Uncertainty and Disturbance Estimator-Based Control for Current-Source Inverter-Interfaced Photovoltaic Systems

Abstract

Although voltage-source inverters are extensively used as the interface between the photovoltaic systems and the grid, the current-source inverter can be a viable interfacing choice due to its specific characteristics. Obtaining maximum power from the panels at unity power factor is the main goal for a photovoltaic control system. In this paper, the control structure includes two cascaded loops: the outer-loop for dc-side control, and the inner-loop for ac-side control. An uncertainty and disturbance estimator (UDE)-based control approach is employed for both outer and inner control loops in order to deal with PV array nonlinearity, model uncertainties, coupling effects, and grid disturbances. As the current-source inverter along with its output filter is a second order system, the ac-side dynamics is split into two cascaded first-order systems and then the UDE-based control is applied to the whole system. The effectiveness of the proposed approach and its robustness are verified through time domain simulation results.