Frequency Control Strategy for Grid-Forming Energy Storage System Based on Virtual Synchronous Generator

To address the challenges of applying grid-forming energy storage systems in the primary frequency control of power grids, this study develops an innovative hybrid energy storage control framework that integrates photovoltaic systems, batteries, and supercapacitors. By designing a comprehensive system topology, bidirectional Buck-Boost converters are utilized to connect batteries and supercapacitors in parallel to the DC bus, allowing for precise regulation of the DC bus voltage. The battery system operates based on a power management strategy, where current references are derived from power setpoints to ensure consistent power output. Concurrently, the supercapacitor stabilizes the DC bus voltage, effectively handling transient power demands and balancing energy fluctuations. By incorporating a virtual synchronous generator (VSG) control algorithm, the system achieves seamless energy conversion from DC to AC for grid integration, delivering robust primary frequency response and frequency stability. Simulations validate that the proposed strategy maintains DC bus voltage stability, improves system responsiveness, and enhances operational reliability.