A Lyapunov Direct Control Method for Large-signal Stability of DC Microgrid Clusters

A Lyapunov-based large-signal stability control method was proposed to address the challenge of large-signal stability in DC microgrid clusters with high penetration of distributed energy resources and high proportion of power electronic devices. First, a state-space model of the DC microgrid with constant power loads was established, and a Lyapunov energy function satisfying global asymptotic stability conditions was constructed, from which the control law for the islanded operation mode was derived. The control strategy was then extended to the cluster system model. It was demonstrated that the tie-line dynamics contributed negatively to the derivative of the Lyapunov function, revealing that the cluster system could maintain stability by implementing feedback control without modifying the original islanded control strategy. Finally, the proposed method was validated using a dSPACE hardware-in-the-loop experimental platform. The results indicate that under large-disturbance conditions such as step changes in constant power loads (0.6 kW→1.2 kW), bus voltage mutations (200 V→220 V), and input voltage jumps in the energy storage system (100 V→150 V), the proposed method is shown to ensure stable operation of the DC microgrid cluster while demonstrating excellent dynamic response performance. A structurally concise and insightful design approach is thus provided for large-signal stability control in microgrids and their interconnected systems.