The rapid growth of mobile data traffic will lead to the deployment of Ultra–Dense Networks (UDN) in the near future. Various networks must overlap to meet the massive demands of mobile data traffic, causing an increase in the number of... more
The rapid growth of mobile data traffic will lead to the deployment of Ultra–Dense Networks (UDN) in the near future. Various networks must overlap to meet the massive demands of mobile data traffic, causing an increase in the number of handover scenarios. This will subsequently affect the connectivity, stability, and reliability of communication between mobile and serving networks. The inclusion of Unmanned Aerial Vehicles (UAVs)—based networks will create more complex challenges due to different mobility characterizations. For example, UAVs move in three–dimensions (3D), with dominant of line–of–sight communication links and faster mobility speed scenarios. Assuring steady, stable, and reliable communication during UAVs mobility will be a major problem in future mobile networks. Therefore, this study provides an overview on mobility (handover) management for connected UAVs in future mobile networks, including 5G, 6G, and satellite networks. It provides a brief overview on the most...
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The integration of distributed generators (DGs), which are based on renewable energy sources, energy storage systems, and static VAR compensators (SVCs), requires considering more challenging operational cases due to the variability of DG... more
The integration of distributed generators (DGs), which are based on renewable energy sources, energy storage systems, and static VAR compensators (SVCs), requires considering more challenging operational cases due to the variability of DG production contributed by different characteristics for different time sequences. The size, quantity, technology, and location of DG units have major effects on the system to benefit from the integration. All these aspects create a multi-objective scope; therefore, it is considered a multi-objective mixed-integer optimization problem. This paper presents an improved multi-objective salp swarm optimization algorithm (MOSSA) to obtain multiple Pareto efficient solutions for the optimal number, location, and capacity of DGs and the controlling strategy of SVC a radial distribution system. MOSSA is a bio-inspired optimizer based on swarm intelligence techniques and it is used in finding the optimal solution for a global optimization problem. Two sets o...
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Seasonal analysis of wind speed includes elements of its evaluation and analysis for wind energy production in complex geographical areas. These analyses require wind energy systems to be set up, integrated, operated, and designed... more
Seasonal analysis of wind speed includes elements of its evaluation and analysis for wind energy production in complex geographical areas. These analyses require wind energy systems to be set up, integrated, operated, and designed according to seasonal differences. Istanbul wind speed data were collected hourly and analyzed seasonally. When the results of the analysis are examined, no significant increase in seasonal transitions was observed, while certain changes were observed between summer and winter. Here, statistical analysis, Weibull distribution function, and signal processing-based PSD analysis for wind speed is performed. In addition, correlation analysis was made between the seasons. Although significant results were obtained in signal-based analyses, results were obtained for seasonal transitions in correlation analyses. Seasonal spectral densities were calculated in the spectral analysis of wind speed data. This study has important implications in terms of extraction of ...
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The main objective of this paper is to present a reliability evaluation method for the electric power substation of the Light Rail DC Traction Electrification System. The Light Rail Systems which is a special part of rail systems will be... more
The main objective of this paper is to present a reliability evaluation method for the electric power substation of the Light Rail DC Traction Electrification System. The Light Rail Systems which is a special part of rail systems will be introduced, power traction of Light Rail Systems (LRS) will be explained and the reliability analysis of power traction in LRS will be performed. In this study, the structural reliability model of the power substation is developed on physical-based modeling of the components and system configuration. This study only concentrates on determining the reliability of a substation, not including system-wide effects. The reliability analysis is carried out individually for each unit that is composing the system, and then the total reliability of the system is determined according to various scenarios. The reliability analysis of power supply to the traction is performed for a real system named Habipler- Topkapi LRS which is located in İstanbul, Turkey.
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This study aims to extract the stationary features from a non-stationary data using continuous wavelet transform. For this purpose a Hall effect sensor is used to obtain current measurements during the welding operation. A welding process... more
This study aims to extract the stationary features from a non-stationary data using continuous wavelet transform. For this purpose a Hall effect sensor is used to obtain current measurements during the welding operation. A welding process includes several stages referred to as the initial case, transient case and operation case. In this manner, some frequency components can be determined for these cases thereby defining behavior of a particular welding machine. Regarding to the wavelet analysis results, fundamental frequency at 50 Hz is determined to be a dominant characteristic for the considered application. Moreover, side band effects are observed around the fundamental frequency. A sinusoidal waveform of 50 Hz is localized with huge amplitude values in very short time of the time-scale plane and this duration is required during the welding operation in terms of contact between the electrode and material surface.
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We present our preliminary results for the ground level electric and magnetic field variations in Turkey using Bozcaada station (GEO: 39.500N, 26.020E, MAG: 40.370N, 26.030E) magnetotelluric measurements. We find that our quiet day... more
We present our preliminary results for the ground level electric and magnetic field variations in Turkey using Bozcaada station (GEO: 39.500N, 26.020E, MAG: 40.370N, 26.030E) magnetotelluric measurements. We find that our quiet day observations agree well with the expected magnetic field variations for the magnetic field components at mid-latitudes, whereas we detect deviations from the mean magnetic field even for minor geomagnetic disturbances with KP=2. Temporal variation of the electric field components follow the changes in the magnetic field strength and likewise, storm effects are evident and lead to higher level of fluctuations in electric field magnitude for events with KP≥2. We note that this is the first time in Turkey that systematic, continuous and simultaneous measurements of the magnetic and electric fields are performed, which provide a great deal of opportunity to study the GIC effects during geomagnetic storms at mid-latitudes in more detail.
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This paper presents an electric power monoring based on Artificial Neural Network (ANN) for the nuclear power plants. The Recurrent Neural Networks (RNN) and the feed-forward neural network are selected for the plant modeling and anomaly... more
This paper presents an electric power monoring based on Artificial Neural Network (ANN) for the nuclear power plants. The Recurrent Neural Networks (RNN) and the feed-forward neural network are selected for the plant modeling and anomaly detection because of the high capability of modeling for dynamic behaviors. Two types of Recurrent Neural Networks (RNN) are used. The first one Elman type of RNN which has a feed-back from hidden layer to the input layer neurons while in the Jordan type, from the outputs of the neural net to the inputs of the neural net. Although this approach enables to realize the whole system condition monitoring in operating nuclear power plant (NPP), we are especially focused on active power and reactive power monitoring as well as power factor monitoring. Today, competition in electric power supply industry needs to properly evaluate plant capabilities and produced power quality, so the monitoring of active and reactive power becomes an important issue. There...
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Purpose - The purpose of this paper is to define the degradation of the bearings in electric motors related to parametric values. Design - Aging tests of an electric motor are performed according to IEEE test procedures. The vibration... more
Purpose - The purpose of this paper is to define the degradation of the bearings in electric motors related to parametric values. Design - Aging tests of an electric motor are performed according to IEEE test procedures. The vibration signals of the bearings are acquired via accelerometers. This step is followed by the analysis of the data in the spectral frequency domain. Finally, the Hurst parameter is calculated as a measure of the degradation. Since there is a simple relationship between the Hurst parameter and the Fractal Dimension concept, the latter can be considered as another parametric approach to define the degradation. Findings - We recognize that the positive Hurst parameter in the healthy case changes to a negative value for the faulty case, which indicates that the degradation is produced by the aging process. The difference between the parameters for the healthy and faulty cases is a measure of the degradation. Research limitations - The frequency band of the raw dat...
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This research describes random process modeling of the accelerated aging process based upon the mechanical degradation in induction motors. In order to show this aging effect, vibration measurements are considered at the end of each aging... more
This research describes random process modeling of the accelerated aging process based upon the mechanical degradation in induction motors. In order to show this aging effect, vibration measurements are considered at the end of each aging cycle, which gradually cause to bearing damage in the motor. In this manner, the accelerated aging study comprises seven aging stage sequentially and collected data set is presented as seven aging cycles and one initial cycle. Hence total aging process is represented by a set of the sequential vibration signals for initial and aged cases. Since the vibration signals are random values which represent the Gaussian distribution character in each period of measurement and this character can be conveyed to the next stage with a scaling of the signal related to elapsed time, the process reminds the Brownian motion or the so-called random walk and it is expected that the degradation can be described as a Wiener process. Examining the collected data proves...
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Contemporary engineering approach shows a trend in which the predictive maintenance i.e., online monitoring and early detection of the failures take the place of the periodic maintenance. This study focused on capturing an aging trend of... more
Contemporary engineering approach shows a trend in which the predictive maintenance i.e., online monitoring and early detection of the failures take the place of the periodic maintenance. This study focused on capturing an aging trend of the bearing of a 5-HP induction motor. Independent Components Analysis (ICA) based on the wavelet package analysis has been used to foreseen the bearing
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This paper presents a new modeling approach using non-linear transformation to represent the changes of the statistical parameters which are dependent on the accelerated aging process. This approach enables the extraction of the... more
This paper presents a new modeling approach using non-linear transformation to represent the changes of the statistical parameters which are dependent on the accelerated aging process. This approach enables the extraction of the statistical character of the bearing damage that has been developed during the accelerated aging process. This proposed transformation approach is applied to assess the statistical properties of
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Determining and forecasting the load behavior in distribution systems are very important in both operational and planning stages. Increased penetration of thermostatically-controlled loads such as air-conditioners, water heaters, heat... more
Determining and forecasting the load behavior in distribution systems are very important in both operational and planning stages. Increased penetration of thermostatically-controlled loads such as air-conditioners, water heaters, heat pumps, etc. has resulted in many investigations on how to determine an accurate dynamic of these loads. Thermostatically-controlled loads are also a candidate for the direct load control because of their
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This paper presents two new performance indices for contingency analysis in a composite electric power system. The proposed indices are derived from active power transmission losses that do not require additional parameters. They can be... more
This paper presents two new performance indices for contingency analysis in a composite electric power system. The proposed indices are derived from active power transmission losses that do not require additional parameters. They can be used effectively for line overloading and bus voltage limit violation performance indices. Their effects are tested on an IEEE RTS and the results have shown
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This paper presents two new performance indices for contingency analysis in a composite electric power system. The proposed indices are derived from active power transmission losses that do not require additional parameters. They can be... more
This paper presents two new performance indices for contingency analysis in a composite electric power system. The proposed indices are derived from active power transmission losses that do not require additional parameters. They can be used effectively for line overloading and bus voltage limit violation performance indices. Their effects are tested on an IEEE RTS and the results have shown
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This paper presents a new active failure simulation for electric power distribution system reliability assessment. The main principle depends on the first and second order groups established for the nodes existing in basic minimal cut... more
This paper presents a new active failure simulation for electric power distribution system reliability assessment. The main principle depends on the first and second order groups established for the nodes existing in basic minimal cut sets. The proposed algorithm is applied to a sample distribution network and three basic reliability indices are calculated. It was seen that the same values
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Minimal path determination is one of the main steps in the reliability assessment of electric power transmission and distribution systems. This paper presents a new method for minimal path determination in electric power distribution... more
Minimal path determination is one of the main steps in the reliability assessment of electric power transmission and distribution systems. This paper presents a new method for minimal path determination in electric power distribution systems. The proposed method is derived from an existing scheme by slight modifications. The method makes use of Boolean algebra and set theory and is easy
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Power system reliability assessment is divided into two basic aspects: system adequacy and system security. This paper is aimed at evaluating the adequacy of composite power systems. A contingency enumeration method is used for the... more
Power system reliability assessment is divided into two basic aspects: system adequacy and system security. This paper is aimed at evaluating the adequacy of composite power systems. A contingency enumeration method is used for the calculation of composite power system adequacy indices. The selections of the contingencies to be examined are determined using different performance indices obtained by making use
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Contingency ranking and selection is an indispensable tool for static security analysis. Several performance indices suffer either from misranking or computational inefficiencies. This paper presents a new performance index for MW line... more
Contingency ranking and selection is an indispensable tool for static security analysis. Several performance indices suffer either from misranking or computational inefficiencies. This paper presents a new performance index for MW line flow contingency selection and ranking. The proposed index is derived from real power transmission losses. It is a quadratic function of bus voltage angles and can easily be