FUZZY Logic Baed Space Vector PWM Controlled Hybrid Active Power Filter for Power Conditioning 1 JARUPULA SOMLAL 2 DR.MANNAM VENU GOPALA RAO 1 Aociate Profeor, 2 Profeor Department of EEE K L Univerity Guntur, Andhra Pradeh INDIA-522502 1 jarupulaomu@kluniverity.in, 2 venumannam@kluniverity.in http://www.kluniverity.in Abtract:- Thi paper invetigate the comparative analyi of a Hybrid Active Power Filter with PI baed SVPWM controller and fuzzy baed pace vector PWM controller for mitigating the harmonic, improving the power factor and increaing the ditribution power of the three phae ditribution ytem. Thi paper concluded that the power conditioning by fuzzy baed SVPWM hybrid active power filter i uperior than PI controller baed SVPWM technique. In the propoed control filter three control circuit are ued uch a PI control unit, fuzzy unit and SVPWM control unit. Fuzzy arithmetic are ued for adjuting proportional integral coefficient timely. The deired output voltage i generated baed on generated reference voltage by fuzzy baed SVPWM. A MATLAB code i developed to generate the SVPWM witching pule fed to the two-level inverter topology. Simulation are carried out uing MATLAB. It i found that the %THD ha been improved from 2.67 to 1.57and power factor i improved to 0.9718. The imulation reult how that the effectivene and feaibility of the propoed filter. Key word:- Hybrid Active Power Filter, Fuzzy Logic Controller, IGBT Inverter, Space Vector PWM, Total Harmonic Ditortion (THD), Ditribution ytem. 1 Introduction Power quality i the main problem that the indutry i facing today. The quality of power ha been deteriorating with the preence of variou current and voltage harmonic, low power factor, voltage ag and well, flicker and many other diturbance. Among the variou diturbance, Harmonic ditortion [1] i one of the mot eriou power quality problem. Particularly, in the ditribution ytem, harmonic are the major concerned problem. The growing ue of electronic equipment i one of the major caue to impute the harmonic, which led to ditortion of voltage and current waveform and increaed reactive power demand in ac main a they pa through the ytem impedance. However, in the preent ituation variou power quality improvement olution are available; Iolate harmonic load on eparate circuit (with or without harmonic filter), Harmonic mitigating tranformer, Phae hifting (zig-zag) tranformer, Filter capacitor bank, Line Reactor, K-Rated / Drive Iolation Tranformer, Harmonic Mitigating / Phae Shifting Tranformer, Paive parallel / erie tuned Filter and Active Filter[2-4]. Paive filtering i the implet conventional olution to reduce the harmonic. But they have many demerit uch a; a) the number of paive filter intalled would depend on the number of harmonic component to be compenated, thi demand for the information of harmonic content to be know in advance. b) Thee cannot function under the aturated condition, c) At ome frequencie, thee filter may lead to reonance. All the above demerit of the filter are overcome by the ue of active filter. But, for highpower application, the Active filter are not cot effective due to their large rating and high witching-frequency requirement of the pule width modulation inverter. For harmonic current tracking control, there are two cheme.one i the linear current control and the other i nonlinear current control. Hyterei nonlinear control method i imple but lead to a widely varying witching frequency [5]. Thi limitation ha been improved with variable hyterei band witching trategie but it require a complex controller to achieve atifactory performance. Predictive current control offer the bet potential for precie current control, but the implementation of a practical ytem can be difficult and complex. Recently, fuzzy logic controller (FLC) [6-8] have received a great deal of attention for their application in active power filter (APF). The advantage of FLC over conventional controller are that they do not require an accurate mathematical model, can work with imprecie input, can handle non-linearity and are more robut than the conventional controller. The Mamdani type of FLC i ued for the control of an APF and it give better reult, but it ha the drawback of a larger number of fuzzy rule. In thi paper, Fuzzy baed SVPWM controller wa E-ISSN: 2224-350X 242 Volume 9, 2014
propoed. The propoed controller filter how horter repone time and higher control preciion. The imulation reult alo how that the new control method i not only eay to be calculated and implemented, but alo very effective in reducing harmonic. 2 Principal of operation In each witching cycle the controller ample are the upply current i a,i b & i c are calculated a -i a =i b +i c (1) A the ummation of three upply current i zero. Thee three phae upply current are meaured & tranformed into direct & quadrature axi component of two dimenional plane. The fundamental component of upply current are tranformed into d-q axi & upply current amplitude I i generated. That I i controlled by the fuzzy controller with V dc & V ref (Reference value of DC bu voltage). The output of fuzzy controller i equivalent to reference voltage vector. By uing Fourier magnitude block, voltage magnitude & angle i calculated. From the obtained ignal, thee value are fed to developed code & compare to the relative equence. The generated witching action are applied to & balancing of the filter take place. by equation (5). Above equation can be reduced a Where a=e j2/3π, i angle of upply current. (5) (6) 3 Configuration of hybrid active power filter Fig.1 how the propoed hybrid active power filter with non linear load conit of both active & Paive Filter. The Paive filter connected in hunt with the ditribution ytem and i tuned to preent low impedance at a particular harmonic current. The hunt active paive filter take a three phae voltage ource inverter a the main circuit & ue capacitor (C) a the Voltage torage element on the DC ide to maintain the DC bu voltage V DC contant. The hybrid active power filter i implemented with fuzzy baed SVPWM current controlled voltage ource inverter (VSI) and i connected at the point of common coupling for compenating the current harmonic and reactive power. Thi ytem i invetigated and the performance of parameter are verified under different non-linear load condition [1]. It can be aumed that the upply voltage and current i ideal and inuoidal and the three-phae balanced parameter are hown a below: (2) (3) (4) Where repreent the upply voltage. If equation (2), (3) and (4) are the three phae voltage. [Va Vb Vc ] in a-b-c can be expreed a two-phae repreentation in d- q reference frame by Clark tranformation and it i given Fig.1 Propoed hybrid active power filter for nonlinear load 4 Compenation Principle Fig.2 and Fig.3 how the equivalent circuit and equivalent impedance circuit model of hybrid active power filter ytem decribed in Fig.2. In the Fig.2, if v fa,1 and v fa,h denote the output fundamental and harmonic voltage of the inverter, repectively. Thee voltage ource are connected to a upply ource ( v ) in parallel via a link inductor L af and capacitor C af of the impedance i Zaf. The upply current i i forced to be free of harmonic by appropriate voltage from the APF and the harmonic current emitted from the load i then automatically compenated. It i known from Fig.4.1, that only fundamental component i taken into account, the voltage of the ac upply and the APF exit the following relationhip in the teady tate E-ISSN: 2224-350X 243 Volume 9, 2014
d I inv V Laf I invdt dt C af 1 Where V i the upply voltage, I inv i the fundamental current of APF, V af i the fundamental voltage of APF, and above variable are expreed in form of pace vector. The APF i joined into the network through the inductor L pf and C pf. Of the impedance Zpf. The function of thee filter i to reduce higher harmonic nearly witching frequency in the current and to link two ac voltage ource of the inverter and the load network. So the required inductance and capacitance can jut adopt a mall value. Then the total reactance caued by inductor and capacitor for the frequency of 50Hz, and the fundamental voltage acro the link inductor and capacitor are alo very mall, epecially compared with the main voltage. Thu the effect of the voltage of the link inductor and capacitor i neglected. So the following implified voltage balanced equation can be obtained from equation (7). V V a f (8) The control object of APF i to make the upply current inuoidal and in phae with the upply voltage. Thu the nonlinear load and the active power filter equal to a pure reitance load R, and the upply voltage and the upply current atify the following equation: V R I (9) V af (7) where 2 0 1 2 I i aa iba ica I d ji q I i. 3 Then the relationhip between I and the upply voltage amplitude V i V R I (10) Subtituting (9), (10) into (8) reult in V V f 1 I (11) I Equation (11) decribe the relationhip between the output fundamental voltage of APF, the upply voltage and the upply current, which enure that the APF operate normally. However, for making the APF normally achieving the required effect, the dc bu voltage V DC ha to be high enough and table. In the teady tate, the power upplied from the upply mut be equal to the real power demanded by the load, and no real power pae through the power converter for a lole APF ytem. Hence, the average voltage of dc capacitor can be maintained at a contant value. If a power imbalance, uch a the tranient caued by load change, occur, the dc capacitor mut upply the power difference between the upply and the load, the average voltage of the dc capacitor i reduced. At thi moment, the magnitude of the upply current mut be enlarged to increae the real power delivered by the upply. On the contrary, the average voltage of the dc capacitor rie, and the upply current mut be decreaed. Therefore, the average voltage of the dc capacitor can reflect the real power flow information. In order to maintain the dc bu voltage a contant, the detected dc bu voltage i compared with a etting voltage. The compared reult i fed to a fuzzy baed controller, and amplitude control of the upply current I can be obtained by output of fuzzy baed controller. Fig.2 Equivalent circuit of hybrid active power filter Fig. 3 Equivalent impedance circuit model I = (12) I l = -Iaf (13) Where I=ource current,v = ource voltage, Vinv =inverter voltage, Iaf = current paing through active filter, Ipf=current paing through paive filter, Zaf= impedance offered by active filter, Zpf=impedance offered by paive filter, Zl=load impedance. Total impedance of hybrid active power filter Z eq = (14) Total voltage from Fig.3 i calculated by V-IZ=I L Z eq (15) Zeq = Equivalent impedance offered by active filter, paive filter and load. E-ISSN: 2224-350X 244 Volume 9, 2014
5 Control trategie of hybrid active power filter 5.1 Control Block Diagram of Fuzzy Baed SVPWM Controller The Fig.4 how the block diagram of active filter controller implemented for reducing the harmonic with hybrid active filter ytem. In each witching cycle, the controller ample the upply current i a, i c and the upply current i c i calculated with the equation of -(i a +i c ), a the ummation of three upply current i equal to zero. Thee three-phae upply current are meaured and tranformed into ynchronou reference frame (d-q axi). The fundamental component of the upply current i tranformed into dc quantitie in the (d-q) axi and the upply current amplitude I generated by the fuzzy logic controller with V dc and V ref, the reference value of the dc bu voltage. The obtained d-q axi component generate voltage command ignal [4]. By uing Fourier magnitude block, voltage magnitude and angle i calculated from the obtained ignal. Thee value are fed to the developed code and compared with the repeating equence. Then the time duration T 1, T 2 and T 0, the on-time of V 1, V 2 and V 0 are calculated [5]. The generated witching action are applied to the APF and power balancing of the filter take place. Fig.4 Control block diagram of Fuzzy baed SVPWM 5.2 Fuzzy logic controller In the Fuzzy logic controller, 1) a generalized integrator control unit and 2) a fuzzy adjutor unit control circuit are ued. The firt control circuit i ued for dividing frequency integral control, to ignore the influence of magnitude and phae, while fuzzy arithmetic i ued to timely adjut the PI coefficient. Since the main objective of thi cheme i to obtain a minimum teady-tate error, the harmonic reference ignal i et to zero. Firt, upply harmonic current i detected. Then, the expectation control ignal of the inverter i revealed by the entire control unit. The ytem tability i achieved by a p-controller, and the exact dynamic tate i obtained by the integral controller. To adjut the parameter of p-control and integral control, a fuzzy adjutor i alo ued. So that the harmonic tracking current controller can reduce the tracking error of the harmonic compenation current. Fig.5 Block diagram of Fuzzy Logic Controller Once the fuzzy controller were developed and incorporated into the imulated ytem, the imulation performance helped in the iteration of the controller and bet adaptive controller to the linear and non linear ytem. Fuzzy controller main part are evaluation and control rule from the rule bae and data bae i called fuzzifier and defuzzifier i take highet MF component. The FLC having different memberhip function (M.F) to analyze the performance of intantaneou real active and reactive current (id iq) control trategy for extracting reference current of SHAF under different ource voltage condition. PWM pattern generation baed on carrier le hyterei current control i ued for quick repone. In addition, the i d i q method i ued for obtaining reference current in the ytem, becaue in thi trategy, angle u i calculated directly from the main voltage and enable operation to be frequency independent; thereby, thi technique avoid a large number of ynchronization problem. The fuzzy inference ytem (FIS) in the fuzzy logic toolbox [5], it conit of FIS editor, Member hip Function (MF) editor, Rule editor, Rule viewer, Surface viewer. Memberhip function are ymmetrical or aymmetrical; it i multi dimenional curve and forming hyper urface. In Fig. 6.1and Fig.6.2, M.F editor of k p and k i having two input (error, cerror) and ingle output curve (K p and K i ). The M.F editor i ued to define the hape of all the M.F aociated with each variable. The rule editor i ued for editing the lit of control rule that define the behavior of the ytem. In the preent model 49 rule are developed in below. Fig.7.1 and Fig.7.2 how rule view of K p and K i. Fig.8.1 and fig.8.2 how hyper urface view of K p and K i are generally obtained from control rule. E-ISSN: 2224-350X 245 Volume 9, 2014
4) For mall value of /e/, ΔK p i effective,and Δk p i larger when /e/ i maller,which i better to decreae the teady tate error. So the tuning rule of ΔK p and ΔK i can be obtained a given Table 1 and Table 2. Fig. 6.1 MF editor for k p Fig.8.1 Hyper urface view of kp Fig.6.2 MF editor for k i Fig.8.2 Hyper urface view of ki Table 1 Adjuting parameter of ΔKp Fig.7.1 Rule view for K p ΔK P NB NM NS O PS PM PB NB PB PB NB PM PS PS 0 NM PB PB NM PM PS 0 0 NS PM PM NS PS 0 NS NM e 0 PM PS 0 0 NS NM NM PS PS PS 0 NS NS NM NM PM 0 0 NS NM NM NM NB PB 0 NS NS NM NM NB NB e c Table 2 Adjuting parameter of ΔKi Fig. 7.2 Rule view for k i The fuzzy control rule deign involve defining rule that relate to the output model propertie. For deigning the control rule bae for tuning ΔKp and ΔK i, the following important factor have been taken into account. 1) For large value of /e/, a large Δk p i required, and for mall value of /e/,a mall Δk p i required. 2) For e, e c >0, a large Δk p i required and for e, e c >0 a mall Δk p i required. 3) For large value of /e/ and /e c /, ΔK p i et to zero, which can avoid control aturation. ΔK i NB NM NS O PS PM PB NB 0 0 NB NM NM 0 0 NM 0 0 NM NM NS 0 0 NS 0 0 NS NS 0 0 0 e 0 0 0 NS NM PS 0 0 PS 0 0 0 PS PS 0 0 PM 0 0 PS PM PM 0 0 PB 0 0 NS PM PB 0 0 6 Reult and Dicuion The imulation model of Hybrid active power filter for non linear load i hown in Fig.1. For an input upply e c E-ISSN: 2224-350X 246 Volume 9, 2014
voltage of 230V (rm) and witching frequency of 5kHz, the imulation reult with PID controlled SVPWM and fuzzy controlled SVPWM hybrid active filter are hown. Table.3 how parameter value required for circuit configuration hown in Fig.2. Sytem parameter Supply ytem Paive Table.3 Parameter value Value of parameter 230 V (rm), 50 Hz, three-phae upply L/mH C/ F Q Output filter 0.2 60 11 th turned 1.77 49.75 50 filter 13 th turned filter 1.37 44.76 50 the harmonic pectrum of the ource current after compenation i done. The harmonic pectrum of the load current and ource current how that the %THD i reduced 1.57 in both. It alo oberved that the magnitude of the 5th, 7th, 11th and 13th harmonic are evidently reduced by fuzzy baed SVPWM controller baed hybrid active power filter when compared to PI baed SVPWM technique. APF 6 th turned filter 14.75 C F :19.65, C I :690 C dc =1000µf, Vref = 750V,C f = 24µf, L f = 30 mh Fig.9. how the imulation reult of hybrid active power filter when PID controlled SVPWM technique i conidered for generating the required witching pule for the operation of the active filter. It how the imulation waveform of ource voltage, load current after compenation and ource current after compenation. From the figure, it can be oberved that there i ome aymmetry during the initial condition in the ource voltage and ource current waveform, wherea the load current waveform are ditorted in nature.fig.10 how the imulation reult of hybrid active power filter when fuzzy controlled SVPWM technique i conidered for generating the required witching pule for the operation of the active filter. It how the imulation waveform of ource voltage, load current and ource current after compenation. From the figure, it can be oberved that under nonlinear load condition the magnitude of three phae ource voltage, ource current and load current are made equal, made in phae with each other and alo how that the reduction of harmonic i better. The imulation of harmonic pectrum of hybrid active power filter when PI baed SVPWM controller i conidered. Fig.11.1how the harmonic pectrum of the load current after compenation i done. Fig.11.2. how the harmonic pectrum of the ource current after compenation i done. The harmonic pectrum of the load current and ource current how that the %THD i reduced from 21.78 to 2.72. It alo oberved that the magnitude of the 5th, 7th, 11th and 13th harmonic i large enough in ource current harmonic pectrum. The imulation of harmonic pectrum of hybrid active power filter when fuzzy baed SVPWM controller i conidered. Fig.12.1. how the harmonic pectrum of the load current after compenation i done. Fig.12.2. how Fig. 9 Wave Form of PID baed SVPWM Fig. 10 Wave Form of Fuzzy baed SVPWM Fig.11.1 Load current Harmonic for PID baed SVPWM E-ISSN: 2224-350X 247 Volume 9, 2014
when fuzzy baed SVPWM controller i conidered. So the propoed controlled filter uch a PI baed SVPWM and fuzzy baed SVPWM controlled hybrid active power filter can be able to reduce the total harmonic ditortion efficiently. Wherea, among the two, fuzzy baed SVPWM controlled hybrid active filter not only functioning on ource ide but alo functioning efficiently on load ide to made phae with each other, to made magnitude equal and to reduce the total harmonic ditortion. Fig.11.2 Source current harmonic of PID baed SVPWM Fig12.1 Load current Harmonic for Fuzzy SVPWM Fig.12.2 Source current harmonic of Fuzzy SVPWM 7 Concluion In thi paper, in detailed analyi of the hybrid active power filter uing fuzzy logic baed SVPWM control methodology i explained. Thi method require a very imple algorithm, which can be able to compenate the harmonic content from both ource a well a load current efficiently. Simulation are carried out in MATLAB / Simulink to obtain the performance of propoed filter. From the imulation reult it i oberved that %THD i reduced from 21.78 to 2.72 with hybrid active power filter when PI baed SVPWM controller i conidered and the harmonic pectrum of the load current and ource current how that the %THD i reduced 1.57 in both current Reference [1] Fang Zheng Peng, Akira Nabae, A new approach to harmonic compenation in power ytem a combined ytem of hunt paive and erie active filter, IEEE Tranaction On Power Delivery, Vol. 24, No. 6, November/ December 1990. [2] Somlal Jarupula, Dr.Venu Gopala Rao.Mannam, Rameh Matta, Power Quality Improvement in Ditribution Sytem Uing Fuzzy Baed Hybrid Active Power Filter, International Journal of Advanced Scientific Reearch and Technology, Vol.3. No.2, JUNE- 2012, ISSN: 2249-9954. [3] Jarupula Somlal, Venu Gopala Rao Mannam, Analyi of Dicrete & Space Vector PWM Controlled Hybrid Active Filter for Power Quality Enhancement, International Journal of Advance in Engineering & Technology, Jan 2012. IJAET ISSN: 2231-196. [4] Hirfumi Akagi, Srianthumrong, Yahurio Tamai, Comparion In Circuit Configuration And Filtering Performance Between Hybrid And Pure Shunt Active Filter, Indutry Application Conference, 2003, 38 th IAS Annual Meeting Conference Record, Vol.2. [5] Sangun Kim, Praad N.Enjeti, A New Hybrid Active Power Filter (APF) Topology, IEEE Tranaction On Power Delivery, Vol. 17, No. 1, January 2002. [6] S. Mikkili, A.K. Panda, Simulation and real-time implementation of hunt active filter id iq control trategy for mitigation of harmonic with different fuzzy memberhip function, Publihed in IET Power Electronic Revied on 7th Augut 2012 doi: 10.1049/iet-pel.2012.0254. [7] Jok A. Torrico, Edon Bim, Fuzzy Logic Space Vector Current Control of Three-phae Inverter, Power Eelectronic Specialit conference, 2000.PESC 00.2000 IEEE 31 t Annual,Volume :1. [8] M. Rukonuzzaman, M. Nakaoka, Fuzzy Logic Current Controller for Three-phae Voltage Source PWM-Inverter, Indutry application conference, 2000, Volume: 2. E-ISSN: 2224-350X 248 Volume 9, 2014