Analysis of Impedance Configuration and Protection Strategy of Electrochemical Energy Storage Power Station Based on Large-capacity Main Transformer

With the growth of global renewable energy scale and the introduction of energy storage-related policies, the rapid development of large-scale energy storage power stations has been facilitated. However, due to the requirements of land intensification and investment cost control for these projects, the integrated design schemes for energy storage power stations have presented unconventional features. Among them, the use of high-capacity main transformers to integrate into the 110kV grid for hundred-megawatt-scale energy storage power stations has become a normalized approach, leading to some related issues such as difficulties in setting protective relays due to reduced equivalent impedance and cascading trips of the station's energy storage system integrated circuits. To address these issues, this paper proposes various equivalent impedance enhancement schemes. Furthermore, an evaluation and analysis framework is introduced, incorporating metrics such as active and reactive power losses, voltage deviations, and other indices. This framework allows for rigorous technical and economic comparisons, supported by simulation modeling analyses. Through this approach, recommended impedance configuration schemes and protective relay setting strategies for energy storage power stations are provided, offering valuable references for subsequent design optimizations.