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  • 1. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME450PVG BASED SMART ENERGY MODELLING FOR AGRICULTURALSECTORCh.Venkateswra rao1, S.S.Tulasiram2, B. Brahmaiah31(PHD Scholar JNTUK, Kakinada, AP, India)2( Professor in EEE Department, JNTUH, Hydrabad, AP, India)3(Principal at PIT, Tirupati, India)ABSTRACTIn this paper evaluates ways in which they can be made efficient. The role ofefficiency standards in achieving this goal and the appropriateness of existing standards isevaluated. With the continuous decrease of the cost of solar cells, there is an increasinginterest and needs in photovoltaic (PV) system applications following standard of livingimprovements. Water pumping system powered by solar-cell generators are one of the mostimportant applications. The fluctuation of solar energy on one hand and the necessity tooptimize available solar energy on the other, it is useful to develop new efficient and flexiblemodes to control motors that entrain the pump. A vectorial control of an asynchronous motorfed by a photovoltaic system is proposed. This paper investigates a photovoltaic-electromechanic chain, composed of a PV generator, DC-AC converter, a vector controlledinduction motor and centrifugal pump. The PV generator is forced to operate at its maximumpower point by using an appropriate search algorithm integrated in the vector control. Theoptimization is realized without need to adding a DC-DC converter to the chain. The motorsupply is also ensured in all isolation conditions. Simulation results show the effectivenessand feasibility of such an approach. Results are presented based on MATLAB/SIMULINK.Keywords: Vector Control, Induction Motor, Solar Power, PV system, Water PumpingSystem.INTERNATIONAL JOURNAL OF ELECTRICALENGINEERING & TECHNOLOGY (IJEET)ISSN 0976 – 6545(Print)ISSN 0976 – 6553(Online)Volume 4, Issue 2, March – April (2013), pp. 450-458© IAEME: www.iaeme.com/ijeet.aspJournal Impact Factor (2013): 5.5028 (Calculated by GISI)www.jifactor.comIJEET© I A E M E
  • 2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME451I. INTRODUCTIONIn this paper, the authors present an indirect rotor field oriented control of aninduction motor (IM) associated to a water photovoltaic pumping system. The motor is usedto drive a centrifugal water pump. A modeling study was performed for the components ofthe proposed photovoltaic pumping system were established and used in the proposed controlscheme. An extensive simulation work was performed to extract the significant results. Toshow up the high system performances, presented results are discussed and prove how theproposed methodology is an efficient water photovoltaic pumping system control procedure.In the isolated sectors as the islands, the rural zones and the mountains, the use of therenewable energy such as wind energy [7-10], photovoltaic [11-13] and hybrid system [14-17] is a better solution to produce the needed electric energy for such applications as thepumping systems. The photovoltaic PV water pumping systems are usually composed of aPV generator, power(s) converter(s) and an electric motor which is usually coupled to acentrifugal pump load. Currently, for the power conditioning, the PV generator is followedby a DC-DC converter. Many types are used such as boost, buck and boost-buck converters.Different types of motors are used in the photovoltaic water pumping system. The DC motoris used in the photovoltaic water pumping system with different coupling mode [15], [17],[18]. The Permanent Magnet Synchronous Motors (PMSM) is also used with differentcontrol strategies [10], [19]. Some applications of the pumping system call for theasynchronous motor [15], [16]. Many techniques of control have been applied to inductionmotor as direct torque control (DTC) and field oriented control. The concept of field orientedcontrol (FOC) is firstly developed by Blasche. The FOC is a flux-torque decouplingtechnique applied to AC machines. Two approaches are possible: the direct field orientation(DFO) based on the rotor flux angle given by a flux observer or estimator and the indirectfield orientation (IFO) based on the rotor slip calculation. In this paper an indirect rotor fieldoriented control is synthesized for an induction motor (IM) associated to a water photovoltaicpumping system in order to produce the required load power. A synchronous boost converteris used in the control scheme to adapt the DC voltage required by the load when theinsulation or the load varies.The increasing of the world energy demand, due to the modern industrial society andpopulation growth, is motivating a lot of investments in alternative energy solutions, in orderto improve energy efficiency and power quality issues. The use of photovoltaic energy isconsidered to be a primary resource, because there are several countries located in tropicaland temperate regions, where the direct solar density may reach up to 1000 W/m. One of themost popular applications of the photovoltaic energy utilization is the water pumping systemdriven by electrical motors. The two main restrictions for using solar energy are the highinitial installation cost and the very low photovoltaic cell conversion efficiency. The cellconversion ranges vary from 12% of efficiency up to a maximum of 29% for very expensiveunits [7]. In spite of those facts, there has been a trend in price decreasing for modern powerelectronics systems and photovoltaic cells, indicating good promises for new installations.Moreover, the maximum power of a photovoltaic system changes with solar intensity, andtemperature; and dynamic loads influence the performance by changing continuously theoperating point. In order to amortize the initial investments, it is very important to optimizethe photovoltaic water pumping system, by the use of power electronics converters to adaptdynamically the electrical impedance to the PV generation for different operating conditions[2, 3]. Various studies have been carried out on optimizing, PV based systems and induction
  • 3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME452motor controls [1-20]. DC motors were initially used since they offered easy implementationwith cheap power conversion. A number of existing operational pumping systems haveshown that these schemes suffer from maintenance problems. To overcome this drawback,brushless permanent magnet motors have been proposed [18]. However, this solution islimited only for Low power PV systems. The induction motor based PV pumping systemoffers an Alternative for a more reliable and maintenance free system [19]. The motorcharacteristics are severely affected by the PVG which was considered as a current generatorwith dependent voltage source. For such applications, where the PV water pumping system isdriven by an AC motor (PMSM or IM), a chopper and/or an inverter should be included inorder to perform the DC-AC conversion stage. For PV water pumping systems, two types ofpumps are widely used, the volumetric pump and the centrifugal pump. It is found that thePVG energy utilized by the centrifugal pump is much higher than by the volumetric pump. Infact, in the case of the centrifugal pumps, the operation takes place for longer periods evenfor low insulation levels, and the load characteristic is in closer proximity to the PVGmaximum power locus. In PV water pumping systems, the maximum power point tracking(MPPT) is usually used as online control strategy to track the maximum output poweroperating point of the PVG for different operating conditions of insulation and temperature ofthe PVG. Different optimization strategies have been proposed to improve the overall systemefficiency .In this paper a vectoriel control method has been proposed to ensure theoptimization of the whole system showed in Fig. 1. Allowing the improvement of theefficiency maximization.Fig. 1. The proposed IM photovoltaic pumping system configurationII. PV SYSTEMThe PV system considered in this paper contains single PV array as shown in Fig.2(a).In this paper a PV model is considered from [1-20]. The modeling is attempted by (1),where, IPV, VPV are the PV array current and voltage respectively. Rsh and Rs are the intrinsicshunt and series resistances of the array, Isc is being the short circuit current of the array, G isthe solar irradiance (W/m2), 1910602.1 −×=q C being the electron charge, Boltzman’s constant23103806.1)( −×=K J/K, p-n junction’s ideality factor 2)( =A , T is array temperature (in 0K), I0 is
  • 4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME453diode reverse saturation current, Tr is cell reference temperature and Irr is reverse saturationcurrent at Tr. For the above PV model, the power-voltage characteristic of the model fordifferent irradiances is shown in Fig. 2(b).( )shsPVPVPVsPVphPVRRIVAKTVRIqIII×+−− +×−= 1exp0 (1)where [ ]1000)(GTTkII rscph −+= and−=TTAKqVTTIIrocrrr11exp30Fig. 2(a): PV systemPower(kW)Fig. 2(b): MPPT curves for different irradiances.Maximum power point tracker (MPPT)For best utilization, the PV cells must be operated at their maximum power point. Toachieve this, according to the perturb and observe (P&O) algorithm [7-8], MPPT adjusts theterminal voltage of PV panels to mppV whose value at an instant k, say, is related to theprevious instant by
  • 5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME454PVPVPVmppPVPVmppmppIVPMVdVdPMkVkV×===×+−=,01.0,0)0(with)(sign)1()((2)As shown in Fig. 1, since PV panels are directly connected to the dc bus, the dc-linkvoltage ( dcV ) equals to the output voltage of PV (VPV). Therefore, the voltage signal, mppV ,generated by P&O algorithm is, hence forth, treated as the reference dc-link voltage ( *dcV ).The direct conversion of the solar energy into electrical power is obtained by solarcells. A PV generation system is composed by many strings of solar cells in series, connectedin parallel, in order to provide the desired values of output voltage.III. PROPOSED WORKThe IM Photovoltaic pumping system modelThe proposed IM photovoltaic pumping system considered in this work is shown inFig. 1.typical model of proposed system is shown in Fig. 3(a). Photovoltaic based waterpumping system is one of the most common applications of distributed energy generationsystem. The three-phase inverter generates a variable frequency output waveform to drive theIM and the motor drives a centrifugal pump that delivers the water output.In general IM drive can be based on v/f control, indirect field oriented control (IFOC)and slip control. The IFOC and the slip control ensure the decoupling between the fluxcontrol and the torque control. Those control methods are necessary in order to ensure theconsumption of energy by the machine acting on the electromagnetic torque, Te. Severaltypes of pumps and motors are available on the PV pumping market. The most commonlyemployed pump type is the Centrifugal pump. Single-stage centrifugal pumps are frequentlyused in PV shallow water pumping for low head applications. For PV subterranean waterpumping and surface water pumping with higher heads, multistage centrifugal pumps aremore suitable. Other pump types such as progressive cavity pumps and piston pumps havealso been utilized. The centrifugal pump is characterized by its head-flow rate performancecurve at the nominal speed. The flow rate is directly proportional to the impeller speed, thehead is proportional to the square of the speed and the hydraulic power is proportional to thecube of the speed. The performance curves of the pump with good accuracy at high speedsbut they are not very accurate at low speeds and/or with constant head applications. For verylow speeds, the pressure produced by the pump is less than the static pressure and the rotationjust circulates the water within the pump. When the speed reaches a threshold or base value(ωt) , the pump starts delivering water and the rate of flow of water (Q, liter/min) varieslinearly with the speed (ω), as expressed in (1) obtained by curve fitting.Q = aω-b, ω ≥ ωt and Q = 0, ω < ωt Where, a and b are the constants.The control of induction motor is shown in Fig. 3(b).
  • 6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME455Fig. 3(a): Typical model of proposed systemFig. 3(b): overall proposed systemIV. RESULTSResults are presented based on individual performances of system components andthose are:Fig. 4 shows the response of dc-link voltage which is equals to the photovoltaic voltageand from Fig. 4, it is clear that stable dc link voltage is achieved by proposed controller.The replies in depicted dc voltage are mainly due to rapidly change in temperature andsolar irradiance. The dc voltage of PV system is almost stable at t=0.6sec. initially (at t=0)it is starting from open circuit voltage because of MPPT algorithm and boost converter.
  • 7. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME456The corresponding output of boost converter is presented in Fig. 5. From Fig. 5, due toboost controller, it mitigates the ripples in input voltage, i.e., solar panel voltage.From Figures 4 and 5, it proves that system is working in maximum power point levelwith constant voltage algorithm.Corresponding electromagnetic torque generated by motor and speed of induction motorare shown in Fig. 6 and Fig. 7 respectively.The motor speed and torques are reached their reference value, after settling dc-linkvoltage. And from Fig. 6 and 7, clearly observed that speed and torques are graduallyincreasing because of proper control algorithm implemented in proposed system. Andalso, noted that due to good and dynamical enhance of proposed system, almost ripples inboth speed and torque are zero.Fig. 4: Solar panel voltageFig. 5: boost converter output voltageFig. 6: electromagnetic torque of induction motor
  • 8. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME457V. CONCLUSIONSControl strategies to regulate the flow of water supply of a PV based water pumpingsystem through induction motor is presented in this paper. Hence, proposed system provides costeffective solution for PV based water pumping system for Agricultural sector. Moreover, for bestutilization of PV, MPPT is incorporated to system. The power balance between PV generationand load is achieved by maintaining dc link voltage at its reference value (Vmpp) and controllingthe speed of induction motor within permissible limits based on vector control. The proposedintegrated controller requires only measurements of dc link voltage and load current and no needto measure the power. Through the simulation results it is concluded that performance of thecontrollers is satisfactory under steady state as well as dynamic conditions.REFERENCES[1] A. Betka and A. Moussi. Performance optimization of a photovoltaic induction motorpumping system, Renewable Energy, No. 29, pp. 2167- 2181, 2004.[2] M. Arrouf and N. Bouguechal. Vector control of an induction motor fed by a photovoltaicgenerator, Applied Energy, No. 74, pp. 159–167, 2003.[3] J. R. Arribas and C. M. V. González. Optimal vector control of pumping and ventilationinduction motor drives, IEEE Transactions on Industrial Electronics, Vol. 49, pp. 889–895,Aug. 2002.[4] Bhat, S. R. Pittet, Andre Sonde, B. S. Performance Optimization of Induction Motor-Pump System Using Photovoltaic Energy Source, IEEE Transaction on IndustryApplications, Vol. 6, pp. 995-1000, Nov-1987.[5] Trishan Esram, Patrick L. Chapman. Comparison of Photovoltaic Array Maximum PowerPoint Tracking Techniques, IEEE Transactions on Energy Conversion, Vol. 22, No. 2, pp439-449, June 2007.[6] Dezso Sera, Remus Teodorescu, Jochen Hantschel, and Michael Knoll. OptimizedMaximum Power Point Tracker for Fast-Changing Environmental Conditions, IEEETransactions on Industrial Electronics, Vol. 55, No. 7, pp. 2629-2631, July 2008.[7] Simoes, M. G.franceschetti, N. N. : Arisc-Microcontroller Based Photovoltaic System forIllumination Applications, Proceeding of IEEE Applied Power Electronics Conference andExposition 15 (2000).[8] Akbaba, M.akbaba, M. C.: Dynamic Performance of a Photovoltaic Boost ConverterPowered DC Motors-Pump System, In: Proceeding of IEEE International Conference,IEMDC99, 16, 1999.[9] Matsui, M.kitano, T.xu, D.yang, Z.: A New Maximum Photovoltaic Power TrackingControl Scheme Based on Power Equilibrium at DC Link, Proceeding of IEEE IndustryApplications Conference, 1999.[10] Shrertha, G. goel, L. : A Study on Optimal Sizing of Stand Alone Photovoltaic Stations,IEEE Trans Energ Conv 13 No. 4 (1998), 373-377.[11] Samin, J. et al : Optimal Sizing of Photovoltaic in Varied Climates, Solar Energy 6 No. 2(1997), 97–107.[12] Akbaba, M. et al : Matching of Separately Excited DC Motor to Photovoltaic Generatorsfor Maximum Power Output, Solar Energy 63 No. 6 (1998), 375–385.[13] Said, M. M. : Matching of DC Motor to Photovoltaic Generators for Maximum Daily GrossMechanical Energy, IEEE Trans Energ Conv 3 No. 3 (1988), 465–471.[14] Weiner, D.levinson, A. : Water Pumping Optimal Operation, Elect Mach Power Syst 24No. 3 (1996), 277–288.
  • 9. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 2, March – April (2013), © IAEME458[15] Appelbaum, J. : Starting and Steady State Characteristics of DC Motor Powered by SolarCell Generator, IEEE Trans Energy Conv 1 No. 1 (1986), 17–25.[16] Appelbaum, J.Sarme, M. S. The Operation of Permanent Magnet DC Motor Powered byCommon Source of Solar Cells, IEEE Trans Energy Conv 4 No. 4 (1989), 635–642.[17] Swamy, C. L. P. et al : Dynamic Performance of a Permanent Magnet DC Motor Powered bya PV Array for Water Pumping, Solar Energy Mat Solar Cell 36 (995), 187–200.[18] Baht, S. R. et al : Performance Optimisation of InductionMotor-Pump using PhotovoltaicEnergy Source, IEEE Trans IndApp 23 No. 6 (1987), 995–1000.[19] Chenni, R.makhlouf, M. et al : Detailed Modelling Method for Photovoltaic Cell, Energy32 (2007), 1724–1730.[20] Yao, Y.bustamente, P.ramshaw, R. S. : Improvement of induction Motor Drive SystemsSupplied by Photovoltaic Arrays with Frequency Control, IEEE Trans Energ Conv 9 No. 2(1994).[21] Prof. Hemant chouhan, Ritesh Kumawat and Dr. H. K. Verma, “Comparative Analysis ofScalar and Vector Control Induction Machine Drive Through Modeling and Simulation”,International Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 2,2012, pp. 39 - 50, ISSN Print : 0976-6545, ISSN Online: 0976-6553.[22] Pradeep B Jyoti, J.Amarnath and D.Subbarayudu, “The Scheme of Three-Level InvertersBased on Svpwm Overmodulation Technique for Vector Controlled Induction MotorDrives”, International Journal of Electrical Engineering & Technology (IJEET), Volume 4,Issue 2, 2013, pp. 245 - 260, ISSN Print : 0976-6545, ISSN Online: 0976-6553.[23] Sofia Lalouni and Djamila Rekioua, “Control of Photovoltaic Water Pumping System withBattery Storage”, International Journal of Electrical Engineering & Technology (IJEET),Volume 4, Issue 1, 2013, pp. 190 - 199, ISSN Print : 0976-6545, ISSN Online: 0976-6553.AUTHORS’ DETAILCh. Venkateswara Rao receieved his M.Tech degree from JNTUK, kakinadaand U.G from IE (India, Kolkata) in the year 1993. A life member inISTE.&IAENG. This Author won first prize in Energy conservations Award forthe year 2009. He is currently working as a professor in the department of EEE,Gandhi Institute of Engineering and Technology, Gunupur, Odisha. He guidedmany UG & PG Projects. He is having overall Industrial & Teaching experience of18 years. His major Research interests are energy conservations and Smart Grids.S S Tulsiram working as a Professor in the Department of EEE in JNTUH,Hyd. He has 30 years of Teaching experience. He is former Head of thedepartment of EEE, JNTUCE, Kakinada. The Author has Published many papersin International & National Journals/ Conferences. His research interests are PowerSystems, High Voltage Engineering & smart grid technology.B Brahmaiah working as a principal in Priyadharsini institute of techonology,Tirupati. He has 30 years of Teaching experience .He worked as Head of thedepartment, EEE & Dean (R&D) in reputed Engineering colleges. Author hasPublished many papers in International & National Journals/ Conferences. Hisresearch areas are Electrical machines, Power Electronics &Electric Drives.