Investigation of the Effect of Synchronization Techniques on the Stability of Grid-Connected Photovoltaic Systems

Due to the increasing use of microgrids, investigation of their stability is of special interest. One of the disadvantages of an inverter-based distribution unit is that at any given time, phase and frequency information at the point of common coupling (PCC) is required that can affect the stability. The synchronization techniques include synchronous reference frame phase-locked loop (SRF-PLL), virtual inertia, and constant K. To minimize cost and improve reliability, the minimum DC link capacitance should be determined. In this article, finding the minimum DC link capacitance is defined as an optimization problem where the particle swarm optimization (PSO) algorithm is used for the solving of the problem, where the stability is studied through eigenvalue analysis. In the stability analysis, harmonics and negative sequence of grid voltage, increasing the grid inductance, changes in the grid frequency, and changes in the solar irradiation intensity are considered. The effect of various synchronization methods on the stability of grid-connected inverters and DC link capacitance value is investigated.