Yazarlar
- Ozden, Talat(16)
- Akinoglu, Bulent G.(15)
- Sezer, İsmet(11)
- Basoglu, Mustafa Engin(9)
- Özden, Talat(8)
- Akpinar, Adem(7)
- Terhan, Meryem(7)
- Başoğlu, Mustafa Engin(6)
- Cakmak, Recep(6)
- Erol, Ismail(6)
- Peker, Iskender(6)
- Turan, Rasit(6)
- Akpinar, A.(5)
- Ar, Ilker Murat(5)
- Kömürcü, Murat Ihsan(5)
- Sezer, Ismet(5)
- Altas, Ismail H.(4)
- Altuner, Elif Esra(4)
- Benli, Tolga(4)
- Bozbeyoglu, Pinar(4)
- Kaygusuz, K.(4)
- Tunç, Merve Tuğçe(4)
- Akyol, Mehmet(3)
- Altan, Aytaç(3)
- Barut, Abdulkadir(3)
- Bilgin, Atilla(3)
- Genc, Omer(3)
- Kankal, Murat(3)
- Kaygusuz, Abdullah(3)
- Kaygusuz, Kamil(3)
- Ozden, T.(3)
- Pilatin, Abdulmuttalip(3)
- Saribiyik, Oguz Yunus(3)
- Searcy, Cory(3)
- Timurkutluk, Bora(3)
- Toros, Serkan(3)
- Turan, İsmet(3)
- Yanarates, Cagfer(3)
- Yanarateş, Cağfer(3)
- Çakmak, Recep(3)
Yayınlar
- MakaleAçık Erişim2020Solar irradiation on the rear surface of bifacial solar modules: a modeling approach
Durusoy, Beyza; Ozden, Talat; Akinoglu, Bulent G.
The transition in the energy sector has started with the growing population leading to the growing energy demands. The use of photovoltaic (PV) technologies has become a crucial way to meet energy demand. There are many ongoing studies for increasing the efficiency of commercial PV modules. One way to increase the energy yield of the PV modules is to use bifacial solar panels by capturing the rear side illumination as well. One of the challenges for estimating the bifacial module performances is to calculate the solar irradiation impinging on the rear side. Many models presented up to now require high computational power, and they are challenging to implement real-life conditions. In this paper, a simple physical modeling approach is presented to calculate the rear side solar irradiation incident on the bifacial modules. For the rear side irradiance estimation, the maximum difference between the measured and calculated rear side irradiance value is approximately 10 W/m2. The model does not require high computational skills since it is neither focused on the view factor nor ray tracing methodologies but instead uses solar geometry. The yield of the module is also modeled, calculated, and compared with the measurements.
- BildiriYalnız künye2020Nine Years Long Term Performance and Degradation Assessment of Two On-Grid PV Systems
Ozden, Talat; Ozgun, Ensar Mesut; Keles, Bedirhan; Akinoglu, Bulent G.
Nine years outdoor testing of the two on-grid PV systems at Central Anatolia under the same ambient conditions is very important to be discovered toward transition to renewables. The systems consist of a monocrystalline silicon and micro-crystalline silicon based amorphous thin film PV technologies. The analyses are carried out on monthly based using the outdoor efficiencies. In addition, degradation rates of these systems are calculated and compared with each other and also with international literature. It is also compared the results using the degradation rates of an earlier study carried out using measurements of a shorter period of time.
- MakaleAçık Erişim2020AN EXTENDED ANALYSIS OF THE MODELS TO ESTIMATE PHOTOVOLTAIC MODULE TEMPERATURE
Ozden, Talat; Tolgay, Doga; Yakut, M. Samet; Akinoglu, Bulent G.
To estimate the performance of the photovoltaic power systems is the key issue in their techno-economic feasibility analysis. Performances, on the other hand, strongly depends on the module temperatures of the photovoltaic systems. In this study, we evaluated the performance of ten different module temperature estimation models using the measured outdoor data of five different modules. The modules are installed at the rooftop of a building located at Central Anatolia where the climate is cold and semi-arid. The results showed that the models having smaller number of parameters perform better than the others. We concluded that such analysis should be carried out at different ambient conditions so that the best performing models for the site can be obtained. Another outcome of the study is that the seasonal evaluation of the performance of the models should be carried out.
- MakaleYalnız künye2020A review study on using diethyl ether in diesel engines: Effects on fuel properties, injection, and combustion characteristics
Sezer, İsmet
This study was compiled from the results of various researches performed on using diethyl ether as a fuel or fuel additive in diesel engines. Three different techniques are used, the reduction of the harmful exhaust emissions of diesel engines. The first technique for the reduction of harmful emissions has improved the combustion by modification of engine design and fuel injection system, but this process is expensive and time-consuming. The second technique is the use of various exhaust gas devices like catalytic converter and diesel particulate filter. However, the use of these devices affects negatively diesel engine performance. The final technique to reduce emissions and also improve diesel engine performance is the use of various alternative fuels or fuel additives. The major pollutants of diesel engines are nitrogen oxides and particulate matter. It is very difficult to reduce nitrogen oxides and particulate matter emissions simultaneously in practice. Most researches declare that the best way to reduce these emissions is the use of various alternative fuels i.e. natural gas, biogas, biodiesel, or the use of fuel additives with these alternative fuels or conventional diesel fuel. Therefore, it is very important that the results of various studies on alternative fuels or fuel additives are evaluated together for practice applications. Especially, this study focuses on the use of diethyl ether in diesel engines as fuel or fuel additive in various diesel engine fuels. This review study investigates the effects of diethyl ether on the fuel properties, injection, and combustion characteristics.
- MakaleAçık Erişim2020Dynamic thermal modelling of PV performance and effect of heat capacity on the module temperature
Tuncel, B.; Ozden, T.; Balog, R. S.; Akinoglu, B. G.
One of the main weaknesses of Si-based Photovoltaic (PV) solar modules is the sensitivity of their efficiency to module (cell) temperature. Especially in locations with long hot seasons, the efficiency loss of PVs due to high temperatures should be considered carefully. Thermal modelling is a method to predict the performance of a PV module using essentially the 1st law of thermodynamics and available data. In this paper, a transient thermal model is described, which considers hourly meteorological data, including wind speed and direction, module parameters, and locational information. In transient analysis, the heat capacity value of PV panel is required, but it is not a parameter specified in the manufacturer's datasheet. Experiments on the heat capacity of PV modules are missing in the literature. The thermal model provides verified performance analysis for a poly-c-Si PV module installed in Ankara, Turkey, with a calculated heat capacity value. And a sensitivity analysis for the heat capacity of the transient thermal model is performed. It is found that the model results are almost invariant under changing module heat capacity values.
- MakaleAçık Erişim2019An Approximate Short Circuit Strategy for Transient MPPT Performance of Uniformly Irradiated Photovoltaic Modules
Başoğlu, M. E.
This paper presents an improved strategy to provide better maximum power point tracking (MPPT) performance and increase energy yield during transient state of MPPT process. This strategy is based on the estimation of short circuit current (SCC) of the photovoltaic (PV) system without short circuit. Besides that, this strategy aims to decrease convergence time to maximum power point (MPP) by preventing real short circuit of PV source and eliminating the additional switch requirement. To determine performance of the proposed strategy, simulation studies have been performed in MATLAB/Simulink and this strategy has been compared with fractional SCC (FSCC) technique and perturb and observe (P&O) algorithm. In addition, to make validation experimentally, a low powered single ended primary inductance converter (SEPIC) is realized. Both simulation and experimental results show that proposed strategy performs better transient MPPT performance than FSCC technique and P&O algorithm.
- MakaleAçık Erişim2019Analyzes of Flyback DC-DC Converter for Submodule Level Maximum Power Point Tracking in Off-grid Photovoltaic Systems
Başoğlu, M. E.
Submodule level maximum power point tracking (MPPT) systems have become popular due to its outstanding performance in partial shading conditions (PSCs) and basic algorithm requirement. MPPT is realized by DC-DC converters. They are power processing units between photovoltaic (PV) module and resistive load. Among DC-DC converter topologies, the flyback is a proper choice since it can either increase or decrease the voltage. Furthermore, power level is small in submodule level (SML) MPPT applications. In this study, analyzes and power circuit design of a flyback converter for continuous conduction mode (CCM) is carried out firstly. Then, the performance of the flyback converter on the SML MPPT system and its superiority over the module level MPPT is shown by using same converter topology and perturb and observe (P&O) algorithm. In order to validate the superior performance of SML MPPT, it is compared with module level MPPT in MATLAB/Simulink environment. Results show that SML MPPT guarantees global MPPT in any PSCs with any kind of basic MPPT algorithm. On the other hand, module level MPPT fails in many PSCs with the same algorithm. According to simulation results, SML MPPT generated more power by 61.2% in average than module level MPPT systems in simulation studies.
- MakaleAçık Erişim2019Finansal gelişme ve enerji tüketimi arasında saklı eş bütünleşme ilişkisi var mıdır
Pala, Fahrettin; Çam, Alper Veli; Ayaydin, Hasan; Barut, Abdulkadir
Enerji, ekonominin vazgeçilmezidir veekonomik büyüme için önemlidir. İnsanoğlununhayatta kalması ve ekonomik büyümesi için enerjitemel bir gereksinimdir ve enerji moderntoplumların temelini oluşturmaktadır. Ekonomikgelişimin can damarı ve sırt kemiğidir. Ticaretinartırılmasında ve büyüme düzeyininyükseltilmesinde önemli rol oynamaktadır.Literatüre göre büyüme düzeyini artırır. Ekonomikliteratürde; ekonomik büyüme, ticaret, enerji vefinansal gelişmeyi içeren dinamik ilişkiler dikkatçekmektedir. Bu bağlamada çalışmanın amacı; E-7ülkelerinde (Brezilya, Çin, Hindistan, Endonezya,Meksika, Rusya ve Türkiye) finansal gelişme, enerjitüketimi ve ekonomik büyüme arasında saklı birilişkinin varlığının 2003-2016 dönemi içinincelenmesidir. Bu amaçla Hatemi- J (2011)tarafından geliştirilen saklı eş-bütünleşme analizi veHatemi- J (2012) Asimetrik nedensellik analizlerikullanılmıştır. Analiz sonuçlarına göre negatifbileşenler arasında saklı bir eş-bütünleşme ilişkisitespit edilmiştir. Diğer yandan ekonomik büyüme vefinansal gelişmeden enerji tüketimine doğru tekyönlü bir nedensellik tespit edilmiştir.
- MakaleAçık Erişim2019A fuzzy logic reasoning based real time energy price regulation approach for smart grids
Cakmak, Recep; Çakanel, Ahmet
Intelligent technologies have become pioneer force to provide flexible, dynamic and efficient energy generation andmanagement. Thus, smart algorithms such as fuzzy logic, artificial neural network, machine learning, soft computingtechniques are sole remedy against growing diverse and numerous distributed generations that make more complicatedpower systems. Real time closed loop controlling requires energy price as a featured variable to procure supply demandequilibrium point for a stable and reliable power system operation, where several dynamic models and estimationsoftware are introduced in the literature. In this study, a fuzzy logic reasoning-based price regulator (FLR-PR) is designedand simulated on MATLAB/Simulink environment using 2018 hourly data of a summer day taken from annual energyreport of Turkey. The proposed model has been compared to Proportional Integral Derivative (PID) price controller basedon performance indexes in the constituted simulation cases. FLR-PR tracks instant reference demand signal changes withminimum steady state error and fast transient response with respect to PID controller.
- MakaleAçık Erişim2019A Comparative Study of Machine Learning and Deep Learning for Time Series Forecasting: A Case Study of Choosing the Best Prediction Model for Turkey Electricity Production
Ünlü, Ramazan Erkin
Over the last decades, Turkey pays special attention to electricity productionto afford its needs. Researchers applied different methodologies including statisticalbased and artificial intelligence-based to correctly predict the future amount of electricityproduction, consumption, and demand. However,limited researchers focused on Turkey’selectricity production prediction problem as a time series analysis. For this reason, wetackle this problem by considering it as a time series analysis in this study. We haveused different methods including traditional machine learning algorithms Support VectorRegression (SVR) and Multilayer Perceptrons (MLP) and a deep learning algorithm LongShort-Term Memory (LSTM) to create a better model for Turkey monthly electricityproduction dataset. Based on our findings LSTM outperforms SVR and MLP approachesin terms of commonly used statistical error evaluation metrics
- MakaleAçık Erişim2019Effect of nano materials additives on fuel properties and combustion characteristics
Sezer, Ismet
This study compiled the results of various researches performed on using nanomaterials additives in diesel engine fuels such as diesel, biodiesel, water emulsified fuels and various fuel blends. Three different techniques are used the reduction of the harmful exhaust emissions of the diesel engine. The first technique for the reduction of harmful emissions is improved the combustion by modification of engine design and fuel injection system, but this process is expensive and time consuming. The second technique is the using various exhaust gas devices like catalytic converter and diesel particulate filter. However, the use of these devices affects negatively diesel engine performance. The other technique to reduce emissions and also improve diesel engine performance is the use of various fuel additives. The major pollutants of diesel engine are oxide of nitrogen (NOx) and particulate matter (PM). It is very difficult to reduce NOx and PM simultaneously in practice. The most researches declare that the best way to reduce the emissions and increase the engine performance is the use of nano material additives and water emulsified fuels. The effects on fuel properties and combustion characteristics of different nano material additives in various diesel engine fuels are investigated in this review.
- BildiriYalnız künye2019Realization of a low cost and fast boost converter based MPPT for PV system
Basoglu, Mustafa Engin
Photovoltaic (PV) modules have a small power conversion efficiency since material technologies used in commercial PV modules is weak and not well developed. In order to provide the maximum available efficiency in a PV module, a power processing unit (PPU) is connected between PV module and load to extract more power from PV modules In other words, DC-DC converters are used for impedance matching between PV module and load in any kind of loading and environmental conditions. Several maximum power point tracking (MPPT) algorithms have been proposed in the literature. But there are still shortcomings to be improved such as reducing the steady state ripples in power, dynamic response time under changing conditions. In this paper, design steps of the boost converter for an MPPT application have been presented and some experiments have been performed. Consequently, a low cost and fast boost converter based MPPT is implemented.
- MakaleYalnız künye2019Forecasting of Turkey’s monthly electricity demand by seasonal artificial neural network
Hamzaçebi, Coşkun; Es, Hüseyin Avni; Çakmak, Recep
Electricity is one of the most important end-user energy types in today’s world and has an effective role in development of societies and economies. Stability of electricity supply is provided by matching of generated and consumed electricity amount during the all-day. So, electricity consumption forecasting is an essential issue for electric utilities. In this study, the monthly electricity demand of Turkey has been predicted. To model the effects of seasonality and trend, four different ANN models have been developed and selected the superior one. In addition, the selected ANN model has been compared with SARIMA model in order to increase the acceptability and reliability of the ANN model. The monthly electricity demand of Turkey has been predicted between 2015 and 2018 via the ANN model that can make successful and high-accuracy predictions according to the performance measures. The forecasting values will help in determining the medium-term and stable energy policies.
- MakaleYalnız künye2019A fuzzy logic embedded energy management software with multi-agent system for a stand-alone PV power plant
Ozden, T.; Kesler, S.; Okumus, H.I.
The worst scenario projected for an off-grid photovoltaic power system is the time interval that the solar irradiation amount is in short to supply the load throughout the day, and this situation is resulted in energy deficiency. Nowadays, an off-grid power generating system, which is designed to consider the worst scenario encountered only during a certain period of time, brings through big financial problems in terms of the initial installation costs. This study proposes a smart software to perform energy management considering users’ comfort and their criteria, which are taking some information from the agents communicating with the consumption units wirelessly and the battery agent. All loads and agents in this system are initially defined by the user according to the importance of the consumption loads such as critical, essential, significant, lesser, and insignificant loads. The proposed energy management software includes fuzzy logic-based decision maker to manage load suspension or put the suspended load into effect again according to the state of the sources. The total amount of consumption is kept less than the total existing energy so that the energy to be consumed by the critical loads is always provided. Considering the existing amount of energy and consumer preferences, the total amount of load units is maximized at each sampling step. The proposed system, which is attained without compromising the user comfort, enables more efficient energy consumption. Also, for supplying the critical loads in case of lack of energy is possible.
- MakaleYalnız künye2019An improved 0.8 V OC model based GMPPT technique for module level photovoltaic power optimizers
Basoglu, Mustafa Engin
Photovoltaic modules may experience some mismatching conditions that affect their available power capacity, causing inefficient maximum power point tracking (MPPT). Furthermore, their power-voltage (P-V) characteristic curve becomes a multi-peak structure in such conditions owing to the presence of bypass diodes included since every part of the modules may receive different solar irradiance. By taking into account these facts, this paper introduces an improved global MPPT technique comprising 0.8 V OC model and the limited and adaptive scan approach. The proposed technique eliminates the requirement of some threshold value, leading to unreliable operation which the classical 0.8 V OC model based studies suffer from. Furthermore, the tracking time has been reduced substantially with the proposed technique by limiting scanning interval. Performance of the proposed technique has been verified by experimental studies and compared with classical 0.8 V OC model and a full scanning technique, which have been already presented in the literature. Experimental results show that the proposed technique is simple to be implemented and it has better performance than classical 0.8 V OC model, full scanning, and perturb and observe algorithms. Therefore, the proposed technique is feasible and it can be used technically in module level distributed MPPT (DMPPT) applications.
- MakaleAçık Erişim2019A fast GMPPT algorithm based on PV characteristic for partial shading conditions
Başoğlu, Mustafa Engin
Photovoltaic (PV) modules experience some partial shading conditions (PSC) due to some various factors. In that kind of a condition, a few maximum power points (MPPs) possibly appear on the power-voltage (P-V) curve, which increases the tracking difficulties. It is known that maximum power point tracking (MPPT) may not be realized by hill climbing (HC) based conventional MPPT algorithms under PSCs. In this context, this paper presents a novel micro converter based algorithm that was developed by using P-V characteristics of PV modules. Unlike voltage or duty ratio scanning techniques, this paper introduces a new deciding method to determine the correct global MPP (GMPP) region. For this, the proposed method uses some duty ratios that were calculated corresponding to each MPP region. Thus, the initialization of duty ratio is done properly, which results in high tracking speed and accurate tracking of the GMPP. The other advantages of the proposed algorithm are structural simplicity, less computational burden, and ease of implementation with a basic microcontroller. The simulation results show that this algorithm has fast tracking capability and it manages to track GMPP for PSCs correctly, since it includes an artificial scanning procedure. Single ended primary inductance converter (SEPIC) is built in order to validate the proposed global maximum power point tracking (GMPPT) algorithm. The performance of the proposed GMPPT technique is verified by experimental studies. The results show that the proposed GMPPT technique is fast by up to five times than an adaptive full scanning strategy and improved IC algorithm. Furthermore, the proposed algorithm can be commercially used in micro converters, since it is compatible with small number of bypass diodes in a module.
- Derleme MakaleAçık Erişim2019A Review Study on the Using of Diethyl Ether in Diesel Engines: Effects on CO2 Emissions
Sezer, İsmet
Vehicle and other fuel combustion emissions can change the composition of the atmosphere, increasing its ability to trap heat. Gases that are effective in trapping heat are called greenhouse gases and include all of the gases in vehicle emissions. The major component of greenhouse gases emissions is carbon dioxide (CO2). Reduction of CO2 emissions has become a concern worldwide. Introduction of biofuels to fueling of automotive engines is the one method to decrease emissions of greenhouse gases. The CO2 from biofuels, is emitted during combustion and absorbed during growth of tree end plants. These biofuels can be applied as blends or sole fuels. The most researches declare that the best way to reduce greenhouse emissions is the use of various biofuels. Therefore, it is very important that the results of various studies on alternative fuels or fuel additives are evaluated together to practice applications. On the other hand, diesel cars are also helping to reduce CO2 emissions. For these reasons, this study especially focuses on the use diethyl ether in diesel engines as fuel or fuel additive in various diesel engine fuels. This review study investigates the effects of diethyl ether addition on the CO2 emissions.
- BildiriYalnız künye2019Design of a MATLAB GUI for Day Ahead Forecasting of PV Panel Power
Bektas, Sibel Cevik; Cakmak, Recep; Altas, Ismail H.
This paper introduces design and utilization of a MATLAB graphical user interface (GUI) platform to forecast day ahead hourly Photovoltaic (PV) panel power by using forecasted day ahead global horizontal solar radiation. This platform, which would be a useful and practical tool for researchers who are study on energy management, planning and forecasting studies, consists of three parts. The first part predicts day ahead global horizontal solar radiation by trained artificial neural network (ANN) model. The second part performs the calculation of solar irradiation on the module, which has a tilted angle according to forecasting solar radiation data. The last part estimates the power generated by PV panel according to the calculated incident radiation. In this study, the solar irradiation forecasting, the calculation of incident radiation to tilted module and prediction of the solar power to be generated by the PV module are done. The designed GUI has been utilized to forecast solar radiation and PV output power for test days. Then obtained forecasted data have been evaluated with mean absolute percentage error (MAPE) and correlation coefficient (R).
- MakaleAçık Erişim2019Preliminary investigations on two different procedures to calculate the efficiency and performance ratio of PV modules
Ozden, T.; Akinoglu, B.G.
Short- and long-term outdoor performances of the photovoltaic (PV) modules are extremely important in reaching their economic viabilities. Such information is very valuable for the investors, customers and researchers of PV technologies. Two different procedures are possible, and both are used by many researchers. However, to the best of our knowledge, there is no comparative investigation to evaluate these two procedures. One of the methods uses instantaneous I–V curves of PV modules taken in a specified instant of time, while the others simply use the integrated energy values of the input and the yield of PV modules. In fact, both have advantages and disadvantages. In the present work, we outlined the advantages and disadvantages of both methods and compared them using the data of two different cell-type modules which are installed at GÜNAM’s outdoor test facility. In the analysis, the data that we used are taken under the same outdoor test conditions and ambient weather conditions. The outcomes of these preliminary analyses can be summarized as follows: (1) The procedure that uses instantaneous I–V curves seems dependent on the specified time intervals and ambient weather conditions at that instant; (2) accordingly, we will propose how to determine an optimal time interval to reach better performance results; (3) using the integrated values, we achieved the variations in performances with different integration time periods; (4) preliminary comparisons of these two procedures resulted in key conclusions on performance and degradation calculations of PV modules.
- MakaleYalnız künye2019Ohmic heating assisted hydrodistillation of clove essential oil
Tunç, Merve Tuğçe; Koca, İlkay
Ohmic heating assisted hydrodistillation is a novel green technology for the extraction of essential oils. In this study, clove bud essential oils (CEO) were extracted by ohmic heating assisted hydrodistillation (OAHD) and compared with conventional hydrodistillation (HD) process, in terms of extraction yield, energy consumption and chemical properties. Ohmic heating assisted hydrodistillation process conditions were optimized by response surface methodology. Voltage gradient (7.5–12.5 V/cm, A), process time (30–120 minutes, B) and mass of clove bud (20–40 g, C) were varied in order to maximize CEO yield and to minimize energy consumption. Optimized extraction conditions were determined as, 12.5 V/cm voltage gradient, 97.967 min for process time and 40 g of mass of clove bud. Yield of CEO and energy consumption were found 13.18 ± 1.50% and 0.214 ± 0.030 kW h/g CEO at optimum extraction conditions, respectively. Under optimum conditions, both OAHD and HD methods were used for CEO extraction. Yields of CEO obtained by OAHD, HD-D (distilled water) and HD-S (salted water) were 13.18 ± 1.50, 8.23 ± 0.35 and 7.88 ± 0.60 respectively. Energy consumptions of OAHD and HD methods were not significantly different (P > 0.05). The main chemical component of CEO was eugenol and the yield of eugenol (g/100 g clove bud) was found higher with OAHD (6.95±0.6) method than HD-D (5.16 ± 0.20) and HD-S (5.13 ± 0.28). Antioxidant and antimicrobial properties of CEOs were investigated by FRAP, DPPH and disk diffusion method. Antioxidant properties of CEOs obtained by different extraction methods were not significantly different (P > 0.05) according to FRAP and DPPH analysis. Although inhibition zones of CEOs extracted with different methods were not significantly different (P > 0.05) for gram positive bacteria's, CEO obtained by OAHD and HD-D have significantly higher (P < 0.05) inhibition zones for K. pneumonia and E. coli, respectively. The results of this study showed that OAHD method is applicable for CEO production.
