Conventional energy resources are being replaced by Renewable energy sources mainly due to increasing environmental concerns. Photovoltaic (PV) and Fuel cell (FC) are suitable to be used in modern DC microgrids due to their DC output. In this research work, a DC microgrid structure is proposed for small residential areas using hybrid PV and FC generation. Power Electronic converters are used to regulate generated voltage of the two sources for integration to a common DC bus. Proposed system is simulated using MATLAB SIMULINK to observe its performance. Simulation results show that output voltage is properly maintained at different DC

1. International Journal of Modern Research in Engineering & Management (IJMREM)
||Volume|| 1||Issue|| 6 ||Pages|| 09-14 || June 2018|| ISSN: 2581-4540
www.ijmrem.com IJMREM Page 9
Performance Analysis of DC Micro Grid with PV-Fuel Cell
Hybrid Generation
1,
Noor – ul -Ain, 2,
Shafi M. Jiskani, 3,
Dr. Anwar A. Sahito
1,
Student M.E. (Electrical Power) IICT, Mehran UET Jamshoro;
2,
Assistant Prof. Electrical Engg. Mehran UET, Jamshoro
3,
Associate Professor, Electrical Engg., Mehran UET, Jamshoro
------------------------------------------------------ABSTRACT----------------------------------------------------
Conventional energy resources are being replaced by Renewable energy sources mainly due to increasing
environmental concerns. Photovoltaic (PV) and Fuel cell (FC) are suitable to be used in modern DC microgrids
due to their DC output. In this research work, a DC microgrid structure is proposed for small residential areas
using hybrid PV and FC generation. Power Electronic converters are used to regulate generated voltage of the
two sources for integration to a common DC bus. Proposed system is simulated using MATLAB SIMULINK to
observe its performance. Simulation results show that output voltage is properly maintained at different DC buses
of the microgrid. FC is suitable to cope up the variation in PV output and maintain load requirements.
INDEX TERMS: DC microgrid, DC-DC Converters, Renewable Energy interconnection
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Date of Submission: Date, 30 May 2018 Date of Accepted: 04 June 2018
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I. INTRODUCTION
Renewable energy sources like solar, wind, fuel cells are increasing rapidly as electricity generation source around
the world. Renewable energy resources being eco-friendly are being promoted by various world health and
environment organizations. On the other hand, renewables also provide diversity in generation resources.
Availability and almost zero fuel cost makes renewables the only choice for power generation [1]. Solar
Photovoltaic (PV) cells are considered as most commonly used renewable energy source. It offers simple
installation and low cost for small power applications. PV power generation is dependent upon weather condition
and solar irradiance therefore nonlinear PV output needs to be controlled to be supplied to loads [2]. Fuel Cell
(FC) is electrochemical device which produce electric current through chemical reaction of hydrogen and oxygen
using electrolyte. Like PV they are intermittent source of generation, because of fast load response, modularity
and high efficiency. Unlike battery they are not rechargeable. Fuel for FC is hydrogen and other hydrogen
containing compounds, which on reprocessing produce hydrogen [3].
Because of intermittent nature of many renewable energy sources (solar, wind etc) hybrid combination of two or
more renewable source along with alternative energy sources and storage can improve system performance. These
hybridized systems also called micro grids. These microgrids may work independently as isolated systems and
may be connected with larger grid to supply loads located at different locations [4]. Nonlinear PV output is
overcome by integrating another renewable source like Wind, Storage (i.e battery) and Fuel Cell that ensure
uninterruptible high-quality power to load and also a maximum Power Tracking Point (MPPT) controller has been
associated with each PV generator in order to obtain an optimal power output under changing climatic condition
[5]. A Suitable control strategy is required to maintain balanced power and voltages at different buses in hybrid
generation fed microgrids. [6] proposed neural network-based controllers for controlling output of hybrid
generation and storage used in grid connected microgrid. Additionally, local controllers are used to regulate output
of the power electronic converters. [7] proposed reactive power compensation for grid connected hybrid PV and
FC generation. Voltage source converter guarantees the maximum utilization of PV array the optimal use of FC.
[8] proposed a hybrid energy system with wind turbine, PV and Fuel Cell to supply standalone loads. They used
three individual boost converters to control power flow to load. DC-DC converter is simple and cost-effective
method for maximum power tracking from wind and PV system. [9] employed the information gap decision gap
theory (IGDT) technique to model the uncertainty of electrical load. The uncertainty modeling o load enables
operator to make decision to optimize the systems operation against possible changes in load.
In this research work, a PV and FC based hybrid generation system is proposed. Output of the two generations
are regulated using DC-DC converters to integrate at a common DC bus of an isolated DC microgrid. Proposed
DC microgrid is suitable for rural electrification in Asian countries.

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II. SYSTEM DESCRIPTION
Proposed system consists of hybrid generation using PV and FC. Block diagram of the system is shown in Fig. 1.
Outputs of the generation resources are regulated through DC-DC boost converters and connected to a common
DC bus of 100V. Heavy load is connected to this common bus. A section of distribution line is added before
another 100V DC bus. Another load is connected to that bus. For the loads operating at 12V, 100V DC voltage is
stepped down to 12V using DC-DC Buck converter. Small loads are connected to this bus.
Fig: 1 Block diagram of DC Micro grid with hybrid PV-FC generation
III. RESEARCH METHODOLOGY
Microgrid system is developed in MATLAB/Simulink@
2017(b) as shown in Fig: 2. Simulation of microgrid is
performed to analyze performance of the proposed microgrid. PV model was developed in matlab/Simulink while
developing a hybrid power generating system. Input parameters of PV are temperature and irradiance and model
generate output voltage and output current of PV module according to these input parameters. According to
Standard Test Condition (STC) normal temperature is 25o
C and PV normal irradiance per square meter is
1000W/m2
. FC is used for simulation analysis SOFC type having power rating of 5KW. The operating temperature
of SOFC is 650o
C-1000o
C and the electrical efficiency is 55-60%. Their durability is about 4x104
hour. Mostly
used for large scale power generation of about 50MW. Constant parameters of SOFC are used as inputs in
proposed model and output voltage, current and power of model are determined.
As the output of PV is variable in terms of voltage and current hence DC-DC Boost converter is used at the output
terminals of PV to increase its voltage to 100V. Boost converter performs function of voltage regulator. Also,
voltage is increased to desired level for utilization of heavy loads and better transfer of power over distribution
line reducing its voltage drop and power losses. Output of DC is also stepped up to 100V using another Boost
converter so that both outputs are connected to one common bus.
Further another DC bus 2 is taken out from bus 1 (100V) with line resistance R to supply a 4kw/100V load. For
low voltage applications at the DC bus 3, the voltages of DC bus 2 are step down by a dc-dc buck converter.
Resistive line model is used to represent a section of the distribution line between two 100V DC buses. Buck
converter model is connected between buses 2 and 3 to step down DC voltage to 12V to be utilized by consumer
appliances. DC-DC converters are controlled though PI controllers. Block diagram for the control scheme
implementation for Boost converter is shown in Fig. 3. The error signal between output voltage and reference
voltage is proceed through PI controller so to control PWM pulse is generated. Thus, generating a pulse sequence
with appropriate duty ratios. Similarly, Buck converter and its implemented control strategy is shown in Fig. 4.
An appropriate response of controller is required because of the nonlinear behavior of Buck converter.

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Fig. 2: Proposed DC micro grid with hybrid Fuel Cell (FC) and PV power generation system
Fig. 3: Boost converter with control loop
Fig. 4: Buck converter with its control loop

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In order to operate the proposed hybrid PV-FC system following conditions are required
[1] The system should transfer energy from dc link to load with controlled output power without injecting any
harmonic current.
[2] A DC power is supplied to load even though output of PV is changed or FC stop/start supplying to load.
[3] The control strategy employed must take care different time constants of PV and FC.
The controlled dc output power of PV is given as:
𝑃𝑃𝑉 = 𝐼 𝑃𝑉 𝑉𝑃𝑉 (1)
𝑃𝑃𝑉 = 𝐼 𝑃𝑉 𝑉𝑃𝑉 (1 − 𝐷 𝑃𝑉) (2)
Where 𝐼 𝑃𝑉 𝑎𝑛𝑑 𝑉𝑃𝑉 are respectively current and voltage of PV array and 𝐷 𝑃𝑉 is the duty ratio of the Boost
converter connected to PV array.
Similarly, controlled output of the FC is given in Eq. (3)
𝑃𝐹𝐶 = 𝐼 𝐹𝐶 𝑉𝐹𝐶 (1 − 𝐷 𝐹𝐶) (3)
𝐼 𝐹𝐶 𝑎𝑛𝑑 𝑉𝐹𝑐 are respectively current and voltage of FC stack and 𝐷 𝐹𝐶 is the duty ratio of the Boost converter
connected to output of FC stack. Any deficit of power supplied to load by PV will be fulfilled by FC stack through
control of duty cycle of FC.
IV. RESULTS AND DISCUSSIONS
In this paper performance of DC micro grid with hybrid PV-FC generation system under normal steady state
operation is analyzed. Proposed system with its individual controllers is simulated using Matlab/Simulink. Fig. 5
shows waveform for PV voltage and current and stepped down voltage and current. Output voltage of PV is 48V
and current of 167A. Voltage and current after Boost converter are 100V and 80A. Fig. 6 shows current and
voltage of the FC generation along with the voltage and current after Boost converter. The output voltage of FC
is 48V and current of 104A. Whereas after Boost converter voltage is 100V and current is 50A.
Fig. 5: Waveforms (a) output voltage of PV b) output current of PV (c) PV boost voltage (d) PV boost
current
Fig. 6: Waveforms (a) output voltage of PV b) output current of PV (c) PV boost voltage (d) PV boost
current

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Fig. 7 shows voltage, current and power at bus 1 where outputs of PV and DC are combined. Similarly Fig.8
shows current. Voltage and power at 100V Bus 2. Step down Buck converter is connected between Buses 2 and
3. Current, voltage and power at Bus 3 are shown in Fig. 9.
Fig. 7: (a) current (b) voltage (c) Power ay Bus 1
Fig. 8: (a) current (b) voltage (c) Power ay Bus 2
Fig. 9: (a) current (b) voltage (c) Power ay Bus 3

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V. CONCLUSIONS
DC microgrid is an efficient and economical power supply system for small area. Isolated microgrid is a suitable
operation for rural electrification. Renewable energy based microgrid is economical and reduce carbon emissions.
Hybrid combination of generation will increase reliability of the microgrid.
In this paper, PV-FC hybrid generation-based DC microgrid is analyzed through simulation using
MATLAB/Simulink@ 2017(b). Steady state analysis shows that voltage at different buses is maintained to rated
voltage through DC-DC converters controlled through PI controllers.
VI. ACKNOWLEDGEMNTS
Authors are thankful to Mehran University of Engineering & Technology Jamshoro for providing necessary
resources for carrying this research work.
REFERENCES
[1] Bayrak, G., & Cebeci, M. (2014). “Grid connected fuel cell and PV hybrid power generating system
design with Matlab Simulink”. International journal of hydrogen energy, 39(16), 8803-8812.
[2] Singh, G. K. (2013). “Solar power generation by PV (photovoltaic) technology: A review”. Energy, 53,
1-13.
[3] El-Shatter, T. F., Eskandar, M. N., & El-Hagry, M. T. (2002). “Hybrid PV/fuel cell system design and
simulation.” Renewable Energy, 27(3), 479-485.
[4] Nehrir, M. H., Wang, C., Strunz, K., Aki, H., Ramakumar, R., Bing, J. & Salameh, Z. (2011). “A review
of hybrid renewable/alternative energy systems for electric power generation: Configurations, control,
and applications.” IEEE transactions on sustainable energy, 2(4), 392-403.
[5] Ou, T. C., & Hong, C. M. (2014). “Dynamic operation and control of microgrid hybrid power
systems.” Energy, 66, 314-323.
[6] Chettibi, N., & Mellit, A. (2018). “Intelligent control strategy for a grid connected PV/SOFC/BESS
energy generation system.” Energy, 147, 239-262.
[7] Tejwani, V., & Suthar, B. (2017). “Power management in fuel cell based hybrid systems.” International
Journal of Hydrogen Energy, 42(22), 14980-14989.
[8] Ahmed, N. A., Miyatake, M., & Al-Othman, A. K. (2008). “Power fluctuations suppression of stand-
alone hybrid generation combining solar photovoltaic/wind turbine and fuel cell systems.” Energy
Conversion and Management, 49(10), 2711-2719.
[9] Nojavan, S., Majidi, M., & Zare, K. (2017). “Performance improvement of a battery/PV/fuel cell/grid
hybrid energy system considering load uncertainty modeling using IGDT.” Energy Conversion and
Management, 147, 29-39.
Noor – ul -Ain, et al. “Performance Analysis of DC Micro Grid with PV-Fuel Cell Hybrid
Generation.” International Journal of Modern Research In Engineering & Management (IJMREM), vol. 1,
no. 6, 11 June 2018, pp. 09–14., www.ijmrem.com.