Data acquisition in power systems and its digital processing for measurement and automation

We present results of comparison of magnitude spectrum estimation of periodical signals by discrete fourier transform (DFT) or fast fourier transform (FFT) and special finite impulse response (FIR) filters, with other methods of spectrum analysis, based on DFT/FFT and sample interpolation in time domain (resampling). All of compared methods use a preliminary accurate estimation of the actual power line frequency, so that a difference between them is determined only by intermediate sample processing, which eliminates leakage related errors appearing because of desynchronization between signal and sample frequencies. Different aspects of real time application of the proposed method are also discussed