Objective To address the common challenges in current project practices of distributed grid-forming energy storage systems, such as complex communication interactions, extensive equipment retrofitting, and high investment costs, this paper proposes a low-cost, easy-to-implement application scheme and control strategy for distributed grid-forming energy storage systems suitable for scenarios with large geographical coverage and less stringent load reliability requirements.

Method First, the basic principles of mainstream grid-forming control technologies, namely droop control and virtual synchronous generator (VSG) technology, were introduced, along with the virtual impedance and pre-synchronization techniques required in practical engineering. Subsequently, from the perspectives of individual equipment configuration and overall system control, this study investigated equipment site selection and evaluation methods, the impact of grid-forming energy storage system integration on existing line protection, virtual impedance configuration, and black start issues.

Result Based on this, the study proposes a scheme to access the "three-remote" (tele-signaling, tele-metering, and tele-control) signals of low-voltage incoming line circuit breakers to maximize the utilization of existing equipment. A "master-slave" ("one-large-supporting-multiple-small") scheme is designed to reduce the system's dependence on the regulation of the upper-level controller, thereby lowering system complexity and minimizing the need for new hardware. To address key issues during the black start process, such as the auxiliary power supply gap, transformer inrush current, and capacitive inrush currents, optimization strategies are devised, including sequencing the auxiliary equipment startup, transformer soft start, and active voltage reduction during closing to mitigate capacitive inrush impacts. The effectiveness of this scheme is demonstrated through engineering application.

Conclusion This scheme requires minimal grid retrofitting, reduces the coupling degree among equipment, and significantly enhances the feasibility of engineering applications while ensuring renewable energy integration and backup power reliability. It provides a valuable technical reference for the deployment of grid-forming energy storage systems.