Secondary Controller for PV Sources in DC/AC Hybrid Microgrid

The use of Photovoltaic (PV) sources has been increased significantly worldwide and applications are found in both DC as well as AC microgrid. The PV sources can be operated either in Grid connected mode or Islanding mode (Off-grid). Several Maximum power point tracking (MPPT) algorithms have been proposed to enhance the PV operation by extracting maximum possible power from the PV module. These methods are very much suitable for Grid connected mode but have a limited performance during Islanding mode. Tracking of Maximum power point (MPP) during Islanding mode may cause power mismatch between generated power ($P_{g}$) and demanded power ($P_{d}$) hence the system will suffer from Overvoltage / Undervoltage and poor power quality. In this paper, an adaptive controller is proposed to improve the performance of the PV system in both modes. It will track the MPP during Grid connected mode whereas during Islanding mode it will operate the PV in such a way that $P_{g}$ will become equal to $P_{d}$. The proposed controller is tested in MATLAB/SIMULINK for different possible system conditions and results are found to be accurate.