Dynamic phasor battery model for frequency stability analysis

Abstract

The increasing penetration of renewable generation is introducing new challenges in power system operation, particularly in terms of frequency stability. Battery Energy Storage Systems (BESS) have demonstrated a strong capability to provide fast frequency support; however, their accurate representation in dynamic simulation tools remains a challenge. This work presents an open-source auxiliary user model compatible with the CBEST battery model developed by EPRI, enabling frequency-based control of BESS in phasor-domain simulations. The proposed model measures the bus frequency and generates an active power signal based on either a droop or a step control strategy, which can be selected depending on the study requirements. This approach allows the analysis of the BESS contribution to frequency response in large-scale transmission systems. Its implementation in a benchmark network demonstrates both its applicability and scalability.