Seamless Control of Solar PV Grid Interfaced System with Islanding Operation

This paper presents a robust control strategy for a solar photovoltaic (PV)-based distributed generation system (DGS) with seamless transition capabilities from islanded to the grid-connected mode and vice versa. The proposed DGS consists of a solar PV array, a dc–dc boost converter, voltage source converter (VSC), and local nonlinear loads. In grid-connected mode, VSC regulates the dc-link voltage and the boost converter operates the solar PV array at the maximum power point. Moreover, the load reactive power compensation and harmonics elimination with unity power factor operation are achieved using the advanced robust shrinkage normalized sign (ARSNS)-based control algorithm. Therefore, the grid current distortion is maintained within the IEEE-519 standard and the IEEE-1547 standard. Under the grid fault condition, the proposed DGS operates in an islanded mode without any storage unit. The grid synchronization and resynchronization operations are executed through the intelligent synchronization control (SYC) algorithm with fast Fourier transform phase-locked loop (FFT-PLL). Test results demonstrate the system capabilities under the abnormal grid and unbalanced nonlinear load conditions.