Implementation of MPPT Tracking Dc-Dc Converter Using PSO With Fuzzy for the Control of Inverter Fed Induction Motor

Transcription

1 Ipleentation of MPPT Trackin Dc-Dc onverter Usin PSO With Fuzzy for the ontrol of Inverter Fed Induction Motor 1 S.Sathyaoorthi, 2 Rola Roy, 1 Assistant Professor, Dept. of lectrical and lectronics nineerin, Pandian SaraswathiYadav nineerin ollee,sivaanai, India. 2 Assistant Professor, Dept. of lectrical and lectronics nineerin, Sree Buddha ollee of nineerin for Woen, Ayathil, Kerala, India 2 Abstract In this paper proposes for the photovoltaic (PV) syste usin a odified particle swar optiization (PSO) alorith an iproved axiu power point trackin (MPPT) ethod. The ain advantae of the ethod is the reduction of the steady- state oscillation (to practically zero) once the axiu power point (MPP) is located. Furtherore, the proposed ethod has the ability to track the MPP for the extree environental condition, e.., lare fluctuations of insolation and partial shadin condition. The alorith is siple and can be coputed very rapidly; thus, its ipleentation usin a low-cost icrocontroller is possible. Finally, a ultiphase dc dc converter is used for hih-voltae and hih power applications. A eneralized converter is confiured such that the boost-half-bride (BHB) cells and voltae doublers are connected in parallel or in series to increase the output voltae and/or the output power. Here a three phase inverter is also added in the output of conventional syste for obtainin A voltae for A load. The device voltae ratin and current ratin are reduced by increasin the nuber of switches in series and nuber of diodes in parallel connection, respectively. Keywords: Buck boost converter, axiu power point trackin (MPPT), partial shadin, particle swar optiization (PSO), photovoltaic (PV) syste. I.INTRODUTION SOLAR photovoltaic (PV) is envisaed to be a popular source of renewable enery due to several advantaes, notably low operational cost, alost aintenance free and environentally friendly. Despite the hih cost of solar odules, PV power eneration systes, in particular the rid-connected type, have been coercialized in any countries because of its potential lon-ter benefits [1] [6]. Furtherore, enerousfinancial schees, for exaple, the feed-in tariff [7] and subsidized policies [8], have been introduced by various countries, resultin in rapid rowth of the industry. To optiize the utilization of lare arrays of PV odules, axiu power point tracker (MPPT) is norally eployed in conjunction with the power converter (dc dc converter and/or inverter). The objective of MPPT is to ensure that the syste can always harvest the axiu power enerated by the PV arrays. However, due to the varyin environental condition, naely teperature and solar insolation, the P V characteristic curve exhibits a axiu power point (MPP) that varies nonlinearly with these conditions thus posin a challene for the trackin alorith. To date, various MPP trackin ethods have been proposed [9]. These techniques vary in coplexity, accuracy, and speed. ach ethod can be cateorized based on the type of the control variable it uses: 1) voltae, 2) current, or 3) duty cycle. For the voltae andcurrentbasedtechniques,twoapproachesareused. The first one is the observation of MPP voltae VMP or current IMP with respect to the open circuit voltae VO [10] and short circuit current IS, respectively [11]. Since this ethod approxiates a constant ratio, its accuracy cannot be uaranteed. onsequently,thetrackedpowerwouldostlikelybebelowthe real MPP, resultin in sinificant power loss [12]. The second approach is to obtain the inforation on the actual operatin point of the PV array (i.e., voltae and current) and these points are updated accordin to the variation in environental conditions. The ost popular technique is the perturb and observe (P&O) ethod. It is based on the perturbation of voltae (or current) usin the present P and previous Pold operatin power, respectively. If P is iproved, the direction of perturbation is retained; otherwise, the direction is reversed accordinly. Despite the siplicity of the alorith, the perforance of P&O ethod is heavily dependent on the trade-off between the trackin speed and the oscillations that occurs around the MPP [13]. A sall perturbation reduces the oscillations but at the expense of opyriht to IJIRST

2 trackin speed, or vice versa. Another ajor drawback of P&O is that durin rapid fluctuations of insolation, the alorith is very likely to lose its direction while trackin thetruempp.severaliproveentsareproposedtoaddressthis issue ainly by considerin adaptive perturbation. However, these techniques are not fully adaptive and hence are not very effective [14]. Moreover, under special condition such as partial shadin and odules irreularities, these ethods often fail to track the true MPP because the PV curves are characterized by ultiple peaks (several local and one lobal). Since the P&O alorith could not distinuish the correct peak, its usefulnessunder such conditions diinishes rapidly. B. Modelin of the PV Array In a typical installation of a lare PV power eneration sys- te, the odules are confiured in a series parallel structure (i.e., Nss Npp odules), as depicted in Fi. 1(b). To handle such cases, the output current equation in (4) has to be odified as follows: I = Npp{IPV Io (Ip + 2)} V + IRsΓRpΓ (7) where Ip = expv + IRsΓ VT Nss +exp V + IRsΓ (p 1)VTNss (8) AndΓ=NssNpp (9) The Boost-Half-Bride (BHB) converter has followin features: sall input filter due to continuous input current, low electroanetic interference (MI) due to ZVS turn ON of all power switches, wide-input voltae rane application due to wide-duty cycle rane. The BHB converter with a voltae doubler rectifier at the secondary has furtheradvantaes, which are no dc anetizin current of the transforer, reduced voltae sure associated with diode reverse recovery, and no circulatin current due to absence of output filter inductor II.MODLLING OF PV ARRAY SYSTM A.Modelin PV Module Aon various odelin ethods of the PV odule, the two-diode odel, as depicted in Fi. 1(a), is known to be the ore accurate one. The output current of the odule can be described as I = I PV I d1 I d2 V + I Rs Rp (1) where I d1 =I o1 expv + I Rs a1vt 1 1 (2) I d2 = I o2 expv + IRs a2vt 2 1 (3) Where I = I PV Io (Ip + 2) V + I Rs Rp (4) where Ip = expv + I RS VT + expv + I Rs (p 1)VT(5) Andp =1+a2. (6) The odel only requires five paraeters to be coputed with no loss of accuracy. where IPV,I0,Rp,R s,p are the paraeters of the individual odule. Fi. 2 shows the P V curves for a coercial PV odule (MSX-60) confiured in a 4 1 PV array. The paraeters of this particular odule under the standard test condition (ST) are shown in Table I. III. ONVNTIONAL H MTHOD To obtain the axiu power fro the PV odules, MPPT is norally eployed. Over the years, various MPPT ethods are proposed; for exaple, P&O, I, H, NN, and FL [4], [9], [12], [15] [19], [22]. In particular, the conventional H ethod is interestin as the duty cycle of the power converter can be varied directly [16]. This can be explained with the help of a flowchart asshowninfi. 3.Thealorithperiodically updates thedutycycle d(k)byafixed stepsize Φwiththedirectionofin- creasin power. The perturbation direction is reversed if P(k) < P(k 1), an indication that the trackin is not ovin toward the MPP. This can be described by the followin equation: dnew =dold +Φ if P>Polddold Φ if P<Pold. (10) A clear advantae of this alorith is that the MPPT alorith does not require proportional (P) or proportional interal (PI) action, which is norally eployed to control the duty cycle with reference to voltae or current. In this case, the duty cycle directly feeds the power converter. opyriht to IJIRST

3 A. General Overview of PSO IV. PSO-BASD MPPT PSO is a stochastic, population-based A search ethod, odelled after the behaviour of bird flocks [30]. The PSO alo- rith aintains a swar of individuals (called particles), where each particle represents a candidate solution. Particles follow a siple behaviour: eulate the success of neihbourin particles and its own achieved successes. The position of a particle is, therefore, influenced by the best particle in a neihbourhood Pbest as well as the best solution found by all the particles in the entire population Gbest. The particle position xi is adjusted xk+1 i = xk i +Φ k+1 i (11) where the velocity coponent Φi represents the step size. The velocity is calculated by Φk+1 i = wφk i + c1r1pbesti xk i+ c2r2gbest xk i (12) where w is the inertia weiht, c1 and c2 are the acceleration coefficients, r1, r2 U(0, 1), Pbesti is the personal best position of particle i, and Gbest is the best position of the particles in the entire population. Fi. 4 shows the typical oveent of particles in the optiization process. If position is defined as the actual duty cycle while velocity shows the perturbation in the present duty cycle, then (11) can be rewritten as dk+1 i = dk i +Φ k+1 i. (13) Fro (10) and (13), it can be seen that both H and PSO aloriths have an equivalent structure. However, for the case of PSO, resultin perturbation in the present duty cycle depends on Pbesti and Gbest. If the present duty cycle is far fro these two duty cycles, the resultin chane in the duty cycle will also be lare, and vice versa. Therefore, PSO can be thouht of as an adaptive for of H. In the latter, the perturbation in the duty cycle is always fixed but in PSO it varies accordin to the position of the particles. With proper choice of control paraeters, a suitable MPPT controller usin PSO can be easily desined. B. Application of PSO for MPPT To illustrate the application of the PSO alorith in trackin themppusinthedirectcontroltechnique,firstasolutionvector of duty cycles with Np particles is deterined, i.e. xk i = d =[ d1,d2,d3,...,d j] j =1,2,3,...,Np. (14) The objective function is defined as P(dk i ) >P(dk 1 i ). (15) To start the optiization process, the alorith transits three duty cycles di (i = 1, 2, 3) to the power converter. In Fi. 5, duty cycles d1, d2, and d3 are arked with trianular, circular, and square points, respectively. These duty cycles served as the Pbesti in the first iteration. Aon these, d2 is the Gbest that ives the best fitness value (which is the array power), as illustrated by Fi. 5(a). In the second iteration, the resultin velocity is only due to the Gbest ter. The (Pbesti d (i)) factor in (12) is zero. Furtherore, the velocity of Gbest particle (d2) is zero due to the (Gbest d (2)) factor in (12) is zero. This results in a zero velocity and accordinly the duty cycle is unchaned. As a result, this particle will not contribute in the exploration process. To avoid such situation, a sall perturbation in duty cycle is allowed, as shown in Fi. 5(b), to ensure the chane in fitness value. Fi. 5(c) shows the particles oveent in the third iteration. Due to the fact that all the duty cycles in the previous iteration attain a better fitness value, the velocity direction of these particles reains unchaned and subsequently they ove toward Gbest alon the sae direction. In the third iteration, all duty cycles (di, i = 1, 2, 3) arrive at MPP with a low value of velocity. In the subsequent iteration, due to very low velocity, the value of the duty cycle is approachin a constant. Therefore, theoperatinpointwillbeaintainedandtheoscillationaround the MPP diinishes. V.SOLAR MODL IN MATLAB A. Model of Solar ell The solar cell block fro SIMSAP tool and is represented as a sinle solar cell as a resistance R s that is connected in series with a parallel cobination of the followin eleents: urrent source Two exponential diodes Parallel resistor R p opyriht to IJIRST

4 - + The atheatical odel of the PV cells is ipleented in the for of a current source controlled by voltae, sensible to two input paraeters, that is teperature (º) and solar irradiation power (W/2). An equivalent siplified electric circuit of a photovoltaic cell is presented + - v 1 volt in Fi 1: quivalent ircuit of Solar ell. The output current Iis iven by equation (14), I = I ph - I s *(e (V+IRs)/(N*Vs) - 1) - I s2 *(e (V+I*Rs)/(N2*Vt)) -1)- (V+I*R s )/R p (14) Vpv Fi 3 MATLAB Ipleentation Fiure 3 shows the voltae source converter odel consistin of six IGBTS. This voltae source converter is operated as the inverter for Solar fars durin day tie. Durin niht tie it is idle in condition as no power is enerated hence it can be used for recative power copensation.. Siulation Results 1. General Ppv 1000 I rradiance Ipv Irradiance + - Soalr cell Fi 2: Solar Array Model in MATLAB P V I V Variable Resistor P S Rvar Vary in R The odels are developed in MATLAB siulink environent. MATLAB (atrix laboratory) is a nuerical coputin environent and fourth-eneration prorain lanuae. Developed by MathWorks, MATLAB allows atrix anipulations, plottin of functions and data, ipleentation of aloriths, creation of user interfaces, and interfacin with proras written in other lanuaes, includin, ++, Java, and Fortran. The above fiure 2 is the MATLAB odel of solar array which has 72 solar cells connected in series to for a solar array. This odel is developed with the help of Sis cape tool block. The solar cell in Siscape tool is developed usin the equation 1. The solar array is connected to the resistive load to view its perforance. B. Model of Voltae Source onverter Fi4:PV Array -Siulation diara opyriht to IJIRST

5 Fi 8: PV syste siulation Fi 5: PSO Alorith Fi 6: Trackin output-1 An additional packae, Siulink, adds raphical ultidoain siulation and Model-Based Desin for dynaic and ebedded systes. MATLAB users coe fro various backrounds of enineerin, science, and econoics. MATLAB is widely used in acadeic and research institutions as well as industrial enterprises. Siulink is developed by MathWorks and is a coercial tool for odelin, siulatin and analyzin ulti doain dynaic systes. Its priary interface is a raphical block diarain tool and a custoizable set of block libraries. It offers tiht interation with the rest of the MATLAB environent and can either drive MATLAB or be scripted fro it. Siulink is widely used in control theory and diital sinal processin for ulti doain siulation and Model-Based Desin. The siulation was done in MATLAB SIMULINK environent with the help of SIMPOWR syste and SIMSAP tools. And the results ot are shown below.this chapter will investiate the results of the proposed odel. Siulated results of the project are shown and discussed. It also ensures the proper workin of the odel. It helps to have a coparative study of perforance of the syste which has been odelled. Fi 7: Trackin output-2 opyriht to IJIRST

6 2. Output Wavefors the hih-voltae low-current side, i.e., N is the nuber of voltae doublers connected. Fi 9 Voltae vs Power curve of Solar ell The fiure 5.1 shows the voltae vs power curve of solar panel where X axis is voltae and Y axis is power. Fi 10 Voltae vs urrent curve of Solar Sell The fiure 5.2 shows the voltae vs current curve of solar panel where X axis is voltae and Y axis is current. VI.PROPOSD MULTIPHAS D D ONVRTR A. Generalized Multiphase D D onverter BHB cell that is used as a buildin block of the proposed ultiphase converter. Fi. 2 shows the eneralized circuit of the proposed ultiphase dc dc converter for hih- voltae and hih-power applications. The eneralized converter has N roups of converters, where each roup of switch les is connected in parallel at the low-voltae hih-current side, while each roup of voltae doublers is connected in series at B. Operatin Principles The key wavefors of the eneralized ultiphase dc dc con- verter are shown in Fi. 5. The interleaved asyetrical PWM switchin is applied to the ultiphase converter, i.e., D and 1 D are the duty cycles of lower and upper switches of a le, respectively, and each le is interleaved with a phase difference of 2π/(N P). The averae value of the inductor current can be obtained. Usin (5) (8), the ZVS currents and ZVS ranes of lower and upper switches as the function of input voltae and output power are plotted, respectively, as shown in Fi. 6. As shown in Fi. 6(a), the ZVS current of the lower switch tends to increase as the output power increases and decrease as the input voltae increases. This eans that the ZVS turn-on of the lower switch can be ore easily achieved under the condition of hiher out- put power and lower input voltae. It is noted that the ZVS rane of the lower switch becoes broader for saller total output capacitance os,tot = oss,sl + oss,su of MOSFTs. For exaple, if MOSFTs with total output capacitance os,tot of 1.5 nf are selected in this exaple, the ZVS turn-on of the lower switch can be achieved with output power, which is reater than 1000 W at input voltae of 40 V.. Interleavin ffect ach le of the ultiphase converter is switched with a phase difference of 2π/(N P). The ripple frequency of the input and input capacitor currents becoes N P ties the switchin fre- quency of the ain switch. The rs current of the input and input capacitor also decrease as N and P increases. The ripple frequency of the output capacitor current becoes P ties the switchin frequency of the ain switch. The rs current of the output capacitor decreases as P increases. Due to the interleaved operation, the weiht and volue of input capacitors,outputcapacitor,andinputinductorsaresinificantly reduced. The interleavin effect on the input inductor and output capacitor of the proposed converter is obvious and has been entioned in any literatures [12] [14]. The interleavin effect on the input capacitors IU and IL differs fro that of the in- put inductor and output capacitor. The capacitor rs currents are calculated and plotted in Fi. opyriht to IJIRST

7 7 as a function of input volt- ae and N. It tends to decrease as N increases in eneral. A dc voltae is iven as input, which is converted in to ac by controlled switches, which act as inverter when switches are off. Its output is iven to the transforer, then to the voltae doublers, which rises the voltae level and the diode rectifier converter ac to dc voltae. Three phase inverter is connected for ac. load. D. Interleavin ffect The ripple frequency of the input and input capacitor currents becoes N P ties the switchin frequency of the ain switch. The rs current of the input and input capacitor also decrease as N and P increases. The ripple frequency of the output capacitor current becoes P ties the switchin frequency of the ain switch. The rs current of the output capacitor decreases as P increases. Due to the interleaved operation, the weiht and volue of input capacitors, output capacitor, and input inductors are sinificantly reduce. The interleavin effect on the input capacitors IU and IL differs fro that of the input inductor and output capacitor. The capacitor rs currents are calculated and as a function of input voltae. chares the upper input capacitors. When it chares to axiu voltae, it dischares and inductor transfer thecurrent to one side of correspondin transforer. Then correspondin upperswitches are open & neative supply voltae is iven to the lower capacitor by correspondin lower switches and it is also available for the transforer and in this way the transforer et both the positive and neative voltae. The output of the transforer iven to the voltae doubler and its D output converted into A by a three phase inverter. Its output used for runnin IM. The averae value of the inductor current is: I L,av = [V 2 0 /V s R 0 ][1/NP] (16) IL =V s D/Lf s (17) To ensure the ZVS turn ON of upper switch SU, the followin condition should be satisfied: 1/2Lk I2SU,ZVS>12os,tot (Vs/1 D)2 --- (18) To ensure the ZVS turn ON of lower switch SL, the followin condition should be satisfied: 1/2Lk I2SL,ZVS>12os,tot ( VS/1 D)2 --- (19).Voltae onversion Ratio The ideal voltae conversion ratio of the proposed converter can be obtained by VO/VS=N/(1 D)(NS/NP) (15) Basically, as level of switches & diodes increases the voltae conversion ratio linearly increases. onsiderin the effect of voltae drop across the leakae inductance of the transforer, the actual voltae conversion ratio can be obtained.the actual voltae conversion ratio is plotted as a function of duty ratio D with different N and P,N is the nuber of switches and P is the nuber of diodes. It can be seen that as P increases the voltae conversion ratio also slihtly increases (theoretically, it converes to the ideal voltae conversion ratio as P increases to infinity), since the effect of the voltae drop across the leakae inductance on the voltae conversion ratio becoes saller. Fi. 11. Proposed ultiphase dc dc converter (N is the nuber of series- onnected voltae doublers, and P is the nuber of diode les connected to thesae output capacitors). The key wavefors of the eneralized ultiphase dc dc converter are shown in Fi. 5. The interleaved asyetrical PWM switchin is applied to the ultiphase converter, i.e., D and 1 D are the duty cycles of lower and upper switches of a le, respectively. VII. OPRATING PRINIPLS Durin positive supply voltae current flow throuh respective inductors, and upper switches,and it opyriht to IJIRST

8 VIII.SIMULATION RSULT A.Siulation Diara Of Proposed Syste Fi 12 Siulation diara of proposed syste Fi 14 A input voltae and output current wave for for the IM with filter Here eiht MOSFT SWITHS and four isolated transforers and four voltae doublers are connected in series. Switches connected in low voltae side and voltae doublers in hih voltae side of transforer. Its output is converted in to ac by usin 3 ph inverter, its output for ac load. Input voltae = 35V Output voltae = 380 to 480V Load induction otor V doubler = 600 V I doubler = 0.78 to 1.2 Fi 15Speed wave for of the induction otor Fi 13 output voltae and current wave for of voltae doubler Fi16stator urrent Of IM opyriht to IJIRST

9 IV.ONLUSION The conventional syste can only be used for D load application and not for A load also the voltae and current ratin of the devices in the syste are hih. These drawbacks are overcoe in proposed syste by usin 3 phase inverter and thus it can be applied fro ac load. The current and voltae ratin of the devices are reduced by increasin the nuber of switches and diodes which also increases the output voltae. In future the output voltae can be increased further by increasin the nuber of switches and diodes. RFRNS [1] A. R. Prasad, P. D. Zioas, and S. Manias, Analysis and desin of a three-hase offline D D converter with hih-frequency isolation, I Trans. Ind. Appl., vol. 28, no. 4, pp , Jul./Au [2] D. de Souza Oliveira, Jr. and I. Barbi, A three-phase ZVS PWM D/Dconverter with asyetrical duty cycle for hih power applications, I Trans. Power lectron., vol. 20, no. 2, pp , Mar [3] D. S. Oliveira, Jr. and I. Barbi, A three-phase ZVS PWM D/D converter with asyetrical duty cycle associated with a three-phase version of the hybride rectifier, I Trans. Power lectron., vol. 20, no. 2, pp , Mar [4] H. Ki,. Yoon, and S. hoi, A three-phase zero-voltae and zerocurrent switchin D D converter for fuel cell applications, I Trans. Power lectron., vol. 25, no. 2, pp , Feb [5] J. Lai, A hih-perforance V6 converter for fuel cell power conditionin syste, in Proc. I VPP 2005, pp [6] R. L. Andersen and I. Barbi, A three-phase current-fed push pull D D converter, I Trans. Power lectron., vol. 24, no. 2, pp , Feb [7] S. Lee and S. hoi, A three-phase current-fed push-pull D-D converter with active clap for fuel cell applications, in Proc. AP 2010, pp [8] H. ha, J. hoi, and P. njeti, A three-phase current-fed D/D converter with active clap for low-d renewable enery sources, I Trans.Power lectron., vol. 23, no. 6, pp , Nov [9] S. V. G. Oliveira and I. Barbi, A three-phase step-up D-D converter with a three-phase hih frequency transforer, in Proc. I ISI 2005, pp [10] H. ha, J. hoi, and B. Han, A new three-phase interleaved isolated boost converter with active clap for fuel cells, in Proc. I PS 2008, pp opyriht to IJIRST