Small-Signal Modeling and Voltage PID controller-Synthesis for Cascade Regulation of Renewable Energy Conversion System

this paper solves the ripple issue that occurs in the electrical energy supplying a variable resistive load in varying climatic conditions. The desired voltage can be reached by optimally controlling the duty cycle of a DC-DC boost converter that connects the previous resistive load with a KC200GT photovoltaic generator GPV. Since the ripple issue is often generated by the direct application of Maximum Power Point Tracking MPPT control strategies, in particular the one based on the Perturb and Observe P&O algorithm that we will choose in this paper. Improving the performance of this preceding strategy would therefore be the main aim of the present study, in which a new control strategy is highlighted, which is called: Improved P&O-MPPT. The voltage regulation provided by the standard P&O-MPPT control strategy is usually achieved by the direct update of the duty cycle control. This last is done in accordance with the existing PV power and PV voltage, where a fixed step-size, user-preset, is used to perform this update. Unfortunately, choosing a large or small size of this step leads to the failure of this control strategy which in turn leads to the presence of malfunctions in the functioning of all devices implemented in the Renewable Energy Conversion REC system. The automatic update of the previous duty cycle control by the proposed voltage PID controller overcomes the drawback of the standard P&O-MPPT control strategy where the needed step-procedures that include both modeling and controller-synthesis stages making the main contribution of this paper.