Observer-Based Nonrecursive Control Scheme of PV-Interfaced Boost Converters in DC Microgrids for Large-Signal Stability

Photovoltaic (PV) systems serve as essential power generation units in DC microgrids. Therefore, ensuring their reliable and efficient operation remains a fundamental challenge. Nevertheless, the operation of PV system is susceptible to different types of disturbances, including internal nonlinear dynamics, environmental conditions, and operational states of either DC microgrids or main grids. Here, we propose an observer-based nonrecursive controller for PV-interfaced boost converters to achieve accurate and rapid regulation of PV array voltage even when large disturbances occur. First, the dynamics of the PV system are converted to a controllable canonical form via exact feedback linearization, by which the real-time PV power, parameter uncertainties, and unmodeled dynamics are packed into lumped disturbances. Subsequently, disturbance observation techniques are utilized to estimate these disturbances, and the estimated values are incorporated into the design of the feedforward compensation loops. Finally, a systematic coordinate transformation with feedback control techniques yields a compact controller that facilitates the practical implementation. On this basis, a rigorous stability analysis is conducted using Lyapunov stability theory. The effectiveness of the proposed controller is validated through Matlab/Simulink simulations, real-time simulation on the RT-LAB platform, and experimental results obtained from a laboratory-scale PV-based DC microgrid testbed. The evaluation includes typical operating scenarios as well as comparative studies with state-of-the-art control methods, which demonstrate the superior voltage tracking performance of the proposed controller.