Real-time implementation of optimal operation of single-stage grid interfaced PV system under weak grid conditions

This study presents a real-time implementation of the optimal operation of a single-stage three-phase grid interfaced solar photovoltaic (PV) system with active shunt filter capabilities. The control approach is based on the least logarithmic absolute difference with an adaptive filtering technique. It serves manifold objectives of power quality improvements in the distribution network as well as grid side abnormalities such as voltage distortions, voltage sag and voltage swell. The proposed control algorithm has advantages of better steady state as well as dynamic performances as compared to conventional algorithms. The perturb and observe-based maximum power point tracking algorithm is used to harness crest power from the PV array. The proposed system is simulated in MATLAB/Simulink platform using Simscape power systems toolbox and its performance is compared with conventional algorithms. A prototype of the proposed system is developed in the laboratory and its responses are found satisfactory under various operating conditions such as load unbalancing, reactive power compensation, variable solar insolation, voltages distortion, voltage sag and voltage swell. The total harmonic distortions of grid currents and grid voltages are found within limits of an IEEE-519 standard.