Degree

Doctor of Philosophy (PhD)

Department

The Department of Electrical and Computer Engineering

Document Type

Dissertation

Abstract

This dissertation presents a method of adaptive compensation, capable of handling power factor and the supply quality improvement under non-sinusoidal conditions. The focus in this dissertation is put on developing compensation for ultra-high power metallurgical plants, meaning on compensation in three-phase, four-wire ultra-high power dynamic, distribution systems. A separate attention in the dissertation is put on the adaptive compensation of ultrahigh power arc furnaces. The dissertation also presents an original method of adaptive compensation of DC current generated by such arc furnaces.

The proposed compensator is developed in the frame of the Currents’ Physical Components (CPC) – based power theory. Elements of this theory are compiled in the dissertation. A design of an adaptive reactive compensation in four-wire systems with nonsinusoidal voltages is described in this dissertation. The method of compensation is based on (CPC) – power theory. Moreover, the selection of a special structure of Thyristor Controlled Susceptance (TCS) branches and their LC parameters has effectively improved the compensator’s performance in the presence of supply voltage distortion.

The dissertation also discusses the possibility of balancing ultra-high power ac arc furnace directly at the furnace’s terminals, i.e., on the furnace transformer's secondary side. In the first, uneasy phase of the furnace operation the extinction of the arc in one direction causes the arc current asymmetry and a DC component occurs in these currents. The dissertation presents a rationale for the selection of thyristors’ firing angles that enables simultaneous compensation of the reactive and unbalanced currents and DC current by the same compensator. This is the main original contribution of this dissertation. The method proposed was confirmed by computer simulation.

Date

7-20-2022

Committee Chair

Czarnecki, Leszek S

Available for download on Thursday, July 10, 2025

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