Rapid identification of Sub-/Super-Synchronous oscillations by interpolated Zero-padding DFT

Sub-/super-synchronous oscillations pose significant threats to the safety and stability of the smart grid. Fast and accurate parameter estimation is essential for identifying sub-/super-synchronous oscillations, providing a foundation for addressing this challenge. However, with a short window length, frequency resolution is limited, making it difficult for existing interpolated-DFT-based methods to accurately estimate the parameters of closely spaced sub-/super-synchronous components near the fundamental frequency. To enhance real-time and precise identification, an interpolated zero-padding DFT method is proposed for estimating parameters of these oscillations from time-domain waveform data. This method accounts for the influence of multiple frequency components and uses spectral leakage as useful information. By examining the relationship between signal parameters and DFT bins, a linear equation system is constructed and solved to accurately determine the frequencies, amplitudes, and phases of the sub-/super-synchronous oscillations. Test results indicate that, compared to existing methods, the proposed method (i) reduces latency by a factor of 7.8 and (ii) offers a wider estimation range for the damping factor of sub-/super-synchronous components.