IFLL Based Control for PV System at Adverse Grid Conditions

This work proposes a control algorithm based on improved frequency locked loop (IFLL) applied to single stage grid connected solar photovoltaic (PV) system at adverse grid situations like voltage distortion, voltage swell/sag etc. The proposed IFLL control algorithm extracts the grid voltage fundamental component, under various adverse grid conditions like voltage distortion and voltage swell/sag. For a single stage system, during dynamics, a fixed gain PI (Proportional-Integral) controller doesn’t provide satisfactory performance. Thus, a shuffled frog leaping algorithm tuned PI (SFLAPI) controller is used to overcome the disadvantages of PI controller with fixed gains. The VSC (Voltage Source Converter) of PV system, supplies the PV energy to the grid even under the worst situations of voltage distortion and voltage swell/ sag. An incremental conductance (INC) based MPPT (Maximum Power Point Tracking) is used for the peak power extraction from the PV array. Tests are conducted under various odd states like voltage distortion and voltage swell/sag, insolation change etc. and for the same, a prototype is built in the research laboratory. Performance of proposed system is found to be satisfactory, as recommended by the IEEE-519 and IEEE-1547 standards.