This product integrates a power conversion system (PCS), batteries, a battery management system (BMS), thermal management, power distribution, and fire protection, adopts single-serial design, and enables zero damage of parallel connection. Meanwhile, harmonic governance, reactive compensation, and three-phase imbalance governance are integrated to realize peak-load shifting and peak load and frequency modulation. Multiple cabinets can be directly connected in parallel to expand the capacity of the energy storage system and allow plug-and-play.