Load-Independent Harmonic Mitigation in SCR-Fed Three-Phase Multiple ASD Systems with Deliberately Dispatched Firing Angles

Publikation: Forskning - peer reviewTidsskriftartikel

Abstract

Adjustable Speed Drives (ASDs) are widely used in three-phase multi-drive applications in industry for energy savings, where low-cost rectifiers (mainly Diode Rectifiers - DRs) are still employed as the front-ends in practice, also for simplicity in control and reliability in operation. However, significant harmonic distortions appear at the grid, which should be properly tackled according to increasingly stringent standards and/or grid-connection rules. If remain untreated, a poor power quality will cause efficiency drops of the entire system. Currently, communication technologies are still not of much cost-effectiveness, and hence, the use of communication in multiple parallel motordrive systems for harmonic control is rarely witnessed in industry. In this sense, this paper proposes a harmonic mitigation strategy for multiple parallel ASD systems, where another type of low-cost rectifiers (i.e., Silicon-Controlled Rectifiers - SCRs) with boost converters in the dc-link have adopted to increase the harmonic-current controllability. More specific, the SCR firing angles are deliberately dispatched among the SCR drive units, which results in certain phase shifts of the SCR currents on purpose. In such a manner, the harmonics appearing in the grid current can be mitigated to some extent in multi-drive systems without communication. The effectiveness is independent of the power loading of each drive, when a number of drives are connected. Simulations are carried out to verify the discussion. Furthermore, to make the most use of the SCR-fed structure for harmonic cancellation, a customized modulation scheme has been experimentally demonstrated. Both simulation and experiment results have verified the discussion.
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Detaljer

Adjustable Speed Drives (ASDs) are widely used in three-phase multi-drive applications in industry for energy savings, where low-cost rectifiers (mainly Diode Rectifiers - DRs) are still employed as the front-ends in practice, also for simplicity in control and reliability in operation. However, significant harmonic distortions appear at the grid, which should be properly tackled according to increasingly stringent standards and/or grid-connection rules. If remain untreated, a poor power quality will cause efficiency drops of the entire system. Currently, communication technologies are still not of much cost-effectiveness, and hence, the use of communication in multiple parallel motordrive systems for harmonic control is rarely witnessed in industry. In this sense, this paper proposes a harmonic mitigation strategy for multiple parallel ASD systems, where another type of low-cost rectifiers (i.e., Silicon-Controlled Rectifiers - SCRs) with boost converters in the dc-link have adopted to increase the harmonic-current controllability. More specific, the SCR firing angles are deliberately dispatched among the SCR drive units, which results in certain phase shifts of the SCR currents on purpose. In such a manner, the harmonics appearing in the grid current can be mitigated to some extent in multi-drive systems without communication. The effectiveness is independent of the power loading of each drive, when a number of drives are connected. Simulations are carried out to verify the discussion. Furthermore, to make the most use of the SCR-fed structure for harmonic cancellation, a customized modulation scheme has been experimentally demonstrated. Both simulation and experiment results have verified the discussion.
OriginalsprogEngelsk
TidsskriftIET Power Electronics
Sider (fra-til)1-8
Antal sider8
ISSN1755-4535
DOI
StatusAccepteret/In press - 2018
PublikationsartForskning
Peer reviewJa

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