A normal form-based power system out-of-step protection

• Published in: Electric power systems research 2022-07, Vol.208 (C), p.107873, Article 107873
• Main Authors: Ugwuanyi, Nnaemeka Sunday, Kestelyn, Xavier, Thomas, Olivier, Marinescu, Bogdan, Wang, Bin
• Format: Article
• Language: English
• Subjects: Canonical forms; Electric power; Engineering Sciences; Equal area criterion; Frequencies; Frequency shift; Identification methods; Mechanics; Monitoring systems; Nonlinear phenomena; Nonlinear systems; Normal form; Oscillation frequency drift; Out-of-step detection; Power supply; Transient stability; Vibrations
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2022.107873

•The frequency of electromechanical oscillations declines during faults.•Tracking the frequency descent helps detect out-of-step in power systems.•The Normal Form technique allows tracking the frequency deterioration of electromechanical oscillations.•Faster and system-wide out-of-step identification and mitigation technique emerges.•Possible online application of the method. This paper proposes a new system-level application for monitoring out-of-step (OOS) events in power systems. As already known, amplitude-dependent frequency shift is a nonlinear phenomenon of electromechanical oscillations under large disturbances. The frequency shift indicates the system’s nearness to instability. This new tool utilizes the Normal Form method to identify the named phenomenon, leading to accelerated OOS detection. The proposed strategy is illustrated and compared to the equal-area criterion method in a single-machine-infinite-bus power system. Extensive tests on IEEE 3- and IEEE 50-machine power systems prove the efficacy and potential of the proposed method for online warnings of instability and ranking of vulnerable system modes.