Deformation of steel lattice towers for overhead lines—case study

2016 ◽  
pp. 565-570
Author(s):  
M Just
Keyword(s):  
Overhead Lines ◽  
Lattice Towers

scholarly journals Reliability cost/worth assessment of distribution network formed by underground cables and overhead lines. Case study of Latvia

Energetika ◽  
2015 ◽  
Vol 61 (1) ◽  
Author(s):  
Aleksandrs Ļvovs ◽  
Ilze Priedite
Keyword(s):  
Power Supply ◽  
Distribution Network ◽  
Distribution Networks ◽  
Actual Distribution ◽  
Underground Cables ◽  
Overhead Lines ◽  
Capital Costs ◽  
Reliability Level ◽  
Fault Statistics

The increasing number of severe weather occurrences that influence the number of large scale outages, especially in rural distribution networks, makes the question on the need of increasing reliability level of power supply of the distribution network even more actual. Distribution system operators and national regulators shall not only find a reliable but also a cost-effective solution for further distribution network development: the optimal reliability level of power supply. One of the reliability improvement solutions that allows effectively dealing with the reduction of the number of outages in rural distribution networks is the cablification of network. Construction costs of the aforementioned solution are quite high in comparison to other network line types, and due to that, the implementation of the solution always raises discussions on cost-effectiveness. The paper presents approaches for the cost/worth assessment of power line lifetime costs in the distribution network and for the assessment of customer costs of reliability that takes into account time-varying loads and outage costs (previously developed by authors of this paper [6, 7]) as well as for the assessment of traders’ losses due to electrical energy not supplied. The case study included in the paper is performed for Latvian conditions and takes into account information on the real customer costs of reliability of Latvian customers (information from the study of the Institute of Physical Energetics), fault statistics of Latvian underground cables and overhead lines, information with a high level of details on the capital costs, operational and fault elimination costs of distribution lines in Latvia.

scholarly journals An Improved Statistical Method for Calculating Lightning Overvoltages in HVDC Overhead Line/Cable Systems

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3121 ◽  
Author(s):  
Oscar Lennerhag ◽  
Jan Lundquist ◽  
Christiaan Engelbrecht ◽  
Tanumay Karmokar ◽  
Math H. J. Bollen
Keyword(s):  
Statistical Method ◽  
Statistical Treatment ◽  
Statistical Characteristics ◽  
Lightning Strikes ◽  
Overhead Lines ◽  
Shielding Failure ◽  
Dc Line ◽  
Cable Systems ◽  
Soil Ionization

HVDC cable systems connected to HVDC overhead lines are subject to fast front overvoltages emanating from the line when lightning strikes a shield wire (backflashover) or a pole conductor (shielding failure). Representative fast front overvoltage levels for HVDC cable systems are usually established without considering their statistical characteristics. A statistical method to determine overvoltages related to the acceptable mean time between failure (MTBF) for the cable system was developed previously. The method accounts for the statistical distribution of lightning current magnitudes as well as the attenuation of the overvoltage wave due to corona discharges on the line, since this effect dominates for system voltages up to about ±320 kV. To make the method suitable for higher system voltages as well, this article introduces an improved statistical method which also accounts for surge attenuation through resistive effects, soil ionization, and statistical treatment of overvoltages due to shielding failures. To illustrate the improved method, it is applied to a case study for a ±525 kV DC line.

A Power Quality Case Study of Contact Overhead Lines in the Medellin Metro System

2019 ◽  
Author(s):  
Andres Emiro Diez ◽  
Mauricio Restrepo ◽  
Julian Vega ◽  
Camilo Melendez ◽  
Jose Dariel Arcila ◽  
...  
Keyword(s):  
Power Quality ◽  
Overhead Lines ◽  
Metro System

scholarly journals A constraint-based approach for optimizing the design of overhead lines

2020 ◽  
Vol 14 (3) ◽  
pp. 1121-1139
Author(s):  
Paolo Cicconi ◽  
Steve Manieri ◽  
Miriam Nardelli ◽  
Nicola Bergantino ◽  
Roberto Raffaeli ◽  
...  
Keyword(s):  
Design Optimization ◽  
Low Voltage ◽  
Expert Knowledge ◽  
Constraint Satisfaction Problem ◽  
Variable Number ◽  
Climate Conditions ◽  
Overhead Lines ◽  
Single Structure ◽  
Geometrical Dimensions

AbstractThe use of computational methods in engineering design is a long-standing issue. Several mathematical approaches have been investigated in the literature to support the design optimization of engineering products. Most of them are focused on the optimization of a single structure, without considering a system of structures. The design of supports for electric lines requires tools for the management and sizing of a system of structures that interacts with each other under specific load conditions. This paper deals with a framework to support the design optimization of an overhead line using methods related to the theory of the Constraint Satisfaction Problem. The object-oriented model of a transmission line has been described and then implemented into a prototypical software platform. The parameters to be considered as variables are defined by the designer at the beginning of the optimization process. These variables are geometrical dimensions, poles locations, cable pre-tension, etc. The set of constraints is related to normative, climate conditions, datasheets, material limits, and expert knowledge. To demonstrate the effectiveness of this approach, a case study has been developed considering a variable number of constraints and parameters. In particular, the case study is focused on the design of a low-voltage sub-network between two distribution substations.

Analysis of the Effect of Environmental Factors on Outage Rates of Overhead Distribution Feeders: A Case Study of Zaria Distribution Network

2013 ◽  
Vol 824 ◽  
pp. 120-128
Author(s):  
Boyi Jimoh ◽  
Juliet N. Adegboye ◽  
Babatunde A. Adegboye
Keyword(s):  
Environmental Factors ◽  
Energy Loss ◽  
Distribution System ◽  
Power Losses ◽  
Overhead Lines ◽  
Intrinsic Factors ◽  
Holding Company ◽  
Hot Season ◽  
Entire Nation

The paper is aimed at analysing the environmental factors on the outage rates of the overhead distribution feeders. This was facilitated using daily outage data on the six 33kV feeders of the Zaria distribution system collected from the Zaria Transmission substation of the Power Holding Company of Nigeria (PHCN) for twelve months. Outage models were developed from where power losses due to the feeder outages were obtained. Frequent and delayed forced outages occur during the rainy season, the peak being in August and during harmattan, especially in October. There were relatively high outage rates during the hot season, the maximum occurring in May. Feeders 2, 3 and 6 were most frequently on forced outages. The causes of the high outage rates are attributable to damages done to the overhead lines due to heavy winds, thunder strikes and other disturbances associated with rain. Other reasons include animal-caused outages, increase in the simultaneous use of weather sensitive devices, trees and vehicular accidents. As a result, energy loss was found to be 2947.62GWh, which translates to high revenue loss if the entire nation is considered. The forced outage rates are mapped to external environmental factors while the scheduled outages are due to the intrinsic factors. The paper proposes recommendations for minimizing the outage rates and hence improving the performance of the feeders.

scholarly journals Utilizing Load and Loss Factors in Determination of the Technical Power Losses in Distribution System’s Feeders: Case Study

2020 ◽  
Vol 26 (7) ◽  
pp. 83-96
Author(s):  
Dara Hama Amin
Keyword(s):  
Distribution System ◽  
Loss Factor ◽  
Load Factor ◽  
Power Losses ◽  
Technical Data ◽  
Overhead Lines ◽  
Route Length ◽  
Recorded Data ◽  
Loss Factors

This study uses load factor and loss factor to determine the power losses of the electrical feeders. An approach is presented to calculate the power losses in the distribution system. The feeder’s technical data and daily operation recorded data are used to calculate and analyze power losses. This paper presents more realistic method for calculating the power losses based on load and loss factors instead of the traditional methods of calculating the power losses that uses the RMS value of the load current which not consider the load varying with respect to the time. Eight 11kV feeders are taken as a case study for our work to calculate load factor, loss factor and power losses. Four of them (F40, F42, F43 and F45) are overhead lines while the others (F185, F186, F187 and F188) are underground cables. The greater differences between their losses were obtained, due to various types of route length, type, and dimension of conductors. The study takes different configuration feeders for computation with determination in power losses.  

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

Culture and the plasticity of perception

2020 ◽  
Vol 43 ◽  
Author(s):  
Michael Lifshitz ◽  
T. M. Luhrmann
Keyword(s):  
Cultural Context ◽  
Sensory Experience ◽  
Cultural Learning ◽  
The World

Abstract Culture shapes our basic sensory experience of the world. This is particularly striking in the study of religion and psychosis, where we and others have shown that cultural context determines both the structure and content of hallucination-like events. The cultural shaping of hallucinations may provide a rich case-study for linking cultural learning with emerging prediction-based models of perception.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

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