A novel power-line oriented DFT method with error elimination at off-line frequency operation

This paper presents a novel method for harmonic decomposition of power-system periodic signals based on extended Discrete Fourier Transform. At off-nominal frequency operation, DFT introduces significant frequency dependent error. Thorough DFT analysis was performed to discover how the error occurs. The algorithm for error cancellation is developed and implemented in a form of extension of conventional DFT method. Successful implementation depends on how accurate the signal frequency is known. The method is tested and verified through worst-case simulations. In comparison to conventional DFT, it has shown significant improvements.