Accurate Power Sharing and Synchronization Strategies in Mesh Islanded or Grid-Connected Microgrids

In microgrids with a high penetration rate of distributed generators (DGs), the intermittency of renewable energy can cause microgrid instability, especially in islanded mode. In this case, it can be connected to the main grid; this possibility also improves its reliability and voltage quality. The transition between the islanded mode and the grid-connected mode of the microgrid requires an efficient synchronization strategy that doesn't affect power sharing between different DGs connected to the microgrid. Many researchers have already studied and discussed power sharing and synchronization strategies to ensure a seamless transition between the two operating modes of the microgrids for which several DGs and Loads are connected to the same Point of Common Coupling (mono-PCC microgrids). In this paper, a nonlinear distributed control for DGs synchronization to the microgrid as well as active and reactive power sharing in islanded and grid-connected mesh microgrids is proposed while the real characteristics of the power lines connecting the PCCs are considered. In addition, an investigation of communication delay impact on the proposed control is also conducted. The simulation results using Simulink/Simscape and experimental results using the Hardware-in-the-Loop (HIL) real time simulation in opal-rt and dSPACE platforms confirm the effectiveness of the proposed strategies.