| 摘要 |
<p>Method for operating a frequency relay and frequency relay for carrying out the method which, via measuring transformers, senses the frequency of an electric power network, determines the value of the frequency and delivers an output signal when the frequency thus determined drifts out of a permissible frequency range. Specific to the invention is the method of determining the currently prevailing frequency of the power network. The measurement signal (y/< ANd >(t)) obtained from the network is transformed, after filtering (1) and digitizing (2), into an analytic model (4) in the form of a truncated Fourier series (y(t)), the coefficients of which are determined in a parameter estimator (3) which operates with a method of estimation (5) in accordance with the least squares method. Starting from model values, according to the invention a computation of the frequency can be carried out in a frequency estimator (6), the output signal of which, on the one hand, is returned as current frequency value to the parameter estimator and, on the other hand, constitutes a measure of the current frequency ( omega /< ANd >) when determining the limits of permissible frequency variations.</p> |
