Yea Zong Kuo

Graduation Semester and Year




Document Type


Degree Name

Doctor of Philosophy in Electrical Engineering


Electrical Engineering

First Advisor

Wei-Jen Lee


Voltage sags are considered to be the most frequent type of disturbances in the field based on recent power disturbances studies. Their impact on sensitive loads is severe. The impact ranges from load disruptions to substantial economic losses. Despite the technical advances in electronics, there are still some pieces of equipment that are so sensitive that they are unable to withstand voltage sags. An example is the equipment in semiconductor manufacturing. As a result, there is still a search for different ways to manage voltage sags. There are many different methods to mitigate voltage sags, but a CUstom Power Supply (CUPS) device is considered to be the most efficient method. There are many types of CUPS. This dissertation studied various methods and concluded that the Dynamic Voltage Restorer (DVR) is the most efficient and effective device to protect sensitive equipment against voltage sags. Its appeal includes lower cost, smaller size, and its dynamic response to the disturbance. There are two general types of DVRs: Minimal Energy Control DVRs and In-Phase Control DVRs. One includes energy storage, and the other does not include energy storage, respectively. This dissertation focuses on the In-Phase Control DVRs, the one without energy storage. This dissertation describes the DVR from the initial phase of research and analysis to the final phase of testing and constructing the device. The DVR described in this dissertation consists of many different features. One feature is that the filter used in the harmonics correction is based on the Wavelet Transform (WT). The selection of the WT based filter is different from conventional methods such as the Fast Fourier Transform (FFT) in other DVRs. Another feature of the dissertation DVR is the hardware implementation. An FPGA board was selected to implement the dynamic controls instead of the traditional DSP board. Yet another feature is the power factor correction that was added later to the design in order to further enhance the dissertation DVR's overall capabilities. These features differentiate the dissertation DVR from other types of DVRs.


Electrical and Computer Engineering | Engineering


Degree granted by The University of Texas at Arlington