Direct methods for transient stability analysis of power systems: Recent results

TLDR

Transient stability analysis ensures power systems remain synchronized after disturbances, but long simulation times hinder online use, prompting a shift toward Lyapunov direct methods and recent progress on energy functions and online criteria. The paper critically reviews research on direct methods for transient stability analysis since 1970. The authors review the literature on Lyapunov direct methods, focusing on theoretical properties of energy functions and online criteria. The review finds that while current theory adequately handles voltage‑dependent reactive power, transfer conductances, and flux decay, it fails to include exciter control and lacks rigorous justification for online criteria, and recent evidence of chaotic behavior indicates incomplete understanding of power system dynamics.

Abstract

Transient stability analysis of a power system is concerned with the system's ability to remain in synchronism following a disturbance. In utility planning, transient stability is studied by numerical simulation. The long CPU run times for simulation preclude their use for on-line security analysis. Interest has therefore shifted toward the Lyapunov direct method of stability analysis. This paper provides a critical review of research on direct methods since 1970. Considerable progress has been made on both theoretical properties of energy functions and on criteria suitable for on-line implementation. Current theory provides a satisfactory treatment of voltage-dependent reactive power demand, transfer conductances, and flux decay. However, it cannot incorporate the exciter control Proposed on-line criteria appear to work very well on sample examples; but, they still lack rigorous justification. Finally, recent work has shown that power systems can exhibit chaotic behavior. This surprising fact demonstrates that our understanding of the dynamics of power systems remains incomplete.