MAXIMUM POWER POINT TRACKING OF PV IN HYBRID SYSTEM FOR SAVING FUEL OF FUEL CELL

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 10, October 2018, pp , Article ID: IJMET_09_10_052 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed MAXIMUM POWER POINT TRACKING OF PV IN HYBRID SYSTEM FOR SAVING FUEL OF FUEL CELL Soedibyo, Feby Agung Pamuji, Sjamsjul Anam and Mochamad Ashari Dept.of Electrical Engineering, Institut Teknologi Sepuluh Nopember *Corresponding Author Nurvita Arumsari Dept.of Marine Engineering, Politeknik Perkapalan Negeri Surabaya Surabaya, Indonesia ABSTRACT In this paper, a new control method based on fuzzy logic controller is proposed to control the maximum power point tracking of photovoltaic system (PV) in a hybrid photovoltaic/ fuel cell (FC) system. The purpose of the maximum power point tracking controller is to shift the actual voltage of PV to the optimum voltage. In the hybrid system, the FC is running in normal condition, that is the voltage of FC is not shifted by converter, the voltage of FC is just influenced by demand. When PV produces the maximum power, the fuel consumption can decrease. The proposed method maximizes the PV power by shifting the voltage to the optimum voltage of PV with considering the voltage of FC, because the voltage of PV must be same with the voltage of FC in order the PV can transfer the power to the demand well, that can not be done using P & O method because P & O method does not consider the voltage of FC. The configuration of PV and FC in hybrid system is in parallel, If the voltage of FC is higher than the voltage of PV, The PV can not transfer the power well to the demand, if the voltage of PV is higher than the voltage of FC, the FC can not transfer well to the demand. From the simulation, we can see that the power of hybrid system with proposed method is in the maximum power comparing with P & O method and hybrid system with proposed method can save average % of fuel and % of Air comparing with using P & O method. Keywords: Photovoltaic, Fuel Cell, Maximum Power Point Tracking. Cite this Article: Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari, Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell, International Journal of Mechanical Engineering and Technology, 9(10), 2018, pp

2 Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell 1. INTRODUCTION In this century, as there are still many areas that have not been supplied electricity in rural areas in Indonesia, the government takes the initiative to build power plants in such areas. In rural areas that are difficult to reach the grid, the government builds many renewable energy plants such as microhydro stations and photovoltaic systems (PV). However, due to limited funding and difficulties in terms of transportation, many renewable energy plants are built using low voltage distribution networks. The hybrid PV/fuel cell (FC) is the solution to fulfill the demand in rural areas, however, the problem is the FC needs H2 and O2 to produce the power. As it is difficult to distribute H2 and O2 to rural areas, we must optimize the power of PV and save H2 and O2. Hassan Fathabadi, et al, proposed to use, two maximum power point tracking (MPPT) units in a hybrid PV/FC systems, one for the PV subsystem and the other for the FC stack. However, the system is significantly complicated for the implementation, and increases the cost[6]. In this paper is proposed the method to maximize the power of PV and to save fuel and air consumption of FC. The controller is based on fuzzy logic controller. It consists four inputs and one outputs, that is, the inputs are delta voltage of PV between the actual voltage and optimum voltage,irradiance of sun light, cell temperature of PV and delta voltage between the voltage of FC and PV, the output is duty cycle of converter. The hybrid PV/ FC system in this research is for maximazing the power of the PV and the FC works in normal condition, that is the voltage of FC is not shifted by converter, the voltage of FC is just influenced by demand. this configuration of hybrid system PV/FC can save fuel and air of fuel cell. 2. HYBRID PV/FC STAND-ALONE SYSTEM The configuration of hybrid PV/FC system in this paper is shown in Fig. 1. The output power of PV is maximized by the proposed MPPT controller and the power of FC is in normal condition, that is the voltage of FC is not shifted by converter, the voltage of FC is just influenced by demand. The configuration of PV/FC consists of the PV that is connected to buck boost converter and the ouput of buck boost converter is in parallel with output of FC, the ouput of hybrid PV/FC system is connected to inverter, the output of inverter is connected to 3 phase 380 V AC load. The buck boost converter is stepping up or stepping down the voltage of PV in order to the voltage of PV is in optimum condition and same with the voltage of FC. The inverter converts the DC voltage to the 3 phase 380 V AC. VFC Photovoltaic 1/Z E(Irradiance) Tc(Cell Temperature ) - + Delta Voltage PV Fuzzy Logic Controller PWM + - VPV Vpv(Actual Voltage) AC Bus Buck-Boost Converter Inverter Fuel Cell Stack Load Figure 1 Hybrid PV/WT System

3 Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari Fuzzy Logic controls the buck-boost DC/DC converter to obtain the maximum power by shifting the PV voltage to the optimum voltage. When PV produces the maximum power, it will decrease the fuel and air consumption of FC for the same demand. The fuzzy logic controller has 4 inputs. Those inputs are the irradiance and cell temperature indicating the characteristic of PV, delta voltage of PV shifting to optimum condition and delta voltage of FC/PV indicating the voltage difference between FC and PV. Because the controller must control the voltage of PV to approach the voltage of FC in order to transfer the power to the load well, because PV and FC are in parallel configuration Photovoltaic System The current voltage (I V) characteristic of a solar cell is given by Eq. (1). { [ ( ) ] } ( ) (1) where V_PV and I_PV represent the output voltage and current of PV, R_s dan R_sh are the series and shunt resistance of the cell; q is the electron charge (1.6e^(-19) C); I_SC is the light-generated current; I_o is the reverse saturation current; A is a dimensionless junction material factor; k is the Boltzmann constant (1.3e^(-23) J/K); T is the temperature (K); n_p and n_s are the number of cells connected in parallel and in series. The characteristic of PV as shown in Fig. 2 is shown in Fig.2. Figure 2 Characteristic of Photovoltaic From Fig. 2, it can be seen the curves have the maximum power point. The voltage at this point is called the optimum voltage. We need the converter to shift from the actual voltage to the optimum voltage to get the maximum power from PV. The specification of PV is listed in Table I. PV type is monocrystalline sillicon. Table 1 Specifications of photovoltaic Parameters Rating values Module type Sunpower SPR-305-WHT Number per cell per module 96 Power 50 kw Voltage at maximum condition VDC 2.2. Fuel Cell Stack System Fuel cell (FC) stack is an electrochemical device which converts between hydrogen and oxygen into electricity by chemical reaction [2]. The characteristic of FC stack is shown in Fig

4 Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell Figure 3 The characteristic of Fuel Cell Stack. From Fig.3, we can see that the voltage and power are changing, when the load of FC is changing. We can maximize the power of FC by shitfting the voltage of FC from the actual voltage to the optimum voltage. The specification of FC stack is listed in Table II, The type of FC stack is polymer electrolyte membrane. Table 2 Specifications of FC stack Parameters Type Nominal stack power VDC Rating values PEMFC 50 kw 625 Volt 2.3. Buck-boost DC/ DC Converter The Buck Boost converter is a converter that can step up or step down the DC voltage. The switching mode can be seen in Fig

5 Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari Vs L C Vo Circuit Vs L C Vo Equivalent circuit for the switch closed Vs L C Vo Equivalent circuit for the switch open Figure 4 Buck Boost converter In Fig.4, when the switch is closed, the inductor is charged by voltage source and the capacitor is discharging to fulfill the load. when the switch is open the inductor is discharging to fulfill the load and charge the capacitor. The equation for stepping up and stepping down is equation (2). From the equation 2, that can be explained that the buck boost converter has two area of duty cycle, the amount of duty cycle 0 to 0.5 is for stepping down the DC voltage and 0.5 to 1 is for stepping up the DC voltage. 3. CONTROL OF MAXIMUM POWER POINT TRACKING The hybrid system PV/FC is controlled by Fuzzy logic control, To design the fuzzy logic control for MPPT controller, we must decide the parameters of fuzzy logic controller. To control the Buck-Boost DC/DC converter, delta voltage of PV, which is the difference between the actual voltage and the optimum voltage of PV, should be one of the parameters to know the condition of input and output of the converter. Temperature of cell and irradiance should also be parameters of controller, because irradiance influences the energy produced by PV and the temperature of cell influences the efficiency of PV. The Delta voltage between FC and PV is used to indicate the defference between the voltage of FC and PV, because the controller must shift the voltage of PV to approach the voltage of FC in order that the PV can transfer the power to load well. The proposed MPPT control is to maximize the PV power with considering the voltage of FC, because the PV and FC are in parallel configuration. The controller shifts th evoltage of PV to the optimum power, based on delta voltage of PV and the difference voltage of FC and

6 Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell PV, and the FC works in normal condition, that is the voltage of FC is not shifted by converter, the voltage of FC is just influenced by demand. Power VPV = VFC Characteristic of FC Characteristic of PV Power of FC Optimum Power of PV Pmax V Voltage VPV = VFC Figure 5 The proposed maximum power point method From Fig. 5, The proposed method MPPT control shifts the voltage of PV based delta voltage of PV to the optimum voltage with considering the voltage of FC. The proposed method control shifts until the voltage of PV is same with the voltage of FC, because in the configuration of hybrid system PV/FC, the PV and FC is in Parralel configuration. The equivalent circuit of hybrid system is shown in Fig. 6. Ipv Ifc Vo VPV VFC Figure 6 Equivalent circuit of hybrid system PV/FC From Fig. 6., the hybrid system PV/FC is in Parralel configuration. if the voltage of FC is higher than the voltage of PV, the PV can not transfer the power well to the load. If voltage of PV is higher than the voltage of FC, the FC can not transfer well the power to the load. In this configuration, the controller must make the voltage of PV is same with the voltage of FC in order that the PV and FC can transfer well to the load. Fuzzy logic controller that controls the maximum power point of PV is shown in Fig

7 Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari Delta Voltage_ PV TC MPPT_PV Duty Cycle Ir Delta Voltage_ PV/FC Figure 7 Fuzzy Logic Controller of Photovoltaic Fuzzy logic controller has duty to provide the output amount of duty cycle which is suitable for multi-input DC/DC converter. That the duty cycle of the converter can shift the actual voltage to the optimum voltage of PV. Membership functions of fuzzy logic controller are shown in Fig Small Large 0, Volt Figure 8 Membership Function of Delta Voltage PV Delta voltage of PV is the difference of the optimum voltage and the actual voltage. The range of membership function is decided from the characteristic of PV. The largest range of delta voltage is 560 volt. For shifting the voltage of PV, there are two membership functions. Membership function small is from 0 volt to 10 volt, which indicates the voltage of PV approaches the optimum voltage. Membership function large is between 5 volt and 560 volt, which indicates the voltage of PV is far from the optimum voltage. Then, the controller must give the high duty cycle to shift the voltage to the optimum voltage

8 Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell 1 Cold Warm Hot 0, Figure 9 Membership Function of Cell Temperature Cell temperature affects the efficiency of PV power. The membership function for warm is between o C, the membership function for cold is between 0 20 o C, and the membership function for hot is between o C. The cell temperature is always influenced by air temperature. 1 dark cloudy sunny 0,5 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 Figure 10 Membership Function of Sun Light Irradiance When irradiance is between kw/m2, PV can produce much power. We use two more membership functions, that is, irradiance between kw/m2 and irradiance between kw/m2. 1 Small1 Large1 0, Volt Figure 11 Delta Voltage of FC voltage and PV voltage The delta voltage of FC voltage and PV voltage indicates the defference voltage between the voltage of FC and PV. The controller must shift the voltage of PV to approach the voltage of FC in order that PV can transfer the power to load well, there are two membership function, small1 is indicating that the voltage of PV close to the voltage of FC and large1 is indicating that the voltage of PV is far from the voltage of FC

9 Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari 1 Low High 0,5 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 Figure 12 Membership Function of output Duty Cycle Figure. 12 shows the membership function for the output of controller, Each membership function assigns the duty cycle of the converter to shift the actual voltage to the optimum voltage. We divide two membership functions, membership function low is between that indicates the voltage of PV is approaching the optimum voltage, The membership function high is between that indicates the voltage of PV is far from the optimum voltage. The ouput of fuzzy logic control is decide by the rule. if the delta voltage of PV in large membership fuction and the delta voltage of PV and FC in large1 membership function, the output duty cycle in membership function high. if the delta voltage of PV in small membership function and the delta voltage of PV and FC in small1 membership function, the output duty cycle in membership function low. if the delta voltage of PV in small membership function and the delta voltage of PV and FC in large1 membership function, the output duty cycle in membership function high. if the delta voltage of PV in large membership function and the delta voltage of PV and FC in small1 membership function, the output duty cycle in membership function low. The membership function of cell temperature and irradiance is decided by following this rule. 4. SIMULATION OF HYBRID PV/ FC STAND-ALONE SYSTEM Hybrid PV/FC stand-alone system simulation is done by changing irradiance for PV, At the beginning, the irradiance is 0.9 kw/m 2. The irradiance changes to 1 kw/m 2 at 0.1s, the irradiance changes to 0.8 kw/m 2 at 0.2s, the irradiance changes to 0.9 kw/m 2 at 0.3s, the irradiance changes to 0.7 kw/m 2 at 0.4s, the irradiance changes to 0.7 kw/m 2 at 0.4s, the irradiance changes to 0.9 kw/m 2 at 0.5s, the irradiance changes to 0.9 kw/m 2 at 0.6s, the irradiance changes to 1 kw/m 2 at 0.7s, the irradiance changes to 0.8 kw/m 2 at 0.9s, the irradiance changes to 0.9 kw/m 2 at 1s, the irradiance changes to 0.7 kw/m 2 at 1.1s and returns to 0.9 kw/m 2 at 1.2s. In this simulation model, the controller just maximizes the power of PV in order to reduce the fuel and air of FC. The result of simulation is shown in Fig 13, comparing with the result with P & O method

10 Proposed method P & O Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell Power (kwatt) OUTPUT POWER OF HYBRID SYSTEM WITH MPPT CONTROLLER(PROPOSED METHOD) Power (kwatt) OUTPUT POWER OF HYBRID SYSTEM WITH MPPT CONTROLLER(P & O METHOD) Time (second) Time (second) Figure 13 Power of PV From the Fig. 13, we can see that the power of hybrid PV/ FC with MPPT controller proposed method is optimum power in 120 kw load. On the other hand, the power of hybrid system PV/ FC with P & O method can reach the optimum power in 0.4 second after that is not in optimum condition because P & O always perturbs the voltage of PV. The voltage of PV and the voltage of FC must be same in order to the PV can transfer well to the load. The MPPT controller proposed method can shift the actual voltage of PV to the optimum voltage with considering the voltage of FC, so the power of hybrid system PV/ FC with MPPT controller proposed method at the optimum condition. fuel air fuel air Load 80 kw Load 90 kw Load 110 kw Load 120 kw lpm Figure 14 Air and Fuel of Fuel Cell Stack. From Fig. 14, we can see that the consumption of fuel and air of FC in hybrid system. The proposed MPPT controller decreases % of fuel and % of air in average comparing with P & O method. The P & O method can not transfer the power well to the load because the P & O always pertubs the voltage of PV without considering the voltage of FC

11 Soedibyo, Feby Agung Pamuji, Sjamsjul Anam, Mochamad Ashari and Nurvita Arumsari 5. CONCLUSION The proposed MPPT controller can control the hybrid PV/FC stand-alone system to maximize the power of PV. As the controller shifts the actual voltage of PV to the optimum voltage with considering the voltage of FC, PV can produce the optimum power and save the fuel and air of FC comparing PV with P & O Method. The hybrid PV/FC can save % of fuel and % of air in average comparing with using P & O method. This method is useful, because it is difficult to distribute the fuel of FC to rural area, if we use the hybrid PV/ FC stand-alone system in rural area, PV/FC hybrid system is easily introduced to rural areas by using the proposed control system. REFERENCES [1] Feby Agung Pamuji, Hajime Miyauchi, Maximum Power Point Tracking of Multi-input Inverter for connected Hybrid PV/Wind Power System Considering Voltage Limitation in Grid, International Review on Modelling and Simulations (I.REMOS), Vol.11, No.3, [2] Mourad Tiar, Achour Betka, Said Drid, Sabrina Abdeddaim, Mohamed Becherif, Abdulkader Tabandjat, Optimal energy control of a PV-fuel cell hybrid system,elsevier, [3] Soedibyo, Feby Agung Pamuji and Mochamad Ashari, Grid Quality Hybrid Power System Control of Microhydro, Wind Turbine and Fuel Cell Using Fuzzy Logic, International Review on Modelling and Simulations (I.RE.MO.S), Vol 6, No 4, Agust 2013, pp , Indexed in Scopus, ISSN : / e-issn : X. [4] Chih-Ming Hong, Chiung-Hsing Chen, Intelligent control of a grid-connected windphotovoltaic hybrid power Systems, Elsevier, [5] Y.-M. Chen, S.-C Hung, C.-S. Cheng, and Y.-C. Liu, Multi Input Inverter For Grid Connected Hybrid PV/Wind Power System, IEEE, [6] Hassan Fathabadi, Novel Fast and High accuracy Maximum Power Point Tracking method for hybrid photovoltaic/ Fuel Cell energy Conversion System, Elsevier, [7] Yaow Ming chen, Yuan chuan Liu, Shih Chieh Hung, and Chung sheng Cheng, Multi Input Inverter for Grid - Connected Hybrid PV/Wind Power System, IEEE TRANSACTION ON POWER ELECTRONICS, VOL.22, NO.3, MAY [8] N. E. Mitrakis, J. B. Theocharis and V. Petridis, A Multilayered Neuro Fuzzy Classifier with Self Organizing Properties, Sience Direct, [9] Abdelkrim menadi, Sabrina Abdeddaim, Ahmed Ghamri, and Achour Betka, Implementation of Fuzzy Slidding Mode Based Control of a Grid Connected Photovoltaic System, Elsevier, [10] N. F. Guerrero Rodriguez and Alexis B. Rey Boue, Adaptive Frequency Resonant Harmonic Compesator Structure For a 3 Phase Grid Connected Photovoltaic System, Elsevier, [11] Hussain Shareef, Ammar Hussein mutlag and Azah Mohamed, A Novel Approach For Fuzzy Logic PV Inverter Controller Optimization Using Lightning Search Algorithm, Elsevier, [12] Chih Ming Hong and Chiung Hsing Chen, Intelligent Control of a Grid Connected Wind Photovoltaic Hybrid Power Systems, Elsevier, [13] Nabil A. Ahmed, Masafumi Miyatake, A. K. Al Othman, Power Fluctuations suppression of stand alone Hybrid Generation Combining Solar Photovoltaic/ Wind Turbine and Fuel Cell Systems, Elsevier, [14] Nicu Bizon, Mihai Oproescu and Mircea Raceanu, Efficient Energy Control Strategies For a Standalone Renewable / Fuel Cell Hybrid Power Source, Elsevier,

12 Maximum Power Point Tracking of Pv in Hybrid System for Saving Fuel of Fuel Cell [15] Daniel W Hart, Power Electronics, McGraw Hill, [16] Mohammad Kalimullah, Power Loss Comparison of Single and Two Stage Grid Connected Photovoltaic Systems Connected With Microgrid: International Journal of Electrical Engineering & Technology, 9(4), 2018, pp [17] R. Senthil, S. Araavind and Nilanshu Ghosh, Optimization Techniques for Solar Photovoltaic-Wind Turbine Hybrid Energy Systems, International Journal of Mechanical Engineering and Technology 9(1), pp