Modeling and simulation on long-term dynamics of interconnected power system using area COI concept

In order to study long-term frequency and voltage dynamics of interconnected power systems under cascading events, the paper has developed a proper mathematical model and simulation algorithm for it with network structure preserved. Similar to the traditional dynamic power flow, the proposed model assumes that the system has survived in the transient stability and has enough damping torque. Therefore, the relative swings among generator rotors in one area will be neglected in long-term dynamics; and each control area is assumed to have a uniform frequency, represented by its area center of inertia (COI). Fast decoupled method has been extended to solve the structure-preserved multi-area network equations. Computer test results from a modified IEEE30-bus power system demonstrate the validity and effectiveness of the proposed model and algorithm. The work establishes a simulation platform for future study on long-term frequency and voltage stability control strategy and coordination of interconnected power systems.