Selim Koroglu - Academia.edu (original) (raw)

Papers by Selim Koroglu

International Journal of Energy Research, 2022

Journal of Electrical Systems, 2016

This paper presents methodologies for power transformer fault diagnosis using dissolved gas analy... more This paper presents methodologies for power transformer fault diagnosis using dissolved gas analysis and electrical test methods. These methods are widely used in determination of inception faults of power transformers. Dissolved gas analysis test provides fault diagnosis of power transformers. On the other hand the electrical test methods are used for detection of root causes and fault locations and they provide more specific information about the faults. The aim of this work is to study the faults that are measured and recorded in Turkish Electricity Transmission Company (TEIAS) power systems. For this purpose, four specific cases are considered and analyzed with dissolved gas analysis and electrical testing methods. Three of these cases are defective situations and one case is a non-defective situation. These real cases of measurements have been analyzed with both methods in detail. Assessment results showed that a single method cannot yield accurate enough results in some specif...

Energy usage and environment pollution in the transportation are major problems of today’s world.... more Energy usage and environment pollution in the transportation are major problems of today’s world. Although electric vehicles are promising solutions to these problems, their energy management methods are complicated and need to be improved for the extensive usage. In this work, a heuristic optimization approach, Particle Swarm Optimization is used to provide an optimal energy management system for a battery/ultracapacitor powered electric vehicle without prior knowledge of the drive cycle. The proposed scheme has been simulated in Matlab and applied on the ECE driving cycle. Results show the effectiveness of the applied method for the energy management problem of the multi-source electric vehicles with the lowest possible energy usage.

Energy usage and environment pollution in the transportation are major problems of today's world.... more Energy usage and environment pollution in the transportation are major problems of today's world. Although electric vehicles are promising solutions to these problems, their energy management methods are complicated and need to be improved for the extensive usage. In this work, the heuristic optimization methods; Differential Evolution Algorithm, Genetic Algorithm and Particle Swarm Optimization, are used to provide an optimal energy management system for a battery/ultracapacitor powered electric vehicle without prior knowledge of the drive cycle. The proposed scheme has been simulated in Matlab and applied on the ECE driving cycle. The differences between optimization methods are compared with reproducible and measurable error criteria. Results and the comparisons show the effectiveness and the practicality of the applied methods for the energy management problem of the multi-source electric vehicles.

Nowadays, electric vehicle usage and the use of LiFePO4 batteries in electric vehicles gradually ... more Nowadays, electric vehicle usage and the use of LiFePO4 batteries in electric vehicles gradually increase. However, there are important features to be considered to use these batteries safely and efficiently. Incorrect use of these batteries can lead to burning, explosion or shortening of the life of batteries. In this paper, a Battery Management System (BMS) for lithium based batteries is designed that operates more efficiently and communicates with UART between master and slave modules and can communicate via CAN protocol with external devices. Micro controller based control and protection equipment is designed that help to measure and monitor the voltage, temperature and current values of the batteries. They protect the battery cells from the conditions such as over charge, over discharge, high current, high temperature. BMS balances battery cell voltages during charging process with passive cell voltage balancing. In addition to the main controller module in the BMS, slave contr...

2018 2nd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT), 2018

Short-term load forecasting is an important issue for the electric power system in efficiently ma... more Short-term load forecasting is an important issue for the electric power system in efficiently managing the network and reducing operating costs. In addition, with the recent improvements in distributed generation and storage systems, this has become even more important. Access to the high-resolution dataset derived from smart counters allows new forecasting strategies to evolve to match distributed load on the demand side. In this study, short-term load forecasting (STF) of a small region was performed using Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) methods. For load forecasting, the electricity consumption and temperature data for the year 2017 were used as input to the network and next hour demand was predicted. The smallest forecasting error is investigated with the Mean Absolute Percent Error (MAPE) and Root Mean Square Error (RMSE) performance criteria. It showed that RMSE is better than ANFIS with 616.2753 and MAPE 8.8688 prediction error.

Academic Perspective Procedia, 2021

Tamamen elektrikli araçlarda, Batarya ve Ultrakapasitör (UC) enerji depolama birimlerinin birlikt... more Tamamen elektrikli araçlarda, Batarya ve Ultrakapasitör (UC) enerji depolama birimlerinin birlikte kullanılması sıklıkla tercih edilmektedir. Burada ana enerji kaynağı olarak batarya kullanılırken yardımcı kaynak olarak UC kullanılmaktadır. Böylelikle aracın temel güç ihtiyacı bataryalardan karşılanırken anlık güç talepleri UC tarafından sağlanır. İki kaynağın birlikte kullanılmasında pasif, yarı aktif ve aktif olmak üzere; birçok bağlantı grupları oluşturulabilmektedir. Bu çalışmada, en yaygın kullanılan beş farklı bağlantı topolojisi için ağırlık, maliyet, kontrol karmaşıklığı, bataryadan faydalanma oranı, UC’nin etkin kullanımı, sistem verimi gibi göreceli bir karşılaştırma yapılmıştır. Yapılan değerlendirmede yarı aktif UC topolojinin en avantajlı seçenek olduğu sonucuna varılmıştır.

Electric Power Systems Research, 2020

Abstract This paper considers the problem of classifying power transformer faults in the incipien... more Abstract This paper considers the problem of classifying power transformer faults in the incipient stage by using dissolved gas analysis (DGA) data. To solve this problem with high accuracy, we propose to use the common vector approach (CVA) that is a successful classifier when the number of data is insufficient. The feature vector required for the training and testing phases of the CVA is established by using both raw dissolved gas analysis data and some characteristics extracted from this data. The performance of the proposed method is evaluated over DGA data sets supplied from the Turkish Electricity Transmission Company and is compared with some conventional and intelligent methods in terms of classification accuracy and training/testing duration. The achieved results show that the proposed method exhibits superior performance than that of the other methods compared in the meaning of both diagnosis accuracy and computational time. Analysis performed on the physical faults, where the transformers fault types are verified with the electrical test methods, confirms the validity and reliability of the proposed method, as well. Being free from parameter settings is another advantage of this method for using it in online oil-gas analysis applications.

International Journal of Energy Research, 2020

Academic Perspective Procedia, 2018

Otonom taşıtlar üzerine yapılan çalışmalardaki artışın neticesinde, taşıt üzerin... more Otonom taşıtlar üzerine yapılan çalışmalardaki artışın neticesinde, taşıt üzerindeki mevcut sistemlerde değişimlere gidilmektedir. Günümüzde otomobillerde genel olarak kullanılan direksiyon dişli kutuları kremayer tipinde olup, bunların tahrikinde düşük hız ve yüksek momente sahip elektrik motorlarının kullanılması gereksinimi dişli kutularında yeni yaklaşımların ele alınmasını gerekli kılmıştır. Bu çalışmada düşük moment ve yüksek devirli bir elektrik motor ile tahrik için uygun redüksiyon oranına sahip olan, literatürde kullanımına rastlanmamış bir direksiyon dişli kutusu tasarlanmıştır. Hiposikloid dişli sistemlerinin hem istenilen redüksiyon oranının sağlanmasında hemde tekerlek dönüş açılarının hassasiyetinde büyük bir avantaja sahip olduğu görülmüştür.

Journal of Cleaner Production, 2018

Abstract Energy management strategies for an electric vehicle (EV) with multiple power sources ha... more Abstract Energy management strategies for an electric vehicle (EV) with multiple power sources have been widely described in literature. The investigated energy sources are batteries, ultracapacitors, fuel cells, flywheels and solar panels. The management strategy decides how to combine two or more sources in an optimal way. However, the behavior of these sources and also the behavior of the electric drives depend on their temperature. Moreover, the temperature can have extreme values in automotive applications and affect the energy management task. In this paper, to investigate the temperature effect on battery/ultracapacitor powered EV, temperature dependent models are presented for these storage components, as well as for the drive train components itself: power electronics and motor. The average motor iron loss and ultracapacitor loss tend to decrease with increasing temperature, while the average motor copper loss and power electronics loss tend to increase with increasing temperature. These two opposing trends cause the total loss of the drive train to have a rather small variation with temperature for the considered EV and in the considered temperature range. By consequence, the energy management strategy of the EV does not have to depend on the temperature in order to obtain maximal efficiency.

Pamukkale University Journal of Engineering Sciences, 2015

Üç fazlı yeraltı kabloları için silindirik ekranlama etkinliği, sonlu elemanlar yöntemi (SEY) kul... more Üç fazlı yeraltı kabloları için silindirik ekranlama etkinliği, sonlu elemanlar yöntemi (SEY) kullanarak çeşitli ekran malzemeleri için incelenmiştir. Bu SEY modeli ferromanyetik ekran malzemelerinin doğrusal olmayan histerezis davranışlarını da dikkate almaktadır. Kullanılan ekranlar silindir yapılı ve ekran içerisinde kabloların yerleştirilmesi ise düz şekildedir. Aynı ekran geometrisinde farklı ekran malzemelerinin ekranlama etkinliği karşılaştırılmıştır. Burada kullanılan ekran malzemelerinden ikisi ferromanyetik özellikli lineer olmayan histerezis davranışlarını sahip (Arceler-Mittal tarafından üretilen Magnetil ve DX52) ekranlardır. Diğeri ise ferromanyetik olmayan yüksek iletkenlikli ekran (Alüminyum) malzemesidir. Bu çalışmada; ekran yarıçapı, kablolardan geçen akımın genliği ve ekran kalınlığı gibi parametrelerin ekranlama etkinliği üzerindeki etkisi analiz edilmiştir. Ekranlama etkinliği açısından en iyi ekran malzemesinin Magnetil olduğu görülmüştür. Sayısal yöntem ekransız durum için deneysel sonuçlarla da doğrulanmıştır.

Electric Power Components and Systems, 2016

Abstract This article presents an intelligent diagnosis and classification method for power trans... more Abstract This article presents an intelligent diagnosis and classification method for power transformer fault classification based on dissolved gas analysis: the support vector machine. It is a powerful algorithm for classification of faults that needs a limited set of small sampling data, a case of applications with non-linear behavior, and a high number of parameters; however, appropriate model parameters must be determined carefully. The selection of parameters has a direct effect on the machine's classification accuracy. In this study, a multi-layer support vector machine classifier is optimized by a grid search method and three heuristic approaches: (1) genetic, (2) differential evolution, and (3) particle swarm optimization algorithms. The performance analysis of the support vector machine hybridized with these optimization methods is demonstrated using the same classification set. The employed structure has five support vector machine layers, each of which uses a Gaussian kernel function due to its advantages of needing one parameter for optimization and providing excellent classification ability for non-linear data. The proposed approach gives highly accurate performance for diagnosis of power transformers. The support vector machine optimized with the particle swarm optimization algorithm has the best accuracy and requires less computational time compared to the other methods.

International Journal of Vehicle Design, 2016

This paper presents an integrated design of a drivetrain for a single-person ultra-light electric... more This paper presents an integrated design of a drivetrain for a single-person ultra-light electric vehicle (ULEV). To calculate losses and efficiency of the inverter, the permanent magnet synchronous machines (PMSMs) and the gearbox, parameterised analytical models are used. For the gearbox-which has a single gear ratio-the studied parameters are the gear ratio, the number of stages, the number of teeth and the module of each spur gear combination. The novelty of the paper is that it learns how the total average efficiency and the total mass of the drivetrain depend on the gear ratio, on the number of stages in the gearbox, on the motor parameters and on the chosen several driving cycles including the new European driving cycle (NEDC). On the basis of the presented results, it is possible to choose the right configuration of power electronics, PMSM and gearbox in order to have a good trade-off between high efficiency and low mass.

Pamukkale Universitesi Muhendislik Bilimleri Dergisi, 2015

The shielding efficiency of cylindrical shields for three phase underground cable is investigated... more The shielding efficiency of cylindrical shields for three phase underground cable is investigated for several shields material using finite element method (FEM). This FEM model takes into account the nonlinear hysteretic behavior for ferromagnetic material in the shield. The shields are cylindrical shaped and the power cables are positioned in flat configuration. The shielding efficiency is compared for shields with the same geometry but several shielding materials with nonlinear hysteretic behavior (Magnetil and DX52, both from Arcelor-Mittal firm) and a non-ferromagnetic and electrically conducting shielding material (Aluminium). The paper investigates the influence of several parameters on shielding efficiency: the size of the shield radius, the current amplitude in the cable and the thickness of the shield. Magnetil shield material is the best in terms of shielding performance. The numerical models are validated with experimental results for without shield.

Progress In Electromagnetics Research, 2011

The electromagnetic losses and shielding efficiency of shields for a buried three phase high volt... more The electromagnetic losses and shielding efficiency of shields for a buried three phase high voltage cable are studied for several shielding configurations. The shields are U-shaped gutters covered with plates, and the power cables are positioned either in trefoil or in flat configuration. The shielding efficiency and the losses are compared for shields with the same geometry but several shielding materials: aluminium, and two ferromagnetic steel grades. The numerical models are validated with experimental results. From the experiments, it is observed that the average reducing factor of the flux density is about 7 with the flat cable configuration while the average reducing factor of the flux density is about 5 with the trefoil cable configuration. But the power losses in the DX52 shield for trefoil configuration is about 40% lower compared to the flat configuration. In case of trefoil configuration, the losses are 12.14 W/m per meter length in the shield for a current of 750 A. Next to the shield material and the cable configuration, the paper investigates the influence of several parameters on both the shielding efficiency and the losses: the size of the shield, the current amplitude in the cable and the thickness of the shield.

This study presents a model of a drivetrain for an integrated design of a light electric vehicle ... more This study presents a model of a drivetrain for an integrated design of a light electric vehicle (EV). For the drivetrain of each front wheel of the single-person, battery-powered EV tricycle consists of a battery, an inverter, and an outer rotor permanent magnet synchronous motor (PMSM), which is connected to an in-wheel gearbox. The efficiency of the inverter, motor, and gearbox is analyzed over the New European Driving Cycle. To calculate the losses and efficiency of the PMSM, the power electronics in the inverter and gearbox are used. The analytical models provide a fast, but less accurate result, useful for optimization purposes. To accurately predict the efficiency of the PMSM, a finite element model is used. The models are validated by test setups. Correspondingly, a good agreement between the measurements and the calculated results is achieved. A parameter study is performed to investigate the influence of the detailed component parameters (i.e., outer rotor radius, gear ratio, and number of pole pairs and stator slots) on the average efficiency of the drivetrain.

Electrical Engineering, Apr 30, 2009

Abstract In this work, the low frequency electromagnetic flux density around induction motors is ... more Abstract In this work, the low frequency electromagnetic flux density around induction motors is studied; the main objective is to provide safety regions for humans in the vicinity of these motors, especially in electrical vehicles, where high currents and hence high flux density ...

Shielding of buried three phase high voltage cables can be done by placing the cables in conducti... more Shielding of buried three phase high voltage cables can be done by placing the cables in conducting ferromagnetic U-shaped gutters covered by plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, the induced currents in the shield efficiently reduce the field generated in the vicinity of the cables. However, as a perfect contact cannot be guaranteed, it is useful to quantify the effect of a bad electrical contact on the shielding performance. From 2D FEM, 3D FEM and experiments, it is observed that a bad contact does not influence significantly the shielding if the axial length of the plates is relatively long compared to their other dimensions.