Many automation and power control systems are integrated into the 'Smart Grid' concept for efficiently managing and delivering electric power. This integrated approach created several challenges that need to be taken into consideration such as cyber security issues, information sharing, and regulatory compliance. There are several issues that need to be addressed in the area of cyber security. Currently, there are no metrics for evaluating cyber security and methodologies to detect cyber attacks are in their infancy. There is a perceived lack of security built into the smart grid systems, but there is no mechanism for information sharing on cyber security incidents. In this thesis, we discuss the vulnerabilities in power system devices, and present ideas and a proposal towards multiple-threat system intrusion detection. We propose to test the multiple-threat methods for cyber security monitoring on a multi-laboratory test bed, and aid the development of a SCADA test bed, to be constructed on the Georgia Tech Campus.

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<p>Measurements of film mass flow rate for annular, diabatic steam-water flow in tubes are presented. The measurements were carried out with four axial power distributions and at several axial positions at conditions typical for boiling water reactors, i.e. 7 MPa pressure and total mass flux in a range from 750 to 1750 kg/m2s. The results show that the influence of the axial power distribution on the dryout power corresponds to a consistent tendency in the film flow rate and that the film tends to zero when dryout is approached. Furthermore it is demonstrated that two selected phenomenological models of annular flow well predict the present data. A model for additional entrainment due to boiling is shown to degrade the predictions.</p>

Thesis--Ph. D., University of Hong Kong. / Mimeographed.

(Uncorrected OCR) Abstract of thesis entitled liField analysis in power supply lines by integraJ. equation methodll subm1 tted by FOe, PIK YlJE for the degree of Ph.D at the University of Hong Kong in December, 1974. Abstract In this thesis, the integral equation (I.E.) method has been employed successfully to solve field problems in power supply lines. Though the I.E. method is mathematically quite involved, it is shown that it is possible to treat the integral equation as a system of linear equations. Hence the transformed simultaneous linear equations can be considered as the starting point for solving problems either in overhead lines or \Ulderground power cables. In overhead lines, especially in Extra-High-Voltage and Ultra- High-Voltage systems, an evaluation of the electric field near each conductor, especially the maximum electric field, is essential as corona and radio interference become important considerations in the design of such lines. The I.E. method has many advantages over the other existing methods in calculating the potential gradient at the surface of the overhead lines in that it yieldS reasonably accurate results with comparatively simple numerical computations. The difference between the present method and the existing methods is the basic assumption. In the I.E. method, subconductor surfaces are treated as equipotential lines whereas in other existing methods, the subconductor surfaces usually do not coincide with the simulated equipotential lines. The method can also be applied equally well to symmetrical or asymmetrical bundle conductors with or without ground wires. Other parameters such as capacitances, potential gradients at the earth surface etc. are also included in the computer program. In underground cable systems, the I. E. method proves to be very effective in tackling the thermal field problem, especially when the cables are buried shallow and thus the earth i s surface can no longer be treated as isothermal. .It has been found that the thermal resistance (external) obtained wi::;h a non-isothermal earth surface is considerably higher than that obtained under the assuumption of an isothermal earth surface. With non.-isothermal earth surface, the temperature difference on the earth surface between the spot vertically above the cable and the spot at a distance eClual to twice the depth of burial of the cable away could be as high as lOoe. The finite-difference or fini te-搪lement method could likewise be used to solve the problem of a non-isothermal ea>:>th surface, but the computer storage re'luired and the execution time would be much more than that using the I.E. method. / abstract / toc / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical Engineering / Master / Master of Philosophy

The aim of this study was to assess the electrical performance of the Cahora Bassa HVDC scheme. For practical reasons a database was developed to hold and analyse the performance data. Microsoft® Access 2002 relational database management system was chosen for this work. The principle of simplicity and flexibility were used in the design of the database. The Apollo year 2002 faults data was populated into the database. The database stored the information in a format that enables the user to extract results and the information required by Ciqre, The Ciqre Working Group 14 collects performance information from all the participating HVDC schemes around the world annually. The Apollo converter station's 2002 performance data was compared to other similar HVDC schemes that submitted to Cigre in the year 2002. In addition performance trends were drawn from similar schemes that submitted to Cigre over the past years. The Apollo performance data is quite comparable to other similar schemes in 2002 and over the past years. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

Conventional Current Transformers (CTs) provide the input signal required by protection relays, control equipment and energy metering in power networks. Catastrophic failures of CTs may lead to injury of personnel within the substation, interruption of power supply and damage to adjacent high voltage equipment. One of the causes of CT failures is high values of insulation power factor. Research indicates that with increasing primary insulation power factor values, partial discharges develop between the paper insulation leading to its exponential decay with the end result of an ultimate CT failure. Reports in Eskom Distribution indicated that a number of CTs from one manufacturer were exceeding the specified insulation power factor value. This research was initiated to investigate the impact of high power factor on the premature failure of CTs. This study serves to analyse the significance of power factor on paper-oil insulation within a hair-pin type CT. The internal primary insulation of a hair-pin type CT used in Eskom Distribution is reviewed in terms of its design, construction and relevant tests. Sample CTs rated at 132kV and manufactured in the year 2007 to 2009 from the specific manufacturer were selected for insulation power factor testing. The Doble M4100 diagnostic test system was used to perform the testing that also assisted in providing a comparison between the units with high insulation power factor values and that which were within the specified limits. The results show that the high values of insulation power factor give a direct indication of the dielectric losses (I2R) within that CT, which inadvertently indicates the shortened serviceable life of that CT. High moisture content within the primary insulation, low quality insulating oil and inadequate quality assurance were identified as some of the contributory factors in the CTs non compliance. The effects of high values of insulation power factor are the primary factor for continuous on-line condition monitoring techniques that enable data trending and provide for early warning of an imminent CT failure. The testing of the sample CTs provided a more dynamic approach for recommendations to prevent the installation of such units into the power network. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2010.

Modern transmission systems are becoming heavily loaded. In addressing this issue Eskom has been installing series capacitors in their power transmission grids for the purposes of ensuring improved system stability, increased transmittable power, reduced transmission losses, enhanced voltage control and more flexible power flow control. Environmental concerns are also addressed at a fraction of the cost when compared to the alternative. However, with the utilization of series capacitors and their over-voltage protection devices typically the Metal Oxide Varistors and Spark Gaps when installed on transmission lines, several problems are created for the distance protection relays. This is because series capacitors when used on transmission lines can have serious effects on the performance of distance relay protection. This is because of the change of impedance seen by the distance relay since the electrical impedance measured by the relay is no longer a unique correspondence of the physical distance from the relay location to the point of fault when the protection of the series capacitors comes into play. The research results will show that, because of subsynchronous oscillations and voltage inversion phenomena as a result of series compensation, can cause distance protection’s zone 1 directional elements to operate incorrectly, more specific to internal faults which may appear as external faults and external faults which may appear as internal faults. The research will be investigating some of the challenges that are encountered by the distance protection relays when protecting a transmission line incorporating series capacitors. In answering the research question: “What are the issues associated with the utilization of series capacitors on the Eskom Transmission grid to the performance of distance protection?” the Digsilent PowerFactory software simulator package will be utilized to achieve the desired objectives. Other research projects have looked into the research question at hand utilizing the physical REL 531 relays and a real time model of the Eskom Hydra South Network, a system that supplies power to the Western Cape. In this research the author will be looking at the ability of Digsilent and its REL 531 Models to repeat and confirm the same conclusions, before considering possible alternative solutions. The Muldersvlei-Bacchus and Bacchus-Droerivier lines forming part of the Eskom Hydra South Network were selected as the area of focus. The decision to select these two particular mentioned lines as the area of focus was because the studies will be able to cover impact of external series capacitors to both the performance of the relays on lines that are series compensated and those that are not. The performance of the relays will involve analyzing the impact of series capacitors on the relays for faults before and after series capacitors. The research will also be investigating the possibility of utilizing the current supervised zone 1 configuration, which has recently been introduced on some Eskom distance protection relays as a solution, to overcome the impact of series capacitors on the performance of the distance protection relays. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

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