Local Input to State Stability Based Stability Criterion with Applications to Isolated Power Systems

Compared with a wide-area grid, an isolated power system (IPS) is usually operated under persistent disturbances and is vulnerable to external disturbances. The reliability of an IPS is often achieved through reconfiguration and emergency controls, which lead to variable topologies of an IPS. A fast and efficient stability criterion is required to ensure the stability of an IPS with changing structures. This paper proposes a stability criterion for dynamic systems based on local input-to-state stability (LISS) and local input-to-output stability (LIOS) properties of subsystems. The proposed stability criterion decomposes the stability analysis of the whole system into analyzing its subsystems' stability and connections. Since the LISS/LIOS properties of subsystems are completely decoupled and can be analyzed offline, the proposed stability criterion has the potential for online stability analysis through checking several algebraic inequalities. This method has good adaptability for topology changes and switching operations of subsystems. Algorithms for estimating subsystems' LISS/LIOS properties are also presented. Case studies on a typical isolated power system verify the proposed stability criterion.