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Analysis of electromagnetic and loss effects of sub-harmonics on transformers by Finite Element Method
(Springer India, 2020) Ozupak, Yildirim; Mamis, Mehmet Salih
Power 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.
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 Faruk
Importance 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.
Discrete-time state-space modeling of distributed parameter transmission line
(Ieee, 2007) Mamis, Mehmet Salih
This 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.
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 Emin
In 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.
Fault location method on two-terminal transmission line using synchronized time information of traveling waves
(Springer, 2022) Akmaz, Duzgun; Mamis, Mehmet Salih
In 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.
Fault Location on Series Compensated Power Transmission Lines Using Transient Spectrum
(Ieee, 2015) Akmaz, Duzgun; Mamis, Mehmet Salih; Arkan, Muslum; Tagluk, M. Emin
Nowadays 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.
Harmonic Analysis in Power Systems With Discrete Fourier Transform
(Ieee, 2015) Akmaz, Duzgun; Mamis, Mehmet Salih
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. 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.
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, Ramazan
Lightning 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.
Lumped-parameter-based electromagnetic transients simulation of non-uniform single-phase lines using state variable method
(Inst Engineering Technology-Iet, 2020) Mamis, Mehmet Salih
The 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.
Management Simulation of Multi-Source Renewable Energy Microgrids
(Ieee, 2016) Baran, Burhan; Mamis, Mehmet Salih; Alagoz, Baris Baykant
In 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.
Non-iterative nodal approach for transient simulation of nonlinear elements
(Ieee, 2007) Mamis, Mehmet Salih
A 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.
Non-iterative nodal solution for transient simulation of nonlinear and time-varying elements
(Elsevier Sci Ltd, 2011) Mamis, Mehmet Salih
A 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.
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 Ismail
The 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.
Price-Efficiency Relationship for Photovoltaic Systems on a Global Basis
(Hindawi Ltd, 2015) Cengiz, Mehmet Sait; Mamis, Mehmet Salih
Solar 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.
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, Yilmaz
In 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.
Realization of electromagnetic flux and thermal analyses of transformers by finite element method
(Wiley, 2019) Ozupak, Yildirim; Mamis, Mehmet Salih
When 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.
Transmission line fault location using traveling wave frequencies and extreme learning machine
(Elsevier Science Sa, 2018) Akmaz, Duzgun; Mamis, Mehmet Salih; Arkan, Muslum; Tagluk, Mehmet Emin
In this research, a new approach was proposed for determining the fault location in transmission lines. Traveling wave frequencies and an extreme learning machine (ELM) were used to determine fault location. Transient signals in the time domain were transformed to the frequency domain using the fast Fourier transform (FFT) and the traveling wave frequencies were detected from the transient frequency spectrum. In order to detect the location of fault, traveling wave frequency was used initially to predict the fault location. The prediction of this fault location was tested for many different fault conditions and was found to be adversely affected by only the source inductance value. This is due to the negative effect of source inductance on wave velocity. Regression feature of ELM was used in order to improve the prediction of fault location and to minimize the negative effect of source inductance. For ELM regression training, values of the fault distance estimated from the traveling-wave frequencies and the source inductance values were used as ELM input data, and the actual distance values were used as ELM output data. After ELM regression training, ELM predicted a new fault location using the input data. The Alternative Transients Program (ATP/EMTP) was used to model J. Marti frequency dependent line model, and the MATLAB program was used to perform fault-detection algorithms. Simulation results show that the proposed method is very successful against many variables such as different fault resistances, source inductances, transmission line characteristics, transmission line lengths. (C) 2017 Elsevier B.V. All rights reserved.
Transmission lines fault location using transient signal spectrum
(Elsevier Sci Ltd, 2013) Mamis, Mehmet Salih; Arkan, Muslum; Keles, Cemal
This paper proposes a method for fault location on transmission lines, which is based on time to frequency domain transformation of transient signals of the fault instant measured at one end. Fast Fourier Transform (FFT) is used for time to frequency domain transformation and frequency of the first fault generated harmonic is utilised for determination of the fault location using the travelling wave theory of the transmission line. The accuracy of the method has been tested using the simulations carried out in Alternative Transients Program (ATP/EMTP) with frequency-dependent distributed parameter transmission line model by considering several cases and various types of faults, different values of fault resistance and phase angle at fault instant. The method has good accuracy and the simulation results show that the accuracy of the method is insensitive to the fault resistance and phase angle of the fault instant. Reactive elements may affect the resolution but, it can be removed by applying the correction procedure proposed. (C) 2013 Elsevier Ltd. All rights reserved.
Utilization of Energy from Waste Plants for Microgrids
(Ieee, 2016) Baran, Burhan; Mamis, Mehmet Salih; Alagoz, Baris Baykant
Energy from Waste (EfW) should be taken account as an alternative renewable resource for local energy generation in microgrids. This study theoretically demonstrates benefits of EfW plants for microgrids. Power flow simulation results were shown for a scenario of town grid with the population size of 115000. IEEE 9 Bus system is used to model distribution system of this town. 5 MW Energy from Waste Incineration (EfWI) plant and 10 MW solar plant are integrated to distribution system. Simulation results demonstrate that despite the fact that EfWI plant provides a limited energy generation potential, it can be utilized as a secondary renewable source to reduce peak demand in the hours of excessive demand.
Utilization of energy from waste potential in Turkey as distributed secondary renewable energy source
(Pergamon-Elsevier Science Ltd, 2016) Baran, Burhan; Mamis, Mehmet Salih; Alagoz, Baris Baykant
Running out of fossil fuels and rising of environmental issues pressurize energy policies in the direction of increasing renewable energy utilization. As a part of full-recycling scheme, Municipal Solid Waste (MSW) can be accounted as an alternative and prevalent source of renewable energy for smart grid applications. This study presents a case study investigating the future of dry combustion in Turkey and gives some projections on Energy from Waste (EfW) utilization potentials as secondary local generators. EfW potential of MSW incineration plants is modeled depending on MSW mass function. An empirical formula for prediction of EfW potential of Turkey is derived by curve fitting to yearly MSW data. Dependence of EfW potential on human population is modeled and thus spread of EfW potential over the territory of Anatolia landscape is illustrated. Analyses reveal that EfW has a potential to be local source of renewable energy for future smart grids due to the fact that EfW exhibits energy generation distribution correlated with city population. We concluded that EfW incineration plants can act on sustainable development of Turkey by serving as a consistent, distributed, near-field generators integrated to waste management systems of cities. (C) 2016 Elsevier Ltd. All rights reserved.

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