Abstract
Time-frequency analysis (TFA) is an essential tool in power harmonic analysis. However, the traditional TFA method tends to generate a fuzzy time-frequency distribution. In order to enhance the energy aggregation of harmonic time-frequency distribution, the multisynchrosqueezing transform (MSST) is introduced to analyze the time-frequency and mode decomposition of power harmonics. Firstly, the result of the synchrosqueezing transform of a harmonic signal is calculated iteratively. Subsequently, the time-frequency distribution energy of the harmonic signal is compressed further to obtain a more accurate time-frequency graph of the harmonic signal. Secondly, MSST's powerful reconstruction ability is utilized to decompose the harmonic signal mode, resulting in a series of intrinsic mode type functions (IMT) of varying frequencies to extract each harmonic component. An improved multisynchrosqueezing transform (IMSST) was proposed to solve the problems of non-rearranged points and endpoint effects in MSST. Simulation experiments and measured data demonstrate that the proposed method can achieve more accurate time-frequency analysis and mode decomposition of harmonic signals. It also reveals the time-frequency characteristics and variations of harmonic waves in power grids, which is crucial for harmonic control in power grids.