Frequency Security Assessment in Power Systems With High Penetration of Renewables Considering Spatio-Temporal Frequency Distribution

A team of researchers from Tsinghua University, including Changjun He, Hua Geng, Xiuqiang He, and Yushuang Liu, has introduced a novel framework for assessing frequency security in power systems heavily integrated with renewable energy sources. Their work, published on arXiv (2604.21262), addresses the growing challenge of spatial and temporal frequency variations caused by renewables like wind and solar, which can destabilize grids. The core innovation is a generic Effective Nodal Frequency (ENF) model that simplifies complex nodal frequency dynamics into three key parameters: effective nodal inertia (ENI), damping, and primary regulation. This model allows for tractable analytical formulas to predict nodal frequency trajectories and security indicators.

The study's quantitative analysis under temporary power disturbances reveals that ENI is the most critical parameter for maintaining frequency security. The authors analytically derived the critical nodal inertia needed to prevent frequency violations. They then proposed a system-level frequency security index based on the ratio of actual ENI to critical inertia. To make this practical, they implemented an 'offline calculation, online evaluation' strategy using a lookup table and interpolation method, enabling real-time assessment without heavy computational loads. Simulations on the modified IEEE 39-bus system confirmed the method's effectiveness, offering a scalable solution for grid operators managing high renewable penetration.