Papers by Maria Samarakou
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A rule-based intelligent control system is proposed for a photovoltaic (PV) system which consists... more A rule-based intelligent control system is proposed for a photovoltaic (PV) system which consists of a PV generator, batteries, and variable load. The control system uses prediction to program the operation of the PV system. Specifically, the PV system is simulated on the basis of qualitative process theory. The intelligent system then allows for maximization of the life duration of the batteries by predicting and avoiding undesirable conditions as well as maximum possible coverage of the electrical demand based on the predicted available energy. An advantage of the control program is that it can enlarge its knowledge base (with the use of certain additional rules) by incorporating real data. Changing the contents of the knowledge base makes it possible to modify the performance of the controller so that it can be used in different systems with different needs
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ABSTRACT Electricity demand forecasting is an imperative tool for the planning and operation of e... more ABSTRACT Electricity demand forecasting is an imperative tool for the planning and operation of electric utilities. With today’s uncertainty and turbulent economies, the development of long term forecasting models requires careful consideration. The mixed forecasting model proposed in this paper was developed for the long term electricity demand forecasting for the countries of south Europe andis capable of determining the per person annual electricity demand by using economic variables alone. The forecasting model displays excellent fit to historic data for all four of the countries under study, namely Greece, Spain, Portugal and Italy, the four of which were hit the hardest by the latest economic recession. Furthermore, the economic variable’s coefficients need not to be recalculated for each country as the proposed model was developed in order to fit the electricity consumption profiles of all 4 countries. Finally, additional investigations revealed that the proposed model also fits the historic data of countries in central Europe, with the variable coefficients still unchanged.
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International Journal of Energy Research, Mar 1, 1988
ABSTRACT Two optimization techniques have been tested on an hour-by-hour simulation of a combined... more ABSTRACT Two optimization techniques have been tested on an hour-by-hour simulation of a combined wind and solar power plant. The system also includes a battery storage system as well as a group of diesel generators. The two optimization techniques are: simplex from the package of MINUITS written at CERN and a modified steepest descent algorithm. Both techniques are suited to hour-by-hour simulation for the above system since the function being minimized is monotonically decreasing towards a minimum. The comparison results showed that the steepest descent algorithm converges slightly faster than the simplex one. Moreover, the application of the techniques for two different sites with different load profiles let us conclude that the results are stable.
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Expert Systems With Applications, May 1, 2007
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Journal of Engineering and Applied Science, Apr 18, 2023
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Photovoltaic systems (PVS), like all energy production systems, must be monitored in order to be ... more Photovoltaic systems (PVS), like all energy production systems, must be monitored in order to be able to detect failures in near real-time so that they will maintain their performance to an optimum level, thus achieving the greatest possible reliability. There are several algorithms for identifying faults during the operation of a PVS based on I-V curves. These algorithms can be applied to PVS telemetry data either locally or remotely. Implementations can be simple like the recording and comparing measurements, but they can also be more advanced like the use of neural networks to detect PV faults. In the present paper, fault detection and identification methods based on I-V curves are presented. The discussed methods are selected according to the recent literature, are presented and analyzed so that their differences, advantages, and limits are pointed out.
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During the last decade, exponential growth in energy production by Photovoltaic systems (PVS) has... more During the last decade, exponential growth in energy production by Photovoltaic systems (PVS) has been observed. Although very promising concerning energy production, PVS are often prone to faults that arise either due to environmental conditions or to the quality of materials used for their manufacturing and handling during installation. If these faults are left untreated, a risk arises both to the operation of the system itself (risk of destruction) and to its very ability to produce energy reliably. This paper discusses methods for fault detection and identification on the DC side of the photovoltaic systems. The methods are studied for their ability to identify various fault types as well as their complexity and limitations.
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The use of an algorithm based on data from I-V curves, a simple and cost-effective method for fau... more The use of an algorithm based on data from I-V curves, a simple and cost-effective method for fault detection and identification in Photovoltaic Systems (PVS), is presented. When determining whether or not to invest in a PVS, life expectancy and reliability are critical considerations. In this paper, the development of an I-V curve-based algorithm for fault detection and identification in PVS is presented. The method calculates the single diode model that describes the Photovoltaic cell in use, for the irradiance and temperature of a certain location. After that, a threshold monitoring approach identifies the presence and the nature of a fault. Measurements were performed to certify the ability of the algorithm to detect both the normal operation at maximum power point and the ability to detect and identify errors introduced during the operation of the experiment. The algorithm can identify open-circuit, short-circuit and mismatch faults. The results are promising, implying that the method could be applied in PVS.
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Papers by Maria Samarakou