Out-of-Step Protection Modeling for Virtual Playback Testing Applied to Industrial Generators

Abstract

The protection characteristics used for the detection of power systems’ oscillations are adjusted according to the recommendations of the equipment manuals and validated through transient stability studies. Once the characteristics are adjusted, the parameters do not change when topological changes occur in the system, which opens up the possibility of malfunction of the protection equipment, either by not considering special cases of failure during the study or by errors in the system. This paper describes the modeling and implementation of a virtual out-of-step protection algorithm based on traditional, unconventional methods. The proposed framework allows the user to implement a customized out-of-step protection algorithm and analyze a real fault event recorded in a COMTRADE file. Furthermore, the programming advantages include the possibility to import COMTRADE files from specific simulations and assess the adequate settings of the protective relay. The result brings a computational tool compatible with different simulation programs capable of reproducing stable and unstable power swing events through playback techniques. By assessing critical cases in which the omission of the tripping is reflected in a generator slip condition, this study proposes an alternative with the instantaneous power theory to analyze the oscillation conditions in the definite time frame.