Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Hybrid Renewable Energy Systems Design for Green Campus-Iztech(01. Izmir Institute of Technology, 2022) Ramazan, Beste; Çağlar, Başar; Açıkkalp, EminThis study focuses on evaluating of standalone PV and Wind systems integrated with energy storage technologies to meet the electricity needs of the Izmir Institute of Technology campus in Izmir. University campuses with their high energy demand are one of the most important application areas for renewable energy systems and it’s critical to determine the types of renewable energy technologies, their size, and techno-economic feasibility for possible future implementation. Solar and wind energy were chosen as renewable energy sources based on the location and renewable energy potential of the IZTECH Campus. Two different energy storage systems are proposed to prevent any loss of power supply in standalone mode: (i) Lead-acid battery and (ii) Electrolyzer, hydrogen storage tank, and hydrogen-powered generator. Models were developed using the dynamic library-based structure of the TRNSYS program. The hourly electrical load was generated based on monthly data taken from the electricity supplier and the power output of PV modules was calculated based on the fixed tilt angle based on real meteorological data for the campus location. The electricity demand and generation were analyzed hourly for one calendar year. The number of PV modules was determined to meet the annual electricity demand of the campus while the capacity and number of energy storage modules were determined based on the maximum accumulative energy deficiency in a year. The round-trip efficiencies and the depth of discharge for the battery and the hydrogen storage efficiency for the hydrogen-based storage option were considered in the analysis. Parameters were calculated for both systems and simulation analyzes were evaluated. An economic cost analysis was performed for each system. In addition, suggestions are made for possible system improvements.Master Thesis Hydrodynamic Investigation of an Innovative Floating Platform for Offshore Wind Turbines(01. Izmir Institute of Technology, 2022) Girgin, Elif; Özbahçeci, BergüzarWith the realization of the potential of wind energy in deep water, interest in floating platforms is increasing. In this study, the hydrodynamic behavior of offshore floating wind turbines was examined experimentally and numerically. This study is the first small-scale experimental model study on floating offshore wind turbines in Turkey. Experiments were carried out in the wave channel with dimensions of 40.0m×1.0m×1.4m in the hydraulic laboratory of the IZTECH Civil Engineering Department. A new floating platform developed through a Tübitak project was tested under various wave and extreme wind conditions. Responses of the turbine and platform system and the tensions in the mooring chains were measured. Free decay, hydrostatic, quasi-static, and regular and irregular wave and wind tests were performed. Results were compared with the results of the existing spar platform model tests under the same test conditions. It was concluded that the innovative platform was more stable than the spar platform, especially in terms of rotation in the y direction, which is critical for stable energy generation and fatigue loads. The new platform, together with the turbine and the mooring lines, was also modeled numerically using a potential theory-based program. Experimental free decay tests were used to calibrate the numerical model. After calibration, regular and irregular wave test results were used for the validation. Agreement between the numerical and experimental model studies showed that the numerical model of the innovative floating platform was verified and could be used to develop and examine the platform on a prototype scale.Master Thesis Wind Turbine Control Via Power Measurements in Complex Terrain(01. Izmir Institute of Technology, 2022) Dirik, Deniz Gökhan; Bingöl, FerhatThis work presents an approach to the assessment of wind farm yaw control to utilize wake steering in complex terrain based on power measurements. Aerodynamic interactions between closely spaced wind turbines reduce the power output significantly. The standard wind turbine control strategy currently focuses on optimizing the wind turbines individually. However, there is growing evidence that these wake losses can be improved by optimizing for aerodynamic interactions between the turbines. In a case study, an assessment of wake steering gain and optimum yaw offset angles for each wind turbine are simulated for an operational wind farm. Wake losses are simulated for the wind farm and are validated using historical power measurements. Data analysis procedures for implementing operational wind farm data for the wake steering approach are described. Optimum yaw offset angles are calculated in simulations using operational data. A lookup table is generated for the optimum yaw angles required for each wind direction and speed bin. Using 5-year-long operational data, an average of 0.48% wake losses are calculated for the site. FLORIS simulations suggest 9.6% possible power improvement in wake losses using the optimum yaw offset angles. Using SCADA measurements for potential wake steering assessment allows rapid assessment and implementation without requiring expensive and year-long LIDAR or meteorological mast tower measurements.Master Thesis Investigation on Fluctuating Forces on Horizontal Axis Wind Turbines Due To Tower Shadow Effect(01. Izmir Institute of Technology, 2020) Demircioğlu, Hasan Metehan; Özkol, ÜnverIn order to assess aerodynamic performance of wind turbines an in house Blade Element Momentum (BEM) code is developed in Python programming language. Blade element momentum theory is a powerful tool to predict aerodynamic performance of wind turbines and it requires relatively low computational time compared to other aerodynamic performance analysis tools. Therefore, it is frequently used by wind turbine manufacturers especially, at the initial design phase. In this method, wind turbine blade is divided into multiple stations and it is assumed that there are no aerodynamic interactions between these stations. Blade element computations are performed for a given wind speed, rotational speed, blade radius, number of blades, airfoil profiles, twist angle and chord length along the blade span. Aerodynamic data, related to airfoils are taken from experimental studies in the literature. Later, airfoil data were updated by integrating National Renewable Energy Laboratory (NREL) airfoilprep.py tool to in house BEM code. Airfoilprep.py contains stall delay model and Viterna extrapolation. Stall delay model refers to correction of 2D airfoil data to account 3D effects caused by rotation of blades. Viterna extrapolation is used to extend airfoil foil data obtained from experiments or computational tools to 360o angle of attack range since wind turbines often operate at high angles of attack values. Finally, interaction of rotor and tower to power production is implemented in BEM code. Effect of tower presence is modelled by applying potential flow to non-rotating cylinder. Lastly, results obtained from BEM simulations are compared with the data obtained from NREL's Phase VI unsteady experimental study.Master Thesis Wave Generation and Analysis in the Laboratory Wave Channel To Conduct Experiments on the Numerically Modeled Spar Type Floating Wind Turbine(01. Izmir Institute of Technology, 2020) Aktaş, Kadir; Özbahçeci, BergüzarThe oceans offer immense potential for harvesting sustainable wind energy, with stronger and steadier winds for locations further offshore. Since the feasibility of fixed-bottom offshore wind turbines decreases with increasing water depth, floating offshore wind turbines (FOWT) becomes a promising field of study. As part of a TÜBİTAK project (217M451) that investigates the dynamic performance of different FOWT designs under wind and wave loads, the necessary laboratory wave generation, analysis, and test set-up to conduct physical model experiments of a spar-type FOWT model is established in this study. An investigation of the wavemaker theory yielded that using first-order wavemaker solutions in the laboratory leads to the generation of spurious harmonic waves that do not appear in natural waves. Therefore, the second-order solutions are applied to the piston-type wave generator for a closer approximation of natural waves in laboratory conditions. A numerical model investigation of a reference spar-type FOWT is conducted to gain insights into spar design using ANSYS AQWA. The results indicate that the spar model dynamic responses are susceptible to low-frequency waves in pitch and surge degrees of freedom as its natural frequency lies in that region which further emphasizes the importance of generating laboratory waves using second-order wavemaker theory. Additionally, a spar-type floating platform is modeled at the 1/40 Froude scale, to use in the hydraulic model experiments. The wave measurement set-up is fully implemented and theoretically generated waves are measured for validation. In conclusion, regular and irregular wave generation and wave analysis in the time and the frequency domain could be possible in the wave channel of IZTECH Civil Engineering Hydraulic Laboratory.Master Thesis Wind Turbine Power Curve Update Based on Atmospheric Conditions and Structural Fatigue(Izmir Institute of Technology, 2020) Demir, Erdem; Bingöl, Ferhat; Gökçen Akkurt, GüldenWind energy is still developing industry and people who work in this industry working hard to accomplish the difficulties. Problems are not arise only by nature of wind but technological developments, methods and even market pressure itself. Wind turbine theoretical power curves are given only for certain conditions and one can easily say that those conditions are not met in real sites. This difference generates a uncertainty in AEP calculations thus financial models become less reliable. Shifting power curve by taking atmospheric effects into account will give more realistic power curve thus more accurate AEP and financial models. In this study, effects of atmospheric conditions and correction methods on NREL 5MW wind turbines power curve have been investigated and importance of corrected power curve has been discussed.Master Thesis Scaled Down Modelling of a Horizontal Wind Turbine for a Floating Wind Turbine Research(Izmir Institute of Technology, 2020) Erol, Serkan; Özkol, ÜnverFloating wind turbines have to operate under the influence of hydrodynamic and aerodynamic forces which are usually coupled in nature. Due to complicated interactions of wave and wind forces on its structure, predicting motion and performance of a floating wind turbine usually depend on many assumptions. In order to understand the dynamics of the system, experimental studies are required to obtain results by taking into account all parameters. This study is a part of a Tübitak project (217M451) that investigates the dynamics of different floating platforms with a wind turbine attached to it under an atmospheric boundary layer wind profile. In this thesis, a scaling methodology was used to model a wind turbine to use in experimental studies. Reynolds number discrepancy was demonstrated in floating wind turbine modeling. For this reason, the method was created by using Froude number and tip speed ratio similitude, and geometric, kinematic and dynamic similarity was achieved. According to the created methodology, an onshore wind turbine that has 320kW nominal power was scaled down to be used in experimental studies according to the open sea conditions. Along with the model turbine, a thrust force measuring mechanism, hot-wire sensor travers system and a motion detection method by a video have been realized. A wave maker and a wind nozzle which are the part of the Tübitak project of which the model turbine described in this thesis will be used, therefore; small description of those are also given in the thesis.Master Thesis Numerical Investigation of Thermal Management for an Airfoil Profile To Prevent Ice Formation(Izmir Institute of Technology, 2019) Kök, Çağatay; Çetkin, ErdalIn this study, we present a design alternative to prevent the icing of a wind turbine blade in the cold climate wind zones. The main objective is to create a thin film around the wing profile that can protect the surface from ice formation. In order to form this insulating layer, the leading edge, which is the region where the icing started first, the circular openings that could provide hot air to the outside of the wing, were added to geometries. By means of these openings, it has been tried to provide a solution that will prevent ice on the surface without the need to heat the entire wing. At the same time, the effect of these openings on the wing, the distance between the openings and the positions and diameters of the wings on the lifting performance of the wing were investigated. Throughout the study, the design parameters were all proportional to the chord length of the wing. In the model stage, instead of the entire wing, only one section of the wing was modeled using symmetry boundary conditions in order to use the existing limited computing power more efficiently. In this way, both the number of network elements and the calculation time can be modeled in such a way that the distance between the openings is equal to the width of the section. The results show that the lifting force, as can be expected, is small. As the width, i.e. the distance between the openings increased, the lifting force became more stable, while the film layer temperature decreased.Master Thesis Frequency Control in an Isolated Power System With High Penetration of Wind Power(Izmir Institute of Technology, 2019) Hassan, Ali; Bingöl, Ferhat; Altın, MüfitAs the percentage of wind energy in global energy portfolio rises, the wind turbine control is becoming increasingly important for the integration of wind turbines in power systems. The early control objective of wind turbine control was only to maximize the power output but now the wind turbines are required to provide frequency control as well. To emulate the inertia response (IR) of the conventional synchronous machines the wind turbines can be provided with an inertia emulation controller. The modelling work presented in this thesis aims at equipping the modern Type D wind turbine with inertia response and primary frequency control capabilities. Two controllers — inertial and droop, are implemented and their frequency control capabilities are compared in an isolated power system consisting of a conventional steam turbine generator and a wind farm. A model of one Type D wind turbine is simulated and aggregated for the whole wind farm. The ability of wind turbines to provide inertial response (IR) and primary frequency control (PFC) after a frequency deviation shows a better performance than the case when there is no contribution to frequency control through wind turbines.