No description available.

No description available.

No description available.

No description available.

Harmonic impedance characterizes the voltage response of a power system when it is subjected to the influence of high-frequency currents. The impedance is a key parameter of a power network and must be known to diagnose power system problems caused by high-frequency disturbances and to design disturbance-mitigation measures. Unfortunately, determining an operating power systems harmonic impedances is very difficult; they must be measured when the system is energized. In fact, how to measure a power systems high-frequency impedances has been a challenging and frequent research topic in the power engineering field. This thesis presents a measurement methodology that can determine the harmonic impedances and sources at both sides of utility-customer interface. This methodology is applicable to single-phase three-wire systems under energized conditions. A potential application of the method is to determine the harmonic contributions of the supply system and its customers at the interface points. / Power Engineering and Power Electronics

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No description available.

This thesis describes a novel harmonic domain approach for assessing the steady state performance of Flexible AC Transmission System (FACTS) devices. Existing harmonic analysis techniques are reviewed and used as the basis for a novel iterative harmonic domain model for PWM FACTS devices. The unified Newton formulation adopted uses a combination of positive frequency real valued harmonic and three-phase fundamental frequency power-flow mismatches to characterise a PWM converter system. A dc side mismatch formulation is employed in order to reduce the solution size, something only possible because of the hard switched nature of PWM converters. This computationally efficient formulation permits the study of generalised systems containing multiple FACTS devices. This modular PWM converter block is applied to series, shunt and multi-converter FACTS topologies, with a variety of basic control schemes. Using a three-phase power-flow initialisation and a fixed harmonic Jacobian provides robust convergence to a solution consistent with time domain simulation. By including the power-flow variables in the full harmonic solution the model avoids unnecessary assumptions regarding a fixed (or linearised) operating point, fully modelling system imbalance and the associated non-characteristic harmonics. The capability of the proposed technique is illustrated by considering a range of harmonic interaction mechanisms, both within and between FACTS devices. In particular, the impact of transmission network modelling and operating point variation is investigated with reference to ac and dc side harmonic interaction. The minor role harmonic distortion and over-modulation play in the PWM switching process is finally considered with reference to the associated reduction in system linearity.

The honey bee is one of the most important crop pollinating insects in the world. Researchers have recently identified a disease that has begun to impact the honey bee population. Colony Collapse Disorder results in the death of many bee colonies every year, but the cause for this remains unknown. Investigating the cause, harmonic radars are being considered to track the foraging patterns of honey bees. This research endeavors to find an optimized waveform for use in tracking foraging bees. Harmonic oscillators were developed for a transmit frequency of 1.2 GHz and various waveforms were tested against the oscillators. Ultimately, the waveform was found to be arbitrary. The amount of power that the harmonic oscillator receives is the determining factor. Given this, a general pulsed waveform can be developed that attempts to provide the maximum possible return for a predetermined maximum range of interest.

Yes / A novel design strategy for microstrip harmonic-suppression antennas is presented. The computational method is based on an integral equation solver using adaptive surface meshing driven by a genetic algorithm. Two examples are illustrated, all involving design of coaxially-fed air-dielectric patch antennas implanted with shorting and folded walls. The characteristics of the antennas in terms of the impedance responses and far ¯eld radiation patterns are discussed theoretically and experimentally. The performances of all of the GA-optimised antennas were shown to be excellent and the presented examples show the capability of the proposed method in antenna design using GA. / MSCRC