Yazar "Mamis, Mehmet Salih" seçeneğine göre listele
Listeleniyor 1 - 20 / 25
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Analysis of electromagnetic and loss effects of sub-harmonics on transformers by Finite Element Method(Springer India, 2020) Ozupak, Yildirim; Mamis, Mehmet SalihPower transformers are generally designed to be used in conditions where voltage and current are sinusoidal. However, nonlinear loads are increasing in modern power systems with the developing technology. Therefore, line voltages and currents often have harmonically distorted or non-sinusoidal waveforms. In this article, a model has been developed. The mathematically developed model has been proven experimentally and numerically. In this paper, different sub-harmonic content parametric analysis of the loss of transformer under no-load conditions with voltage excitation was performed. For this purpose, the Finite Element Method (FEM) based modeling of the core and windings of the transformer has been developed. An efficient method based on harmonic field model of transformer windings and FEM based modeling of transformer core is used. ANSYS@MAXWELL program, which realizes a solution based on FEM, is used for this. From the results of the analysis, it was seen that the effect of harmonic voltages on the loss of the transformer core is negligible. However, these tensions have been shown to increase winding losses in the unloaded state. This case reveals the importance of harmonics to be taken into account in calculating the losses of power transformers.Öğe Comparative Assessment of Electromagnetic Pollution from Base Station with Instant and Continuous Measurements(Institute of Electrical and Electronics Engineers Inc., 2024) Karadag, Teoman; Mamis, Mehmet Salih; Yildiran, NisanurCommunication devices, which take a longer place in our lives with the developing technology, generally use the wireless communication infrastructure. Frequently used of these systems are; Called Wi-Fi (Wireless Fidelity), GSM (Global System for Mobile), UMTS (Universal Mobile Telecommunications Service), LTE (Long Term Evolution), Bluetooth, DECT (Digital Enhanced Cordless Telecommunication), NFC (Near Field Communication). The main element that distinguishes all these wireless systems from each other is the frequency bands they operate. Wireless communication times are increasing year by year in our country, which has a young population in the world and parallel to this. Mobile phone operators are adding new systems to their infrastructure day by day in order to ensure a sustainable mobile communication that increases day by day. Increasing communication traffic and wireless infrastructure systems through which this traffic is transported also increase electromagnetic pollution in living spaces and this issue is reflected in legal processes. With the study, electromagnetic pollution measurements made in living spaces within the legal processes and suggestions for these measurements to give more accurate results are presented. © 2024 IEEE.Öğe Detecting Fault Type and Fault Location in Power Transmission Lines by Extreme Learning Machines(Ieee, 2015) Tagluk, M. Emin; Mamis, Mehmet Salih; Arkan, Muslum; Ertugrul, Omer FarukImportance of supplying qualified and undisturbed electricity is increasing day by day. Therefore, detecting fault, fault type and fault location is a major issue in power transmission system in order to prevent power delivery system security. In previous studies, we observed that faults can be easily determined by extreme learning machine (ELM) and the aim of this study is to determine applicability of ELM in fault type, zone and location detection. 8 different feature sets were exacted from fault data that produced by ATP and these features were assessed by 15 different classifier and 5 different regression method. The results showed that ELM can be employed for detecting fault types and locations successfully.Öğe Detection of Arc Faults in Transformer Windings via Transient Signal Analysis(Mdpi, 2024) Alpsalaz, Feyyaz; Mamis, Mehmet SalihIn power transformers, lightning strikes, switching operations, and short circuit faults can deform the winding insulation, resulting in an electric arc between the windings. If the arc is not detected in its initial phase, it may lead to a solid short circuit and damage the transformer, potentially causing an explosion due to overheating and high pressure. In this study, winding arcs in the transformer are identified from the terminal current and voltage signals. A 3D magnetic model of a 15 MVA power transformer is constructed in Ansys@Maxwell, and the nonlinear arc model is simulated in Matlab@Simulink. The transient voltage and current signals related to the arcing conditions at five different points in the high-voltage side winding are obtained by running Ansys and Matlab simultaneously using ANSYS@Simplorer (Twin Builder). These signals are transformed into the frequency domain using Fast Fourier Transform (FFT). The arcs are detected from the transient-generated frequency components of the transformer voltage and current signals.Öğe Discrete-time state-space modeling of distributed parameter transmission line(Ieee, 2007) Mamis, Mehmet SalihThis work presents a new approach for statespace modeling of distributed parameter transmission tine for transient analysis. The lossless line model based on the method of characteristics is used and the state equations are derived. These equations are converted to a set of difference equations using the trapezoidal rule of integration. By solving these equations, the state of system at discrete time points is obtained. An illustrative example is given and the obtained results are compared with those obtained using conventional methods based on s-domain and fast inverse Laplace transform (FILT). The study also investigates the effects caused by lumped parameter approximation of tine losses.Öğe Enhancing Fault Location Accuracy in Transmission Lines Using Transient Frequency Spectrum Analysis: An Investigation into Key Factors and Improvement Strategies(Mdpi, 2024) Akdag, Mustafa; Mamis, Mehmet Salih; Akmaz, DuzgunFault location estimation in transmission lines is critical for power system reliability. Various methods have been developed for this purpose, among which transient frequency spectrum analysis (TFSA) stands out as a recent method based on travelling wave (TW) theory. TFSA determines the fault location by analyzing the frequency spectrum of transient currents and/or voltages at the instant of the fault, offering advantages such as independence from fault impedance and the ability to locate faults with one-side measurements. Despite its success in fault location, TFSA has several considerations that warrant detailed investigation. This study explores the effects of source inductance, series compensation, fault arc, and current transformer (CT) characteristics on transient frequencies. Additionally, the impact of noise on TFSA results is examined. The new proposed source inductance compensation method can reduce the error of 6.55% to 0.88%, where the same error can be reduced to 3.45% with the compensation method given in previous study. Strategies to enhance accuracy are discussed and compared to previous studies, including a proposed detection approach providing appropriate data size and precise wave propagation speed calculations. These findings contribute to a deeper understanding of TFSA's limitations and inform practical improvements for fault location accuracy in power transmission systems.Öğe Fault location determination for transmission lines with different series-compensation levels using transient frequencies(Tubıtak scıentıfıc & technıcal research councıl turkey, ataturk bulvarı no 221, kavaklıdere, ankara, 00000, turkey, 2017) Akmaz, Duzgun; Mamis, Mehmet Salih; Arkan, Muslum; Tagluk, Mehmet EminIn this paper, based on the theory of traveling waves, the fault distances on long transmission lines with various series-compensation levels are determined using transient current and voltage frequencies. Transmission lines with series compensation are modeled using Alternative Transients Program software with frequency-dependent effects on the line included in the simulation. The transient current and voltage signals are obtained from the model. A fast Fourier transform is used for frequency-domain conversion and fault location is estimated from the frequencies of fault-generated harmonics in the transient spectrum. The algorithm is implemented in MATLAB. To investigate the effect of compensation on accuracy, the results are obtained for different series-compensation levels. The undesirable source-inductance effect is removed and estimation accuracy is further improved using a waveform-relaxation method. The method is found to be successful in determining fault location on series-compensated transmission lines. The effects of the compensation level, fault resistance, and phase angle are investigated.Öğe Fault location method on two-terminal transmission line using synchronized time information of traveling waves(Springer, 2022) Akmaz, Duzgun; Mamis, Mehmet SalihIn this study, approximate derivative (AD) signal processing method using synchronous voltages data, based on the traveling wave theory, was developed to determine fault locations in transmission lines. The first aerial mode voltage signals were obtained by applying the Clarke transformation to the voltage signals that occur after a short circuit fault. Then, by taking the first AD of the aerial mode voltage signals, the traveling waves were obtained. Finally, the location of the fault was found by using the time difference information of the traveling waves, wave velocity value and transmission line length. The proposed signal processing method was found to be effective in determining the location of faults. It was tested and compared to the discrete wavelet transform (DWT) for various fault conditions. Based on the simulation results, the proposed method was found to have a slightly higher success rate than DWT, in general. Moreover, it can work with low sampling frequencies, and it provides a better resolution than DWT to display the traveling waves in noise conditions.Öğe Fault Location on Series Compensated Power Transmission Lines Using Transient Spectrum(Ieee, 2015) Akmaz, Duzgun; Mamis, Mehmet Salih; Arkan, Muslum; Tagluk, M. EminNowadays sustainability and quality of energy have gained more importance. Power outages due to failures particularly cause interruption of production at industrial facilities may lead to loss of manpower and resources. One of the major causes of power outages in the power system is the short-circuit faults occurring in transmission lines. The most important requirement to clear the fault in a short time is to estimate the fault location quickly and accurately. In this study, fault location is determined in series compensated power transmission lines utilizing transient frequency spectrum. It has been shown that the method is suitable for series compensated lines.Öğe Fault Location Prediction in Power Transmission Lines Using an Artificial Neural Network Model(Institute of Electrical and Electronics Engineers Inc., 2024) Alpsalaz, Feyyaz; Yalcinoz, Zehva; Kaygusuz, Asim; Mamis, Mehmet SalihEnergy transmission lines are an important element that ensures the sustainability of existing living conditions and the uninterrupted need for electricity. Therefore, it is of great importance to locate short circuit faults that may occur in transmission lines and to intervene in these faults immediately. In this study, a fault location study is carried out in a power system designed as a real line model. Firstly, a 478.9 km long transmission line with three transpositions was created using the EMTP/ATP program. The study starts from a point close to the beginning of the line until the first transposition, and a three-phase ground fault is simulated in the system at certain intervals. The input current and voltage values of the line are then taken. The obtained data were analyzed by applying Modal Transformation to the current and voltage signals in the fault condition. Thus, the occurrence of high-frequency harmonics of the fault condition is characterized. Afterwards, in order to locate the fault in the system, Fast Fourier Transform (FFT) spectra were obtained using MATLAB software. These spectra were trained with Artificial Neural Networks (ANN) using fault data analyzed at 74 different points, and the fault location was determined with 99% accuracy. © 2024 IEEE.Öğe Harmonic Analysis in Power Systems With Discrete Fourier Transform(Ieee, 2015) Akmaz, Duzgun; Mamis, Mehmet SalihHarmonics has become more significant issue due to the increasing of utilization of the non-linear loads and switching elements such as inverter on the power system recently. Harmonics disrupts the shape of the current and voltage signals in power systems and leads to many problems in power systems. It has made harmonic analysis necessary on the power system. Harmonics has become more significant issue due to the increasing of utilization of the non-linear loads and switching elements such as inverter on the power system recently. In this study a method is designed to obtain a basic signal by using Discrete Fourier Transform (DFT) in order to determine harmonics on power systems. The simulation of this method has been implemented by using Matlab/Simulink software package.Öğe Lightning surge analysis of Faraday cage using alternative transient program-electromagnetic transients program(Inst Engineering Technology-Iet, 2016) Mamis, Mehmet Salih; Keles, Cemal; Arkan, Muslum; Kaya, RamazanLightning surge analysis of protective structures is significant for the design of system. However, simulation models are limited. In this study, a Faraday cage with four air terminals and 2 x 6 grounding rods built to protect a switchyard control building in a 380 kV substation is simulated in alternative transient program for the analysis of lightning surges. Distributed line modelling is used for cage conductors. Down conductors are represented by considering non-uniform variation of the conductor parameters. Current waveforms through the system and voltages at some critical points after a lightning stroke are computed. The traditional lightning parameters needed in structural protection such as lightning peak current, maximum current derivative, current rise time and current duration are determined. The effects of mesh size and some system parameters such as grounding resistance and lightning surge impedance are investigated.Öğe Lumped-parameter-based electromagnetic transients simulation of non-uniform single-phase lines using state variable method(Inst Engineering Technology-Iet, 2020) Mamis, Mehmet SalihThe characteristic impedance of a transmission line, a wire or a conductor changes in a non-uniform manner if the distance to the ground at all points longitudinally is not the same. Vertical conductors, transmission towers and sagging overhead lines are examples for the non-uniform lines. In this study, lumped-parameter-based state variable representation of the single-phase non-uniform line is described. From the lumped-parameter non-uniform line model a linear set of first-order differential equations is obtained in the form of state equations and this analytical expression is solved in closed form using MATLAB to obtain the transient response directly in the time domain. The closed-form solution has the advantage of obtaining the response of the system at an instant without the need for data in the previous states except for the initial conditions. The method also allows attaining the voltage and current profile of the system for any instant. In the illustrative cases presented, the systems with different surge impedance variations are considered and the surge response of a vertical conductor, an exponential line, and a horizontal cone and a vertical cone with constant and also varying propagation velocity are computed. The results are verified by those obtained using s-domain simulations of distributed-parameter transmission line and inverse Laplace transform.Öğe Management Simulation of Multi-Source Renewable Energy Microgrids(Ieee, 2016) Baran, Burhan; Mamis, Mehmet Salih; Alagoz, Baris BaykantIn this study, we present a management simulation of microgrid composed of waste (EfW) plant, solar power and wind energy plants as renewable energy sources and a Pumped Hydroelectric Energy Storage (PHES) as distributed storage unit. In this manner, simulations were carried out for different production and consumption scenarios by using the simulation models developed in Matlab environment and the results are discussed. Strong and weak renewable energy generation states are considered at the presence and absence of PHES. Thus, we analyze energy dispatching rates of microgrid from transmission grid for the both presence and absence of PHES. Also, the dependence of microgrid to transmission grid is evaluated. A conditional flow control algorithm is employed for management algorithm.Öğe Non-iterative nodal approach for transient simulation of nonlinear elements(Ieee, 2007) Mamis, Mehmet SalihA non-iterative nodal solution method for transient simulation of nonlinear elements is presented. Terminal equations of inductors and capacitors are transformed into algebraic equations using the trapezoidal rule of integration. Nodal equations are formulated as a set of algebraic equations by treating all nonlinear elements as linear and LU factorization is used for the solution of these equations at each time step. A nonlinear variation of the system elements is represented by renewing the nodal conductance matrix at each time step of the solution. Several examples with various circuit configurations and different nonlinear characteristics are considered, and comparisons with available methods are included. As the solution method is not iterative, convergence and initialization problems are avoided. Formulation and solution steps are simple and the method can be easily implemented in the nodal solution-based circuit simulators such as SPICE and EMTP.Öğe Non-iterative nodal solution for transient simulation of nonlinear and time-varying elements(Elsevier Sci Ltd, 2011) Mamis, Mehmet SalihA non-iterative algorithm based on nodal equation formulation is proposed for transient simulation of nonlinear and time-varying elements. Terminal equations of inductors and capacitors are transformed into algebraic equations using the trapezoidal rule of integration by treating all nonlinear elements as linear and nodal equations are formulated as a set of algebraic equations. LU factorization is used for the solution of nodal equations. Variation of system elements is represented by renewing the nodal conductance matrix at each time step of the solution accordingly. In the first illustrative example, a nonlinear oscillator circuit is considered. In the second, the transient response of a transmission line with a surge arrester is computed by including the corona effects and in the third, a time-dependent primary arc model of a faulty transmission line is examined. Obtained results are compared with those obtained using EMTP and state-space method. Change of simulation time with respect to the step length of the numerical integration is also investigated. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Photovoltaic Panel Efficiency Estimation with Artificial Neural Networks: Samples of Adiyaman, Malatya, and Sanliurfa(Hindawi Ltd, 2019) Icel, Yasin; Mamis, Mehmet Salih; Bugutekin, Abdulcelil; Gursoy, Mehmet IsmailThe amount of electric energy produced by photovoltaic panels depends on air temperature, humidity rate, wind velocity, photovoltaic module temperature, and particularly solar radiation. Being aware of the behaviour patterns of the panels to be used in project and planning works regarding photovoltaic applications will set forth a realistic expense form; therefore, erroneous investments will be avoided, and the country budget will benefit from added value. The power ratings obtained from the photovoltaic panels and the environmental factors were measured and recorded for a year by the measurement stations established in three diverse regions (Adiyaman-Malatya-Sanliurfa). In the developed artificial neural network models, the estimation accuracy was 99.94%. Furthermore, by taking the data of the General Directorate of Meteorology as a reference, models of artificial neural networks were developed using the data from Adiyaman province for training; by using Malatya and Sanliurfa as test data, 99.57% estimation accuracy was achieved. With the artificial neural network models developed as a result of the study, the energy efficiency for the photovoltaic energy systems desired to be established by using meteorological parameters such as temperature, humidity, wind, and solar radiation of various regions anywhere in the world can be estimated with high accuracy.Öğe Price-Efficiency Relationship for Photovoltaic Systems on a Global Basis(Hindawi Ltd, 2015) Cengiz, Mehmet Sait; Mamis, Mehmet SalihSolar energy is the most abundant, useful, efficient, and environmentally friendly source of renewable energy. In addition, in recent years, the capacity of photovoltaic electricity generation systems has increased exponentially throughout the world given an increase in the economic viability and reliability of photovoltaic systems. Moreover, many studies state that photovoltaic power systems will play a key role in electricity generation in the future. When first produced, photovoltaic systems had short lifetimes. Currently, through development, the technology lifecycle of photovoltaic systems has increased to 20-25 years. Studies showed that photovoltaic systems would be broadly used in the future, a conclusion reached by considering the rapidly decreasing cost of photovoltaic systems. Because price analysis is very important for energy marketing, in this study, a review of the cost potential factors on photovoltaic panels is realized and the expected cost potential of photovoltaic systems is examined considering numerous studies.Öğe PROVIDING ELECTRICAL POWER INCREASE BY STIMULATING TEMPERATURE DIFFERENCE AT LOW TEMPERATURES IN STIRLING MOTORS(Yildiz Technical Univ, 2018) Cengiz, Mehmet Sait; Mamis, Mehmet Salih; Yurci, YilmazIn this research, the variation of electrical power according to the temperature in Stirling motors was analyzed. The performance characteristics of a low power Beta type Stirling motor were determined in the situation of working gas becoming air gas in this research, Results were compared and are presented graphically. Performance tests of a Stirling motor heated by thermal specifications of the sun were made at heater temperatures of 673 K, 773 K and 873 K. Also, an electrical power increase was provided by raising the temperature difference between the hot edge of the displacer and cooler temperatures.Öğe Realization of electromagnetic flux and thermal analyses of transformers by finite element method(Wiley, 2019) Ozupak, Yildirim; Mamis, Mehmet SalihWhen designing transformers, the system to which transformers are to be used, the electrical power to be transferred, and the continuity and safety of the system must be taken into consideration. Paired physical and mathematical models help to develop a system that is both accurate and easy to implement. In this study, a model was developed to determine the electromagnetic flux distribution, losses, and electromagnetic forces of the transformer. A thermal model was also developed to measure the heat generated and to determine the temperature distribution of the transformer. The performances of the proposed models were compared with the performance of the transformer, which was determined analytically, and the performance of the transformer was also determined experimentally and the results were confirmed. When the results were compared, it was seen that the proposed models gave more optimum results. In this way, electromagnetic flux, electromagnetic force, and thermal distribution at each point of the transformer can be easily determined. On the other hand, in this study, the windings and the core were optimized, the electromagnetic forces formed in the windings were calculated, the heat distribution in the winding and core was determined, the electrostatic field distributions were examined, and the problematic areas were determined. The thermal effects of the total losses of the transformer were investigated and optimum design parameters were determined. It was concluded that the methods proposed in this study were more practical than the methods reported in the literature. (c) 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
