For limiting the short-circuit current level, the rapid identification of the power frequency short-circuit current in a short-window is the key to fast and accurate response. This paper analyzes the transient characteristics of short-circuit faults, while introduces the basic principles of phaselet algorithm, least squares algorithm and extended Prony algorithm. Based on the transmission system simulation data, this paper analyzed the accuracy and calculated amount of the three algorithms, and explored the influences of three factors such as fault-point voltage phase, sampling frequency and data window length. Synthesizing performance comparison and theoretical analysis, the application range of the three algorithms is divided. The research results provide a reference for the selection of the short-window fast algorithm for identifying power frequency short-circuit current.

short-circuit current,amplitude identification,effect comparison,application range