Theses supervised by Prof. Dr. Bülent Yeşilata
10 theses · Ankara Yıldırım Beyazıt University
Optimal management of a virtual power plant considering renewable energy resource plus energy storage unit
The global effort to address extreme carbon emissions has garnered significant attention from both public and private sectors, notably through initiatives spearheaded by the United Nations, such as the Sustainable Development Goal 7 (SDG7).Within this context, renewables are crucial for achieving the SDG7; however, the inherent intermittency and unpredictability of RES outputs impose serious reliability challenges on power systems, often resulting in unforeseen power imbalances, outages, and abrupt shutdowns. To manage these technical challenges, this study proposes a data-driven modeling approach utilizing Battery Energy Storage Systems (BESS) and Diesel Generators (DGs) in a Distributionally Robust Joint Chance-Constrained Optimization (DR-JCCO) framework, formulated through Mixed-Integer Linear Programming (MILP) to maintain convexity. This study integrates tractable algorithms, specifically the Conditional Value-at-Risk (CVaR) and H-X algorithms, to improve system performance within Integrated Energy Modeling Systems (IEMs). The findings indicate that CVaR provides efficient BESS operation and operational cost minimization without necessitating wind power curtailment, though it is associated with higher computational burden. In contrast, the H-X algorithm demonstrates superiority in terms of tractability, achieves faster BESS cycling, and results in reasonable profit output margins. Furthermore, the H-X algorithm establishes a new benchmark for enhancing existing optimization models such as REopt applied in IEM applications. Finally, Binomial Expansion (BE) has been applied to selectively reformulate a non-linear upper-level objective function, to demonstrate the robustness and efficiency of linear models solved by the off-the-shelf solvers such as Gurobi.
Design and modeling of energy storage systems integrated with solar photovoltaic energy
Fossil energy resources on the world are rapidly being depleted. It is seen that the speed of energy consumption has increased with the developing technology in recent years. Therefore, it was ensured that the solar energy, which emerged with the researches for energy resources that can renew itself and never run out, was transformed into a usable energy source. However, with the day and night situation of the Earth around itself, the use of solar energy only during the day and other natural reasons have started to work to store the energy produced when there is no solar source. These studies, also called solar energy storage, will be more valuable and improved day by day and their efficiency will be maximized. In this study, previous studies are reviewed and presented in a comprehensive way. Many different methods for storing solar energy and increasing its efficiency are discussed with mathematical and experimental methods. The gaps in existing literature are identified and recommendations for future research are precisely outlined. In this study, the outputs of the chosen method for the storage of solar energy in different geographical regions were analyzed.
Design and concepts of nearly-zero energy buildings
Global warming and climate change have become increasingly important issues in recent decades. The use of fossil fuels is one cause. The use of fossil fuels causes CO2 emissions. Therefore, buildings need to be designed with a new strategy on low energy with very high energy efficiency. In order to reduce the dependence of the building on primary energy, the concept of nearly-zero energy building (NZEB) is created. It is recommended that the definition of near-zero energy buildings, renewable energy and efficiency measures work together. The European Union (EU) aims to drastically reduce domestic greenhouse gas (GHG) emissions by 80% by 2050 compared to 1990 levels. In this work, design strategies, the use of low conductivity materials, the installation of low energy devices to reduce the energy demand of buildings and the necessary additions of renewable energy systems are presented to achieve a near zero energy building design. These aforementioned approaches are implemented in an example building as a case study. The obtained results show that there are many ways to achieve a near-zero energy building, but the cost issue remains the most important decision parameter.
Design and analysis of a greener disposal system for energetic materials and munitions
Demilitarization is becoming more and more significant in management of the munitions since all munitions have a finite lifetime and these munitions can reach their service life for a variety of reasons such as; the process of natural aging, becoming obsolete due to the development of new systems, becoming surplus because of the changed requirements or requirement to be destroyed owing to international agreements. Military munitions, pyrotechnics, and vehicle airbag propellants are examples of energetic materials, which contain a large quantity of stored chemical energy that can be released. In this study, it has been aimed to review available demilitarization process, asses their environmental impact and identify their advantages and disadvantages. The study is primarily focus on disassembly, removal of energetics and destruction phases. Computational Fluid Dynamics (CFD) analyses has been carried out for the multiphase flow of the water-explosive slurry and flow behavior in different configurations has been investigated. Results of the analysis are discussed considering sensitivity of energetic material in these configurations.
A case analysis for optimizing the balance between solar photovoltaic electricity supply and electricity demand of a facility
Today, energy constitutes the common agenda of the world. Despite the increasing individual and global energy demand with developing technology, the limited conventional fossil fuel reserves cause interruptions in energy supply. Because of this strategic importance, energy has become the security and strategic policy of countries rather than the problem of a family or a production line. In order to meet the increasing energy demand due to the inadequacy and finiteness of fossil resources, renewable energy sources have quickly come to the agenda of the world. Since renewable energy sources are insufficient to meet the consumption demand on their own, research and development studies are carried out to support these systems. With this thesis, the energy production of the unlicensed rooftop solar power plant with a generation capacity of 404.6 kWp connected to the grid from the low voltage level and the energy consumption of the facility where it is installed are analyzed in detail and solution proposals are presented in detail in order to minimize the differences between production and consumption. For the data to be used in the study, real-time data were obtained from the energy analyzers of the production and consumption facilities. In the light of the data obtained, solution suggestions are given in order to achieve the production-consumption balance.
Developing a case study for efficient utilization of solar PV systems in Somalia
This thesis explores the potential of photovoltaic systems as a solution to Somalia's power problems, such as lack of access and high costs. The study looks at a rural area called Jazeera, 15km away from Mogadishu, which faces power shortages. The results show that grid extension and microgrid systems are not cost-effective, but solar home systems are suitable solutions for homes that fall into three categories according to power consumption. The thesis also analyzed Safari Hotel, located at latitude (2.033) and longitude (45.3044), where electricity bills are high, the design and investigation of this project is carried out by using a mathematical approach and Photovoltaic Geographical Information System (PVGIS) for getting all necessary data and calculating monthly and annual PV generation in this project. The result showed that hybrid and grid-connected solar systems could reduce costs by at least fifty percent. 126 solar panels, 72 batteries, and 4 inverters would be required for a hybrid solar PV system; the estimated capital cost for this system is $83,800, and this system has an estimated payback period of 2.5 years, while the grid-connected solar system in this study used two different feed-in-tariff models: a grid-tied PV system that uses the gross metering billing method would require 189 solar panels and 5 grid-tied inverters; this system has the annual capability of producing 175223.24 kWh; the estimated capital cost for this system is $33,490 with a 1-year payback period; while another one that uses the net metering billing method would require 126 solar panels and 4 grid-tied inverters, this system has the annual capability of producing 116815 kWh; the estimated capital cost for this system is $25,000 with a 9-month payback period. Through the use of the designs and analyses in this thesis, there is a chance of eliminating at least 93452.456 kg per year of carbon dioxide that would have been emitted from a diesel generator producing the same amount of electricity. This also provides an opportunity to save $33,292 per year that would have been paid to electric utility companies. This thesis concludes that solar energy is the best solution for Somalia's electricity challenges.
Performance analysis of photovoltaic-thermal (PV/T) solar systems
Hybrid Photovoltaic/Thermal systems, also called as PV/T systems or solar cogeneration systems, are innovative power generation technologies that convert solar radiation into usable thermal and electrical energy. Such systems combine a solar photovoltaic module, which convert sunlight into electricity, with a solar thermal collector, which captures the remaining energy and removes waste heat from PV module. The performance of PV/T system is higher than that of PV module. To improve the performance of PV/T systems a lot of the studies have been done and researchers keep on investigating these systems. A comprehensive review on these previous research studies are presented here. Many methods and approaches to enhance the performance of the PV/T systems are discussed along with the mathematical models used. The gaps in existing literature are identified and recommendations for future research are precisely outlined. It is emphasized here that only few experimental studies on PV/T systems based on nanofluids are exist. Therefore, comprehensive experimental studies under real atmospheric conditions should be done with these systems, without neglecting effects of variations in mass flow rate of nanofluids. The aim of our study is to investigate the performance of PV/T systems under the climatic conditions of Niamey the capital city of Niger. Niger has a great solar potential with a monthly average irradiation of 9 hours. Thus, a theoretical study was conducted, followed by a comparison of the performance of PV/T system with stand-alone PV module. The obtained results were consistent with the previous works on these systems. The electrical efficiency of the PV/T system increases by 0.1 percent per degree Celsius, and the cell temperature decreased by 15 degree Celsius. In addition, the useful heat and instantaneous thermal efficiency were calculated to be 648.27 W and 66.69 percent, respectively.
Hibrit fotovoltaik-termoelektrik (PV/TE) sistemlerin performans analizi
The improvement of the efficiency of the photovoltaic (PV) modules is the focus nowadays of so many researchers. Many test and research were conducted in order to reach that goal. That is how they came with the idea of a hybrid. Combining the PV module with the thermoelectric module is an innovative approach to improve the efficiency. Thus, not only a part of the solar spectral is exploited as for the PV alone, but a larger spectrum is exploited because the heat too is used. It allows the cooling of the panel and provide an additional power. A comprehensive review on these previous research studies are presented here. Many methods and approaches to enhance the performance of the PV/TE systems are discussed along. The gaps in existing literature are identified and recommendations for future research are precisely outlined. It is emphasized here that only few experimental studies on PV/TE systems are exist. Therefore, it is highly recommended here that comprehensive experimental studies under real atmospheric conditions should be done with these systems. Our work was based on a simulation of the efficiency of a tandem made of a PV panel and a TEG module. The simulation was done using the atmospheric conditions of Niger, which is a promising site for the exploitation of solar energy. The results obtained support the previous work and confirm the hypothesis that the addition of a TEG enhance the power output of the PV panel. It was shown that the Hybrid had a better efficiency than the PV stand alone. The lowest efficiency for the two modules were recorded at a cell temperature of 72.03 ℃. The enhancement in efficiency of the hybrid is more noticeable at that point: the efficiency of the stand-alone PV is of 12.24% and the efficiency of the hybrid is slightly higher with a value of 19.62%.
Virtual power plant application for managing rooftop solar photovoltaic systems
This thesis examines the comprehensive definitions of a Virtual Power Plant (VPP) along with how it is integrated with other components to work in synergy. A VPP system is made up of DERs and a centralized control system. A VPP system is named either wind VPP or solar VPP depending on the type of the generation unit. Investigating the integration of rooftop solar VPPs into the entire systems of traditional grid systems is a prerequisite. MATLAB simulation software is used for building a simplified Solar VPP system. The outputs of generation units are optimized to avoid large turbulences and interference of power dissemination processes. The main control procedure is based on whether there is a surplus or shortage of power. In any case shortage or surplus has to be compensated by the grid. The VPP network consists of three individual rooftop solar generators connected to the grid. The main goal of a renewable energy-based VPP system is to help reduce energy generation costs and integrate renewable energy sources (RES) into the total power output of the grid, as it indirectly contributes to low levels of carbon in the atmosphere. Several countries are taking the lead in experimentation and installation of solar VPP systems as pilot programs. VPP systems are meant to replace the traditional grids with the collective involvement of consumers and suppliers.
Design and performance analysis of floating solar photovoltaicsystems
The floating solar photovoltaic system is a new trend in the world. This system is suitable for hybrid solutions with hydropower plants. There are a lot of advantages of the floating solar photovoltaic systems. Solar energy is an intermittent energy source so with a hybrid solution of floating solar and hydroelectric power plant can balance each other's energy generation. It can be said that this hybrid solution can increase the capacity factor of the hydropower plant. Turkey has the second greatest hydropower installed capacity in Europe with about 31.493 MW so the floating solar photovoltaic and hydropower hybrid solutions will be very beneficial to Turkey's solar installed capacity growth without using land areas. In this respect Gursogut-1 HEPP with 38.08 MW installed capacity which is located in Ankara was chosen for the hybrid solution in this study. During the literature survey period it was seen that there aren't a lot of academic studies about floating solar and hydropower plant hybrid systems' performance analysis. The aim of this study is to investigate the performance analysis of the floating solar photovoltaic and hydropower plant hybrid system. In this study the gain in the energy yield when a floating solar photovoltaic system mounted on this hydropower water reservoir has been analyzed. The performance analysis has been carried out on PVsyst software according to the system's key parameters including meteorological data, available installation area, photovoltaic module properties and inverter features. Results obtained for system's total energy production, performance ratio and specific energy are discussed.