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40220130406011 2-3-4 40220130406011 2-3-4 Document Transcript

  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING & ISSN 0976 – 6553(Online) Volume 3, Issue 3, October – December (2012), © IAEME TECHNOLOGY (IJEET) ISSN 0976 – 6545(Print) ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), pp. 110-120 © IAEME: www.iaeme.com/ijeet.asp Journal Impact Factor (2013): 5.5028 (Calculated by GISI) www.jifactor.com IJEET ©IAEME MODELING OF THERMAL PHOTOVOLTAIC PUMPING SYSTEM OPTIMIZED Bouden Abdelmalek1, M. Marir Benabbas2 Laboratory (MoDERNa), Faculty of the science and the technology Department of electronics, University of Constantine 1, Algeria ABSTRACT During the photovoltaic conversion of the solar collector, a heat is generated, what will increase the temperature of the photovoltaic cell and will cause a fall of its efficiency. This phenomenon is due to the part of the solar radiance non absorbed by the cells and that will be to the origin of its warming-up. This warming-up has been considered like ominous for the photovoltaic solar thermal collector, and several efforts have been agreed to evacuate this heat. There was also help to exploit this phenomenon by the photovoltaic system combination with a thermal system to form the collector hybridize PVT, that is going to generate electricity and the heat at the same time. The objective of this work concerns the photovoltaic pumping system improvement by the insertion of a thermal photovoltaic collector (PVT) to increase the efficiency of this system. Follows a general presentation on the photovoltaic systems. The comparison between the direct coupling and the technique of pursuit of the point of maximal power (MPPT) with and without PVT collector proves to be necessary. Finally, the use of this technique to supply a converter, while showing the influence of the climatic parameters around this point. The results gotten extended were promising and remain to validate practically. Keywords: Photovoltaic Systems, Pumping, Optimization, Point of Maximum Power MPPT, PVT. 1. INTRODUCTION The solar energy remains a significant source of energy savings, especially for conditions where sunlight is abundant and conventional energy is more expensive. This energy becomes more competitive if it improves the performance of thermal conversion systems [1]. For solar collectors, thermal efficiency can be improved by promoting the exchange of heat between the plate and the 110
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME coolant; the PVT collector can simultaneously produce heat and electricity. It is composed of a flat plate water heating collector inserted into a photovoltaic module. [2] 2. ELEMENTS OF CONSTRUCTION OF PVT COLLECTOR The studied system consists of three main components, namely, (Fig. 1): •The photovoltaic module, which has the role of converting sunlight into electrical energy and is composed of three layers: the first layer is a glass, whose front face is exposed to radiation, the second layer containing the photovoltaic cells and the third layer is the rear face of the module, made of tedlar. •A galvanized steel plate whose role is to absorb heat, •A pipe assembly as radiator or coil, the absorption plate welded to ensure a good thermal contact between the two elements, and in which circulates a coolant that has the function to remove the heat stored by the absorption plate. Finally, to minimize heat loss from the system, insulate walls with one or more layers of insulation. [3] Fig.1: Elements of construction of PVT collector 3. MODEL OF THERMAL SYSTEM The power recovered by the heat transfer fluid is defined as the difference between the incident solar energy and the heat losses. It is given by: [3] Qu = AcFr[( ) eff E - U L (Te - Ta)] τα (1) The average temperature of the plate is given by T = Te + Qu (Te - Ta) (AcU L Fr) (2) With Fr = MC P [1 - exp( - Ac.U L ) Fc) ] UL MC P 111 (3)
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME Fc = 1 / WU L 1 U L [(W - d)F + d] + 1 W.hPVA 1 + πdih f m  tanh  (W − di )  2  F = m (W − di ) 2 m= (4) (5) UL K abc L abc + K pv L pv (6) Ac: Collector Area (m2) Fr: Collector heat removal factor (τα)eff: Effective transmissivity-absorptivity product. E: Global radiation received by an inclined surface. UL: Coefficient of heat loss, W/m2 ° C. Te: Fluid temperature at the collector input. Ta: Ambient temperature. Qu: Useful energy recovered by the fluid M:Mass of absorber. Cp: Specific heat of absorber. Fc: Collector efficiency factor. W: Distance between the tubes. d: Diameter pipe hydraulics. F: Effectiveness coefficient. hPVA: Coefficient of heat transfer from cell to absorb. hf: Thermal coefficient of the fluid. m: Surface flow, kg / s m2 Kabs: Conductivity Absorber. Labs: Thickness Absorber. KPV: PV Conductivity. LPV : PV thickness. 4. MODEL OF A PHOTOVOLTAIC CELL Figure (2) shows the diagram of a photovoltaic cell Fig. 2: Circuit diagram of a photovoltaic cell 112
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME The term of current I generated by the cell and supplied to the load is given by:   ( V + Rs I )    V + Rs I  − 1 −  I = I ph − IS exp      A UT    R Sh I ph = E I ph0 + K0∆T Er [     ] (8) With ∆T = T − Tr K0 = ∆Tn I CCr (7) (9)   E   1 − Er  I CCr − α ∆ T n     (10) k: Boltzman's constant; q: electron charge. T: Temperature (Kelvin). V: Terminal voltage of the cell. UT : Thermal stress. E: Illuminance. Iph: Current photo. Is: Saturation current of the diode. A: Quality factor of the diode. Rs, Rsh: Series resistance and shunt a) Short-circuit ISCr: V(I SCr) = 0   R R I ⇒ I SCr = I ph0 − I S 0 exp( S 0 SCr ) − 1 − S I SCr AUT   RSh ⇒ I ph0 = (1+  R I  Rs )I SCr + I S0 exp( S0 SCr ) −1 Rsh AUT   (11) (12) b) Open circuit voltage, VOC I (VCOr ) = 0   R V ⇒ 0 = I ph0 − I S 0 exp( OCr ) − 1 − S AU T   R Sh   V V ⇒ I ph0 = − I S 0 exp( OCr ) − 1 + OCr AU T   RSh 113 (13) (14)
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME Donc I S 0 = VOCr − ( R S 0 + R Sh 0 ) I SCr  R I V RSh 0 ( S 0 SCr ) − exp( OCr AU T  AU T  )  RS = RS 0 RSh = I SC = (15) (16) AU T V I S 0 exp( OCr ) AU T (17) E I SCr + α∆Tn Er (18) (19) VOC = VOCr + β∆Tn 5. CHARACTERISTIC I(V) AND P(V) OF PV GENERATOR AND PVT COLLECTOR The power delivered by a photovoltaic generator depends on the irradiation what receives. One notices that the maximum power for a system with a thermal photovoltaic collector (PVT) superior to the maximum power for a photovoltaic generator (GPV) system. Fig. 3. Characteristic I (V) of GPV and PVT Collector Fig.4. Characteristic P(V) of GPV and PVT Collector 6. OPTIMIZATION OF PV PUMPING SYSTEM 6.1. The tracking techniques maximum power The point of working of the photovoltaic system, situated to the intersection of the characteristic I(V) of generator and the motor - pump group, move according to the value of the sunshine. For high values of the sunshine, the characteristics intersect in the zone where the power produced by the generator is optimal. By contrary, for small values of sunshine, the point of working remote of this zone. Says otherwise, during the morning and evening the performances of the system 114
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME are mediocre and the generator is under used. A question gets, it is possible to force the system to function in the zone where the power produced by the generator is optimal, more precisely, one can force the generator to produce its maximal power some are the climatic conditions? 6.2. Basis of the impedance adaptation by a converter DC – DC We will concede a motor DC to constant flux, while disregarding the reaction of induced and the phenomenon of commutation, the tension of the motor will be equal to: [4, 5] Vch = Ra I ch + La . dI ch + k eω dt (20) and the couple of the motor (21) Ce=ktIch The centrifugal pump opposes a resistant couple: Cr=krω2+CS (22) Ke(V/rad.s-1), kt(Nm/Ampère) et kr(Nm/rad.s-1) are coefficients of proportionality. [6] On the other hand we have the mechanical equation: dω = Ce − Cr dt With Jm: the moment of inertia of the group. [7] Jm (23) 6.3. Techniques of research of point of power maximal (MPPT) In general the point of functioning is not in the MPPT of the photovoltaic panel. Then in the direct coupling loads, the photovoltaic panels are often oversized to assure a sufficient power to provide to the load, this leads to an overly expensive system. To surmount this problem, the maximal power tracking can be used to maintain the functioning of the photovoltaic panel at its maximum power for this one to use methods of research of the MPPT among methods is: 6.3.1. Method of Conductance incremental This method is more efficient and complex compared to other methods such as perturbation and observation. It is based on the fact that the derivative of the exit power PPV in relation to the tension of panel VPV is equal to zero to the maximum point of power. The characteristic P(V) of PV panel shows that this derivative is positive to the left of the maximum power point and negative to the right of the maximum power point. Figure (5) Fig.5. Characteristic of power 115
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME This leads to the following set of equations: [8, 9, 10] In-MPP: dppv dVpv -A Left MPPT: dp pv dV pv - A right MPPT: dp pv dV pv = = = d(I pvVpv ) dVpv = I PV +Vpv d (I pvV pv ) dV pv d (I pvV pv ) dV pv These equations can be written as: dI pv I pv =− dV pv V pv dI pv dIpv dVpv = I PV + V pv = I PV + V pv (24) =0 dI pv dV pv dI pv dV pv >0 (25) <0 (26) Au MPP I pv À gauche du MPP dV pv V pv dI pv I pv À droite du MPP <− dV pv V pv The equations can be used above as algorithm of control to order the point of function of the converter while measuring the growth of conductance and the converter's instantaneous conductance dIPV / dVPV and IPV / VPV respectively. [9] The organization chart of the control algorithm is shown on the figure (6). >− Fig.6: Organization chart of the method of conductance incremental. 116
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME 7. RESULTS AND DISCUSSION 7.1. Comparison between optimized and non-optimized system Whatever the nature of the couple of motor-pump group to the PV generator, with or without ptimization criterion, the load characteristic, power, efficiency and the quantity of water provided by the pumping system are the main parameters permit the assessment and the validation of the exploitation of the photovoltaic pumping system. 7.1.1. Characteristic of load and power The function of the system is improven by the use of the technical MPPT, where the motor to continuous current is supplied by nearer tensions to the face values , the effect of the technique compared to the direct coupling is very clear. - GPV system For small values of the illuminance at 200W/m2, the supply voltage is increased to a value as low as 75V for the direct coupling to a result value of 130V. - PVT collector system For small values of the illuminance at 200W/m2, the supply voltage is increased to a value as low as 80V for the direct coupling to a result value of 150V. The powers obtained by the MPPT technique are the highest possible values, where the operating system is ideal. Thus, the overall power of PVT sensor is used. Figures (7) and (8) watch the big gap between the maximized powers and those of direct coupling. Fig.7: Characteristic I(V) of pumping system GPV and PVT, optimized and unoptimized. Fig.8: Characteristic P (V) of pumping system by GPV and PVT, optimized and unoptimized. 7.1.2. Characteristic of efficiency and the debit of pumping system The efficiency of the system is defined by: η PPV = Ph ρ . g .Q.H m = Pe E . N S .N P .S (27) With Ph: hydraulic power, Q: Quantity of given by: [12] 117
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME si E 〈 Et  0   Q=  2   1  α + 4 α ( E − δ ) − β  si E 〉 Et 2  α α     (28) Et = 180W/m2; α, β and δ are constant. Figures (9) and (10) illustrious gaits efficiency, which is 100% for the idealized MPPT technique, against the direct coupling is characterized by a low yield, especially for low luminance values. But from E = 900W/m2 and the values of the efficiency will be close, reconciliation proves the good matching between the motor-pump group and the generator for the direct coupling of strong illumination. Fig.9. Efficiency of pumping system PV Fig.10. Efficiency of pumping system PVT The figures (11) and (12) represent the paces of the debits, to the direct coupling and with the technique of MPPT according to the illuminance. -For the PVT collector system: In the case of the direct coupling system begins to supply water at an luminance of 280W/m2, thus maximizing power strength of the pump supplying water to from 175W/m2. [12]. -For the PVT collector system: In the case of the direct coupling system begins to supply water at an luminance of 190W/m2, thus maximizing power strength of the pump supplying water to from 100W/m2. 118
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME Fig.11. Quantities of water of Pumping system by GPV Fig.12. Quantities of water of Pumping system by PVT 8. CONCLUSION In the photovoltaic conversion in the solar collector, a heat is generated, thereby increasing the temperature at the photovoltaic cell and causing a drop in performance. This phenomenon is due to the part of not absorbed by the cells and solar radiation will cause its warming-up. On the other hand, this part of the absorbed radiation is lost as heat. The objective of this work is twofold, increase the electrical efficiency of the collector, that is to say the electrical efficiency by reducing the operating temperature and using the same heat for heating water or the surrounding space. For the photovoltaic pumping system of solar energy, we have optimization technique; This technique based on the simplest system consists of a direct coupling of the motor-pump to the photovoltaic generator. For an ideal optimization of the energy delivered by the generator. The tracking technique maximum power point MPPT is used. But this technique has several disadvantages such as the complexity of implementation and the high price. The direct coupling of the generator and moto-pump group has been studied as a basic reference. It represents the type of connection the easiest and least expensive course. However, this coupling is acceptable only in very specific conditions where the load is properly adapted to the generator and provides acceptable performance. This is noticed in this study for high irradiance. By cons outside of this condition, the yield decreases and solar energy is converted poorly exploited. Thus it is necessary to recover this loss of energy. REFERENCES [1] [2] [3] [4] H. Abdi et N. Aït Messaoudène" Etude Expérimentale et Théorique des Performances de deux Capteurs Plans à Contact Direct Eau-Plaque d’Absorption" Rev. Energ. Ren. : Chemss 2000 53-60. K. Touafek1*, M. Haddadi2, A. Malek3 et W. Bendaikha-Touafek1"A dynamic model of hybrid photovoltaic/thermal panel"International Renewable Energy Congress, November 5-7, 2009 - Sousse Tunisia LARHYSS Journal , 2002. A. Khelifa et K. Touafek "Etude de l’influence des paramètres externes et internes sur le capteur hybride photovoltaïque thermique (PVT) " Revue des Energies Renouvelables Vol. 15 N°1(2012) 67–75. C. Alonso "Contribution à l’optimisation, la gestion et le traitement de l’energie" université Paul sabter, toulouse. 2003. 119
  • International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 – 6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 6, November - December (2013), © IAEME [5] Anto Joseph, Nagarajan and Antony Mary, “A Multi Converter Based Pure Solar Energy System with High Efficiency MPPT Controller”, International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 4, 2013, pp. 205 - 212, ISSN Print: 0976-6545, ISSN Online: 0976-6553. [6] Sofia Lalouni and Djamila Rekioua, “Control of Photovoltaic Water Pumping System with Battery Storage”, International Journal of Electrical Engineering & Technology (IJEET), Volume 4, Issue 1, 2013, pp. 190 - 199, ISSN Print : 0976-6545, ISSN Online: 0976-6553. [7] K.Kassmi1, M. Hamdaoui1 et F. Olivié "Conception et modélisation d’un système photovoltaïque adapté par une commande MPPT analogique" Revue des Energies Renouvelables, Université Mohamed Premier, Maroc, 2007. [8] D. P. Hohm, M. E. Ropp "Comparative study of maximum power point tracking algorithms", Progress in photovoltaic, research and applications, 11: 47-62, 2003. [9] C.Wei Tan, C.Green " An Improved Maximum Power Point Tracking Algorithm with Current-Mode Control for Photovoltaic Applications" Departnent of Electrical and Electronic Engineering, Inperial College London, United Kingdom, IEEE PEDS 2005. [10] Vikrant.A.Chaudhari"Automatic peak power tracker for solar pv modules using dspacer software" thesis of the master of technology inenergy, maulana azad national institute of technology (deemed university), 2005. [11] M D Goudar, B. P. Patil and V. Kumar, “A Review of Improved Maximum Peak Power Tracking Algorithms for Photovoltaic Systems”, International Journal of Electrical Engineering & Technology (IJEET), Volume 1, Issue 1, 2010, pp. 85 - 107, ISSN Print: 0976-6545, ISSN Online: 0976-6553. [12] A. Abdulrahman Mohammed "Optimum Selection of Direct-Coupled Photovoltaic Pumping System in Solar Domestic Hot Water Systems" Thesis of doctorate of philosophy, University of wisconsin-madison, 1997. AUTHOR’S DETAIL Bouden Abdelmalek: got his degree engineer in electronics in the university of Jijel, Algeria, June 2006, and his degree magister in electronics option composing electronics and photovoltaic system to the university of Constantine - Algeria, November 2008. The domain of his research is the renewable energy. M.MARIR BENABBAS: He received the DES degree in physic energetic, from the university of Constantine in 1981, and the magister photovoltaic from the university of Constantine with associated of university of Belgium, Leuven 1984, her dissertation research is concerned with the breakdown phenomena in solar cells, from 1984 she joined the electronically institute of Constantine university, where she served successively as instructor, assistant master. In 1993, where she was obtained her doctorate as sciences of microelectronic from the university of Constantine with collaboration from Institute national Polytechnic (INP, ENSEEIHT) of Toulouse his dissertation is concerned with the physics and modeling quantum compound semiconductor devices such as high electron mobility transistors (HEMTS).Since 1993, she served as associate professor in the electronically department. She is now an associate research scientist in the material and electronically compound laboratory of engineering science faculty where she has been engaged in research on heterostructure quantum well devices and physics, and photovoltaic system, working on OPVC cells until a few years. She works in several scientific projects with the different institution of ministry. 120