Advanced control and synchronization approaches of voltage source converters for integration of distributed energy resources

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dc.contributor Abu Qahouq, Jaber A.
dc.contributor Brovont, Aaron D.
dc.contributor Haskew, Tim A.
dc.contributor Lemmon, Andrew N.
dc.contributor Mahmoodi, S. Nima
dc.contributor.advisor Li, Shuhui Ramezani, Malek 2018-12-14T18:12:13Z 2018-12-14T18:12:13Z 2018
dc.identifier.other u0015_0000001_0003121
dc.identifier.other Ramezani_alatus_0004D_13526
dc.description Electronic Thesis or Dissertation
dc.description.abstract Voltage source converter (VSC) is an inseparable interfacing fixture for utilizing distributed energy resource (DER) as an AC power supply. This dissertation investigates different control and synchronization techniques for stand-alone and grid-connected DC-AC VSCs. The most common control reference frame for VSCs is the dq reference frame (dq-RF), also known as the synchronous reference frame. The main challenge associated with the VSC control in this reference frame is the strong coupling between d and q axes. In this dissertation, a multi-loop dq-RF control system with a coupling compensation scheme is presented. Then, the droop-based power control technique, which eliminates the need for communication between parallel-connected VSCs and consequently offers a higher reliability, is investigated. A dq-RF-based approach of impedance design, for compensating the inequality of parallel VSCs connecting lines, along with the dq-RF droop control are also proposed. This approach results in an accurate power-sharing among parallel VSCs. The major challenges related to the synchronization unit of a grid-connected VSC control system in the presence of a distorted AC voltage are also briefly investigated in this dissertation. To deal with these challenges, an enhanced complex coefficient filter based PLL is designed and presented. This PLL completely removes the grid voltage imbalance and considerably attenuates the grid voltage dc offset and harmonics while maintaining a fast dynamic response and a simple structure. The VSC-interfaced DER is often required to switch between the islanded and grid-connected operation modes. The VSC integrated into the grid is current-controlled, while in the islanded operation mode is controlled as a voltage source. In the transition between these two modes, first the intended VSC operation mode should be detected, then its control system is reconfigured. To avoid the complexity of the control system and alleviate the drawbacks associated with the control mode transition, a VSC control approach, which mimics the traditional synchronous generator’s universal mode of operation, is studied. A method of power-based active synchronization of the VSC-interfaced DER, with the ability of seamless transition between the islanded mode and connected to the grid, is proposed and integrated with this technique of the VSC control.
dc.format.extent 180 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Electrical engineering
dc.title Advanced control and synchronization approaches of voltage source converters for integration of distributed energy resources
dc.type thesis
dc.type text University of Alabama. Department of Electrical and Computer Engineering Electrical and Computer Engineering The University of Alabama doctoral Ph.D.

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