冯宽,王思华.计及谐波次自然频率和VMD的混合线路故障测距[J].电测与仪表,2019,56(17):109-115. fengkuan,wangsihua.Considering Harmonic Subharmonic Natural Frequency and VMD Hybrid Line Fault Location[J].Electrical Measurement & Instrumentation,2019,56(17):109-115.
Considering Harmonic Subharmonic Natural Frequency and VMD Hybrid Line Fault Location
The fault distance measurement method based on traveling wave natural frequency depends on the accurate extraction of the main natural frequency. However, for the overhead line-cable hybrid line, due to the difference of the line wave impedance and the number of traveling wave foldback shots, aliasing spectrum will be generated.For this reason, on the one hand, it is necessary to effectively eliminate spectrum aliasing, and on the other hand, relying only on a single primary natural frequency for ranging, the extraction results cannot be guaranteed. Based on this, this paper proposes a new hybrid ranging method that considers the harmonic natural frequencies and uses the VMD algorithm. The method firstly decomposes the traveling wave signal by EMD, and uses the Hurst exponent to screen the IMF as a modal parameter for VMD decomposition so as to avoid over-decomposition of the signal; then a MUSIC algorithm is introduced to perform spectrum analysis on the VMD decomposition result to extract fault signals. The frequency and its harmonic frequency. Finally, using its corresponding relationship to calculate the fault distance.The EMTDC simulation analysis of the hybrid line verifies that this method can effectively eliminate the spectrum aliasing and improve the reliability of the method based on traveling wave natural frequency ranging.