Ramazan Ayaz

An Improved Matlab-Simulink Model of PV Module considering Ambient Conditions

A photovoltaic (PV) model is proposed on Matlab/Simulink environment considering the real atmospheric conditions and this PV model is tested with different PV panels technologies (monocrystalline silicon, polycrystalline silicon, and thin film). The meteorological data of Istanbul—the location of the study—such as irradiance, cell temperature, and wind speed are taken into account in the proposed model for each technology. Eventually, the power outputs of the PV module under real atmospheric conditions are measured for resistive loading and these powers are compared with the results of proposed PV model. As a result of the comparison, it is shown that the proposed model is more compatible for monocrystal silicon and thin-film modules; however, it does not show a good correlation with polycrystalline silicon PV module.

A New MPPT Algorithm for Vehicle Integrated Solar Energy System

Photovoltaic (PV) systems are considered as a support unit and eco-friendly energy source for the electric vehicles. If the surface of the electric vehicle is covered by PV cells, it is possible to store considerable amount of energy in the battery system. In this study, different maximum power point trackers (MPPT) with different maximum power point (MPP) tracking algorithms have been tested on a PV structure moving according to a predefined motion loop. Compatibility of each algorithm to moving systems, such as electric vehicles, is presented in a real experimental environment. As a result of these experiments, positive factors in each algorithm have been defined and a new MPP tracking algorithm convenient for moving vehicle has been proposed. The proposed MPPT algorithm shows a better performance than other MPPT algorithms under fast varying radiations. However, proposed algorithm brings slightly higher costs compared to usage of other MPPT algorithms since it requires the measurement of solar irradiance. The developed algorithm is described in detail and comparative analysis and performance evaluation with other algorithms are presented. Autor Nakir, Ismail; Durusu, Ali; Akca, Hakan; Ajder, Ali; Ayaz, Ramazan; Ugur, Enes; Tanrioven, Mugdesem Quelle Transactions of the ASME, Journal of Energy Resources Technology * Band 138 (2016) Heft 2, Seite 021601/1-9 (9 Seiten)

Thermal management of power LED system

LEDs are used in many areas today. Street lighting is one of them and high-power LEDs are utilized in this area. Electrical energy is converted into light with an efficiency in 10-25% range. The rest is converted into heat. The generated heat is largely caused from LED chip. Furthermore, Driver circuit would also causes heat rise. Removing of this heat from the system is important in order to LED system efficiency because increasing of temperature causes a reduction of luminous flux. Excellent thermal management plays a significant role in terms of efficiency, reliability and durability. In this study, losses are caused from the LED chip and the heat sink which are part of the LED lighting systems are examined. These elements are thermally analyzed. The impacts of these losses on efficiency will be presented.

A new approach for relationship between daylight and indoor illumination level

In recent years, the studies on energy efficiency in both industry and academia increased visibly worldwide. As the result of these studies, DIN V 18599-4 is published in 2007. According to this pre-standard, calculation methods about building energy performance were prepared. During design process of building for high energy efficiency, pre-standard contains daylight supply factor. However these calculations are so complex for software development. Our studies on these calculations indicate that there are a lot of parameters which affect the results so realistic results cannot be obtained easily. Also, indoor lighting energy is affected from these results. These are disadvantages of this method. This study provides an alternative for calculation methods of daylight supply factor which is given in DIN V 18599-4 pre-standard. The relationship between global radiation on horizontal surface and building zone that has window is established and it is formulized empirically. Therefore, by using this formula the effect of daylight in windowed zone can be calculated. The number of calculations of this presented method is quite simpler and these calculations provide more realistic results than the pre-standard method in terms of indoor lighting energy.

The influence of voltage and frequency variations on insulation quality of a high voltage cable

Insulation quality issue has had a significant place in high voltage systems for long years. Especially for high voltage cables, which is one of the most crucial elements in power systems, the measurements of dissipation factor or tan delta has a great importance on the insulation life time. Besides, when the power system parameters such as frequency and voltage level are not steady, tan delta measurement values will also be changed. Therefore, tan delta and dielectric loss measurement should be realized in case of unsteady power system conditions to get more exact results. In this study, tan delta measurement of a 20,1/34,5 kV, single core high voltage cable is carried out. By changing the frequency and voltage level, dissipation factor, capacitance (Cs), insulation resistance (Rs) and dielectric losses (Pk) measurement values are obtained.