Estimation of harmonics and interharmonics using phase-locked loop

Abstract

In recent times, the parameters of power systems are highly distorted, due to the increased application of nonlinear loads. The monitoring of harmonic and interharmonic distortion is an essential issue for delivering high quality power. The proposed harmonic and interharmonic estimation algorithm employs a filter bank and multirate signal processing. An enhanced phase-locked loop is used to estimate the parameters of the harmonics. The filter bank consists of a set of bandpass filters. The filters extract each of the harmonic and interharmoniccomponents. Further, the noise level of the components is also reduced. The extracted components are downsampled. In the last stage, the enhanced phase-locked loop estimates the amplitude, phase and frequency of the decomposed signal. The bandpass filters are centered at the estimated frequency. The estimation time and accuracy of this method compares favorably with alternate methods.