Voltage/Current Large Transient Suppression in DC Microgrids Using Local Information and Active Stabilizing Capability

This paper presents a nonlinear control strategy for the suppression of large voltage-current transients in a dc microgrid (dc-MG) with a high penetration of constant power loads (CPLs). The voltages and currents in a dc-MG experience significant transients during large changes in the CPLs with their nonlinear voltage-current characteristics. Herein, an auxiliary nonlinear stabilizer is designed for a super-capacitor (SC) module for actively stabilizing a dc-MG. Due to the limitations in the energy of the SC module; a fuel cell (FC) stack is paralleled with the SC module in the form of a hybrid SC/FC unit to provide the steady-state power demand of dc-MG. The proposed controller is designed using Lyapunov theory and is robust with respect to the output current transients imposed on power converters from the rest of the dc-MG. In the presented control strategy, only one-generation unit is designed and implemented in the form of a hybrid SC/FC unit to suppress the large transients. The proposed stabilizer in the SC module operates based on local information. The effectiveness of the proposed control strategy has been validated in a multisource dc-MG using time domain simulations carried out in MATLAB/Simulink software environment.