A modified FOGI-FLL feature-based control algorithm for single-stage grid-interfaced solar PV system

This paper presents an overview of power quality improvement of the distributed network by using a novel robust control algorithm. The novel robust control algorithm is modified fourth-order generalized integral action with frequency-locked loop feature (Mod.FOGI-FLL) for a three-phase grid-interfaced single-stage solar photovoltaic (PV) system with distribution static compensator capabilities. The functions taken into features for robust control algorithm (Mod.FOGI-FLL) are load balancing, reactive power compensation, power factor correction with active power generation for proposed topology, and behavior of proposed control with different faults at point of common coupling (PCC). The perturb and observe (P&O) algorithm is used to extract maximum power from the PV array under variable atmospheric conditions. To adapt with variation in terminal voltage at the point of common contact (PCC), PV feed-forward term is also added in the control algorithm to make fewer oscillations in grid current. Test results demonstrate satisfactory response for steady-state and dynamic conditions at load unbalancing, variations in insolation level, and fault profile at VSC. The DC rejection capabilities of a proposed control methodology obtained are around 60 decibel which is 22 decibel more than FOGI-FLL techniques with the same gain parameters 38 decibel. The distortion in grid currents and voltages is obtained from MATLAB/SIMULINK within limits IEEE-519 standard.