analysis and modeling of a stand-alone power system for the ...

Fuel Cell Power,
Watt
2nd International Conference on Renewable Energy Sources and Energy Efficiency
18 – 21, October 2007, Athens, Greece
Charging
Time, h
Discharging
Time, h
Electrolysis
Time, h
1000 574 803 87 69
2000 564 812 88 60
4000 530 834 100 38
Fuel Cell
Operation Time, h
Table 4: Results for the operation time of the different subsystems for three values
of the output power from the Fuel Cell
5. Conclusions
In this study, the simulated results for the various subsystems of the Stand-Alone Power
System during a two-month period were presented. When shortage of power occurred, the
Lead-Acid Accumulator provided the necessary power to the system. On the contrary, when
surplus of energy was available, the Lead-Acid Accumulator was charged and potential
operation of the Electrolyzer was possible. The applications scenarios that took place,
revealed that there was sufficient amount of stored hydrogen at the end of month. The Fuel
Cell autonomy for the stored hydrogen was calculated at approximately 19.1h, which is
equivalent to 38.2kWh (in the case of SOCmin=84% and Fuel Cell output power equal to
2kW). One important outcome of the study, was that several charges and discharges took
place during the month. This situation can be hazardous for the Accumulator as it reduces its
lifetime. Thus, in order to protect the accumulator and increase its lifetime, it is vital to
introduce a back-up Diesel Generator (DG) which would provide the system with the
necessary power when there is lack of energy.
6. Future Work
Multiple scenarios, which take into account the State-of-Charge of the Accumulator, variable
conditions regarding the renewable energy sources are going to be used for the optimization
of the system operation. The experimental results from the system operation will be examined
in contrast with the simulated data in order to form the basis for the analysis and design of a
reliable control system for the integrated energy system. New Energy management algorithms
will be developed to achieve an efficient and reliable operation of the system, under variable
supply and demand conditions. All these results will be used as the basis of developing and
evaluating a ‘’plant-wide’’ model based control strategy.
7. Acknowledgements
The financial support by the General Secretariat for Research and Technology of Greece
(Ministry of Development) is gratefully acknowledged. This study is conducted in the
framework of the research project ΑΜΘ-9.
8. REFERENCES
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stand-alone hybrid wind/PV/fuel cell power generation systems, Renewable Energy
31, pp. 1641-1656
3. Ulleberg Ø. (1998), Stand-Alone Power Systems for the Future: Optimal Design,
Operation & Control of Solar-Hydrogen Energy Systems. PhD thesis, Norwegian
University of Science and Technology, Trondheim
4. Kolhe M., Agbossou K., Hamelin J. and Bose T.K. (2003), Analytical model for
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