Dynamic Characteristics Analysis of Grid-Forming Type Renewable Energy/Storage for Active Frequency Support

In recent years, the proportion of renewable energy has been continuously increasing, leading to a significant decline in the inertia and frequency regulation capability of the power grid. Consequently, the risk of frequency instability has become increasingly severe. Grid-forming type renewable energy and energy storage systems, by mimicking the characteristics of traditional synchronous generators, can autonomously adjust their active power output in response to frequency fluctuations, thereby providing effective frequency support. It is particularly noteworthy that their control strategy is not based on real-time power grid frequency sampling but rather relies on an internally constructed frequency to achieve closed-loop control. This fundamental characteristic profoundly affects inertia response characteristics and primary frequency regulation performance. However, existing studies generally overlook this critical feature, resulting in insufficient model accuracy and a lack of rigorous mechanistic analysis. To address this issue, this paper conducts a targeted study. First, it reviews the frequency regulation requirements of the power grid and the impact of large-scale renewable energy integration on frequency regulation capability. Then, through simulations, it identifies that traditional grid-forming control overlooks the mismatch between the constructed frequency and the actual frequency during transient processes, leading to three major phenomena. Finally, it preliminarily analyzes the mechanisms behind these phenomena and emphasizes that establishing a targeted model that accounts for the deviation between the constructed frequency and the actual frequency after disturbances is a fundamental step toward improving grid-forming type frequency support.