Elektrik Elektronik Mühendisliği Bölümü

Permanent URI for this communityhttps://hdl.handle.net/20.500.12416/410

Browse

Now showing 1 - 7 of 7

Citation - WoS: 1
Citation - Scopus: 2
Analysis of Lightning Impulse Effects on Three Winding Transformer Used in Solar System Based Ansys Maxwell
(Ieee, 2022) Iskender, Ires; Yukselen, Emir
Transformers are in more critical applications in the renewable energy world and having a transformer fail in such a cyclical power station can be disastrous. Over voltage or voltage strike is the most important phenomena for the transformers. Thus, the evaluating and estimating the effects and stresses of these sudden high voltages is important during the transformers life time operation and design stage. Accordingly in this paper the electromagnetic field analyses of the lightning impulse on Photovoltaic (PV) transformer are investigated using ANSYS Maxwell software. The 3D and 2D model simulation of the PV transformer is carried out to determine the electric field and voltage distribution on critical regions which can cause breakdown on insulation material and damage transformer windings and affects transformer working. Afterwards according to the simulation result, the subjected transformer was designed considering the relative critical regions and performs the full wave lightning impulse test in factory area to verify the dielectric strength of the transformer. This study provides better understanding of the lightning impulse voltage effects with localization of the critical regions on the PV transformer and helps to improve the withstand capability of the transformer against the lightning impulse voltages during the design and production stage.
Citation - WoS: 1
Citation - Scopus: 3
Comparative Analysis of Novel Long Life Routing Methods in Mobile Networks
(Ieee, 2010) Safak, Aysel; Preveze, Barbaros
In this study we propose two novel ABR extended Long Life Routing Methods called Alternative enhancement for Enhanced Associativity Based Routing (AEABR) and Associativity Tick Averaged ABR (ATAABR) methods which are also modifications of Associativity Based Routing (ABR). Comparison of these associativity based long Life routing algorithms in Mobile Networks are done for route speeds, life times and outage times Since ABR at most focuses on power strength, it will be preferable in most systems to establish long life routes from source to destination considering the power constraints. It is shown in this paper that, the novel algorithms that we propose provide better life time, link speeds and outage time results than EABR (Enhanced Associativity Based Routing) method and other relay selection algorithms taken into consideration in this work. It's illustrated that the performance of EABR method, is really better than other relay selection algorithms for number of Route reconstructions (RRC) or relay changes and Connected Status Percentage (CSP). On the other hand it has also been illustrated that AEABR and ATAABR improve the connection stability of EABR by keeping the connection outage time at lower levels where ATAABR require less modification on algorithm and needs less computation time. AEABR improves either connection outage times or number of RRC. During this analysis message overhead and bandwidth wastage of each algorithm is also investigated. The proposed algorithms can be used in designing a unicast mobile network having power constraints to provide longer path life and lower number of route reconstructions.
Citation - WoS: 6
Citation - Scopus: 7
Coreloss Estimation Via Long Short-Term Memory Model (Lstm) of Dry-Type Transformer Based on Fea
(Ieee, 2021) Yildiz, Berat; Tamyurek, Bunyamin; Iskender, Ires; Kul, Seda
Accurate estimation of losses is very important in transformer designs for energy systems. Therefore, in this study, a long short-term memory model (LSTM) was performed to predict the core loss of three-phase dry-type transformers based on Finite Element Analysis (FEA) analysis. Since, in ordinary multilayer networks, learning problems occur when the gradient value gets too small during backpropagation. LSTM, on the other hand, can store information better thanks to its extra layers that communicate. Thus, the learning process takes place more efficiently. The analysis and estimation processes were performed using a primary number of turns, excitation voltage, and three different cross-section area parameters. 486 data randomly selected from 506 data obtained by ANSYS/MAXWELL in the training of the LSTM model were used. The remaining 20 data were used in the testing process to measure system performance. The error obtained by the validation test is 0.15. It is very close to the simulated value, thus LSTM can be used as a reliable estimation method during the design stage.
Management of Open-Access Renewable Resources With Depensation Dynamics: Control Systems Perspective
(Ieee, 2021) Cifdaloz, Oguzhan
Renewable resources are being over exploited at an increasing rate. Institutions/governments are compelled to devise effective policies and strategies to sustainably manage renewable resources under social, ecological and environmental pressures that stem from increasing demand, model uncertainties, disturbances, and measurement errors. Open-access policies to harvest renewable resources are still widely used around the world. They are mildly regulated by implementing landing quotas, defining harvesting seasons, and/or constraining the technology used for harvesting. In many parts of the world, including the regions that are highly developed, open-access fisheries a refailing. In this paper, management of an open-access renewable resource (fishery) with depensation dynamics is formulated as a control systems problem and a strategy to sustainably manage the renewable resource is proposed. First, dynamics of an unregulated open-access fishery is described and its vulnerabilities are stated. Then, an easy-to-implement regulation strategy based on classical control systems ideas is proposed and its robustness characteristics are provided. The management policy (control law) is implemented via manipulating economic variables, i.e. by adjusting the (opportunity) cost of harvesting. An agent-based model is used to model the resource exploiters (i.e. fishermen). It is shown that a classical control law can be used to effectively manage an open access fishery subject to sampling effects.
Citation - WoS: 13
Citation - Scopus: 38
New Dual Band Dual-Mode Microstrip Patch Bandpass Filter Designs Based on Sierpinski Fractal Geometry
(Ieee, 2013) Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K.
Dual band dual mode chebychev microstrip bandpass filter designs are introduced for first time in this paper. The proposed filter designs are based on the use of dual mode square slotted patch microstrip resonator. These filter structures are fractally generated using Sierpinski fractal curve geometry applied to the conventional square microstrip patch from 1st to 2nd iteration levels where the first band designed at fundamental frequencies (5.475, 5.45 and 5.4) GHz for each iteration while the second band(8.925, 9.15, 9.05) GHz for each iteration. These filters have been designed using a substrate with a dielectric constant of 10.8 and thickness of 1.27mm. The performance of filter structures, based on resonators has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures are compact in addition to good frequency responses and narrow bands gained.
Citation - WoS: 5
Citation - Scopus: 31
A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based on Fractal Geometry
(Ieee, 2012) Eyyuboğlu, Halil Tanyer; Mezaal, Yaqeen S.; Eyyuboglu, Halil Tanyer; Elektronik ve Haberleşme Mühendisliği
A narrowband, compact, and easily fabricated microstrip bandpass filter design is introduced in this paper as a candidate for use in modern wireless systems. The proposed filter design is based on the use of dual-mode (two pole) square slotted microstrip resonator. This microstrip bandpass filter has the advantages of possessing much narrower and sharper performance responses than those of the single mode resonator and conventional square patch filter. The proposed microstrip filter structure is fractally generated using Sierpinski fractal curve geometry applied to the conventional square microstrip patch. Filter structures resulting from the successive iterations in the fractal generation process show a considerably low insertion loss, and sharper response of about 1% fractional bandwidth as compared with the conventional microstrip square patch filter of 3% fractional bandwidth designed at the same frequency using the same substrate material. The performance of filter structures, based on dual-mode resonators up to the third iterations, has been evaluated using a full-wave based electromagnetic simulator Sonnet software package. Performance simulation results show that these filter structures offer narrower fractional bandwidth percentages as compared with other types of non- fractalized filter structures.
Citation - WoS: 3
Citation - Scopus: 6
A Novel Transformerless Single-Phase Three-Level Buck-Boost Inverter
(Ieee, 2023) Demirkutlu, Eyyup; Iskender, Ires
This paper proposes a novel transformerless, single-phase, three-level, buck-boost inverter. The proposed inverter can suppress the leakage current drawn from the input power source and provide a long-lasting solution for applications with a wide range and unregulated input voltage. Unlike similar topologies, in the proposed inverter there is no need to have a mid-point of DC sources or DC bus capacitors at the input side of the inverter. A single-phase, three-level, buck-boost inverter for realizing the power stage with 110-Vrms output AC voltage and a range of 100V-200V input DC voltage is investigated in this study. The proposed topology has been proven through theory, computer simulations, and experimental studies with SiC MOSFETs-based prototype of a 300-VA power supply. Theory, computer simulation, and experimental results are all correlated.

Browse

Browsing Elektrik Elektronik Mühendisliği Bölümü by browse.metadata.publisher "Ieee"