Development of control schemes for power converters and coordinated grid operation

Development of proper control schemes for three-phase pulse-width modulated (PWM) converters is crucial to achieve intended functions such as high conversion efficiency, low harmonic distortion and accurate control of real and reactive power flows. In this thesis, a complex-vector repetitive control...

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Bibliographic Details
Main Author: Tang, Yi
Other Authors: Loh Poh Chiang, Andrew
Format: Theses and Dissertations
Language:English
Published: 2012
Subjects:
Online Access:https://hdl.handle.net/10356/50719
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Institution: Nanyang Technological University
Language: English
Description
Summary:Development of proper control schemes for three-phase pulse-width modulated (PWM) converters is crucial to achieve intended functions such as high conversion efficiency, low harmonic distortion and accurate control of real and reactive power flows. In this thesis, a complex-vector repetitive control scheme is first proposed for grid-connected inverters to achieve precise power flow control and also to reject harmonic disturbances induced from the grid and loads. Based on this control concept, a double-loop control scheme is then proposed for controlling power converters with output inductor-capacitor filters, and they can continuously supply critical and emergency loads during ac mains outage. In order to transfer electrical power into the grid more efficiently, an inductor-capacitor-inductor (LCL) filter is introduced and the accompanied stability issues are addressed. A systematic design of LCL-filter-based active power filter is presented to improve system power quality. To achieve harmonic free AC/DC power conversion, a one-cycle controlled active rectifier is proposed and its operation under non-ideal supply voltage conditions is also investigated. All the control algorithms and design methodologies presented in this thesis are verified by laboratory experimental results, which demonstrate their effectiveness and practicality.