Development of control schemes for power converters and coordinated grid operation
Date of Issue2012
School of Electrical and Electronic Engineering
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.
DRNTU::Engineering::Electrical and electronic engineering