An Instantaneous Frequency Identification Algorithm for the Dynamic Frequency Signals in power system

Dynamic behaviors of the power system may cause the time-varying and non-stationary characteristics of voltage and other signals. To solve the problem that the dynamic frequency of non-stationary signals is difficult to estimate, we proposed a Parameterized Frequency Undetermined Coefficient method (PFUC) to identify the instantaneous frequency (IF). The PFUC utilizes the Taylor expansion of the time-varying function to parameterize the IF. Based on the relationship between phase and time, the linear equations about the parameters of IF expansion are constructed. By substituting the solution into the IF expansion, the IF values at any time can be obtained. The PFUC achieves the goal of frequency identification with high-precision. In addition, the PFUC combined with empirical mode decomposition (EMD) can effectively deal with the situation that the signal has a trend term. The performance was demonstrated through simulations for various scenarios possibly existing in actual power systems.