APPARATUS AND METHOD FOR ESTIMATING FREQUENCY OF SIGNAL IN POWER SYSTEM

摘要

A frequency estimating apparatus and method of a power system are provided to estimate precise frequency regardless of the change of a signal by obtaining three sample values by sampling cosine and sine signals generated through an orthogonal filter at regular intervals. A frequency estimating apparatus(100) of a power system is composed of an A/D(Analog To Digital) conversion unit(130) receiving a current or voltage value detected from the power system and converting the current or voltage value into a digital signal; a cosine filter(161) generating a cosine signal(Xr[n]) of a real-number axis from the digital signal converted in the A/D conversion unit; a sine filter(165) generating a sine signal(Xi[n]) of an imaginary axis from the digital signal converted in the A/D conversion unit; and a frequency estimating unit(170) extracting three sample values by sampling the orthogonal signals generated from the cosine and sine filters at regular intervals. The frequency estimating unit obtains a compensation coefficient of the third sample value sampled finally, calculates a sample compensation value by computing the third sample value and the compensation coefficient together, and estimates frequency of a digital signal by using the sample compensation value and the first sample value sampled first.