Intrabuilding power distribution circuits offer a number of unique advantages for local area networking. To enable the selection of proper error-control codes and protocols for reliable data communication services, error pattern statistics of intrabuilding power line channels are obtained. Also, error-causing disturbances are identified and their relationships to specific types of error patterns are determined. It is found that error occurrence is highly periodic, with periodicity being a function of the power line frequency which is nominally 60Hz in North America. Furthermore, results indicate that error pattern behaviour is relatively insensitive to communication carrier frequency and modulation schemes. Based on the measurement results, hybrid ARQ with bit-interleaving is suggested for reliable data transmission at high data rate (19,200bps). Burst error correcting codes can be used to reduce decoder cost and complexity with some sacrifices in performance. At lower data rates (1,200bps or below), effective error control can be accomplished more easily. Finally, the attenuation characteristics of a number of typical power line channels are presented. It is found that high frequency bypass can be used to improve signal transmission between different phases of the distribution transformer. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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The objective of the research is to develop a cost-effective, dynamic grid controller called the controllable network transformer (CNT) that can be implemented by augmenting existing load tap changing (LTC) transformers with an AC-AC converter. The concept is based on using a fractionally rated direct AC-AC converter to control the power through an existing passive LTC. By using a modulation strategy based on virtual quadrature sources (VQS), it is possible to control both the magnitude and the phase angle of the output voltage of the CNT without having any inter-phase connections. The CNT architecture has many advantages over existing power flow controllers, like absence of low frequency storage, fractional converter rating, retro-fitting existing assets and independent per-phase operation making it potentially attractive for utility applications. The independent control of the magnitude and the phase angle of the output voltage allow independent real and reactive power flow control through the CNT-controlled line. In a meshed network with asymmetric network stresses this functionality can be used to redirect power from critically loaded assets to other relatively under-utilized parallel paths. The power flow controllability of CNT can thus be used to lower the overall cost of generation of power. The solid state switches in the CNT with fast response capability enable incorporation of various additional critical functionalities like grid fault ride through, bypassing internal faults and dynamic damping. This bouquet of features makes the CNT useful under both steady state and transient conditions without compromising the grid reliability.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / High Voltage Direct Current (HVDC) transmission is a safe and efficient technology designed to deliver large amounts of electrical power over long distances with minimal losses and at low costs. HVDC links require converters and filters at both terminal stations. The core component of the HVDC system is the power converter that connects the DC and AC systems together. The conversion from AC to DC, and vice versa, is achieved mainly through electronic switches called thyristors. The thyristor-based Line Commutated Converter (LCC) is a mature and trusted technology for HVDC transmission throughout the world. HVDC converters are bidirectional and can function in either rectification (AC to DC) or inversion mode (DC to AC). This is achieved when the voltage polarity across the converter gets swapped by the controllers, because current cannot change its direction in thyristors. In this thesis an analytical model of the HVDC converters is developed in the frequency domain by modelling it in DIgSILENT. The objective is to study the harmonics induced to the AC side from HVDC converters. Therefore, it is important in the real world to understand the principles, what causes harmonics to be generated in HVDC and transferred to the HVAC system. The objective of this thesis is to investigate the effectiveness of mitigation techniques used, on how they reduce harmonics by keeping these harmonic levels within specified values admissible by international standards (e.g. IEEE, etc).

M.Ing. / Traditionally, the Electricity Supply Industry (ESI) organisational structure consisted of generating plant, transmission and distribution networks, a regulating authority and network control, all vertically integrated into single organisational structure. The result of the vertically integrated organisational structure, in other words an organisation where all the functions belong to a single organisation, and some of the organisation's functions are not the sole responsibility of one specific functional area, has been a captive market for the industry. No real market forces existed to control the industry. The responsibility for the industry was traditionally left in the hands of a single organisation, accountable only to the regulating authority. However, the industry has recently been subjected to incredible pressure to reform. The incentive to reform is based on various factors, ranging from sound business decisions, the need to reduce government debt, reduction of primary energy cost for key industries to political pressure. A common thread throughout the reform exercise is the requirement that competition must be introduced into the ESI to ensure market forces on the industry. To introduce competition into the industry, the authorities often start by unbundling the different functions in the industry. The second step is to identify the functions that can only operate effectively as a monopoly. The authorities then need to determine the optimum balance between regulatory rules and requirements and market forces on the. industry. By introducing the optimum balance between industry regulation, market forces and the specific needs of each country, the changes in the industry may result in long term gain for the industry's host country. The gains are often measured in reduced electricity cost and growth in industries dependant on the ESI as a primary energy source. The study incorporates a wide range of issues, starting with the drivers behind the deregulation effort through management tools to regulatory rules and requirements in the deregulated environment. The study evaluates the risks and benefits of the deregulated market, and examines the tools adopted from the financial markets and used in the new electricity markets. The requirement for regulatory rules will be evident throughout the dissertation, and will be discussed in detail in the final chapter. The study is concluded with the message that the common factors and resultant solutions are of such a nature that it would not be necessary to develop a new set of rules, regulations and management tools for a country starting down the road of deregulation. It would however be required to determine the needs of the industry's host country and to adapt the current tools and regulatory rules to the country it is implemented in. The final outcome of the dissertation is that the post-deregulated industry has only just started operating under the new regulatory regime and using the newly developed electricity markets. The industry is still subject to a severe learning curve, adapting and developing daily to satisfy the needs of a deregulated industry. There are sections of the industry that still need to be examined and optimised. However, the success of some of the deregulation efforts in the industry, and especially the deregulation in the UK confidently underwrite any equivalent exercise in the ESI.

M.Com. (Informatics) / Critical Infrastructure is the term used to describe assets that are of utmost importance, or in other words, essential in the functioning of an environment. Societies depend on their critical infrastructure in order to maintain and continuously improve on their population’s standard of living. The creation of more self-sustainable methods of energy consumption and generation drives towards the creation of a better and more efficient evolution of the power grid critical infrastructure, named the smart grid. The introduction of the smart grid brought in a paradigm shift towards the practices used to manage the generation and distribution of electric power. The introduction of highly capable information systems to intrinsically work with current power grid technologies provided the ability to enhance economic and environmental efficiency of power systems. Although providing a wide variety of benefits, such information systems also created new points of vulnerabilities, which if exploited, place the smart grid at risk of disruptions. In order to address the security issues that occur at the application and data exchange level of smart grid information systems, the dissertation proposed the use of a security model to protect the smart grid. The Multi-Agent Smart Grid Security (MA-SGS) model is based on the use of multiple autonomous intelligent software agents which attempt to create operational stability and efficiency in the smart grid...

The objective of this research is to assess the impact to the Nelson Mandela Bay Municipality due to ongoing Electricity Distribution Industry Restructuring in South Africa as directed by the Electricity Distribution Industry Holdings on behalf of the Department of Minerals and Energy’s adopted Electricity Distribution Blue Print Report of 2001. Literature review of scholarly literature was conducted on privatisation of public utilities that offered an international perspective on experiences of other countries that has undergone similar experiences of restructuring of public assets, the state of Electricity Supply Industry in South Africa with the demonstration of structural financial and physical flows and historical background of the restructuring, proposed future model and strategic plans to achieve the future goals. Research methodology and design was done through combination of the four-research types classification in their order of sophistication except the predictive research, namely exploratory, descriptive, and analytical or explanatory researches with a further inclusion of deductive research. The compilation of data through questionnaires was also employed. Perceptions on internal impact to the NMBM due to electricity services restructuring were solicited from the sample of the top management of the NMBM, the intention was to ensure the economies of scale, greater transparency and competition in terms of service delivery were sustained during and beyond Regional Electricity Distributor establishment. Financial position of NMBM as a critical instrument for its progress has to be protected to ensure it fulfils its constitutional development mandate. The findings of the research were in strong support of ensuring operational financial viability; to meet the legitimate employment, economic and social interest of all employees; development and implementation of change management strategies; and NMBM assuming leading role in the process.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

An Integrated Power System (IPS) with a DC Zonal Electrical Distribution System (DC ZEDS) is a strong candidate for the next generation submarine and surface ship. To study the implementation of an IPS with DC ZEDS, members of the Energy Sources Analysis Consortium (ESAC) are currently constructing a reduced-scale laboratory. One fundamental component of DC ZEDS is the Ships Service Converter Module (SSCM), commonly known as a buck DC-DC converter. This thesis documents the design, simulation, construction and testing of a 500V/400V, 8kW resonant soft-switched DC-DC converter. In theory, resonant converters will operate more efficiently and generate less Electromagnetic Interference (EMI) when compared to a standard hard-switched converter. In this thesis, the resonant converter is tested and compared to a hard-switched DC-DC converter that was designed for ESAC's reduced-scaled IPS. The results verify that the resonant DC-DC converter realizes significant efficiency and EMI generation improvements over the hard-switched converter at the cost of a more complex control system and power section. / US Navy (USN) author