Fuzzy Logic Based Synchronization Method for Solar Powered High Frequency On-Board Grid

Abstract

This paper proposes a method for synchronizing a grid inverter with the voltage of an on-board high-frequency power grid. The described synchronization method belongs to the adaptive methods, which use fuzzy logic in the process of estimating the fundamental component of the voltage. The synchronization system has been tuned to achieve the primary goal of achieving synchronization in the shortest possible time. This is to allow for the efficient energy fed from photovoltaic sources into the on-board grid at 400 Hz. The proposed method was implemented in the field programmable gate array (FPGA) based power converter controller and static and dynamic tests for harmonic, interharmonic and subharmonic voltage disturbances were performed. Dynamic tests for phase jump, frequency jump and sag of the on-board voltage were also performed. To evaluate the effectiveness of synchronization with high-frequency voltage, the grid current control system in the grid tied inverter was elaborated. Proper current waveforms at the perturbed voltage were recorded while identifying the effectiveness of power ripple suppression. The results obtained were compared with the enhanced phase locked loop (EPLL) synchronization method. Satisfactory test results confirmed the suitability of the proposed method in systems coupling the photovoltaic source to the on-board high-frequency power grid.