Risk-based probabilistic System Security Assessment: Swissgrid's Approach from Operational Planning to real-time System Operation

European TSOs rely on deterministic network security assessments (dNSA) from outage planning to real-time system operations. This can either overlook low-probable but high-impact exceptional contingencies (EC) or rare contingencies (RC) or trigger costly overreactions to ordinary contingencies (OC) with limited consequences. Motivated by this, the paper presents a risk-based probabilistic security assessment methodology that Swissgrid plans to apply from