A Droop Control Strategy for Mode Smooth Switching of Power Conversion System in Island Microgrid

Island microgrids play a vital role in remote areas such as islands and regions susceptible to grid instability, where the challenge of maintaining a stable power supply during transitions from grid-connected to island modes is particularly demanding, highlighting the necessity for sophisticated control strategies. This research presents an advanced droop control strategy designed to address the challenges of voltage shock, power oscillation, and frequency fluctuation during the transition from grid-connected to island mode in island microgrid power conversion systems (PCS). The strategy optimizes the design of voltage and current controllers by integrating a novel feedback mechanism into the PCS structure, enhancing the droop controller, and employing a synergistic approach of virtual impedance, integral, and differential control techniques to facilitate a stable operational transition. The system's damping properties are strengthened through the introduction of output current feedforward and capacitor current feedback, effectively reducing the transition time and overshoot, thus improving overall performance. Furthermore, the incorporation of virtual impedance recalibrates the system to inductive characteristics, enhancing robustness and stability. The traditional droop controller is refined and combined with integral and differential controllers, with control parameters and gains meticulously adjusted to optimize dynamic response and stability. This ensures precise control of the energy storage converter's output voltage and current during the transition, providing a robust guarantee for micro grid stability. The proposed strategy surpasses conventional control approaches by resolving issues inherent in mode transition and significantly improving micro grid stability, offering essential technical support for the reliable operation of island microgrids amidst grid instability.