Development of a novel MPPT system based on inflection voltages method for PV system and its applications

In this thesis study, novel and innovative MPPT algorithms based on inflection voltages have been developed for PV systems, which can operate under all atmospheric conditions. The first algorithm called the Inflection Voltages Method (IVM), is the first MPPT algorithm in the literature that utilizes inflection voltages. This method measures all possible local maximum power points that may occur under partial shading by using inflection voltages and selects the peak where the global maximum power point is formed to operate the system at this power point. This thesis produced an improved version of inflection voltages, called I2VM. In the first stage, this technique uses the IVM for the selection of the peak at which the GMPP is formed, and is aimed at achieving a high efficiency of convergence with the GMP using the P&O algorithm. The third algorithm developed in the thesis is the adaptive IVM algorithm. This method has the feature of irradiance condition detection in the first stage. With this feature, it aims to increase the tracking speed by narrowing the search space when the photovoltaic array is exposed to uniform irradiance. In the second stage, it aims to solve the oscillation problem and achieve high convergence speed through the adaptive P&O method, which dynamically controls the step size. To demonstrate the effectiveness of the proposed algorithms, a simulation model and experimental setup consisting of a photovoltaic array using the Solarex MSX-60 panel and a buck-type DC/DC converter controlled by an ATmega328PTM controller were developed. Separate computer simulations and experimental studies were conducted for each proposed algorithm. The conducted studies have shown that inflection voltage-based algorithms can perform tracking successfully under all atmospheric conditions. The prominent common features of these methods are low processing power requirements and high convergence success. Among the proposed algorithms, the most efficient one is Adaptive IVM. The studies conducted have shown that Adaptive IVM reduced the tracking time under uniform irradiance conditions by approximately 50.00% for the array consisting of four panels. Additionally, the Adaptive P&O used in the second stage reduced the oscillation around the MPP by approximately 75.00%. Keywords: MPPT, GMPPT, Inflection voltages, Partial Shading, Bypass Diode