PWM Based Fixed Frequency Equivalent SM Controller for Stability of DC Microgrid System

Abstract

DC microgrids are localized and independent power distribution networks which show high efficiency when batteries and renewable sources are interconnected with the system. This paper addresses the stability of the dc microgrid through a decentralized control scheme. A centralized control architecture can improve the stability but reliability is compromised if the central controller fails. Droop control is commonly used to address the stability problem based on techniques through linear controllers. However, the Droop controller requires a tradeoff between voltage regulation and droop gain. Further, the global stability of the systems cannot be ensured through linear control techniques. Additionally, for different operating requirements and load conditions, it is difficult to optimize the parameters of these controllers. To address limitations, a PWM Based fixed frequency equivalent sliding mode (SM) control technique is proposed for dc microgrid stability. SM controllers show high robust performance. To formulate the problem, system equations are modeled and the operation of the system under SM is verified for existence and stability conditions. To examine the transient performance, the responses for critically damped and underdamped are investigated and presented. The results of detailed experiments simulations are presented which show the efficiency of the proposed control method.