ROGI with FsLMS Based Control Technique for Solar PV System under Weak Grid

Abstract

This paper deals with a proposed modified ROGI-FLL (Reduced Ordered Generalised Integrator Frequency Locked Loop) based control for a double stage, 3P4W (Three-Phase Four-Wire) grid-tied solar photovoltaic (PV) system. This modified FLL based control extracts the positive sequence components of grid voltages. This FLL based voltage control deals with the grid voltage issues such as voltage distortion and voltage unbalancing. The proposed robust FsLMS (Filtered-s Least Mean Square) based control strategy is used to extract the fundamental active current component of load to generate the reference grid current for DC-AC converter. The proposed LMS based control addresses multiple power quality concerns such as harmonics minimisation, grid currents balancing, and power factor correction. An INC (Incremental Conductance) based MPPT (Maximum Power Point Tracking) technique tracks the crest power, which is used to generate the gating pulses for the boost converter. The VSC (Voltage Source converter) is used to sustain the DC link voltage across the capacitor. The extricated solar PV power is used to feed the real power demand of load and surplus power is injected into the grid. The proposed system is simulated into the MATLAB\Simulink environment and a developed prototype is realised in the laboratory to validate the proposed control. Test results of proposed system shows satisfactory responses under various dynamic conditions such as varying solar irradiation levels, load unbalancing, grid voltage distortions and grid voltages unbalancing. The total harmonic distortions (THD) of the grid voltages and grid currents are observed well within the IEEE-519 and 1159 standards.