Grid Model Reduction For Interconnection Studies of Inverter-Based Resources
Xiaowen Su, Chufeng Sun, Bin Wang · 2024
As the integration of inverter-based resources (IBRs) increases in electric power systems, new dynamic risks such as subsynchronous oscillations and nuisance tripping are emerging. Interconnection studies become crucial for reliable operation and planning. This paper proposes a model reduction methodology to significantly reduce the size of a given large-scale power grid dynamic model while retaining essential characteristics such as the load and generation in each area, tie-line flows among areas, short circuit current (SCC) at pre-specified points of interconnection (POIs), and frequency response. The reduced model can facilitate efficient dynamic simulation studies of IBRs as well as the additional network required for the integration such as high voltage direct current (HVDC) transmission systems. To retain the transient frequency response characteristics of the given large-scale system, a distance metric is proposed to quantify the difference in the response between the full system and the reduced system, and an optimization problem is formulated to identify the best values for pre-selected dynamic parameters of the reduced system leading to a minimum difference in response. A 2000-bus synthetic grid on the footprint of Texas is tested to show the effectiveness of the proposed model reduction method. The PSS/E RAW and DYR files of the reduced model are made free and publicly available on GitHub.