Impact of System Impedance on Harmonics Produced by Variable Frequency Drives (VFDs)

dc.contributor.authorMorton, Daniel Daviden
dc.contributor.committeechairDe La Ree, Jaimeen
dc.contributor.committeememberCenteno, Virgilio A.en
dc.contributor.committeememberPhadke, Arun G.en
dc.contributor.departmentElectrical and Computer Engineeringen
dc.date.accessioned2015-05-12T08:00:07Zen
dc.date.available2015-05-12T08:00:07Zen
dc.date.issued2015-05-11en
dc.description.abstractVariable Frequency Drives (VFDs) are utilized in commercial and industrial facilities to improve motor efficiency and provide process flexibility. VFDs are nonlinear loads that inject harmonic currents into the power system, and result in harmonic voltages across the system impedance. This harmonic distortion can negatively impact the performance of other sensitive loads in the system. If a VFD serves a critical function, it may be necessary to supply the VFD from a Diesel Generator or Uninterruptible Power Supply (UPS). These sources have relatively high impedance when compared to a standard utility source, and will result in greater harmonic voltage distortion. This increases the likelihood of equipment failure due to harmonics. The full extent of the impact, however, is typically unknown until an extensive harmonic analysis is performed or the system is installed and tested. This thesis evaluates the impact that source impedance has on the harmonic voltage distortion that is produced by nonlinear loads such as VFDs. An ideal system of varying source types (Utility, Generator and UPS) and varying VFD rectifier technologies (6-Pulse, 12-Pulse and 18-Pulse) is created to perform this analysis and plot the results. The main output of this thesis is a simplified methodology for harmonic analysis that can be implemented when designing a power system with a VFD serving a critical function and a high impedance source like a generator or UPS. Performing this analysis will help to ensure that other sensitive loads will operate properly in the system.en
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:5347en
dc.identifier.urihttp://hdl.handle.net/10919/52247en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectHarmonic Analysisen
dc.subjectPower Electronicsen
dc.subjectVariable Frequency Drivesen
dc.titleImpact of System Impedance on Harmonics Produced by Variable Frequency Drives (VFDs)en
dc.typeThesisen
thesis.degree.disciplineElectrical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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