Augmentation of State Feedback Control and Integral Action for Stabilization Issues in Islanded DC Microgrid

When the switched-mode power electronic converters are tightly regulated with feedback control, they exhibit negative incremental impedance due to Constant Power Loads (CPLs) behavior. As a consequence, the output voltage exhibits growing oscillations leading to instability. This work addresses the problem of handling this instability issue using a state feedback control approach to increase the damping and ensure stability. To attain zero steady-state error, an integral action is augmented to the state feedback control. The design of a state feedback control with integral action has been carried out using the classical pole-placement method. The poles are placed at the desired locations using Butterworth polynomial such that the proposed controller stabilizes the overall system. To validate the effectiveness of the proposed state feedback control with augmented integral action for CPL, the simulations are carried out using MATLAB/Simulink on a buck-type DC-DC converter. The results show that the converter voltage is stabilized and in addition, exhibits improved dynamic performance for external disturbances such as sudden changes in the input voltage.