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Abstract

The invention relates to a frequency measuring method and measuring device. The method comprises: firstly sampling the current signal to be measured, and discretizing the sampled signals; secondly obtaining sampling matrixes [I_n] and [I_n,] of the current signal to be measured at time n and time n−1 from the discrete sampled signals, setting a reference frequency f_ref, constructing a reference voltage signal u(t) from f_ref, and discretizing u(t) to gain reference matrix; finally, attaining phase values of time n and time n−1 from the eigenvalues of matrixes [I_n]⁺[U] and [I_n−1]⁺[U], and determining a calculation frequency f_comp. The invention uses sampled matrixes constructed from the reference signals and the signals to be measured. Through QR decomposition and similarity transformation of matrixes and the eigenvalues calculation of the corresponding matrixes, phases of the matrixes to be measured are gained, and the frequencies of the signals to be measured are calculated through the phase difference between the former and the latter sampling moment. The solution simplifies calculating process and reduces calculation, in comparison to the prior art, and can calculate the frequencies of the sinusoidal signals quickly and precisely in the power frequency data window.

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