Robust LMI-based voltage control strategy for DC microgrids under disturbances and constant power load uncertainties

With the growing trend of using DC renewable energies and energy storage devices in DC microgrids and considering that many loads need to be supplied from DC sources, it is essential to design a control system that can guarantee stability and robust performance of DC microgrids. Uncertainties, disturbances, and noises usually occur in microgrids and may affect the stability of such systems. In addition, the negative impedance characteristics of constant power loads (CPLs) may lead to DC bus voltage deviations and even instability of whole DC microgrid system. In this paper, a robust dynamic output feedback voltage controller based on linear matrix inequalities (LMIs) is proposed to stabilize the voltage of DC microgrids in the presence of uncertainties. The proposed controller is robust against the DC bus reference voltage changes, input voltage disturbances, and polytopic uncertainties of CPLs. It also guarantees the stability of the system by the Lyapunov theory and does not require any pre-filter to adjust the transient responses. The proposed LMI conditions is less conservative than the existing LMI-based methods, leading to a significant reduction in computational complexity. The proposed controller is designed using the YALMIP toolbox and implemented and validated in the MATLAB/Simscape Electrical toolbox.