| 摘要 |
A measuring method for determining the amplitude and the phase of the fundamental tone/frequency of an alternating voltage in an ac network wherein the determination is performed in a numerical relay (12) which is based on a constant sampling frequency and which comprises a Fourier filter (7) for determining the amplitude and the phase of the alternating voltage, which measuring method is characterized in that the Fourier filter is an adaptative Fournier filter which is adapted in such a way with respect to the number of sample points that the deviation between the filter frequency of the adaptive filter, adapted to the nominal fundamental tone/frequency of the ac network, and a fundamental tone/frequency determined with a calculating unit (10) is minimized. |
