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Öğe An efficient methodology based on coverage area to modify location and power ratings of distribution transformers(IEEE-Inst Electrical Electronics Engineers Inc, 2021) Akar, Onur; Terzi, Ümit Kemalettin; Özgönenel, Okan; Petrichenko, Lubov; Sönmezocak, TemelThe Technology development and rising standards of living are increasing the demand for electricity in city centres. In addition, the density of electric power in different areas of a city changes with the construction of new residential areas. Variation in load density can be managed by adjusting the voltage on distribution lines, installing new lines and transformer centres, and reconfiguring existing lines and transformer centres. In this study, the Istanbul Uskudar District of Kanlica-Cubuklu Region was examined and coverage areas were modified depending on the load density and power of the existing transformers. A novel systematic approach to determine the coverage area of transformers is presented. In this approach, the coverage area and overlap of each transformer with its neighbours were determined. Subsequently, transformers that are under-used or have significant overlap with neighbouring transformers were removed from the network. The transformers were placed into an optimal structure in the network by distributing the load of an excluded transformer to its nearest neighbours. This approach further allows the minimum route for the high voltage distribution wiring between transformers and cost to be determined.Öğe Comparative Analysis of Lighting Elements’ Effects on Electric System(2021) Terzi, Ümit Kemalettin; Dursun, Sait; Akar, Onur; Sonmezocak, TemelDue to the increase of demand for energy requirement, and the decrease of energy sources day by day, it is being understood that it is required to efficiently use the energy sources in order to ensure the balance of demand for electric energy. The lighting elements use about 1/5 of the electric energy produced in our country. Especially while selecting the lamps with high energy efficiency, it is important to consider the circumstances which may create negativities such as harmonics, power factor, crest factor, inrush current, and flicker effect in terms of quality of power. Moreover, impurity which may occur in the network affects the other devices negatively. In this study, the quality of power of lighting elements of more than one type was examined in detail. In the experiments, technical analyses were performed by the use of 13 different lighting elements extensively used in our country at site, factory, and domestic environments, and they were evaluated in terms of their positive and negative effects on the network.Öğe Comparative evaluation of stand-alone hybrid power system with different energy storages(Parlar Scientific Publications (P S P), 2021) Öztürk, Zafer; Tosun, Salih; Öztürk, Ali; Akar, OnurNowadays, increasingly technological improvements and population augmentation lead to searching for new energy resources. The limited energy resources against growing energy demand lead increase in the trend towards Renewable Energy Resources (RES) such as solar and wind. The lack of continuity in energy generation of RES due to weather conditions causes fluctuations in the power network. The energy surplus from RES can be charged, and then the stored energy can be discharged if needed to prevent the fluctuation. The utilization of storage increases energy costs. However, it is possible to reduce this cost thanks to proper energy management. Thus, it is of great importance to determine the most appropriate storage management according to generation and loading profile. In this study, management of a hybrid power system (HPS) is proposed for the facility location in Balikesir, Turkey. The proposed HPS includes modeling of solar panels (PV), wind turbine (WT), diesel generators (DC), and six different battery types. The technical and economic performances of HPS configurations containing six different battery types are optimized. Besides, the sensitivity of the results is analyzed. A new approach for optimal battery selection is presented to increase the efficiency of HPS.Öğe Discrimination of magnetizing inrush and internal fault currents based on stockwell transform and ANN approach for transformer protection(IEEE, 2019) Özgönenel, Okan; Terzi, Ümit Kemalettin; Akar, Onur; Kurt, ÜnalIn this study, Stockwell transform and artificial neural network were used in determining the inrush current and the internal current fault based on the power transformer protection. The S-transform is a robust transform that incorporates the time and frequency characteristics used in the analysis of non-stationary short term transient signals. It is used for pattern recognition for distinction between internal faults and inrush current. Time-frequency images were obtained by using S-transform, and the obtained images were observed to be different in internal faults and inrush current. The feature extraction is based on statistical methods, standard deviation and average value, the classification process was performed with the multilayer feed forward artificial neural network. The classification performance is calculated at a hundred percent accuracy.Öğe High performance adaptive active harmonic filter design for non-linear led loads(Znack Publishing House, 2022) Sönmezocak, Temel; Akar, Onur; Terzi, Ümit KemalettinToday, illumination systems use approximately 1/3 of the electrical energy produced. For this reason, new technologies constantly increase energy efficacy in illumination technology. Consequently, the use of LED type light sources gets more widespread with low power electronics-based versions. The most important advantage of this type of systems has high luminous efficacy. However, since electronic systems have non-linear static loads, they cause unwanted harmonics in electrical distribution systems. Harmonics affect the operational safety as they cause unnecessary heating of the conductors in the electrical network. It also adversely affects the measuring and control systems of the buyers and so decreases the energy performance. In this study, an adaptive Butterworth low pass active harmonic filter model that can cut all current/voltage harmonics outside the operating frequency of different types of LED driver light sources is designed. In addition, harmonic analysis of different LED driver systems is performed experimentally by considering the total harmonic distortions (THD,%). In this way, harmonic components and (THD) values of different LED systems are obtained. These harmonic components obtained is filtered with the designed filter structure and the effects of the filter structure at each filtering degree on the harmonic components and THD were investigated. In this way, the designed filter is proved to be an adaptive model that can be adjusted automatically for different types of LED systems.Öğe Kinetic investigation of AISI 304 stainless steel boronized in indirect heated fluidized bed furnace(Technical Faculty, Bor-Serbia, 2016) Topuz, Polat; Çiçek, Bünyamin; Akar, OnurIn this study, kinetic examinations on boronized AISI 304 Stainless Steel samples were described. Samples were boronized in indirect heated fluidized bed furnace consists of Ekabor 1 (TM) boronizing agent at 1123, 1223 and 1323 K for 1,2 and 4 hours. Morphologically and typically examinations of borides formed on the surface of steel samples were studied by optical microscope, scanning electron microscope (SEM) and X-Ray diffraction (XRD). Boride layer thickness formed on the steel XSCrNi 18-10 ranges from 12 to 176 mu m. The hardness of the boride layer formed on the steel XSCrNi 18-10 varied between 1709 and 2119 H nu(0.1). Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature. The kinetics of the reaction has been determined with K=Ko exp (-Q/RT) equation. Activation energy (Q) of boronized steel X5CrNi 18-10 was determined as 244 kj/mol.
