1.School of Electrical and Information Engineering, Hunan University, Changsha410082, China;2.Electric Power Research Institute of China Southern Power Grid Company Limited, Guangzhou510663, China

The grid-connected converter with photovoltaic and energy storage has the characteristics of low inertia, weak damping, weak voltage regulation ability, and frequent power fluctuations. Large-scale integration of grid-connected converters with photovoltaic and energy storage will affect the safe and stable operation of the power system. For this kind of grid-connected converter with energy storage, this paper proposes a current-based control strategy with embedded synchronous generator support characteristics to enhance the inertial support capability of the system. This strategy simulates the dynamic behavior of synchronous generators and controls the external characteristics of the grid-connected converter output to a controlled current source with synchronous generator control characteristics. It combines the advantages of grid-forming control based on the virtual synchronous generator and grid-following control based on the phase-locked loop, which demonstrates the significant comprehensive advantages in inertia support, fault ride-through, power grid harmonic, and islanding operation. The proposed strategy does not require detection and sampling of the output frequency differentiation of the system, which avoids noise interference caused by frequency differentiation detection. In addition, to address the irreconcilable contradiction between the inertia support capability on the AC side and the voltage stability on the DC side, this paper designs a fuzzy adaptive proportional-integral (PI) control strategy to coordinate the voltage stability on the DC side and the inertia support on the AC side. Finally, the hardware-in-the-loop experimental results verify the feasibility and effectiveness of the proposed strategy.