Predefined-Time Virtual Synchronous Generator Control for Voltage Stability Enhancement in DC Microgrids using Hybrid Electric Vehicle Support

The increasing penetration of renewables has driven the evolution of converter-dominated DC microgrids (MGs), which offer improved efficiency and simplified control architectures compared to conventional AC systems. However, the absence of mechanical inertia in converter-based DC MGs results in pronounced voltage instability during sudden load or generation fuctuations. To address this challenge, this paper proposes a predefined-time virtual synchronous generator (PdT-VSG) control strategy integrated with a hybrid electric vehicle (HEV) as an energy storage system. The HEV system integrates a fuel cell, a supercapacitor, and a battery to provide coordinated virtual damping and inertial support. Irrespective of the initial operating conditions, the predefined-time controller is intended to guarantee that the DC-bus voltage returns to its nominal level within a specified time bound. Simultaneously, the VSG emulates the behavior of a conventional synchronous machine, thereby enhancing system damping and transient stability. To assess the controller’s performance under different load situations and low-inertia scenarios, a comprehensive MATLAB/Simulink® model of an islanded DC MG was developed. The outcomes demonstrate that the PdT-VSG-based HEV provides superior transient voltage recovery, less overshoot, and a quicker settling response compared with existing inertia-emulation and damping-based control approaches. Overall, the proposed control scheme offers a fast, predictable, and robust voltage regulation solution well suited for future hybrid and renewable-dominated DC MGs.