A DFT‐based method for estimating interharmonics in wind power generation

Monteiro, Henrique Luis Moreira; Camponogara, Ândrei; Ribeiro, Moisés V.; Duque, Carlos A.; Poor, H. Vincent

doi:10.1049/stg2.12072

Cited by 4 publications

(2 citation statements)

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“…Interharmonics mainly originate from nonperiodic changes in current and voltage caused by loads operating in nonsteady states and/or amplitude modulation in control strategies [4]. Several factors contribute to their generation, including the use of nonlinear loads, double conversion systems, cascaded subsynchronous converters [5,6], asymmetric induction motors and the incorporation of AC/DC and DC/AC conversions in renewable energy sources such as photovoltaic systems [7][8][9] and wind turbines [10,11]. Additionally, double-stage systems, which consist of two AC systems operating at different frequencies interconnected through a DC link [12,13], have also been identified as significant sources of interharmonics.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Interharmonics Generation in Induction Motors Driven by Variable Frequency Drives and AC Choppers

Gudiño-Ochoa,

Jalomo-Cuevas,

Molinar-Solís

et al. 2023

Energies

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In modern power systems, interharmonics have emerged as noninteger frequency components that appear in current or voltage signals. Double-stage AC-DC-AC converters have been identified as a primary source of interharmonics. Previous studies have highlighted modulation techniques, filters, passive components, unbalanced conditions and DC link effects as relevant factors. However, the interaction between these factors and the inertial properties of induction motors has not been explored. This study assesses various types of AC drives, including variable frequency drives (VFDs) and soft starters (AC choppers), to investigate their interaction with machine inertial properties in interharmonic generation. The employed technique for time-frequency spectral analysis is the wavelet synchrosqueezed transform combined with a clustering method. This paper demonstrates that the interaction of the inertial properties of low-power induction motors with the variations of the switching frequencies of the VFDs, the filters used in the DC link and a soft start indirectly contribute to harmonic generation and potentially to interharmonics in the electrical grid and the outputs of the inverter.

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Section: Introductionmentioning

confidence: 99%

Analysis of Interharmonics Generation in Induction Motors Driven by Variable Frequency Drives and AC Choppers

Gudiño-Ochoa,

Jalomo-Cuevas,

Molinar-Solís

et al. 2023

Energies

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“…In [32], it was shown that the combination of a re-sampling method, based on the Lagrange function, with the IpDFT is an interesting strategy to estimate the harmonics and interharmonics components for frequency deviation scenarios and noisy signals. Although this method presents accurate results, the analysis is made until the second harmonic and the re-sampling method was based on the Lagrange function.…”

Section: Introductionmentioning

confidence: 99%

Harmonic and Interharmonic Estimation Based on Re-Sampling and IpDFT Methods

Monteiro

Rodrigues

Ferreira

et al. 2023

Preprint

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Harmonic and interharmonic estimation is essential for Power System monitoring, particularly for Power Quality (PQ) analysis. These components can interfere with the device functionality, leading to motor heating and energy consumption inefficiency. Usually, the estimation of these components is performed by Fourier Transform; however, the estimation accuracy can decrease in specific scenarios. If the sampled signal is asynchronous or is composed of interharmonics, for example, the energy is spread along the frequency spectrum, causing estimation errors. In this context, this work proposes an innovative method to estimate the harmonic and interharmonic, combining a re-sampling method, based on B-spline with a pre-filter, and Interpolated Discrete Fourier Transform (IpDFT) to avoid the leakage caused by asynchronous sampling and interharmonics. Three real-time re-sampling methods combined with IpDFT are analyzed via simulated voltage signals. The results show that the proposed method is accurate, and robust for all scenarios.

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