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Planning the expansion of distribution systems (DS) is a nonlinear and combinatorial problem that combines technical and regulatory constraints. Commonly, the planning of DS is intended to achieve a radial topology to reduce its complexity. However, in a smart-grid context, distribution feeders are subject to reconfigurations to transfer load between feeders in failure events, or to compensate for...
Shield wire segmentation has proven to be an effective method for reducing real power losses of high voltage (HV) and extra-high voltage (EHV) transmission lines. The purpose of this paper is to present a methodology for performing a cost benefit analysis of shield wire segmentation to aid decision makers in determining whether or not it is an economical means of reducing losses. The proposed methodology...
This paper describes enhancements to ATC's cascading study criteria and the implementation of a fast automated process using POM/OPM software for conducting comprehensive steady state multiple element contingency screening and cascading analysis, finding mitigations to restore the system to be within emergency and/or normal performance limits, and automatically tabulating significant results and summaries...
A study was performed to determine the impact of single-phase photovoltaic (PV) generation on distribution laterals at high penetration levels. The study addresses concerns about the impact on load balance, fault current balance, power quality and islanding conditions. Methods and tools used for this study, which are appropriate for general analysis of PV on single-phase laterals, are discussed. Guidelines...
This paper describes hands-on solid modeling experience of the safe optimal ground grid design (less copper) for a large Extra High Voltage (EHV) substation. The optimized ground grid meets the IEEE-80 standards for safety without compromising on step or touch potential thresholds. The ground grid has been designed in CDEGS using fault current flow concepts, and multiple injection points simulate...
Ampacity, sag, creep and annealing of overhead high-voltage conductors are influenced by the radial temperature distribution. In this paper, a radial thermal circuit model in the form of state equation is established, and parameters are identified by linear regression method. Polynomial relationships between current level and model parameters are fitted based on the identification result. A radial...
This paper introduces analytical models for accurate prediction of failure probabilities of existing conductors and recommends the optimum time window for conductor replacement at an acceptable failure threshold. The tensile failure probability is determined by solving the limit state equation of the corroded conductor subjected to environmental loading such as wind and ice using Monte Carlo simulations...
A modified forward backward sweep load flow algorithm for unbalanced radial distribution systems is proposed in this paper. The proposed algorithm modifies branch current calculation approach in backward sweep by using three matrices. They are matrices A, B and C. These matrices are used in identifying downstream buses and also in calculating branch current or power flow in an easy manner. For accurate...
This paper presents MatLVDC, i.e. an open source Matlab toolbox to analyse dynamic phenomena in DC distribution networks, that are gaining importance because of reported energy savings and the increasing number of DC loads and distributed energy resources (DER). The toolbox aims at facilitating the design processes and research on DC distribution networks including a high share of renewable energy...
Lightning is the leading cause of power interruptions on overhead transmission lines. The insulators used on overhead 69 kV and 138 kV transmission lines are likely to flashover whenever there is a direct lightning strike on the phase conductors due to their relatively low insulation levels. However, significant improvement can be achieved with the appropriate design of transmission line tower structures...
Conductor galloping seriously threatens the safety operation of power transmission lines, especially for the compact transmission lines with small distance between phase conductors. The conductor galloping maximum amplitude is an important parameter for transmission line inter-phase short circuit failure analysis. In this paper, a single degree freedom model is employed to analyze the relationship...
Among many works reported in the literature for mutual inductance (MI) calculation, Grover's filament method remains the most accepted standard for firsthandMI computation till today. Although Grover's method is fairly accurate, its implementation process becomes complicated due to the use of different formulae for various arrangements of filaments in a coil. The work presented in this paper describes...
Power Line carrier system works at a much higher frequency than the electricity fundamental frequency. Normally the working bandwidth is carefully selected to prevent interferences from communications on neighboring lines or possible antenna phenomenon due to the line topology. In this paper a relay misoperation caused by transfer trip when the line was taken out for construction is discussed and...
Conductors for most buildings in the United States are sized using the National Electrical Code (NEC). The 2014 NEC now requires that a value be added to the ambient temperature used to determine the ampacity of conductors installed on rooftops. This paper reports the results of a related experimental test (on both energized and non-energized cables) that is conducted on a rooftop of a building located...
Unprecedented expansion of native direct current (DC) powered equipment (computers and consumer electronics) has increased household DC electricity consumption over the past decade. Since power utilities deliver alternating current (AC) rather than DC, the conversion process (rectifier) used to supply DC loads is very inefficient. This paper investigates the suitability of employing conventional AC...
Rating of an overhead transmission line is defined as the maximum current that the line can safely carry without damaging the conductor. This current limit has been treated conventionally as a constant under the worst weather conditions. Dynamic line rating (DLR) is the current limit determined by real weather conditions surrounding the conductor. Using DLR has potential to increase the line rating...
A somewhat novel approach is presented in this paper to predict, analytically, the vortex-induced vibration (i.e. Aeolian vibration) of an overhead power line's single conductor due to wind. An analytical solution is derived to the basic problem of the Aeolian vibration of a conductor span with equivalent supports on both ends by using the energy balance principle as well as the semi-empirical equations...
Active control and monitoring of the distribution system is a crucial part to successfully integrating variable generation in the distribution grid. This may require a large deployment of Phasor Measurement Units (PMU's) on the distribution system, which can be prohibitively expensive due to installation cost. Additionally, devices at medium to high voltage possess a significant risk to system reliability...
Early and reliable detection of a back-fed ground fault is of critical importance in the operation of a power distribution system. The operating distribution companies have been searching for a fully acceptable solution for decades. A current carrying conductor on the Earth ground that is not tripped by conventional protection systems presents a safety hazard for the general public. In this paper...
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