳ23 Ω at t 0.6 secbridgeUnbalanced load200 ϳ103 Ω, 160 ϳ63 Ω,100 ϳ110 Ω.Dc link Voltage (Vdc2)(a)(b)Time (s)SourceVoltagesFig. 6. (a) dc-link voltage Vdc1, (b) dc-link voltage Vdc2.Fig. 7. Phase-a source current %THD & harmonic spectrum withDSTATCOM.(a)SourceCurrentsCase B: Performance of DSTATCOM with Unbalanced andControlled Bridge LoadThe three phase source voltages, source currents, phase-asource current and voltage without DSTATCOM are shownin Fig. 8. It is observed from Fig. 8(b) that, the three-phasesource currents are unbalanced and distorted, and from Fig.8(c) phase-a source current is lags voltage by some angle,due to reactive load. The phase-a source current %THD is20.53% and harmonic spectrum shown in Fig. 9. In Fig. 10shows the load current, DSTATCOM currents, sourcecurrents and phase-a source voltage and current. It isobserved from Fig. 10(c), the source currents are perfectsinusoidal and balanced. Fig. 10(d) infers that, the sourcecurrent of phase-a in-phase with source voltage of phase-a.The %THD of phase-a source current and harmonic spectrumare shown in Fig. 11, and it is observed that the %THD ofphase-a current is reduced to 3.85% from 20.53%. The dclink capacitors are charged through anti-parallel diodes to thevoltages Vdc1 & Vdc2 shown in Fig. 12(a & b)Phase-avoltage ¤t(b)(c)Time (s)Fig. 3. Simulation results without DSTATCOM (a) source voltages, (b)source/load currents, (c) phase-a source voltage & eCurrentsDSTATCOMLoadCurrentsCurrentsFig. 4. Phase-a source current %THD & harmonic spectrum withoutDSTATCOM.Phase-a Voltage& Current(b)Phase-aVoltage &Current(c)(d)(c)Time(s)Fig. 8. Simulation results without DSTATCOM (a) 3-ph source voltages, (b)3-ph source currents, (c) phase-a source voltage & current.Fig. 5. Simulation results with DSTATCOM (a) 3-ph load currents, (b) 3-phDSTATCOM currents, (c) 3-ph source currents (d) phase-a source voltageand current.978-1-5090-3892-3/15/ 31.00 2015 IEEETime (s)185
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)Case C: Performance of DSTATCOM for load variationsIn order to show the effectiveness of the proposed method,the following variations are considered.(1) At t 0.3 sec DSTATCOM connected at PCC point.(2) At t 0.4 sec gate signals applied to DSTATCOM(3) At t 0.7 sec load decreasedIn Fig. 13 shows three phase source voltages, sourcecurrents and phase-a source current lags source voltagewithout DSTATCOM. It is observed from Fig. 13(b), thesource currents are non-sinusoidal and unbalanced, and fromFig. 13(c), the phase-a source current lags phase-a sourcevoltage. The phase-a source current %THD is 22.93% andharmonic spectrum without DSTATCOM are shown in Fig.14.It is observed from Fig. 15 that, when DSTATCOMconnected at PCC point through circuit breaker at time t 0.3sec, the current drawn from source increases suddenly andcomes down to normal current after few cycles shown in Fig.15(c), because during which the DSTATCOM draws currentfor charging of dc-link capacitors through anti-parallel diodesshown in Fig. 15(e) and (f). When gate signals are given toIGBT switches of DSTATCOM at time t 0.4 sec,DSTATCOM start to send compensating currents towardsPCC shown in Fig. 15(b), so that source currents are becomebalanced, sinusoidal which are shown in Fig. 15(c) andphase-a source current becomes in-phase with the phase-asource voltage shown in Fig. 15(d). When load decreased attime t 0.7 sec, voltage across capacitors increased andcomes to constant value near to 350V shown in Fig. 15 (e &f). The %THD of phase-a source current is 4.11% withDSTATCOM & harmonic spectrum are shown in Fig. 16.LoadCurrentsFig. 9. Phase-a source current %THD and harmonic spectrum b)Phase-a Voltage&Current(c)(d)Time (s)SourcevoltagesFig. 10. Simulation results with DSTATCOM (a) 3-ph load currents, (b) 3ph DSTATCOM currents, (c) 3-ph source currents, (d) phase-a sourcevoltage and current.Sourcecurrents(a)Phase-avoltage ¤t(b)(c)Fig. 11. Phase-a source current %THD and harmonic spectrum withDSTATCOMLoaddecreasedTime (s)dc link Voltage (Vdc1)Fig. 13. Simulation results without DSTATCOM (a) 3-ph source voltages,(b) 3-ph source currents (c) phase-a source voltage and current.dc link Voltage (Vdc2)(a)(b)Time (s)Fig. 12. (a) dc-link voltage Vdc1, (b) dc-link voltage Vdc2.Fig. 14. Phase-a source current %THD & harmonic spectrum withoutDSTATCOM.978-1-5090-3892-3/15/ 31.00 2015 IEEE186
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE currentsand source current balancing is not affected under loadvariations also. The main advantage is dc-link voltagesensing elements are not required. It has been shown that theDSTSTCOM is able to keep the %THD of supply currentwithin the limits according to IEEE-519-1992 standard( 5%), without dc voltage regulator also.Phase -avoltage ¤ts(c)REFERENCES[1][2]dc linkvoltage(Vdc1)(d)(e)dc linkvoltage(Vdc2)[3](f)DSTATCOMconnected atPCCGate pulsesapplied toDSTATCOMTime (s)Loaddecreased[4]Fig. 15. Simulation results with DSTATCOM (a) 3-ph load currents (b) 3-phDSTATCOM currents (c) 3-ph source currents (d) phase-a source voltage ¤t (e) dc link voltage Vdc1 (f) dc link voltage Vdc2.[5][6][7][8]Fig. 16. Phase-a source current %THD & harmonic spectrum withDSTATCOM.CasesCase ATABLE II%THD OF SOURCE 91.761.652.06Case B20.53*Case C22.93* after t 0.7 4.86[11]The comparison of %THD of source currents fordifferent cases: diode bridge load, controlled bridge load andvariable load, before and after compensator are shown inTable II. The %THD values in each case are well within thelimits specified by IEEE standards 519-1992. This shows theeffectiveness of the proposed compensation without dc-linkvoltage regulation.VI.[12][13][14]CONCLUSIONA DSTATCOM topology without dc-link voltageregulation loop and design parameters has been explained inthis paper. The suggested DSTATCOM without dc-linkvoltage regulation is also validated through simulation forvariable loads. It is observed from simulation studies that, theperformance of DSTATCOM is not affected, even withoutthe dc-link voltage regulation. The compensation capabilityin terms of source current %THD, power factor correction978-1-5090-3892-3/15/ 31.00 2015 IEEE[15][16]187C. R. C. P. Llc, Power quality. 2002.J. Arrillaga, N. R. Watson, and S. Chen, Power system qualityassessment. Wiley, 2000.E. Engineers and T. P. Avenue, “Guide for ApplyingHarmonic Limits on Power Systems,” vol. 12, pp. 1 - 124,2012.A. Ghosh and G. Ledwich, Power Quality Enhancement UsingCustom Power Devices. Boston, MA: Springer US, 2002.B. Singh, P. Jayaprakash, S. Kumar, and D. P. Kothari,“Implementation of Neural-Network-Controlled Three-LegVSC and a Transformer as Three-Phase Four-WireDSTATCOM,” IEEE Trans. Ind. Appl., vol. 47, no. 4, pp.1892–1901, Jul. 2011.H.-L. Jou, K.-D. Wu, J.-C. Wu, and W.-J. Chiang, “A ThreePhase Four-Wire Power Filter Comprising a Three-PhaseThree-Wire Active Power Filter and a Zig-Zag Transformer,”IEEE Trans. Power Electron., vol. 23, no. 1, pp. 252–259, Jan.2008.H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneouspower theory and applications to power conditioning. JohnWiley & Sons, 2007.M. P. Kazmierkowski and L. Malesani, “Current controltechniques for three-phase voltage-source PWM converters: asurvey,” IEEE Trans. Ind. Electron., vol. 45, no. 5, pp. 691–703, 1998.S. Buso, L. Malesani, and P. Mattavelli, “Comparison ofcurrent control techniques for active filter applications,” IEEETrans. Ind. Electron., vol. 45, no. 5, pp. 722–729, 1998.S. Bhattacharya, D. M. Divan, and B. Banerjee, “Synchronousframe harmonic isolator using active series filter,” inEuropean conference on power electronics and applications,vol. 3, pp. 030 - 035, 1992.N. Geddada, M. K. Mishra, and M. V. Manoj Kumar, “SRFbased current controller using PI and HC regulators forDSTATCOM with SPWM switching,” Int. J. Electr. PowerEnergy Syst., vol. 67, pp. 87–100, May 2015.S. Srikanthan and M. K. Mishra, “DC Capacitor VoltageEqualization in Neutral Clamped Inverters for DSTATCOMApplication,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp.2768–2775, Aug. 2010.L. P. Kunjumuhammed and M. K. Mishra, “A controlalgorithm for single-phase active power filter under non-stiffvoltage source,” IEEE Trans. Power Electron., vol. 21, no. 3,pp. 822–825, May 2006.B. N. Singh, P. Rastgoufard, B. Singh, A. Chandra, and K. AlHaddad, “Design, simulation and implementation of threepole four-pole topologies for active filters,” IEE Proc. - Electr.Power Appl., vol. 151, no. 4, pp. 467 - 476, 2004.C. Y. Hsu and H. Y. Wu, “A new single-phase active powerfilter with reduced energy-storage capacity,” IEE Proc. Electr. Power Appl., vol. 143, no. 1, pp. 25–30, 1996.M. K. Mishra and K. Karthikeyan, “A Fast-Acting DC-LinkVoltage Controller for Three-Phase DSTATCOM to
2015 IEEE IAS JOINT INDUSTRIAL AND COMMERCIAL POWERSYSTEMS / PETROLEUM AND CHEMICAL INDUSTRY CONFERENCE (ICPSPCIC)Compensate AC and DC Loads,” IEEE Trans. Power Deliv.,vol. 24, no. 4, pp. 2291–2299, Oct. 2009.[17] B. Singh, P. Jayaprakash, T. R. Somayajulu, and D. P.Kothari, “Reduced Rating VSC With a Zig-Zag Transformerfor Current Compensation in a Three-Phase Four-WireDistribution System,” IEEE Trans. Power Deliv., vol. 24, no.1, pp. 249–259, Jan. 2009.[18] H. Fujita, S. Tominaga, and H. Akagi, “Analysis and design ofa dc voltage-controlled static var compensator using quadseries voltage-source inverters,” Ind. Appl. IEEE Trans., vol.32, no. 4, pp. 970–978, 1996.[19] F. Liu and A. I. Maswood, “A novel variable hysteresis bandcurrent control of three-phase three-level unity PF rectifierwith constant switching frequency,” IEEE Trans. PowerElectron., vol. 21, no. 6, pp. 1727–1734, 2006.978-1-5090-3892-3/15/ 31.00 2015 IEEE188
The power quality problems and its mitigation techniques are reported in the literature [1], [2]. There are many standards proposed to control the power quality of supply system in the distribution system [3]. The power quality is improved by using the custom power devices, such as DSTATCOM, Dynamic Voltage Regulator (DVR) and Unified Power Quality
The enhancement itself is performed in two steps: auto-enhancement, and personalized enhancement. The auto-enhancement step (Section 4.3) is necessary to handle bad quality photos that the system is not trained to handle. This step generates some kind of a baseline image that is then further adjusted using personalized enhancement.
Speech enhancement based on deep neural network s SE-DNN: background DNN baseline and enhancement Noise-universal SE-DNN Zaragoza, 27/05/14 3 Speech Enhancement Enhancing Speech enhancement aims at improving the intelligibility and/or overall perceptual quality of degraded speech signals using audio signal processing techniques
Electric Power Quality Enhancement by Reduced Voltage Sag/Swell Dr. Suad Ibrahim Shahl Abstract— Electric Power quality is a term which has tacked increasing attention in power engineering in the recent years. The term power quality re-fers to maintaining a sinusoidal waveform of bus voltages at rated voltage and frequency.
these power quality problems. This paper proposes the STATCOM control scheme for grid connected wind energy system for power quality enhancement. The simulation has been done in MATLAB/Simulink block set. It is shown that STATCOM enhances the power quality of power grid consisting induction generator based wind plant.
Enhancement of Power Quality and Mitigation of Harmonics by Using Distributed Interline Power . Power quality in the system is effected due to unbalance in voltages, faults, voltage sags and swells, flickers, over voltages etc. To overcome these problems and to supply quality power to the consumers many conventional devices, .
method. In Sections 7and8, we compare the quality of the proposed MME method to a wider range of enhancement methods, including different acoustic domain MMSE for-mulations and a number of modulation domain based speech enhancement methods. Final conclusions are drawn in Section 9. 2. AMS-based framework for speech enhancement in the
Controller Ordering Information Parameter Frequency Phase Current Neutral Current Phase to Phase Current* Phase Voltage Neutral Voltage Phase to Phase Voltage Active Power (kW) Reactive Power (kVAr) Apparent Power (kVA) Power Factor Time of use (TOU) - in, out, net, total: Active Energy (kWh) Reactive Energy (kVARh) THD at Phase Current THD at .
Any dishonesty in our academic transactions violates this trust. The University of Manitoba General Calendar addresses the issue of academic dishonesty under the heading “Plagiarism and Cheating.” Specifically, acts of academic dishonesty include, but are not limited to:
