The discrete Hartley transform (DHT) has proved to be a valuable tool in digital signal/image processing and communications and has also attracted research interests in many multidimensional applications. Although many fast algorithms have been developed for the calculation of one- and two-dimensional (1-D and 2-D) DHT, the development of multidimensional algorithms in three and more dimensions is still unexplored and has not been given similar attention; hence, the multidimensional Hartley transform is usually calculated through the row-column approach. However, proper multidimensional algorithms can be more efficient than the row-column method and need to be developed. Therefore, it is the aim of this paper to introduce the concept and derivation of the three-dimensional (3-D) radix-2 /spl times/ 2 /spl times/ 2 algorithm for fast calculation of the 3-D discrete Hartley transform. The proposed algorithm is based on the principles of the divide-and-conquer approach applied directly in 3-D. It has a simple butterfly structure and has been found to offer significant savings in arithmetic operations compared with the row-column approach based on similar algorithms.

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Radix-2 /spl times/ 2 /spl times/ 2 algorithm for the 3-D discrete Hartley transform

ldquoPower qualityrdquo (PQ) is a generic term often used in relation with unwanted disturbances of the electricity supply. In recent years, there has been an increased number of PQ related problems. This is mainly due to the rapid growth in the use of equipment that generate PQ disturbances and also increase of equipment that are sensitive to these disturbances. This increased concern about PQ issues from both suppliers and consumers of electricity has increased the demand for advanced PQ monitoring systems. Each PQ disturbance has a unique wave shape resembling its characteristics. Therefore PQ disturbances could be identified by monitoring the voltage/current signal waveform and analysing its features. PQ monitoring instruments can vary from a simple true r.m.s. meter to advanced techniques that are capable of automatically capturing and classifying PQ events. This paper presents an overview of the characteristics, effects and causes of PQ events and addresses recent trends in PQ monitoring.

Power Quality: Overview and monitoring

To increase their usability wind and kinetic-tidal generators and Electric Vehicles (EVs) require efficient conversion between mechanical and electrical energy. The brushless dc machine (BLDCM) is entirely suitable for such a task, and to exemplify its use this thesis details a high efficiency kinetic-tidal energy generator test system. To maximise the energy yield it uses a low solidity turbine, an efficient transmission system, a BLDCM generator, and a maximum power point tracker. BLDCM cogging torque is also addressed. Measured results are presented, with the measured efficiency of the water-turbine being 30%in real-world conditions. Although the BLDCM is an efficient energy converter, it requires power electronic control; the soft-switched Actively Clamped Resonant DC Link Inverter (ACRLI) is an ideal choice for such. This thesis details a complete mathematical analysis of the ACRLI topology, and develops formulae for all important voltages, currents, and timing. A complete list of loss formulae for all major components, including a MOSFET clamp device, is presented. These formulae can be used to optimally design ACRLIs, and an optimal design for a 10 kW EV is described. Since the inductor in a high power ACRLI is problematic, this thesis addresses large ferritecored inductor design, analysing hysteresis and eddy current core loss and Litz wire conduction loss. An optimal but non-realisable design is shown, followed by a near-optimal, realisable and economical very low loss inductor design; an inductor was fabricated in accordance with this design and its measured loss in resonant link operation, being less than 20W for the 10kW high current inverter, is consistent with theory. The BLDCM’s applicability in the general EV field has been questioned due to its rectangular torque versus speed characteristic. To modify this characteristic a voltage booster could be used. The ACRLI can provide such boosting with the addition of a few components, the main one being a rectifier grade thyristor, thus creating the Actively Clamped Resonant DC Link-Boost Inverter (ACRL-BI) topology. This new topology is analysed along with an optimal thyristor dv=dt snubber, a suitable current control method with minimum switching frequency, and a novel driver interface for EV use. A 10 kWACRL-BI prototype was built and measured results of resonant and boost operation are shown.

Resonant link inverters for trapezoidal flux electrically commutated machines

Power quality is a subject of great concern for electric utilities and their customers, since disturbances can have a very adverse effect on customer equipment. Several techniques have been developed over the last decades to simulate and analyze power quality problems using a digital computer. The EMTP (ElectroMagnetic Transients Program) and like are among the most popular tools based on a time-domain method. The aim of this paper is to summarize the current status of the use of these tools in power quality studies. The paper includes an introduction to the solution methods and capabilities implemented in transients programs.

Power quality analysis using electromagnetic transients programs

The introduction of life cycle management (LCM) into power system asset management is very helpful for maintaining the secure and economic operation of the power system concerned, reducing the life cycle cost (LCC) and improving the management of electric power assets. Given this background, a brief survey is first made on the state-of-the-art of LCM in power system asset management, including cost accounting, evaluation and external environmental factors. Then, problems associated with the LCM applications in power system asset management are examined. Finally, prospects are addressed for future research in this area.

Asset management in power systems

An analog to the Fourier series based on the cosine-and-sine function is considered. The new series is related to the Hartley transform and thus it is termed the Hartley series. Properties and applications of the Hartley series are discussed in general. It is pointed out that the technique is valuable for the assessment of power quality in industrial and commercial power distribution systems. In particular, the impact of switched and pulse-modulated loads and AC/DC converters may be analyzed. An example is presented in which an industrial distribution system impacted by a six-pulse rectifier is analyzed. >

The Hartley series and its application to power quality assessment

The unique combination of excellent thermal, electrical, and mechanical properties makes synthetic diamond a legitimate material candidate for thermal management strategies in integrated drive modules Over the past several years, joint research programs between academe have resulted in substantial diamond synthesis and post-synthesis processing time and cost, This is largely attributed to major advances in diamond synthesis using chemical vapor deposition (CVD) techniques In this paper, an overview of diamond synthesis and post-synthesis processing is presented followed by a comparison of thermal heat spreading efficacy of silicon and CVD-diamond substrates for power electronic applications

http://ieeexplore.ieee.org/iel4/5899/15733/00730284.pdf

On the use of diamond in a multichip power module (MCPM) based induction motor drive

The influence of a large concentration of variable-speed high-efficiency heat pumps (VSHPs) on the derating of residential single-phase distribution transformers and the quality of electric power is investigated. The harmonic power flow computer program HARMFLO is used to determine the derating of a 50 kVa single-phase distribution transformer supplying the VSHP nonsinusoidal load current. The VSHP is modeled as a fixed-harmonic load whose harmonic spectra were obtained from field measurements. The variations of the voltage total harmonic distortions and the system harmonic I/sup 2/R losses are evaluated for different VSHP penetration levels throughout the distribution system. An analysis of the results obtained seems to indicate that distribution transformers are moderatley derated by the type of VSHP considered here. >

A study of voltage distortion caused by variable speed high-efficiency heat pumps

Improved performance of inverters may be obtained by increasing the switching frequency of the power semiconductor devices. Switching frequencies greater than the hard-switched limits may be obtained by using soft-switching techniques, The MOS-controlled thyristor (MCT) is a relatively new device showing a great potential in soft-switching applications involving high-power densities. Hence, the main objective of this paper is to extend the research work done on both soft-switched (resonant) inverters and MCTs by evaluating the operating characteristics of MCTs for switching frequencies up to approximately 75 kHz under a zero-voltage switching condition. A PCB is developed to subject the MCTs and passive components to stresses similar to those actually occurring in the resonant and actively-clamped resonant DC link inverter topologies. In addition, operation results of the operation of the MCT-based active clamp in the actively-clamp resonant DC link inverter and some practical implementation considerations are included. >

K.J. Olejniczak

Papers

The Hartley series and its application to power quality assessment

On the use of diamond in a multichip power module (MCPM) based induction motor drive

A study of voltage distortion caused by variable speed high-efficiency heat pumps

Operating characteristics of MCTs in resonant DC link inverters

The Hartley series and its application to power quality assessment