active filter by unit voltage template method with...

Active Filter by Unit Voltage TemplateMethod with balanced and unbalanced

load

Kishore Kumar Pedapenki1 and Gurrala Swathi21 Vignan’s Institute of Information Technology

Visakhapatnam, Andhra Pradesh, India - 530049Email : [email protected]

2 Vignan’s Institute of Information TechnologyVisakhapatnam, Andhra Pradesh, India - 530049

Email : [email protected]

May 30, 2017

Abstract

With the use of power electronic converters for con-version of huge electrical power, there are harmonics in-jected into the system and for controlling the huge electri-cal power and there is a reactive power drawing from thesystem. These two problems create some notable problemslike communication interference, heating of electric motors,low power factor etc. Shunt active power filter is used tominimize these two losses effectively. In this paper, the unitvoltage template (UVT) method is used to get the requiredsignals to drive the inverter switches. The results with re-spect to Total Harmonic Distortion (THD) are tabulatedand compared with and without active power filter for bothbalanced and unbalanced system.

Keywords : Active Power Filter, UVT Method, Harmonics, Reac-tive Power

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International Journal of Pure and Applied MathematicsVolume 114 No. 7 2017, 53-63ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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1 Introduction

In this paper, the shunt active power filter (APF) is examined forthe Unit Voltage Template (UVT) Method. The vigorous researchhas been carried out in this area of active power filters. The volt-age controller used in this work, PI controller was replaced withthe fuzzy logic controller [8], [11], neural network controller [10],[12] and neuro fuzzy controller [11] and some other artificial intel-ligent technique based controllers. The UVT method is the latestand the easiest method to get the compensating currents but ear-lier methods instantaneous method, synchronous reference framemethod and some other methods are also efficient and broadly usedin the literature [4-7].The active power filters are developed for threephase, four wire system also [2], [12], some of them are experimen-tally validated [9], [15].

2 System and Control

In figure 1, three phase supply is connected to the rectifier fed RLload which is the nonlinear load. Because of nonlinear loads, har-monics will arise and Reactive power is drawn in controlling processof the power electronic loads. A Capacitor through the Inverter isconnected from the three phase supply via inductors to reduce theharmonics and to compensate the reactive power to obtain the qual-ity of power automatically. The control circuit gets the feedbackfrom source voltage, source current and DC voltage (Vdc ) and itis processed to obtain the required signals for the inverter. In fig-ure 2, the magnitudes of reference currents Isa,ref , Isb,ref , Isc,refare same as that of output obtained from the controller and thefrequencies are same as that of the source voltage. To achieve thisphenomenon from each phase, the unit template of the source volt-age is taken by dividing each phase of source voltage by its peakvalue and the processed error from PI controller by comparing theDC voltage reference and the DC voltage. For getting the signalto upper switch of the each leg, the error is processed in hystere-sis controller with the comparison of reference currents and sourcecurrents. The lower switch of same leg is getting the gating signalsfrom inverted signals.

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International Journal of Pure and Applied Mathematics Special Issue

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Figure 1: Schematic Diagram of Shunt Active Power Filter

Figure 2: Control Circuit of Figure 1

3 Results and Discussion

Figure 3 shows the simulation diagram for shunt active power filter.The results have been taken from the simulation at different firingangles by varying the non linear load and keeping balanced load at1kVA are shown in the tabular form and the simulations are donewithout compensation and with compensation for fully controlledconverter. In this paper two types of analyses are possible basedon the connection of load. They are3.1) Balanced Load: when three phase circuit breaker is opened.3.2) Unbalanced Load: when three phase circuit breaker is closed.

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Table 1: LIST OF PARAMETERS USED IN THE SIMULATIONSTUDYS.No. Name Value

1 Source Voltage(Vs) 100V (peak)2 Load 1KVA3 Filter Inductance (Lc) 3.35mH4 DC Capacitence (Cdc) 4800f5 DC Voltage Reference (Vdc,ref) 290V6 Hysteresis band(HB) 0.01sec7 Firing Angle() 0 to 608 PI parameters Kp= 0.2 and ki=39 Unbalanced load Ra=20 Rb=40 Rc=60

Figure 3: Simulation diagram of shunt Active power filter

3.1 Balanced Load

The load is a rectifier fed RL load. Here two cases are considered asfollows: 1. without APF: from t=0sec to t=0.5sec. 2. with APF:from t=0.5sec to t=1sec. At t=0.5sec, the active power filter isswitched on by using the three phase breaker. Figure 4 shows thatwithout active power filter the compensation current is maintaineda zero value up to 0.5sec. After 0.5sec, the compensating current isgenerated by switching on the active power filter. The load currentand the compensating current are added to make the source currentas a sinusoidal and the source current is in phase with the source

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Table 2: SOURCE CURRENT THD WITH AND WITHOUT APFFOR VARIOUS FIRING ANGLES

S.NOFIRING

ANGLE ()

TOTAL HARMONICDISTORTION (%)

WITHOUTAPF

WITHAPF

1 0 30.40 0.702 5 30.79 0.723 10 31.48 0.764 15 32.45 0.835 20 33.72 0.926 25 34.27 1.027 30 35.32 0.948 35 39.70 1.599 40 42.73 2.5010 45 46.27 2.8111 50 50.76 3.5513 60 64.62 3.64

voltage.

Figure 4: Various Currents and Voltage Waveforms for α=30 de-noting switching on APF at t=0.5secr

Table 2 shows the Total Harmonic Distortion with and withoutactive power filter for various firing angles from α=0 to α=60

by varying the RL-Load for fully controlled converter is tested for1kVA. Without active power filter the total harmonic distortions areincreasing from firing angle α=0(30.4%) and α=60 (64.62%) andwith active power filter the total harmonic distortions are also in-

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creasing from α=0 (0.7%) and α=60 (3.64%) but they are withinthe limits of IEEE standards. The same fact is shown in the graph-ical representation as in Figure 5 . It shows the reduction in totalharmonic distortion from without active power filter to with activepower filter and they are within the limits of IEEE standards.

Figure 5: Total Harmonic Distortion (THD) v/s Firing Angle ( α)

3.2 Unbalanced Load

Three Resistors Ra, Rb, Rc having values 20 Ω , 40 Ω, 60 Ω are con-nected parallel to rectifier fed RL to create unbalance by switchingon the three phase breaker Figure 6 shows the waveform for loadcurrent, compensating current, source current and source voltage.Here two cases are considered as follows:1. with balanced (APF is on) : from t=0sec to t=0.5sec.2. with unbalanced (APF is on) : from t=0.5sec to t=1sec.APF is switched on at t=0sec, the system is balanced up to t=0.5sec.After t=0.5sec, the unbalanced load is introduced. Still the APFis capable to supply sufficient compensating current to make thesource current sinusoidal.

Table 3 shows the total harmonic distortion without active powerfilter and with active power filter when the load is unbalanced forthree phases.In figure 7 the corresponding graphs are shown foreach phase with and without active power filter when the load isunbalanced. The source current THDs are with in the limits ofIEEE standards even though the load is unbalanced.

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Table 3: TOTAL HARMONIC DISTORTIONS FOR ALLPHASES

S.NOFIRINGANGLE

(α)

TOTAL HARMONIC DISTORTION(%)PHASSE A PHASE B PHASE C

WITHOUTAPF

WITHAPF

WITHOUTAPF

WITHAPF

WITHOUTAPF

WITHAPF

1 0 30.57 2.61 30.42 3.01 30.57 2.562 5 30.85 2.66 30.7 3.03 30.83 2.573 10 31.4 2.77 31.24 3.08 31.36 2.594 15 32.23 2.94 32.06 3.12 32.16 2.615 20 33.37 3.13 33.19 3.15 33.27 2.616 25 34.85 3.31 34.66 3.16 34.73 2.597 30 36.73 3.45 36.54 3.15 36.59 2.588 35 39.1 3.56 38.91 3.11 38.93 2.569 40 42.08 3.67 41.89 3.16 41.88 2.6510 45 45.83 3.66 45.63 3.03 45.6 2.5511 50 50.66 3.74 50.45 2.97 50.39 2.612 55 56.97 4.19 56.76 4.09 56.66 2.7813 60 65.41 2.32 65.18 2.51 65.04 2.36

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Figure 6: Various Currents and Voltage Waveforms for α=30 de-noting unbalanced load at t=0.5sec

Figure 7: Total Harmonic Distortion V/S Firing Angle for threephases

4 Conclusion

The active power filter is the ultimate solution to reduce the har-monic content and to make unity power factor. The unit voltagetemplate control method used here is the simplest method whichhas fewer computations and gives very quick results with PI con-troller. The results have been shown for THD with and withoutAPF for various loads ranging the firing angle from =0 to =60 andcorresponding R and L combination to get the load as 1kVA. It isobserved that the THD is kept on increasing from α=0 to α=60.It is concluded that the active power filter is efficient to make theTHD less than 5%. The active power filter used here is also capableto handle unbalanced load to make the source currents sinusoidal

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and balanced.

References

[1] Bhim Singh, Active power line conditioners for power qualityimprovement - a perspective, Journal of Indian Institute ofScience, vol. 78, pp. 565 - 583, 1998.

[2] Chakphed Madtharad, Suttichai Premrudeepreechacharn,”Active power filter for three-phase four-wire electric systemsusing neural networks”, Electrical Power Systems Research,vol. 60, pp. 179 - 192, 2002.

[3] Jain, Shailendra Kumar and Agarwal Pramod, Design Sim-ulation and Experimental Investigations, on a Shunt ActivePower Filter for Harmonics, and Reactive Power Compensa-tion, Electric Power Components and Systems, vol. 31, No. 7,pp. 671 - 692, 2003.

[4] Hasan Kmrcgil, Osman Kkrer,” Globally stable control ofthree-phase three-wire shunt active power filters”, ElectricalEngineering., Springer, vol. 89, pp. 411 - 418, 2007.

[5] S Surendra Kumar, Partha Sarathi Sensarma, ”A multi-bandshunt hybrid active filter with reduced sensor count”, Sadhana,vol. 33, No. 5, pp. 629 - 641, 2008.

[6] Wei Zhao, An Luo, Ke Peng, Xia Deng,”Current control fora shunt hybrid active power filter using recursive integral PI”,Journal of Control Theory Applications, vol. 7, No. 1, pp. 77- 80, 2009.

[7] Naimish Zaveri, Ajitsinh Chudasama, ”Control strategies forharmonic mitigation and power factor correction using shuntactive filter under various source voltage conditions”, ElectricalPower and Energy Systems, Elsevier, vol. 42, pp. 661 - 671,2012.

[8] Kishore Kumar Pedapenki, S P Gupta, Mukesh Kuamr Pathak”Comparison of PI and fuzzy logic controller for shunt active

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power filter”, IEEE - ICIIS, University of Peradeniya, Kandy,Srilanka, pp. 42 - 47, 2013.

[9] L. Merabet, S. Saad, D. Ould Abdeslam, A. Omeiri, ”A com-parative study of harmonic currents extraction by simulationand implementation”, Electr. Power Energy Sys., vol. 53, pp.507 - 514, 2013.

[10] Kishore Kumar Pedapenki, S P Gupta, Mukesh Kumar Pathak”Comparison of PI and neural network based controllers forshunt active power filter”, IEEE - ICCICCT, Noorul IslamUniversity, Nagercoil, Tamil Nadu, pp. 214 - 218, 2015.

[11] Kishore Kumar Pedapenki, S P Gupta, Mukesh Kumar Pathak”Soft Control Techniques for Shunt Active Power Filter”, IEEE- PCITC, SOA University, Bhubaneswar, Odisha, pp. 60 - 65,2015.

[12] J. Jayachandran and R. Murali Sachithanandam, ”ANN basedcontroller for three phase four leg shunt active filter for powerquality improvement”, Ain Shams Engineering Journal, vol.16, pp. 112 - 119, 2015.

[13] Yunmei Fang, Juntao Fei and Kaiqi Mab, Model referenceadaptive sliding mode control using RBF neural network foractive power filter, Electric Power Energy Systems, Vol. 73,pp. 249 - 258, 2015.

[14] Panda, Aurobinda, M. K. Pathak, and S. P. Srivastava. ”En-hanced power quality based single phase photo voltaic dis-tributed generation system”, International Journal of Elec-tronics, Vol. 103, Iss. 8, 2016.

[15] Kishore Kumar Pedapenki, S P Gupta, Mukesh KumarPathak, ” Shunt Active Power Filter with MATLAB anddSPACE 1104 Verification”, International Journal of AppliedEngineering Research, Vol. 11, No. 6, pp. 4085 - 4090, 2016.

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