Enhancement Of Power Quality And Mitigation Of Harmonics By Using .
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939Enhancement of Power Quality and Mitigation ofHarmonics by Using Distributed Interline PowerFlow ControllerT.Vijaya Lakshmi Bhavani11PG Scholar (EEE), Sri Vahini Institute of Science andTechnology, Tiruvuru, Krishna Dt, A.P India.Abstract— this paper describes the power flow control intransmission line with Flexible AC Transmission System(FACTS) family, called Distributed Power FlowController (DPFC) and Distributed Interline Power FlowController (DIPFC). The DPFC is derived from theUnified Power Flow Controller (UPFC). The DPFC canbe considered as UPFC with an eliminated common DClink, to enable the independent operation of the shunt andthe series converters which enhances the effectiveplacement of the series and shunt converters. The activepower exchange between the two converters, which isthrough the common dc link in the UPFC, is now throughthe transmission lines at the third-harmonic frequency inthe DPFC& DIPFC. DPFC & DIPFC is used to mitigatethe voltage sag and swell as a power quality issue. TheDPFC and DIPFC has the same control capability as theUPFC, which comprises the adjustment of the lineimpedance, the transmission angle, and the bus voltage.In DPFC three-phase series converter is divided to severalsingle-phase series distributed converters through thetransmission line and in DIPFC three single phase seriesconverters are placed in between the two transmissionlines. Modelling and principle of operation is presented inthis paper To verify the DPFC principle two case studiesare considered. Case (i) DPFC is placed in a singlemachine infinite bus power system including two paralleltransmission lines. Case (ii) Distributed Interline PowerFlow Controller (DIPFC) is placed between the twoparallel transmission lines of infinite bus. The case studiesare simulated in MATLAB/ Simulink an the resultsvalidate the DIPFC has ability to improve the powerquality then DPFC.I. INTRODUCTIONPower system supplies a good reliable and undisturbedpower supply to the consumer at rated voltage andfrequency. If any disturbance or faults occurs in the systemit may cause losses in the system and the quality of powerwhich is supplied to the consumer will be reduced.IJEDR1602335N.Nageswara Rao 22Assistant Professor (EEE), Sri Vahini Institute ofScience and Technology, Tiruvuru, Krishna Dt, A.PIndia.The main aim of the electrical system is supplying powerwith quality, low cost, safe to the consumer. Main issuewhich is troubling the consumers, industries, and othersectors is loss in quality of power. Firstly power qualitymeans sending the power with no losses to the consumer ormaintaining the quality of power is called power quality.Power quality in the system is effected due to unbalance involtages, faults, voltage sags and swells, flickers, overvoltages etc. To overcome these problems and to supplyquality power to the consumers many conventional devices,facts devices, custom power devices were used andimproved quality of power for some extent. Generally in thepower system the main disturbances which affect the powerquality severely are voltage sag and swell. Thesedisturbances mainly occur due to faults in the lines, shortcircuit mainly at grids and due to inrush currents whilestarting large machines. Due to these there will be up anddowns in the voltage which is to be supplied to theconsumer. To overcome these facts devices are used such asSTATCOM, SSSC, and UPFC etc.II DPFC OBJECTIVEThe main objective of the project is to improve thepower quality in the power system. New devices,Distributed Power Flow Controller and Distributed InterlinePower Flow Controller where used for power qualityimprovement. Distributed power flow controller is achievedby removing link between the converters and by applyingD-facts concept to three phase series converter in unifiedpower flow controller. Distributed Power Flow Controllerhas one shunt controller as UPFC and much number ofseries controllers which are single phased as shown infigure 1. And Distributed Interline Power Flow ControllerInternational Journal of Engineering Development and Research (www.ijedr.org)1905
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939is obtained from DPFC and IPFC. DIPFC act DPFCemploying IPFC concept.voltage cannot be maintained properly. To overcome thissituation in the system reactive power compensationdevices are used and here are some compensating devicesused in electrical power system for voltage stability.SYNCHRONOUS CONDENSERSFigure 1: Block diagram of DPFC connected to single line.III. REACTIVE POWER PROBLEMSWatt less power plays an important role to maintainvoltage to delivery of active power through the transmissionline. Reactive power is also called as wattles power.Decrement in reactive power can cause voltage decrementand the equipment used may damage due to overheating ofmachines and there will losses in lines in the system. Thedecrement in reactive power makes voltage to drop andincrement will raise the voltage, so in the system bycontrolling the reactive power system voltage and systemcapability and ability can be increased. If the reactive powerprovides lower voltage then the current increasers tomaintain the power supply, then system will draw morereactive power and then system voltage will drop. due torise in the current the transmission line goes off andpotentially causing cascading failures.REACTIVE POWER SOURCESReactive power is the main source for transferring thepower .And there are different sources in the power systemwhich produce and absorb reactive power they are, GeneratorsPower transfer componentsLoadsREACTIVE POWER COMPENSATING DEVICESReactive power compensation is the main factor bywhich the system voltage can be maintained and controlled.But due to some reactive power problems in the system theIJEDR1602335Synchronous condenser is also called as synchronouscapacitor or synchronous compensator which is identical tosynchronous motor. Synchronous condensers are used tosupply or absorb reactive power needed to maintainconstant voltage level in the system. These are used since1930’s for both voltage and reactive power control in thetransmission system. These are connected by territorywinding s of transformers .And they come under categoryof active shunt compensation these are mostly located atHVDC converter station which are connected to weekstations these have many advantages when compared withother compensator. During the lector mechanicaloscillations kinetic energy is exchanged between thecondenser and the system during this condition thecondenser can supply large reactive power (twice to itscontinuous ratings).STATIC VAR COMPENSATORSSVC is shunt connected .They supply or consumes reactivepower from power system. These compensators doesn’thave any moving part so they are named as Static VARCompensators they have both conventional capacitors andinductors which have the fast switching ability .By usingthis Static VAR Compensator the voltage of the system canbe regulated .They have capability of controlling thevoltage of individual buses to which they have beenconnected and they have ability of controlling both negativeas well as positive sequence voltage deviations .And heresome basic reactive power controlling elements which arethe parts of Static VAR Compensators they are saturatedreactors, TCR, TSC, TSR.HARMONIC FILTERThese are mainly utilized for controlling or preventingharmonic waves which are caused by nonlinear loads (dueto frequency chopping or high switching).They produce thefundamental frequency reactive power to the transmissionsystem they use capacitors, inductor and resistor harmonicto the ground .The filters can be either passive or active.International Journal of Engineering Development and Research (www.ijedr.org)1906
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939STATIC SYNCHRONOUS COMPENSATOR(STATCOM)STATCOM is one of facts device which is used forcontrolling the voltage of system by controlling the reactivepower. It generates and absorbs the reactive power as perrequirement need of the system. Its response is speed andhas good controlling capabilities as it uses power electronicdevices. It use self-commutated power electronic devices tosynthesize the reactive power output.SERIES CAPACITORSSeries capacitors are used in long transmission lines.Series capacitor compensation improves the transientstability of the system and they reduce the inductivereactance of the transmission line. Series capacitor reactivepower generation will rise when the current squared ordoubled and generates the reactive power when needed thisnature of series capacitor is named as self-regulating nature.SHUNT CAPACITORSShunt capacitors are mainly connected near the loadareas for voltage control and load stabilization. Forproducing the reactive power and for controlling voltage atload area the shunt capacitors with mechanical switched areused .they help the nearby generators to operate at unitypower factor .and have low cost and high switching speed.current limiting rectors are used to minimize switchingtransients.DISTRIBUTED POWER FLOW CONTROLLERThe DPFC is derived from UPFC, which has of one shuntand several single phase series converters which areconnected in series with line. The shunt converter acts as aSTATCOM whereas the series converter employs the DFACTS concept, were instead of single three phaseconverter number of single phase series converters are used.Within the DPFC converters acts independently and theyconsists of their own capacitors for dc voltage requirement.And here the dc link between the converters is removed andthey are connected by transmission line.IJEDR1602335Figure 2: distributed power flow controller.DISTRIBUTE POWER FLOW CONTROLLER ted power flow controller is used for powerquality improvement in the system. Distributed power flowcontroller is achieved by removing link between theconverters and by applying D-facts concept to three phaseseries converter in unified power flow controller .Thebelow flow chart diagram shows how the DPFC is obtainedfrom UPFCFigure 3: Flowchart from UPFC to DPFC.Distributed power flow controller has one shuntcontroller as UPFC and many number of series controllerswhich are single phased .in the DPFC the shunt converterbehaves as STATCOM whereas series converter asDSSC(distributed static synchronous compensator).thesingle phase series converters are connected to the line bycoupling transformer. And the converters of DPFC consistof their own dc capacitors which act as their sources and therating of the converters depends on the rating of the dccapacitor used. And in DPFC for flow of active power fromone converter to other converter transmission lineconnected. The block diagram of DPFC is shown below.International Journal of Engineering Development and Research (www.ijedr.org)1907
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939VdVqcos t(1)sin t(2)The reference voltage in fundamental component is writtenasVFigure 4: DPFC configuration.From the figure 4 it can be observed that DPFC consists ofone shunt converter, several single phase series converters,high pass filter for controlling the harmonics, and two Y–Δtransformers at both the ends of DPFC.SERIES CONTROLLERThe figure below shows block diagram of series controllerwhich used in DPFC for controlling of single phase seriesconverters.ref 1V dcos t V d cos t(3)And the principle of vector control method is used forcontrol in the dc voltage which is taken as input from the dccapacitor of series converter. The error signal in dc linkcapacitor voltage is given by the difference between thereference voltage in dc link capacitor and the actual voltageand the expression is given as,Vdc, se Vref , dc-Vdc(4)The series controller consists of two filters one is the lowpass filter which is used to take the current fundamentalfrequency and another one is the 3rd high pass filter is usedto take the current at third harmonic frequency. And theseare given to the PLL (phase locked loop) and it is written asequation give below. The reference voltage in thirdharmonic component is given by,Vref 3 Vdc, sesin 3 t(5)And the total voltage in series converter is,Figure 5: series controller block diagram.The single phase series converters which hang to the linevia coupled transformer in DPFC consist of independentseries controllers. And controller of series convertermaintains the dc capacitor voltage of the converter byutilizing the third frequency harmonics and generates theseries voltage at fundamental frequency. The inputs ofseries controller are voltage reference signals from thecentral controller in dq reference, dc voltage of dc capacitoris another input, and the line current from the line asanother input. The block diagram of series controller isshown below. The two voltage reference signals are takenin dq reference and are written in equation form.IJEDR1602335Vref Vref 1 Vref 3(6)And the whole outputs of are given to the PWM generatorwhich generates the current pulse signals for operation ofconverter.SHUNT CONTROL:The figure 5 shows block diagram of shunt controller whichis used for controlling the both three phase and single phaseshunt converters.International Journal of Engineering Development and Research (www.ijedr.org)1908
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939The voltages in dq0-reference frame isV V cos 3 t V sin tV V cos 3 t -V sin tV 0q(7) d(8) (9)0Now, the dqo is transformed into abc by using park’stransformation by using the equations (8), (9) and (10). Byusing PWM technique gate pulses are generated for thirdharmonic control circuit.DISTRIBUTEDCONTROLLERFigure 6: The shunt control configuration: (a) forfundamental frequency (b) for third-harmonic frequency.The shunt converter includes a three-phase converter whichis back-to-back connected to a single-phase converter. Thethree-phase converter absorbs active power from grid atfundamental frequency and controls the dc voltage ofcapacitor between this converter and single-phase one. .Thevoltages in dq-reference frame are Vdref and Vqref is taken asinputs, now, the dqo is transformed into abc by using park’stransformation.V VV VVV VVabd , refsin t V q ,ref cos t Vd , ref0POWERFLOWThe Distributed Interline Power Flow Controller (DIPFC)which is FACTS device which is like DPFC consists ofmany single phase series converters connected to number oftransmission lines .The main difference between DPFC andDIPFC is ,in DPFC the series converter had theirindependent controller and dc capacitor, but coming toDIPFC two series converters of two lines are connected bysingle dc link capacitor and controlled by single controller,the below figure 7 gives the interior concept used byDIPFC in connecting the two series converter.(10)sin( t 120) V q ,ref cos( t 120) (11)0c0INTERLINEd , refsin( t 120) V q,ref cos( t 120) (12)By using PWM technique gate pulses are generated forshunt control circuitFigure 7: IPFC concept.Third Harmonic Control: In third harmonic control circuitwe have to change the fundamental frequency in to thirdharmonic frequency so, here we are multiplying with 3 tothe frequency.IJEDR1602335As like DPFC, DIPFC is used for power quality control,power flow improvement in the lines. And here also thirdharmonic frequency is used as carrying barrier of activepower between converters in DPFC.International Journal of Engineering Development and Research (www.ijedr.org)1909
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939MATLAB SIMULATION RESULTSDiscrete,Ts 3.255e-006 Conn6Ccn2VabcIabcN BB BCC CB bC cA aB bC cCIabcabci- --gAIshuntB v-pulsespulsesshunt converterb3rd hormoniccFigure 6.2: simulation of two bus system with two paralleltransmission lines connected with DPFC.The waveform of voltage sag when DPFC is not connectedto the two bus system is shown below in figure 6.3.BA aBVabccbCAA ACA100 MWBB aAcABCBABAABACbCAgAaBN Discrete,Ts 3.255e-006 s.IabcAaThe simulated system consists of three phase programmablevoltage source which is connected to the load usingtransmission lines of length 180km. By applying threephase ground fault the voltage sags and swells are createdin the system. The whole system is simulated in per unit.The parameters used in the system are listed in the table.First the system is simulated without DPFC and therevoltages sag and current swells are created .The simulationof the system without DPFC is shown in figure 8.Vabcvoltage sag2CVabcAThree-Phase Fault1.5Iabc1Bab0.5voltage in p.uCc0ABC-0.5100 MW-1-1.5-2Figure 8: simulation of two bus system with two paralleltransmission lines.Here is the simulated system with DPFC is shown below infigure 8. Where the voltage sag and current swell ismitigated using .16Figure 9: voltage sag waveform when the DPFC is notconnected to the system.The waveform of voltage sag compensated when DPFC isconnected to the two bus system is shown below in figure10.International Journal of Engineering Development and Research (www.ijedr.org)1910
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-99391.5Current Magnitude in P.UVoltage Magnitude in .080.1Time in Seconds0.120.140.1600.020.040.060.08Time in Seconds0.10.120.140.16Figure 13: compensated current swell waveform when theDPFC is connected to the system.And the Total Harmonic Distortion Analysis of the systemwithout DPFC and with DPFC is shown below in figure 6.7and 14.Figure 10: compensated voltage sag waveform when theDPFC is connected to the system. The waveform of currentswell when DPFC is not connected to the two bus system isshown below in figure 11.Selected signal: 8 cycles. FFT window (in red): 6 cycles10-10current swell0.050.10.15Time (s)15Fundamental (50Hz) 0.752 , THD 16.08%40Mag (% of Fundamental)10current in p.u5302010000246Harmonic order810Figure 14: Shows the Total Harmonic Distortion Analysisof the system without DPFC.-5-10Selected signal: 8 cycles. FFT window (in red): 4 0.160.050.10.15Time (s)Fundamental (50Hz) 0.9516 , THD 0.71%Figure 12: current swell waveform when the DPFC is notconnected to the system.The waveform of current swell compensated when DPFC isconnected to the two bus system is shown below in figure13.Mag (% of Fundamental)0.60.50.40.30.20.100246Harmonic order810Figure 15: shows the Total Harmonic Distortion Analysisof the system with DPFC.IJEDR1602335International Journal of Engineering Development and Research (www.ijedr.org)1911
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-9939Here Distributed Interline Power Flow Controller is kept inthe same two bus system where DPFC is placed and it isshown below in figure 6.9.Discrete,Ts 3.255e-006 n4Conn6Conn8ABabcn2AaBbCcCABCVabcIabcabc100 CLUSIONVabcBBb gABCi- --gAIshuntB v-pulsesvalues are placed in a table. The table consists of TotalHarmonic Distortion Analysis values of system WithoutDPFC, with DPFC, with DIPFC.pulsesIn this case study both DPFC and DIPFC are connected inthe system with three phase source connected to the loadwith two parallel transmission lines, it is designed with thehelp of MATLAB. The voltage sag and current swell in thesystem is a caused by using a three-phase fault close to theload. The faults occurred in the system were compensatedby using facts device DPFC and DIPFC results wereobtained and their results were compared. When comparingDPFC with DIPFC, DIPFC has more effectively improvedthe power quality of the system and it mitigated the voltagesag and current swell in the system and it can be observedfrom the THD analysis of the both DPFC and DIPFC.shunt converter3rd hormonicFigure 16: simulation of two bus system with two paralleltransmission lines connected with DIPFC.Total Harmonic Distortion Analysis of DIPFC is show infigure 6.10Selected signal: 8 cycles. FFT window (in red): 4 cycles0.50-0.500.050.10.15Time (s)Mag (% of Fundamental)Fundamental (50Hz) 0.9756 , THD 0.45%0.40.30.20.100246Harmonic order810Figure 17: total harmonic distortion analysis of the systemwith DIPFC.The Total Harmonic Analysis of DPFC and DIPFC arecompared below and Total Harmonic Distortion AnalysisIJEDR1602335REFERENCES1.Zhihui Yuan, Sjoerd W.H de Haan, Braham Frreira andDalibor Cevoric “A FACTS Device: Distributed Power FlowController (DPFC)” IEEE Transaction on Power Electronics,vol.25, no.10, October 20102.S. Masoud Barakati, Arash Khoshkbar Sadigh and EhsanMokhtarpour, “Voltage Sag and Swell Compensation with DVRBased on Asymmetrical Cascade Multicell Converter”, NorthAmerican Power Symposium (NAPS), pp.1 – 7, 20113.Alexander Eigels Emanuel, John A. McNeill “ElectricPower Quality”. Annu. Rev. Energy Environ 1997, pp. 263-303.4.I Nita R. Patne, Krishna L. Thakre “Factor AffectingCharacteristics of Voltage Sag Due to Fault in the Power System”Serbian Journal of Electrical engineering. vol. 5, no.1, May2008,pp. 171-182.5.Zhihui Yuan, Sjoerd W.H de Haan and Braham Frreira“DPFC control during shunt converter failure” IEEE Transactionon Power Electronics 2009.6.J. R. Enslin, “Unified approach to power quality mitigation,”in Proc.IEEE Int. Symp. Industrial Electronics (ISIE ’98), vol. 1,1998, pp. 8–20.7.B. Singh, K. Al-Haddad, and A. Chandra, “A review ofactive filters for power quality improvement,” IEEE Trans. Ind.Electron. vol. 46, no. 5, pp. 960–971, 1999.8.M. A. Hannan and Azah Mohamed, member IEEE, nsator for Power Quality Improvement”, IEEETransactions on Power Delivery, vol. 20, no. 2, April 2005.9.P. Pohjanheimo and E. Lakervi, “Steady state modeling ofcustom power components in power distribution networks,” inProc. IEEE Power Engineering Society Winter Meeting, vol. 4,Jan. 2000, pp. 2949–2954.International Journal of Engineering Development and Research (www.ijedr.org)1912
2016 IJEDR Volume 4, Issue 2 ISSN: 2321-993910. A. L. Olimpo and E. Acha, “Modeling and analysis ofcustom power systems by PSCAD/EMTDC,” IEEE Trans. PowerDelivery, vol. 17, no.1, pp. 266–272, Jan. 2002.11. R. Zhang, M. Cardinal, P. Szczesny and M. Dame. “A gridsimulator with control of single-phase power converters in D.Qrotating frame”, Power Electronics Specialists Conference, IEEE2002.First Author: T. VijayaLakshmi Bhavani is pursuing her M.Tech from SriVahini Institute of Science and Technology, Tiruvuru,Krishna dt. Her Research Interests is Power Systems.Second Author: N. Nageswara Raois working as Assistant Professor in Department OfEEE at Sri Vahini Institute of Science and Technology,Tiruvuru, Krishna dt. Affiliated to JNTUK, Kakinada,A.P, India His Research Interests are Power Systems,Power Electronics, and drives & FACTS devices.IJEDR1602335International Journal of Engineering Development and Research (www.ijedr.org)1913
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, .
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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.
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FOR ENHANCEMENT OF POWER QUALITY IN TRAM WAYS L. Ramesh1, B. kishan2 1 Student, Dept of EEE, Avanthi Institute of Engineering & technology, Telangana, India . of power quality of the power system, while widespread electric vehicle battery charging units [1], [2] have detrimental effects on power distribution system harmonic voltage levels [3
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