Local renewable energy microgrids in remote regions are typically characterized by high renewable energy penetration and weak grid-interconnection channels. These features lead to insufficient inertia and poor stability in both the microgrid and the AC main grid, with a failure to meet the power supply demands of microgrid loads. Conventional grid-forming converters or flexible interconnection devices have limited optional capabilities, making it challenging to comprehensively address these issues. This paper proposes a grid-forming energy-storage-based flexible interconnection system (GFM-ESFIS) which integrates the flexible interconnection converters with energy-storage units to fully meet the stability and power supply reliability requirements of the microgrid–main grid interconnection system in remote regions. Key steady-state and transient control strategies are analyzed and designed for the GFM-ESFIS. Simulations based on MATLAB/Simulink 2024a and hardware-in-the-loop experiments based on RT-LAB verify the effectiveness of the proposed system and control strategies. Compared with conventional schemes, the proposed system can operate flexibly in series or parallel modes, realizing multiple capabilities including dual-terminal grid-forming support, fault ride-through control, power flow regulation, operation mode transition, and black start. It holds significant application value in reducing grid investment costs and improving the power supply reliability of microgrids in remote regions.
Zhao et al. (Wed,) studied this question.