Application of Battery and Flywheel Energy Storage Systems for Frequency Regulation in the Honduran Power Grid

The increasing penetration of inverter-based renewable generation has reduced rotational inertia in power systems worldwide, causing steeper frequency drops after severe contingencies and increasing the risk of load shedding. In the Honduran context, this study evaluates the dynamic response of the National Interconnected System (NIS) operating in island mode through detailed DIgSILENT PowerFactory simulations, explicitly incorporating the national Under-Frequency Load Shedding (UFLS) scheme. Five disturbance scenarios were analyzed, including generation losses of 100 MW, 200 MW, and 262 MW, to assess the frequency support provided by Battery Energy Storage Systems (BESSs) and Flywheel Energy Storage Systems (FESSs). Results show that, in the base case, frequency decreased to 55.3 Hz during a 200 MW loss, confirming the system’s high vulnerability. The integration of a 75 MW BESS improved frequency stability to 58.74 Hz, preventing UFLS activation, while a 320 MW equivalent FESS provided only short-term inertial support with limited effectiveness. Quantitatively, the BESS reduced the minimum frequency, delayed UFLS activation by approximately 3.5 s, and provided sustained support, whereas the FESS contributed mainly during the first 5 s of the disturbance. In the most severe contingency (262 MW generation loss), the combined operation of BESS and FESS prevented total system collapse, improving the frequency nadir to 58.6 Hz. These results confirm that BESS provides more robust and sustained frequency support than FESS under the analyzed conditions, highlighting its effectiveness for improving system stability in low-inertia networks such as Honduras. The findings offer useful insights for future studies on storage integration and frequency regulation strategies.