WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12514/3595

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Citation - WoS: 2
Citation - Scopus: 3
Control Strategy Evaluation for Reactive Power Management in Grid-Connected Photovoltaic Systems Under Varying Solar Conditions
(Nature Portfolio, 2025) Adak, Suleyman
Solar energy is environmentally friendly and one of the most significant renewable energy sources. This energy is a leading renewable energy source, contributing significantly to sustainable development goals. In grid-connected photovoltaic (PV) systems, reactive power management is essential for maintaining voltage stability and ensuring reliable operation. However, the influence of fluctuating solar irradiation (G) on reactive power (Q) behavior is often underrepresented in conventional inverter control strategies. This research addresses this gap by modeling the dependence of reactive power on solar irradiance using a data-driven curve-fitting approach. The methodology involves the acquisition of real-world operational data, preprocessing, selection of an appropriate analytical model, and validation of its performance. The findings indicate that reactive power increases under low irradiance conditions, primarily due to inverter behavior and grid voltage support requirements. The resulting analytical expression offers a practical framework for integrating irradiance-dependent reactive power control into inverter firmware or grid management software. The model performed with high accuracy with an R2 of 0.9955. This contribution enhances the ability of PV systems to respond dynamically to environmental changes, improving grid compatibility, operational efficiency, and voltage regulation in modern distributed energy networks.
Harmonics Mitigation of Stand‑Alone Photovoltaic System Using LC Passive Filter
(Journal of Electrical Engineering & Technology, 2021) Adak, Süleyman
This article investigates modeling and simulation of the of-grid photovoltaic (PV) system, and elimination of harmonic components using an LC passive flter. Pulse width modulation (PWM) inverter is used to convert the direct current to alternating current. It is very important in terms of energy quality that the inverter output current total harmonic distortion (THDI) is below the value given by standards. Harmonic components have negatively efect on of-grid PV power system. THDI should be kept below a certain level in order to prevent damage to the equipment in the of-grid system and to ensure a higher quality energy fow to reduce the total harmonic distortion (THD) of the solar inverter output current; LC passive flter must be connected to the output of the PWM inverter. There are many types of passive flters for solar inverters. One of the most widely used flter types is the LC flter. LC flters are used in of-grid systems. LC flter is smaller in size and lower cost than other flters. But it is more complicated to determine the parameters of the LC flter. Therefore, in order for the system to remain in a steady state, the parameters must be accurately calculated and analyzed. In this study, the output power of the solar inverter, switching frequency, bus voltage etc. values were determined and LC flter parameters were calculated. Since high inductance values are used in LC flters, the voltage drop increases in these flters. To reduce the voltage drop, the DC bus voltage must be increased, which increases the switching losses. LC flter is connected between the inverter and the nonlinear load to flter the harmonic components produced by the DC/DC boost converter, DC/AC inverter and non-linear load. Matlab/Simulink program was used in Simulation and analysis of of-grid solar system. Solar inverter output current THD was measured as 91.55%. After the LC flter is connected to the system, this value has dropped to 2.62%.
Citation - WoS: 6
Citation - Scopus: 11
Power Factor Analysis of Grid-Connected Solar Inverter Under Different Irradiance Levels Throughout the Day
(MDPI, 2024) Adak, Suleyman
The power factor (PF) plays a crucial role in determining the quality of energy produced by grid-connected photovoltaic (PV) systems. When irradiation levels are high, typically during peak sunlight hours, the PV panels generate more electricity. In this scenario, the PF tends to be higher because the real power output closely matches the apparent power drawn from the grid. Whereas, when irradiation levels are low, such as during cloudy weather or nighttime, the PV panels produce less electricity. In these conditions, the power factor may decrease because the real power output diminishes compared to the apparent power drawn from the grid. This could be due to reduced efficiency or increased reactive power flow. PF decreases linearly at solar irradiance values lower than 220 (W/m2). At the same time, it approaches unity at higher solar irradiance values than 220 (W/m2). In this study, the variation of the power coefficient of the grid-connected PV solar system depending on solar irradiation was modeled and analyzed using MATLAB/Simulink 41016490. The analytical expression of the power factor depending on the change in solar irradiation was found using the curve fitting method.

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