I International Conference on Renewable Energy - ICEREH 2026, Valverde (Spain). 10-13 November 2026
Summary:
Underfrequency load shedding (UFLS) is a lastresort tool to protect power systems against frequency collapse.UFLS schemes based on the frequency stability margin (FSM) have been proposed to make load shedding more adaptive, but they have been tuned by heuristic, graphical procedures. This paper proposes a systematic tuning of FSM-based UFLS schemes in which the frequency thresholds, the FSM thresholds and the intentional time delays of every stage are tuned jointly by minimizing the shed load subject to explicit frequency stability and UFLS-related constraints. Robustness is obtained by designing the schemes over representative operating-and-contingency (OC) scenarios selected by clustering. The method is applied to a real isolated Spanish power system and compared with the existing conventional scheme and its systematically designed counterpart. The tuned FSM-based scheme reduces load shedding over the considered OC scenarios without violating frequency limits. A broad, design-oriented sensitivity analysis then quantifies the effect of renewable energy source (RES) penetration, energy storage, the objective-function formulation, and the inclusion of step size as a decision variable.
Keywords: Island power systems, frequency stability, underfrequency load shedding, frequency stability margin, optimization.
Publication date: 10-Nov-2026.
Citation:
M. Vadillo, L. Sigrist, U. Rudez, "Systematic Tuning of UFLS Schemes Based on Frequency Stability Margin", presented at I International Conference on Renewable Energy - ICEREH 2026, Valverde, Spain, 10-13 November 2026
IIT-26-283C
