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Source publication
Low frequency modulation strategies are a
good solution to increase the energy conversion efficiency
in high power applications. The paper is devoted to
presents an innovative way to low order harmonics
mitigation for seven-level Cascaded H-Bridge Inverters. In
particular, this approach is based on the mitigation of
selected harmonics without solve...
Citations
... The analysis of the research and engineering literature, as well as the results of research carried out by our team, show that the leading manufacturers of FC-AFEs, in most cases, cannot properly implement the technical solutions to assure the electromagnetic compatibility of FC-AFE-based high-power electric drives and the mediumvoltage factory grid. The use of specialized PWM algorithms with selective harmonic elimination or mitigation and Selective Harmonic Mitigation PWM algorithms [35][36][37][38][39][40][41][42][43]) or other (Space Vector PWM [44,45]) may not always provide the effect required to assure the set voltage quality in common MSDS sections due to the lack of the adaptation function to the resonant phenomena in the 6-35 kV power grid for these algorithms. Note that the input grid filters in FC-AFEs, as well as the conventional narrow-band higher harmonic filter, installed in the high-power FC-AFE-based electric drives, cannot assure the complete elimination of negative impacts of FC-AFEs on the power quality due to the complexity of resonant phenomena [46], which is manifested in the presence of several resonance maximums in various regions of the frequency response. ...
Today, electric drive systems based on frequency converters with active front-end rectifiers (FC-AFEs) are widespread across industries. In the course of the upgrade of production facilities, such systems replace the conventional converters with thyristor- and diode-based rectifiers. FC-AFEs have the following advantages: the capacity to regenerate the power to the grid and the capacity to operate at the set power factor. The manufacturers of FC-AFEs also claim that their products have the best electromagnetic compatibility (EMC) with the power grid. The best EMC shall be achieved via a multilevel FC-AFE topology and specialized pulse-width modulation (PWM) algorithms for AFE rectifiers. However, the experience of operating mid-voltage high-power electric drives with an FC-AFE in 6–35 kV factory distribution grids with non-linear frequency response due to resonant phenomena refutes the claims of the FC-AFE manufacturers. Resonant phenomena in 6–35 kV grids are caused by the interaction of the inductance of grid components (transformers, reactors) and the capacitance of output cable lines. If the resonance frequency at a sufficient amplitude corresponds to the harmonic frequency of the current consumed by the FC-AFE, the distribution grid will feature high-frequency voltage distortions. This may lead to failures in voltage quality-sensitive electrical consumers. This problem recurred at various metallurgical companies. The purpose of this research is to make a comprehensive overview of the EMC problems during the operation of FC-AFEs at active production facilities, as well as the analysis of the technical solutions aimed at the improvement of the EMC of high-power FC-AFEs with the power grid.
Considering the development of the hybrid wind and solar photovoltaic generation and smart grid, Active Front-End (AFE) converters for high-power applications are facing significant opportunities and challenges related to power quality and efficiency. The Pre-programmed Pulse-Width Modulation (PPWM) techniques can strictly control the harmonic spectrum of a specified voltage or current waveform generated by a high-power AFE converters, and have been extensively applied to reduce or even eliminate the harmonic distortion with low switching losses for high-power converters in order to deal with these issues aforementioned. For the PPWM techniques with low switching frequency, Selective Harmonic Elimination (SHE) and Selective Harmonic Mitigation (SHM) have been the prevailing solutions and gain widespread popularity, among which SHM can provide further control of the harmonic spectrum in cases of similar switching losses to SHE. Over the past several decades, the applications of SHE and SHM have been extended to high-power AFE converters. Thus, the aim of this study is to provide a comprehensive literature review regarding their various formulations, solving algorithms, and existing problems to high-power AFE converters. In addition, the suggestions for future applications of PPWM in high-power AFE converters are also discussed.
