Power Oscillation Damping Capabilities of Grid Forming Based Hybrid Energy Storage Technology

This paper presents the power oscillation damping (POD) capabilities of a Hybrid Energy Storage System (HESS) based on ultracapacitors (UCAP) and batteries, integrated with a Grid-Forming (GFM) conversion system. The proposed system is designed to address challenges associated with low-inertia power grids, providing enhanced damping through both internal (inherent) and external POD control mechanisms. Adapting to the latest requirements set by the Spanish system operator (REE), this study highlights how the HESS-GFM solution effectively mitigates power oscillations while maintaining grid stability under dynamic conditions. By emulating synchronous generator behavior and leveraging hybridization at the DC side of the GFM converter, the system demonstrates superior performance in delivering POD services compared to conventional systems. The proposed activation algorithm for POD, compared to conventional systems, ensures reduced stress on the storage components, thereby extending battery life. This highlights the crucial role of advanced hybrid storage technologies and smart control strategies in enhancing grid stability, meeting evolving grid codes, and supporting a sustainable energy transition. The activation logic recommended by the system operator emerges as the key differentiator from conventional POD approaches.