Abstract
In the dedicated high-precision power quality analyzer, synchronous sampling is required to reduce the effect of spectrum leakage produced by the discrete Fourier transform process. Thus, accurate fundamental frequency measurement is urgently needed. However, due to the harmonics and noise in the power signal, it is difficult to achieve the accurate fundamental frequency measurement. Moreover, with the wide application of high-frequency programmable power supply, the fundamental frequency is gradually increasing, which requires power analyzers to have the abilities of both high precision and a wide range of the fundamental frequency measurement. To solve these issues, a new fundamental frequency measurement architecture used in synchronous sampling is proposed. This architecture consists of a small-point fast Fourier transform module, spectrum refinement algorithm, and a multimodal optimization method to calculate the accurate fundamental frequency under large harmonic conditions. In the practical hardware platform results, this architecture has a large fundamental frequency measurement range from 20 Hz to 200 kHz with a relative error which is <0.004%. The wideband fundamental frequency measurement structure proposed in this article achieves high measurement accuracy.
Highlights
With the rapid development of power electronics technology, high-power electrical equipment such as AC motors and electric vehicles, as well as new energy power generation equipment such as solar power stations and wind power stations are gradually widely used in various fields of industry and residential life
This article sets out to improve the accuracy of fundamental frequency measurement under large harmonic conditions to meet the requirement of the synchronous sampling architecture used in the power quality analyzer
To achieve this goal, in this article, the spectrum refinement strategy is studied first to overcome the disadvantage of the limited frequency resolution of the discrete Fourier transform (DFT) algorithm
Summary
With the rapid development of power electronics technology, high-power electrical equipment such as AC motors and electric vehicles, as well as new energy power generation equipment such as solar power stations and wind power stations are gradually widely used in various fields of industry and residential life. To reduce this influence on harmonic analysis and other power parameter calculations, the literature (Jin et al, 2017) processed the sampled data by windowing and interpolation operations, which significantly improved the accuracy of fundamental frequency measurement and harmonic analysis This windowed interpolation method involves complex transformation formulas and heavy computation, which is difficult to apply in real-time power quality monitoring. When the signal is interfered with noise, harmonics, inter-harmonics, and other adverse effects, the accuracy of the PLL circuit is reduced or even the phase-locking is not possible (Tourigny-Plante et al, 2018)
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