Grid Interfaced Two Stage Solar System with Seamless Transition and Multifunctional Capability

This work presents an improved adaptive notch filter frequency locked loop (IANF-FLL) approach for solar photovoltaic (PV) system interfaced with three phase grid capable of working in both grid connected and islanding mode. The PV system produces active power and delivers to the loads coupled at PCC and excess power is delivered to the distribution grid. The voltage source converter executes various tasks such as mitigation of the harmonics, DC-AC conversion to supply the PV power to the AC load, generation of reference AC voltages during standalone mode of operation. Moreover, it is also capable to operate in the abnormal grid conditions such as DC offset and grid voltage distortion. Simulations are done on various dynamic conditions such as load unbalancing, grid voltages unbalance, PV insolation variation, standalone mode of operation and synchronization. The distortion levels of the grid currents achieved are well within the limits as recommended by the IEEE-519 standard.