TY  - Type of reference 
TI  - Uncovering Weakly Damped Nonlinear Inter-Aria Modes in High-RES Scenarios: A Koopman-Based Analysis of Tunisia’s Future Grid 
AU  - Yassine BOUSSAA
 
AU  - Khadija BEN KILANI
 
AU  - Fethi GHODHBANE 
AB  - The increasing penetration of renewable energy sources (RES) significantly modifies power system dynamics by reducing inertia and amplifying nonlinear interactions. Conventional eigenvalue-based small-signal stability methods capture linearized behavior but fail to reveal hidden nonlinear oscillatory components emerging under renewable-rich conditions. This paper investigates the oscillatory stability of the Tunisian power grid projected for 2030 under a peak-load scenario with 35% RES penetration. Using a detailed nonlinear PSAT model, Classical Linear Modal Analysis (LMA) is combined with Koopman Modal Analysis (KMA), a data-driven operator-based approach extracting spatiotemporal dynamic structures from simulation data. Results show that LMA identifies the dominant inter-area mode near 0.8 Hz, while KMA reveals additional weakly damped nonlinear modes within the critical [0.7–1 Hz] band. Koopman mode shapes highlight a dominant North–[Centre + South] oscillation driven by the 400 kV transmission backbone, with time-domain reconstructions confirming long decay times. The study proposes targeted measures including PSS improvement, transmission reinforcement, PMU-based wide-area monitoring, and advanced control strategies. KMA is demonstrated as a powerful complement to classical modal analysis for future renewable-dominated grids. 
DO  - 10.21494/ISTE.OP.2026.1482 
JF  - Entropy: Thermodynamics – Energy – Environment – Economy  
KW  - Inter-area oscillations, Koopman operator, DMD, non-linear modal analysis, large-scale renewable energy integration, Generators coherency, wide-area monitoring, Tunisian power system, Oscillations interzones, opérateur de Koopman, DMD, analyse modale non linéaire, intégration des énergies renouvelables, cohérence des générateurs, réseau électrique tunisien,  
L1  - https://www.openscience.fr/IMG/pdf/iste_entropie26v7n3_2.pdf 
LA  - en 
PB  - ISTE OpenScience 
DA  - 2026/09/7 
SN  - 2634-1476 
TT  - Mise en évidence des modes interzones non linéaires faiblement amortis dans des scénarios à forte pénétration renouvelable : Analyse basée sur Koopman du futur réseau électrique tunisien 
UR  - https://www.openscience.fr/Uncovering-Weakly-Damped-Nonlinear-Inter-Aria-Modes-in-High-RES-Scenarios-A 
IS  - Special issue CIER 
VL  - 7 
ER  -