Sliding DFT based grid to ground admittance estimation with guaranteed numerical stability

This paper describes the sliding discrete Fourier transform algorithm (SDFT) for parallel admittance estimation. The SDFT is a popular algorithm for continual single-point or several-point spectral analyzes of discrete time signals. The main drawback of the SDFT is a numerical stability issue. The paper describes the algorithm of SDFT with guaranteed numerical stability by parallel spectra computation. Furthermore, the paper presents the application of SDFT for continual parameter identification of grid to ground admittance of ac power distribution network. The grid admittance is analyzed by voltage response on injected current into auxiliary winding of the Petersen coil. The spectral analyses of injected current and voltage response are used for Petersen coil tuning. The current is injected by H-bridge voltage source inverter.