Abstract
The harmonic and interharmonic analysis recommendations are contained in the latest IEC standards on power quality. Measurement and analysis experiences have shown that great difficulties arise in the interharmonic detection and measurement with acceptable levels of accuracy. In order to improve the resolution of spectrum analysis, the traditional method (e.g. discrete Fourier transform) is to take more sampling cycles, e.g. 10 sampling cycles corresponding to the spectrum interval of 5 Hz while the fundamental frequency is 50 Hz. However, this method is not suitable to the interharmonic measurement, because the frequencies of interharmonic components are non-integer multiples of the fundamental frequency, which makes the measurement additionally difficult. In this paper, the tunable resolution multiple signal classification (TRMUSIC) algorithm is presented, which the spectrum can be tuned to exhibit high resolution in targeted regions. Some simulation examples show that the resolution for two adjacent frequency components is usually sufficient to measure interharmonics in power systems with acceptable computation time. The proposed method is also suited to analyze interharmonics when there exists an undesirable asynchronous deviation and additive white noise.
Highlights
2 n is 0.1, the tunable factor is set to 5. It can be seen from Equation (30) that includes the interharmonic components of 44 Hz and 57 Hz
Simulations are presented to demonstrate the anti-noise performance of tunable resolution multiple signal classification (TRMUSIC) algorithm based on cross-spectral estimation comparing to that of the multiple signal classification (MUSIC) algorithm based on auto-spectral estimation
It can be seen that the TRMUSIC algorithm based on cross-spectral estimation is only slightly affected by additive noise because the pseudo-peaks can locate steadily in the corresponding frequency bins
Summary
These loads include static frequency converters, cycloconverters, sub-synchronous converter cascades, induction motors, arc furnaces and so on [1]. A method, which is aimed to standardize the harmonic and interharmonic measurement, has been proposed by the IEC [2]. This method utilizes discrete Fourier transform (DFT) performed over a rectangular time window of exactly 10 cycles for 50 Hz power systems. The interharmonic group is defined as the RMS (Rootmean-square) value of all the interharmonic components between adjacent harmonic groups (see Figure 1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
