CPC G01R 23/177 (2013.01) [H02J 3/241 (2020.01); H02J 3/381 (2013.01); H02J 2300/28 (2020.01)] | 19 Claims |
1. A method for detecting low-frequency oscillations in an electrical supply grid having a line voltage and associated with a rated line frequency, comprising:
recording at least one series of measurements having a plurality of measurement points of a grid variable over a measurement time period for performing a frequency analysis on the at least one series of measurements;
multiplying each measurement point of the at least one series of measurements by a time-dependent sinusoidal test function for the measurement time period to obtain a product for each measurement point, wherein the test function has a test frequency and a test angle as phase angle;
summing a plurality of products of the plurality of measurement points to produce a product sum, wherein summing the plurality of products includes retaining a plurality of signs of the plurality of products, respectively; and
determining, based on the product sum, whether the at least one series of measurements has a low-frequency oscillation having an oscillation frequency in a region of the test frequency and a phase angle in a region of the test angle, wherein the oscillation frequency is below the rated line frequency.
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