Power System Residual Inertia Assessment with Signal-Injection and Event-Based Methodologies: A Case Study in Taiwan

Grid operators face challenges integrating Inverter Based Resources (IBR) due to their lack of inertia, leading to rapid and severe frequency deviations that could trip load and generation or cause islanding. To mitigate these risks, it is essential to measure and leverage the inertia from synchronous motors in the load and unmetered embedded generators, known as residual inertia. This paper details methodologies for real-time continuous inertia measurement using signal injection and event-based estimation from transient recordings. The Taiwanese grid’s total inertia was quantified during 17 generator trips over 18 months and continuously measured for 10 days during the Lunar New Year injecting an active power signal from a Battery Energy Storage System (BESS), collecting 2760 inertia measurement samples. Significant residual inertia, on average 34% of the total inertia, was found. Continuous inertia measurement is crucial for accurate modelling, forecasting, and safe integration of renewable energy sources, demonstrating Taiwan's grid resilience and capacity for future expansion.