Research on Pre-synchronization Control Strategy for the Integration of Individual Microgrid into Microgrid Clusters

Tropical islands frequently face energy supply shortages due to limitations imposed by their natural environment. The utilization of a single microgrid structure often leads to power instability and even network-wide failures. Interconnecting multiple microgrids and operating them in a clustered manner can effectively enhance the reliability of power supply. However, during the process of integrating a specific microgrid into the cluster, voltage magnitude and phase imbalances at the common connection points can give rise to transient stability issues. To address the aforementioned challenges, a microgrid cluster synchronization and integration strategy based on pre-synchronization control is proposed. The voltage magnitude of inverter outputs and the voltage vector of the microgrid cluster are transformed into the rotational coordinate system using Clark and Park transformations, thereby obtaining the phase angle and magnitude deviations of the voltages. With PI control employed, compensatory values for grid frequency and grid voltage are individually determined to ensure consistent voltage phase and magnitude between the pre-synchronization side and the microgrid cluster side. This approach effectively resolves voltage and frequency fluctuations during mode transitions, enabling smooth switching between the islanded and grid-connected modes of microgrid operation. Finally, the effectiveness of the proposed control strategy is verified through simulation to be a feasible solution for the smooth integration of a microgrid into microgrid clusters.