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Variable-frequency drives and harmonics
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
The right side of Figure 6.12 shows both 3rd and 5th harmonic distortions superimposed on the fundamental frequency. In this case, individual frequencies in the composite become less intuitive. In real situations, the composite waveform becomes so distorted that it is virtually impossible to visually dissect out the individual harmonic waveforms. In that case, a spectrum analysis using Fast Fourier Transforms deconstructs the individual harmonic frequencies from the distorted composite. A spectrum analysis uses the frequency domain, instead of time, and each amplitude is plotted in a bar-graph compared to the first harmonic. The signature of the harmonic spectrum analysis is useful in identifying the predominant causes of the harmonics. The spectrum analysis allows engineers to easily discern which harmonics are the most problematic, and to aid in designing a solution to mitigate them.
Linear Electric Circuits
Published in Pedro Ponce, Arturo Molina, Omar Mata, Luis Ibarra, Brian MacCleery, Power System Fundamentals, 2017
Pedro Ponce, Arturo Molina, Omar Mata, Luis Ibarra, Brian MacCleery
The harmonic spectrum is a bar plot of the magnitudes of harmonics described in the Fourier series. Let us take the waveform from Figure 1.32, and by applying an FFT we find the harmonic spectrum presented in Figure 1.33.
Alkali metals in the attosecond pulse train
Published in Journal of Modern Optics, 2022
It should be pointed out that there are two goals for the attosecond pulse synthesis from HHG. One is the generation of isolated attosecond pulse by using HHG with a few-cycle driving pulse or with a many-cycle driving pulse using some of the gating techniques [12]. This implies a continuous harmonic spectrum over the cutoff frequency. In this case, the emission of cutoff harmonics is temporarily confined to one single burst. The other goal is the formation of APT from the broad plateau spectrum. It has been experimentally demonstrated that a train of pulses as short as a few hundred attoseconds is generated when several odd harmonics of an intense, infrared, linearly polarized laser field are combined in a phase-locked manner [13].
Switched capacitor-based quadruple boost multilevel inverter topology with reduced switch count and its extension
Published in International Journal of Electronics, 2023
Oorappan G Murugan, Sivaraman Pandarinathan, B Goldvin Sugirtha Dhas
Figure 14 demonstrates the experimental THD value for the proposed MLI is 6.3%. Since practical power electronics switches have such a finite turning-on and turning-off time that contributes to the quantisation waveform distortion. The output voltage is 120 V and the fundamental frequency is 50 given to the fluke metre to get the harmonic spectrum of one to 50 .
Improved dynamic performance of permanent magnet synchronous generator based grid connected wind energy system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Preeti Rani, Ved Parkash Arora, Naveen Kumar Sharma
As per IEEE 519-1992, value of THD should be less than 5% of fundamental frequency for the balance operation of grid-connected networks. By employing DVR, the harmonic spectrum in terms of 2.80% of fundamental frequency for SRF-controlled DVR is depicted in Fig 18(b) and harmonic spectrum in terms of 1.04% of fundamental frequency for modified hysteresis control DVR is depicted in Fig 18(c).