Thesis (Ph.D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 112-126) Also available in print.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Thesis (Master of Engineering in Electrical Engineering))--Cape Peninsula University of Technology, 2018. / Industry, which forms the lifeblood of South Africa’s economy, is under threat as a result of increased electricity pricing and unstable supply. Wheeling of energy, which is a method to transport electricity generated from an Independent Power Producer (IPP) to an industrial consumer via the utility’s network, could potentially address this problem. Unlike South Africa’s electricity landscape, which is highly regulated and monopolized by Eskom, most developed countries have deregulated their electricity market, which has led to greater competition for electricity supply. This thesis, presents an evaluation of the economic viability and technical concerns arising from third party transportation of energy between an IPP and an industrial consumer. IPP’s are able to generate electricity from various renewable distributed generation (DG) sources, which are often physically removed from the load. In practice, electricity could be generated by an IPP and connected to a nearby Main Transmission Substation (MTS) in a region with high solar, wind or hydropower resources and sold to off-takers a few hundred kilometres away. Using two software simulation packages, technical and economic analysis have been conducted based on load data from two industrial sites, to determine the viability of wheeling energy between an IPP and off-taker. The viability will be evaluated based on levelized cost of electricity (LCOE); net present cost (NPC); DG technology; distance from the load; available renewable resources; impact on voltage profile, fault contribution, thermal loading of the equipment and power loss. The results from both case studies show that the impact of DG on the voltage profile is negligible. The greatest impact on voltage profile was found to be at the site closest to the load. Asynchronous and synchronous generators have a greater fault contribution than inverter-based DG. The fault contribution is proportional to the distance from the load. Overall, thermal loading of lines increased marginally, but decreased based on distances from the load. Power loss on short lines is negligible but there is a significant loss on the line between the load and DG based on the distance from the load. Electricity generated from wind power is the most viable based on LCOE and NPC. For larger wind systems, as illustrated by the second case study, grid parity has already been reached. Wheeling of wind energy has already proven to be an economically viable option. According to future cost projection, large scale solar energy will become viable by 2019. The concept of wheeling energy between an IPP and off-taker has technical and economic merit. Wheeling charges are perceived to be high, but this is not the case as wheeling tariffs consist of standard network charges. In the future, renewable energy will continue to mature based on technology and cost. Solar energy, including lithium-ion battery back-up technology, looks promising based on future cost projections. Deregulation of the electricity market holds the key to the successful implementation of energy wheeling as it will open the market up for greater competition.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 187-192). Also available via the Internet.

D. Tech. Electrical Engineering. / Discusses the operations and planning of power systems is a complex task, mostly with many intricate manoeuvres to ensure reliable network operations such that the active power losses are reduced and the network voltage proles are improved without compromising the network security. Then the question is, what is the role of the inherent structural characteristics in solving power system problems? Although, the inherent structural characteristics of a power system network are embedded within the load flow formulation to some extent, their full capabilities in solving the problems of the network have not been holistically investigated. The fundamental circuit theory law (Ohm's law), which is a linear equation, clearly demonstrates the importance of the structural topology of the network. However, this importance is confounded by the reformulation of the fundamental law to nonlinear load flow equations. This research investigated the role of the inherent structural characteristics in solving power system problems from a circuit theory perspective.

Thesis (PhD) -- University of South Australia, 1993

Thesis (PhD) -- University of South Australia, 1993

Thesis (MTech (Electrical, Electronic and Computer Engineering))--Cape Peninsula University of Technology, 2015. / The growing interest in the use of solar energy to mitigate climate change, reduction in the cost of PV system and other favourable factors have increased the penetration of the PV(Photovoltaic) systems in the market and increase in the worldwide energy supply. The main component in a DG is a smart inverter connected in a grid-tied mode which serves as a direct interface between the grid and the RES (Renewable Energy System). This research work presents a three phase grid-tied inverter with active and reactive power control capabilities for renewable energy sources (RES) and distributed generators (DG). The type of the inverter to be designed is a Voltage Source Inverter (VSI). The VSI is capable of supplying energy to the utility grid with a well regulated DC link at its input. The solution this project proposes is an implementation of the designed filter to effectively reduce the harmonics injected into the grid to an acceptable value according to standards and also an approach to control the real and reactive power output of the inverters to help solve the problems of instability and power quality of the distribution system. The design, modelling and simulation of the smart inverter system is performed in MATLAB/SIMULINK software environment. A 10 kW three-phase voltage source inverter system connected to the utility grid was considered for this research. Series of simulations for the grid-connected inverter (GCI) model was carried out using different step changes in active and reactive power references which was used to obtain the tracking response of the set power references. The effectiveness of the control system which was designed to track the set references and supply improved power quality with reduced current ripples has been verified from the simulation results obtained.

Direct Load Control (DLC) -- the direct control of customer loads by an electric utility for the economic and reliable operation of the power system, is an important and active element of Load Management (LM). Currently attention has focussed on the integration of DLC into system operations. However, as yet, DLC is regarded as a discretionary resource to be used by the system operator based on informed judgment. The integration process has therefore, concentrated on improving the informational inputs to the operator. This dissertation extends the integration from that of a discretionary resource to a dispatchable system resource. The concept of the dynamic dispatch of DLC is formulated and defined to be an online evaluation and utilization of DLC for optimum benefit to the utility, as system conditions change. The concept envisages the use of DLC in an automated mode and coordinated with other system resources for optimum benefit. An important and integral part of the research effort is the development of a cost characterization of DLC. A closed form solution, using a dynamic programming framework, has been developed to estimate the costs of DLC dispatch. The derivation takes into account all operational constraints on the utilization of DLC -- payback characteristics, maximum on-times and minimum recovery times. The cost, defined as the difference in the fuel costs with and without DLC dispatch, were found to be dependent on the cost characteristics of the online generators and the load shape impacts of DLC dispatch. The dynamic dispatch concept is concretized by a power system operations model which incorporates DLC dispatch for fuel cost minimization and peak load shaving. The two modes are toggled by the dispatch algorithm as system conditions change. Results from the model are presented for several combinations of system conditions and DLC system parameters. / Ph. D.

As necessity for improvement in system operation demands the implementation of distribution automation, design of the protection system becomes more involved. Several goals of distribution automation -- improved customer reliability, reduced systems losses, and balancing of substation loading -- are dependent on the ability to perform automatic circuit reconfigurations. A prerequisite for implementing automatic circuit reconfiguration is that the protection system design must operate properly for all configurations. An integrated expert system for the protection system design of interconnected distribution circuits has been developed using the DANE engineering workstation. The expert system incorporates the basic requirements and guidelines as specified by IEEE for protection system design. The expert system uses a relational database management system, integrates system data, and provides a graphical user interface. The expert system incorporates both procedural and declarative, or query, operating modes. Rules dealing with the coordination, placement and selection of protective devices are presented that are used to dynamically, incorporate expert knowledge into the knowledge base. The protection system designer controls which rules are implemented in the design. An example protection system design is presented using the integrated expert system developed for DANE. The example problem consists of three interconnected distribution circuits. Dynamic knowledge, created by the expert system from the rules and system data, is used in the design. System data is presented pertaining to the circuits along with the created dynamic knowledge. The implemented rules dealing with the coordination, placement and selection of protective devices are presented, along with all associated parameter values. The final protection system design and results are presented in a research report. / Ph. D.