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Harmonics Measurement With a Modulated Sliding Discrete Fourier Transform Algorithm | IEEE Journals & Magazine | IEEE Xplore

Harmonics Measurement With a Modulated Sliding Discrete Fourier Transform Algorithm


Abstract:

Accurate harmonics estimation has become a key issue in power quality assessment. This paper deals with a discrete Fourier transform (DFT)-based measurement technique, wh...Show More

Abstract:

Accurate harmonics estimation has become a key issue in power quality assessment. This paper deals with a discrete Fourier transform (DFT)-based measurement technique, which can be easily employed to accurately determine the harmonic components of a distorted signal, i.e., voltage or current. The proposed method is based on a modulated sliding DFT algorithm, which is unconditionally stable and does not accumulate errors due to finite precision representation, and a variable sampling period technique (VSPT) to achieve a frequency adaptive mechanism. It is worth noting that the VSPT changes the sampling period for a variable grid frequency condition, leading to a constant sampling frequency under steady-state conditions. The proposed method provides: 1) high degree of accuracy; 2) structural/performance robustness; and 3) frequency adaptability. Given the modular nature of the method, it is implemented on a field programmable gate array. Simulations and experimental tests are shown to verify the performance of the proposed method.
Published in: IEEE Transactions on Instrumentation and Measurement ( Volume: 63, Issue: 4, April 2014)
Page(s): 781 - 793
Date of Publication: 05 November 2013

ISSN Information:


I. Introduction

With the widespread applications of advanced power electric technologies, such as switching power supplies and adjustable speed motor drives, among others, harmonic currents are increasingly being injected into power systems causing power quality degradation. Harmonics increase power system losses, damages sensitive loads, causes excessive heating in rotating machinery, creates significant interference on communication systems, and generates noise in regulating devices and control systems. In addition, the system frequency may deviate from its nominal value due to power imbalance between generation and load demand. Therefore, measuring grid harmonics, in an accurate and efficient manner, has turned into a major challenge [1]–[3].

References

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