Impact of maximum power point tracking on grid-connected Photovoltaic system dynamics

This paper studies the performance of a single-stage, three-phase Photovoltaic (PV) system that is connected to a distribution network. The control is based on an outer voltage control loop and an inner current regulation loop. A Maximum Power Point Tracker (MPPT) based on Perturb & Observe (P&O) method is interfaced to outer voltage control loop. The outer voltage control loop is based on feed-forward compensation strategy to make the PV system dynamics immune to the PV array nonlinear characteristics. Through simulation and mathematical analysis, it has been shown in previous research work that in the absence of feed-forward compensation change in the operating condition causes oscillation with weather condition unchanged. This paper shows through simulation that incorporation of MPPT in the PV system under steady-state renders an optimal operating point which results in a stable operation irrespective of weather condition and without feed-forward compensation. Moreover, an eigen value analysis is carried out both with the MPPT and without the MPPT to verify the simulated results.