Design of Hybrid-Storage-Based Virtual Synchronous Machine With Energy Recovery Control Considering Energy Consumed in Inertial and Damping Support

The reduced inertia in power system introduces more operation risks and challenges due to the degraded frequency performance. The existing virtual inertia control and fast frequency response to tackle this issue are restricted by the energy resource behind the power converter. In this article, an improved virtual synchronous machine control is proposed, considering the limitation of energy storage in response speed and energy capacity. The fast-acting energy storage system is used to emulate inertia and damping. The energy consumed by both services in dynamic process and steady-state state is also investigated. An energy recovery control is designed to restore the energy consumed in inertia emulation and damping provision, thereby ensuring constant energy reserve. Besides, the slow-acting energy storage with larger energy capacity, is controlled like the governor regulator of synchronous generator and capable of providing long-term energy service. A design procedure considering storage limitation, control stability, and bandwidth separation is proposed. Effectiveness of the proposed control and design is validated by comprehensive simulation and hardware test results.