Power Conversion Performance of a Single-Phase PV Inverter with Fuzzy Logic Algorithm

Abstract

The paper presents a low-power conversion system focusing on implementing new solar inverter control techniques implemented with Fuzzy Logic. The power generated by a solar panel requires robust approaches and efficient methods to be used at its maximum. Therefore, a promising strategy is a Fuzzy Logic based on the Maximum Power Point Tracking (MPPT) algorithm. To gather efficient power conversion, our proposed model uses a control loop composed of Fuzzy Proportional Integrative (PI) regulators, Clarke and Park transform, followed by a synchronization grid mechanism Second-order generalized integrator (SOGI) based phase-locked loops (PLLs). The proposed technique examines photovoltaic system (PV) performance with respect to its non-linearities and eventual shaded conditions that can occur in the PV array. The shading effect is tested by varying the irradiance, which determines the variation of the output current and implicitly of the output power. The simulation results show that the inverter control system is very efficient, generating stable and nearly sinusoidal current and voltage characteristics. Thus, the inverter converts over 99 % of the power generated by PV arrays.

Benefits of Fuzzy Logic on MPPT and PI Controllers in the Chain of Photovoltaic Control Systems

“…The proposed grid-connected PV inverter system setup contains a control system, a solar panel, a single-phase inverter and a load. The control system has several submodules, including MPPT and current-control logic functions, Park and Inverse Park transforms, grid synchronization, and pulse width modulated (PWM) signal generator [14]. The block diagram of the PV system for both approaches investigated is presented in Figure 1 [14].…”

“…The control currents obtained are sent to the inverse Park transformation and later modeled by the PWM generator. Henceforward, the generator's output sends the command pulses to the inverter [14].…”

“…The sinusoidal current injected by the inverter is synchronized in phase and frequency with the grid's voltage. In this way, the inverter is current-mode controlled to obtain the maximum useful power and deliver it to the grid [14]. Solar panel blocks have two inputs: irradiance value and temperature.…”

“…Considering the brief discussions above, the present research proposes developing a comparison between two different techniques to control a 150 W PV system under fluctuating irradiance circumstances and at a fixed temperature (25 • C) [14].…”

“…Both techniques use Clarke and Park Transformation in the control loop. The Clarke and Park Transformations adjust alternating physical quantities, being mandatory in the control of alternating current systems [14].…”