Smooth Transition of a Grid Connected PV System to Standalone operation

Abstract

This work introduces a control approach for a single stage solar photovoltaic (PV) generation system interfaced to the utility. In a single stage system, the voltage source converter (VSC) is used for MPPT (Maximum Power Point Tracking) operation of the PV array. It also maintains the DC-link voltage and converts the DC power produced by the PV array to the AC power to be supplied to the loads connected at PCC. The PSCs (Positive Sequence Components) of the unbalanced grid voltages are estimated for the evaluation of the unit templates. Moreover, it also provides the harmonics compensation of the load currents along with (UPF) unity power factor operation using multi-variable filter-based control algorithm. Thus, the distortion levels in the grid currents are decreased below 5%. During the grid failure, the system operates in standalone mode. A synchronization control is used for the smooth connection of the system to the grid during its availability and disconnection from the grid when it is unavailable. Experiments are done on a laboratory prototype at various dynamics and steady state conditions.