A Real-Time Adjustment of Conventional Under-Frequency Load Shedding Thresholds

Abstract

This letter presents an innovative and easy-to-implement approach for the improvement of conventional under-frequency load shedding, where frequency thresholds are adjusted locally in real time. The proposed method, which would be implemented locally in each under-frequency relay, estimates the forthcoming frequency evolution and adjusts the predefined frequency thresholds values according to the estimated frequency nadir. As a result, significantly improved frequency response by reducing overshoots can be observed. Concept verification was performed by means of Slovenian power-system model simulations, where the comparison with conventional constant-threshold setting showed a high level of efficiency.