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Öğe A novel gene expression programming-based MPPT technique for PV micro-inverter applications under fast-changing atmospheric conditions(Pergamon-Elsevier Science Ltd, 2022) Celik, Ozgur; Zor, Kasim; Tan, Adnan; Teke, AhmetThe erratic behavior of the atmospheric conditions adversely affects efficient energy harvesting and the stable operation of photovoltaic systems. It is therefore critical to draw maximum power from photovoltaic modules regardless of atmospheric conditions. The maximum power point tracking techniques have crucial impacts on both efficient and stable operation of photovoltaic systems as being the controller part of the power converters. In this paper, a novel gene expression programming-based maximum power point tracking technique is proposed for micro-inverter applications under fast-changing atmospheric conditions. In this context, the main objective of this study is to improve the significant performance indices of maximum power point tracking technique including convergence speed during transients, tracking accuracy, steady-state oscillations, and rate of overshoots for ensuring the stable and efficient operation of the photovoltaic micro-inverter system. The proposed maximum power point tracking technique is integrated to a two-stage grid-connected micro-inverter system and tested in terms of the aforementioned performance parameters. The performance analyses of the developed technique are performed under various scenarios by utilizing the PSCAD/EMTDC platform. The obtained results reveal that the rate of overshoots is decreased by 0.6 A while the convergence speed is accelerated by 1.4 s. In comparison with traditional MPPT techniques, tracking accuracy, steady-state stability, and robustness of the whole system are remarkably improved along with increasing overall system efficiency by 4%. It is also worth pointing out that the complexity level of the control technique is significantly reduced by the equation obtained through the symbolic regression analysis.Öğe Capacitor Current Feedback Active Damping for Shunt Active Power Filter with Output LLCL Filter(IEEE, 2017) Buyuk, Mehmet; Inci, Mustafa; Tan, Adnan; Tumay, MehmetA high-order LLCL has excellent attenuation performance of ripple harmonics generated by VSI. The LLCL filter is especially effective at switching frequency to mitigate the switching ripple harmonics. However, like the other high-order filters, LLCL filter has resonance problem, which must be damped to have stable system. In literature, passive damping and active damping methods are proposed for grid-connected VSI. However, the active damping techniques have not been considered for SAPF with LLCL filter yet. Thus, in this paper, LLCL filter for Shunt Active Power Filter with Active Damping method is proposed and analyzed to suppress the resonance of LLCL filter and stabilize the control of SAPF.Öğe Capacitor current feedback active damping for Shunt Active Power Filter with output LLCL filter(Institute of Electrical and Electronics Engineers Inc., 2017) Buyuk, Mehmet; Inci, Mustafa; Tan, Adnan; Tumay, MehmetA high-order LLCL has excellent attenuation performance of ripple harmonics generated by VSI. The LLCL filter is especially effective at switching frequency to mitigate the switching ripple harmonics. However, like the other high-order filters, LLCL filter has resonance problem, which must be damped to have stable system. In literature, passive damping and active damping methods are proposed for grid-connected VSI. However, the active damping techniques have not been considered for SAPF with LLCL filter yet. Thus, in this paper, LLCL filter for Shunt Active Power Filter with Active Damping method is proposed and analyzed to suppress the resonance of LLCL filter and stabilize the control of SAPF. © 2017 EMO (Turkish Chamber of Electrical Enginners).Öğe Design and Analysis of a High-Efficiency Resonant Converter for EV Battery Charger(2023) Erdoğan, Birand; Tan, Adnan; Savrun, Murat Mustafa; Cuma, Mehmet Uğraş; Tümay, MehmetThe interest in electric vehicle (EVs) components such as battery, battery chargers, and battery management systems is increasing in parallel with the spread of electric vehicles. One of the most critical of these components is battery chargers. Battery chargers are equipped with DC-DC converters with high efficiency, low cost, and wide output voltage range. In order to provide reliable operation of the battery charger, it is of great importance that the DC-DC converters are operated with a robust and stable controller as well as designed optimally. In this paper, a design method for a CLLC resonant converter-based bidirectional dc-dc converter (BiDC) is presented for a battery charger. The resonant converter, whose design details are presented, suggests a resonant system to be used in battery chargers with fewer components than the CLLLC converter, and similar voltage gain characteristics for bidirectional power flow operations compared to the LLC converter. The design procedure highlights performing the soft switching operation and determining the resonant tank parameters. In addition, the forward mode and reverse mode gain equations required for the system to operate in the desired output voltage range have been presented. The design procedures have been validated with a CLLC BiDC model with ratings of 1 kW, 400 V input / 300-450 V output in the PSIM environment. The performance results reveal that the zero voltage switching (ZVS) has been performed for primary-side MOSFETs under a wide load range.Öğe DSP controlled voltage disturbance generator(Engineering & Scientific Research Groups, 2018) Savrun, Murat Mustafa; Tan, Adnan; Koroglu, Tahsin; Cuma, Mehmet Ugras; Bayindir, Kamil Cagatay; Tumay, MehmetVoltage disturbance generator (VDG) is a kind of device used to generate voltage disturbances that may occur in the network in order to test and evaluate the performance of the power quality devices such as Dynamic Voltage Restorer (DVR) and Uninterruptible Power Supply (UPS). Some of the voltage disturbance generator systems which are available in the literature and commercially available are complex and expensive while the others are simple, inexpensive but less functional. In this paper, a new transformer based, digital signal processor (DSP) controlled VDG is designed which can generate balanced and unbalanced voltage sag/swell and interruption and can adjust the depth, duration and initiation point of disturbances. The proposed system is composed of bidirectional switches, variable transformers and DSP based controller. 3 phase 20 kVA experimental setup is developed to verify the performance of the designed system with linear and non-linear loads. Moreover, the performance of VDG is also investigated in the compensation tests of DVR and UPS.Öğe DSP controlled voltage disturbance generator(Engineering and Scientific Research Groups, 2018) Savrun, Murat Mustafa; Tan, Adnan; Köroglu, Tahsin; Cuma, Mehmet Ugras; Bayindir, Kamil Çagatay; Tümay, MehmetVoltage disturbance generator (VDG) is a kind of device used to generate voltage disturbances that may occur in the network in order to test and evaluate the performance of the power quality devices such as Dynamic Voltage Restorer (DVR) and Uninterruptible Power Supply (UPS). Some of the voltage disturbance generator systems which are available in the literature and commercially available are complex and expensive while the others are simple, inexpensive but less functional. In this paper, a new transformer based, digital signal processor (DSP) controlled VDG is designed which can generate balanced and unbalanced voltage sag/swell and interruption and can adjust the depth, duration and initiation point of disturbances. The proposed system is composed of bidirectional switches, variable transformers and DSP based controller. 3 phase 20 kVA experimental setup is developed to verify the performance of the designed system with linear and non-linear loads. Moreover, the performance of VDG is also investigated in the compensation tests of DVR and UPS. © JES 2018.Öğe Grid code requirements - A case study on the assessment for integration of offshore wind power plants in Turkey(Elsevier, 2022) Celik, Ozgur; Yalman, Yunus; Tan, Adnan; Bayindir, Kamil Cagatay; Cetinkaya, Uemit; Akdeniz, Mevlut; Chaudhary, Sanjay K.The increasing role of offshore wind power plants in the electricity generation mix in Turkey raises some critical grid operation issues. In this context, the grid code regulation concerning penetration of large-scale offshore wind power plants into Turkey's power system has become a prominent factor in the development of a reliable grid operation. In this paper, a comprehensive benchmark for grid codes of the European countries that have large-scale offshore wind power plants and Turkey is performed by considering voltage regulation, frequency regu-lation, fault ride-through, and power quality features. The compatibility of the grid codes in terms of the min-imum technical requirements is discussed to show the pros and cons. An elaborated assessment of the Turkish grid code reveals the technical properties that need to be improved. The rigorous state-of-the-art review indicates that active power control & frequency regulation, reactive power control & voltage regulation, and voltage ride-through capabilities should be clarified in detail for the Turkish grid code. With this background, various rec-ommendations, key challenges, and future trends related to the improvement of technical requirements for the Turkish grid code for the integration of offshore wind power plants are highlighted to help researchers, plant owners, and system operators.Öğe Impacts of Large-Scale Offshore Wind Power Plants Integration on Turkish Power System(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Yalman, Yunus; Celik, Ozgur; Tan, Adnan; Bayindir, Kamil Cagatay; Cetinkaya, Umit; Yesil, Merden; Akdeniz, MevlutIn this paper, the impacts of large-scale OWPPs penetration on the Turkish power system are addressed. The grid compliance analyses for the large-scale OWPP integration are carried out by using the grid connection criteria defined in the Turkish grid code. PV and QV curves are obtained to assess the effect of OWPP on the static voltage stability limit. Eight scenarios are conducted to analyze the effect of the OWPP on the static and dynamic characteristics of the power grid. To observe the large-scale OWPP impact on the voltage and frequency stability, transient events such as the outage of conventional power plants and three-phase to ground faults are applied. The results of the voltage and frequency stability analysis reveal that the Turkish grid remains stable after the integration of an 1800 MW OWPP. Furthermore, the Turkish system remains stable even in the event of an outage of the international transmission lines to Bulgaria and Greece.Öğe Implementation of a Novel Hybrid UPQC Topology Endowed With an Isolated Bidirectional DC-DC Converter at DC link(IEEE-Inst Electrical Electronics Engineers Inc, 2020) Koroglu, Tahsin; Tan, Adnan; Savrun, Murat Mustafa; Cuma, Mehmet Ugras; Bayindir, Kamil Cagatay; Tumay, MehmetThis paper introduces an original hybrid unified power quality conditioner (HUPQC) topology as an alternative solution to electrical power quality problems. The proposed HUPQC consists of the shunt hybrid active power filter (SHAPF), the dynamic voltage restorer (DVR), and the isolated bidirectional dc-dc converter (BiDC) located at the common dc link. The SHAPF enables reduction in the voltage rating of the dc-link capacitor, helps to reduce the cost and the size of the dc link, and hence reduces switching losses of the voltage source inverter. Besides the novelty of its topology, dynamic reactive power compensation capability is realized for the first time in the literature within HUPQC concept by achieving adaptively controlling dc-link voltage. The BiDC not only provides isolation and bidirectional power flow between the DVR and the SHAPF but also operates to keep the dc-link voltage of DVR constant against adaptively changing dc-link voltage of the SHAPF. In addition to these, a new hybrid voltage sag/swell detection algorithm based on the combination of the improved Clarke transformation and the enhanced phase-locked loop is developed and introduced. In order to verify the viability and effectiveness of the proposed HUPQC topology, experimental studies are carried out.Öğe Improved adaptive notch filter-based active damping method for shunt active power filter with LCL-filter(Springer, 2018) Buyuk, Mehmet; Tan, Adnan; Tumay, MehmetThe LCL-filter has been recently used with grid-connected converters to mitigate switching ripple harmonics. The LCL-filter presents a better attenuation performance for switching ripple harmonics in comparison with L- and LC-type filters. However, the application of LCL-filter has two basic constraints on the circuit design and the resonance problem. These constraints can be effortlessly overcome for grid-connected converters which operate on the utility fundamental frequency. On the other hand, these constraints become a challenging issue when the LCL-filter is used with shunt active power filter (SAPF) because of the wide operation frequency bandwidth of SAPF. This wide operation bandwidth of SAPF causes a narrow bandwidth for the selection of LCL-filter cutoff frequency and the resonance damping control. In this paper, the application constraints of LCL-filter are discussed and the LCL-filter design is provided for SAPF. In addition, an adaptive notch filter-based single-loop active damping method is developed considering the wide operation bandwidth of SAPF. The proposed method consists of a grid impedance estimation algorithm in order to update notch filter parameters adaptively against grid impedance variations. By the help of the single-loop active damping strategy, the proposed controller does not require any additional sensor for the current measurement of LCL-filter capacitor to damp resonance currents. The stability analysis of proposed controller is performed through pole-zero maps. The proposed method is tested, and its performance is verified with comprehensive case studies of a 400-V 80-kVA SAPF simulation model through MATLAB/Simulink.Öğe Improvement of energy harvesting capability in grid-connected photovoltaic micro-inverters(Taylor & Francis Inc, 2024) Celik, Ozgur; Tan, Adnan; Inci, Mustafa; Teke, AhmetIn this paper, a multi-stage micro-inverter system depending on a dual neutral point clamped (D-NPC) inverter is developed for low power photovoltaic (PV) applications. The primary objectives of this study are determined as improving the performance of the proposed D-NPC inverter-based micro-inverter and its controller to ensure better system reliability and promote the overall efficiency. In comparison with conventional systems, the designed system provides many advantages: (1) utilization of lower rating switching components, (2) reduced switching frequency and voltage stress, (3) reduced the size of filter components, (4) higher efficiency, and (5) lower total harmonic distortion (THD). The weighted efficiency of the system is remarkably increased by the value of 2.15% compared to the conventional micro-inverter and reached 93.73%. Furthermore, the THD value of the output current is measured below 3% for the proposed system with the small size of passive filtering elements. Further, dynamic grid support and anti-islanding detection capabilities are provided through the utilized controller structure to fulfill grid codes. Consequently, obtained results demonstrate that the improved system can be a considerable candidate for photovoltaic micro-inverter applications in terms of weighted efficiency, output current THD, and reasonable cost.Öğe Isolated H-bridge DC-DC converter integrated transformerless DVR for power quality improvement(Inst Engineering Technology-Iet, 2020) Savrun, Murat Mustafa; Koroglu, Tahsin; Tan, Adnan; Cuma, Mehmet Ugras; Bayindir, Kamil Cagatay; Tumay, MehmetThis study presents a new H-bridge DC-DC converter-based transformerless dynamic voltage restorer topology (DVR). The proposed system can compensate balanced and unbalanced voltage sag/swell that are the most common electrical power quality problems and offers advantages over conventional DVR topologies by providing the isolation with high-frequency transformer (HFT) rather than bulky injection transformers and by employing shunt converter to eliminate the requirement of an energy storage unit. The system is composed of H-bridge DC-DC converter equipped with a HFT with one primary and three secondary windings and transformerless DVR. The single-phase shift modulation method is used for each series converter independently to provide the bidirectional power flow control of DC-DC converter, whereas in-phase compensation method with a hybrid detection algorithm is used to mitigate voltage sag/swell. An LC filter is employed to attenuate the switching ripple harmonics on the output of the DVR. The performance of the proposed system is verified experimentally on a three-phase, three-wire, 380 V, 10 kVA prototype.Öğe Mitigation of power oscillations for energy harvesting capability improvement of grid-connected renewable energy systems(Elsevier Science Sa, 2022) Celik, Ozgur; Buyuk, Mehmet; Tan, AdnanThe increasing penetration of renewable energy sources in the power system raises several challenges from the power quality and output power fluctuations point of view. However, the output power oscillations and power quality problems caused by the low order harmonic oscillations at the second-order frequency of the utility grid on the dc-link capacitor are emerging as major issues for the efficient operation of power converters. In this manner, a novel method based on modification in the control algorithm to alleviate the output power oscillation and reduce the output current total harmonic distortion is proposed. The proposed control approach seems as a promising solution for the satisfactory grid operation of renewable energy sources regarding not requiring any additional circuit and increment in the capacity of the dc-link capacitor. Moreover, mitigation of oscillations enhances the active power reference tracking capability of the controller that enables the overall efficiency improvement of the system. The performed case studies reveal that the overall efficiency rate of the system is increased by 1.3%. On the other hand, the output current harmonic distortion is decreased below 3% even under low power operating conditions. Also, the complexity level of the control algorithm is quite low for real-time implementation.Öğe Multiple harmonic elimination-based feedback controller for Shunt Hybrid Active Power Filter(Inst Engineering Technology-Iet, 2017) Tan, Adnan; Bayindir, Kamil Cagatay; Cuma, Mehmet Ugras; Tumay, MehmetThis study presents a multiple harmonic elimination-based feedback controller for shunt hybrid active power filter (SHAPF) to perform an effective harmonic compensation performance in a wide harmonic frequency band. The conventional control methods presented for SHAPF cannot perform an adequate performance, because of the disturbances such as phase delays caused by controller methods and measurement circuitries, tolerances of passive filter components and supply voltage harmonics. In the proposed controller, the conventional feedback controller is improved by using supply side individual current harmonics which are extracted by the synchronous reference frame method. To prevent the performance degradation effects of disturbances, proportional-integral controllers are applied to each d and q components of individual current harmonics. The compensation performance of the proposed method is compared with conventional methods both theoretically and experimentally. The experimental results verify the advanced harmonic compensation performance of the proposed control method.Öğe MVT Controlled Voltage Restorer for Fault-Ride Through Capability(IEEE, 2017) Inci, Mustafa; Buyuk, Mehmet; Tan, Adnan; Bayindir, Kamil Cagatay; Tumay, MehmetVoltage dips are the most harmful disturbances which may affect the voltage stability of wind turbines. In these voltage dip conditions, stator/rotor currents and electrical torque increase to fairly high values with failing of voltage stability. In order to provide voltage stability after the faults of voltage dips, the faults must be compensated fast and accurately. The main contribution in this study is that missing voltage technique (MVT) based controller method is tested in dynamic voltage restorer (DVR) to mprove fault ride through (FRT) capability in grid connected wind systems. The proposed method controlled DVR is performed for symmetrical and asymmetrical faults in grid connected wind energy systems by using PSCAD/EMDTC power system simulator program. The case studies demonstrate the superior and effective compensation results.Öğe MVT controlled voltage restorer for fault-ride through capability(Institute of Electrical and Electronics Engineers Inc., 2017) Inci, Mustafa; Buyuk, Mehmet; Tan, Adnan; Bayindir, Kamil Cagatay; Tumay, MehmetVoltage dips are the most harmful disturbances which may affect the voltage stability of wind turbines. In these voltage dip conditions, stator/rotor currents and electrical torque increase to fairly high values with failing of voltage stability. In order to provide voltage stability after the faults of voltage dips, the faults must be compensated fast and accurately. The main contribution iin this study is that missing voltage technique (MVT) based controller method is tested in dynamic voltage restorer (DVR) to mprove fault ride through (FRT) capability in grid connected wind systems. The proposed method controlled DVR is performed for symmetrical and asymmetrical faults in grid connected wind energy systems by using PSCAD/EMDTC power system simulator program. The case studies demonstrate the superior and effective compensation results. © 2017 EMO (Turkish Chamber of Electrical Enginners).Öğe Overview of micro-inverters as a challenging technology in photovoltaic applications(Pergamon-Elsevier Science Ltd, 2018) Celik, Ozgur; Teke, Ahmet; Tan, AdnanOne of the key components of the photovoltaic (PV) system is inverters due to their function as being an operative interface between PV and the utility grid or residential application. In addition, they can be employed as power quality conditioners at the point of common coupling (PCC). It should be noted that in inverter technologies, there has been an increasing interest to achieve robust output power injection capabilities with lesser design complexity in terms of controller part and power circuit topology. Micro-inverters (MIs) are module based type of inverters that have aroused much interest in recent years. Owing to their distributed architecture mounted with individual PV modules, system reliability can be improved remarkably by using MIs. Furthermore, a module based nature of the MI architecture provides a number of advantages, such as low converter power rating, low power losses, accurate maximum power point tracking (MPPT) ability against partially shading conditions and elimination of PV panel mismatches. However, there is still known weighted conversion efficiency of MIs ranges between 90% and 95%. Therefore, novel designs focus on the known weak aspects of traditional MIs and their failure mechanisms. In this paper, state-of-the-art technologies for MIs with a detailed survey on the technical features consisting of power circuit configuration, control structures, grid compatibility abilities, decoupling capacitor placement, energy harvesting capabilities, and safety mechanisms are presented. Additionally, elaborated comparison on MIs topologies is realized and some future research fields on MIs are summarized.
