Elektrik ve Enerji Bölümü Koleksiyonu
https://hdl.handle.net/20.500.12440/1135
2024-03-29T13:27:28Z
2024-03-29T13:27:28Z
Current Sources and Actual PV Modules based Photovoltaic (PV) Emulator for Testing MPPT Algorithms and PV Inverters
Zhou, Zhongfu
Wang, Yidong
Yanarates, Cagfer
MacAulay, John
https://hdl.handle.net/20.500.12440/6073
2023-10-26T13:06:35Z
2023-01-01T00:00:00Z
Current Sources and Actual PV Modules based Photovoltaic (PV) Emulator for Testing MPPT Algorithms and PV Inverters
Zhou, Zhongfu; Wang, Yidong; Yanarates, Cagfer; MacAulay, John
PV array emulator has been widely used for testing PV inverters and their control algorithms such as maximum power point tracking (MPPT) algorithms. Various power electronics converter-based PV emulators have been presented in many research papers. This paper presents a PV emulator that is based on indoor solar panels (without solar irradiance) and external current source (dc power supply). The external current source is used to emulate the photo current that is usually generated by solar panel under sunlight. The advantages of the proposed PV emulator are that it can generate similar electrical characteristics of actual PV panel without sunlight, it is suitable for testing PV inverters and MPPT algorithms in indoor conditions where the sunlight is usually very weak. In addition, a PV array emulator that can emulate electrical performance under partial shading conditions was constructed by using two solar panels and two current sources. Test results show that the proposed PV emulator provides a similar performance of real PV array under real sun light. It provides a low-cost solution for testing PV inverters and control algorithms inside a laboratory environment. © 2023 IEEE.
2023-01-01T00:00:00Z
Performance analysis of digitally controlled nonlinear systems considering time delay issues
Yanarateş, Cağfer
Okur, Serkan
Altan, Aytaç
https://hdl.handle.net/20.500.12440/6063
2023-10-19T06:29:42Z
2023-01-01T00:00:00Z
Performance analysis of digitally controlled nonlinear systems considering time delay issues
Yanarateş, Cağfer; Okur, Serkan; Altan, Aytaç
In this paper, a comprehensive investigation into discretization, effective sample time selection considering delays in the system, and time and frequency domain analysis of a DC-DC buck converter, which plays a vital role in photovoltaic (PV) systems, is conducted to enhance the understanding of their dynamic behavior, optimize control algorithms, improve system efficiency, and ensure reliable power conversion in photovoltaic applications. To effectively address the non-linear behavior and enhance digital control of a buck converter by selecting the best sample time, several approaches can be employed. These include accurate modeling and identification of non-linear elements, development of advanced control algorithms that account for non-linearities, implementation of adaptive control techniques, and utilization of feedback mechanisms to compensate for deviations from linearity. By considering and mitigating the non-linear behavior, digital control systems can achieve improved accuracy, stability, and transient behavior in regulating the buck converter's output waveforms (voltage or current). The results of the study demonstrated that the trapezoidal integration method which is also known as bilinear approximation, or Tustin's approach outperformed other commonly used discretization methods, such as first-order hold (FOH), zero-order hold (ZOH), impulse response matching (impulse invariant), and matched pole-zero (MPZ) technique, in dual-domain (both time and frequency) analysis. The key finding highlighting the superiority of the bilinear approximation was its ability to achieve the closest match in the frequency domain bridging the continuous-time and discrete systems. This finding emphasizes the significance of the bilinear approach in preserving the frequency characteristics of the original continuous-time system during discretization. By employing this method, the discrete system closely approximated the behavior of its continuous-time counterpart, ensuring accurate frequency-domain representation. © 2023 The Authors
2023-01-01T00:00:00Z
A study on the relationship between sociodemographic characteristics and job stress and satisfaction among healthcare workers in Turkey during the COVID-19 pandemic
Tuna, Hasan
Türkmen, Osman Oǧulcan
Albayrak, Sirer
https://hdl.handle.net/20.500.12440/5914
2023-04-25T06:43:58Z
2023-01-01T00:00:00Z
A study on the relationship between sociodemographic characteristics and job stress and satisfaction among healthcare workers in Turkey during the COVID-19 pandemic
Tuna, Hasan; Türkmen, Osman Oǧulcan; Albayrak, Sirer
The aim of this study was to determine the sociodemographic characteristics that affect job stress and job satisfaction in 454 healthcare workers (physicians, nurses, midwives, technicians, and other healthcare personnel) working with COVID-19 patients in primary healthcare institutions in Turkey with a cross-sectional, web-based survey between 9 and 30 August 2021. The survey included a personal information form, a standard job stress scale, and the Minnesota Satisfaction Questionnaire. The levels of job stress and job satisfaction did not differ between male and female respondents. Singles reported lower job stress and higher job satisfaction than the married respondents. Job stress did not differ between departments, but respondents on the front line who worked in a COVID-19 intensive care unit (ICU) (at any point and/or at the time of the study) or the emergency department reported lower job satisfaction than those working in other departments. Similarly, while stress did not differ by educational status, satisfaction of respondents with bachelor's or master's degree was lower than that of the rest. Our findings also suggest that working in a COVID-19 ICU and age are significant predictors of higher stress, whereas lower education, working in a COVID-19 ICU, and being married are good predictors of lower satisfaction. Further research should include other sociodemographic variables that may affect stress and satisfaction at work, and similar studies should follow up to see what was left in the wake of the pandemic. © 2023 Hasan Tuna et al., published by Sciendo.
2023-01-01T00:00:00Z