Special Issue "DC and AC Overhead Transmission Lines from Low to Extra-High Voltages"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Electrical Power and Energy System".

Deadline for manuscript submissions: closed (11 August 2019).

Special Issue Editors

Guest Editor
Prof. Dr. Roberto Benato Website E-Mail
Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
Phone: +390498277532
Interests: multiconductor analysis and more generally the electric energy transmission
Guest Editor
Dr. Sebastian Dambone Sessa Website E-Mail
Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
Interests: multiconductor analysis and more generally the electric energy transmission

Special Issue Information

Dear Colleagues,

The first comprehensive power system (generator, transmission line, and loads) in New York (Pearl Street) was created in 1882. From that year, the spread of electrical transmission grids has been so exorbitant and successful that the National Academy of Engineering has rightly stated that the electrical grid is the greatest engineering achievement of the 20th century. There is no doubt that, even if insulated cables are also playing a growing role in HV and EHV levels (in LV and MV they are widely employed), existing overhead lines remain a fundamental presence in the electric grid. This Special Issue is devoted to all the topics pertaining to overhead lines for ac and dc transmission:

  • installations
  • maintenance
  • sequence-impedance computations
  • electric and mechanic simulations
  • new concepts in planning and design
  • more environmental-friendly towers
  • new conductors
  • dynamic thermal ratings
  • fault location in earthed and unearthed networks
  • mechanical performance
  • insulator design (pollution)
  • cost comparison
  • transmission with higher-order phase lines
  • direct current transmission (technical and economical comparison of DC and AC lines)
  • ice load and de-icing
  • earth-wire selection (earth-wire comprising optical fibres OPGW, and insulated earth-wire for power loss reduction).
  • overhead line-fittings
  • conductor vibrations (galloping)
  • the assessment of lightning performance
  • reliability, availability, and resilience
  • tower earthing including its measurement

Prof. Dr. Roberto Benato
Dr. Sebastian Dambone Sessa
Guest Editors

Manuscript Submission Information

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Published Papers (7 papers)

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Research

Open AccessArticle
The Half-Sine Method: A New Accurate Location Method Based on Wavelet Transform for Transmission-Line Protection from Single-Ended Measurements
Energies 2019, 12(17), 3293; https://doi.org/10.3390/en12173293 - 27 Aug 2019
Abstract
In this work, a new and accurate method based on the wavelet transform is proposed for fault location in transmission-line systems. The proposed wavelet method consists of the analysis of the transient signal measured at a single end of the transmission line. Aerial [...] Read more.
In this work, a new and accurate method based on the wavelet transform is proposed for fault location in transmission-line systems. The proposed wavelet method consists of the analysis of the transient signal measured at a single end of the transmission line. Aerial current modes are used, and zero modes are included in the fault-detection scheme for low fault-inception angles. The fault distance is evaluated using the wavelet modulus maxima technique and a method based on the response to a half-sine voltage is proposed to overcome drawbacks arising from the limited sampling frequency and low fault-inception angle. The fault distance is calculated using the difference between the time when a 100 kHz half-sine signal is sent and the time when the derivative signal is received. The proposed algorithm is tested considering harmonic distortion and varying fault resistance, ground resistivity, location and inception angle. The high accuracy of the proposed algorithm is obtained even for faults close to the bus and low inception angles. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessArticle
Analytical Description of Overhead Transmission Lines Loadability
Energies 2019, 12(16), 3119; https://doi.org/10.3390/en12163119 - 14 Aug 2019
Abstract
The loadability characteristics of overhead transmission lines (OHLs) is certainly not a new topic. However, driven by sustainability issues, the increasing need to exploit existing electrical infrastructures as much as possible, has given OHL loadability a renowned central role and, recently, new investigations [...] Read more.
The loadability characteristics of overhead transmission lines (OHLs) is certainly not a new topic. However, driven by sustainability issues, the increasing need to exploit existing electrical infrastructures as much as possible, has given OHL loadability a renowned central role and, recently, new investigations on this subject have been carried out. OHL loadability is generally investigated by means of numerical methods. Even though this approach allows deducing useful information in both planning and operation stage, it does not permit to capture all the insights obtainable by an analytical approach. The goal of this paper is to tailor a general analytical formulation for the loadability of OHLs. The first part of the paper is devoted to the base-case of uncompensated OHLs. Later, aiming to demonstrate the inherent feasibility and flexibility of the novel approach proposed, the less frequent case of shunt compensated radial OHLs is investigated as well. The analytical formulation is combined with the use of circular diagrams. Such diagrams allow a geometrical interpretation of the analytical relationships and are very useful to catch the physical insights of the problem. Finally, in order to show the applicability of the new analytical approach, a practical example is provided. The example concerns calculation of the loadability characteristics of typical 400 kV single-circuit OHLs. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessArticle
CALAJOULE: An Italian Research to Lessen Joule Power Losses in Overhead Lines by Means of Innovative Conductors
Energies 2019, 12(16), 3107; https://doi.org/10.3390/en12163107 - 13 Aug 2019
Abstract
The ongoing evolution of the power system to implement climate action policies is resulting in a continuous increase in the penetration of renewables and the necessity of strengthening the transmission grid to optimize the usage of those sources and contain operation costs. Reinforcing [...] Read more.
The ongoing evolution of the power system to implement climate action policies is resulting in a continuous increase in the penetration of renewables and the necessity of strengthening the transmission grid to optimize the usage of those sources and contain operation costs. Reinforcing the transmission lines or building new ones is a process that is made difficult due to authorization issues related with environmental and public acceptance concerns. Developing innovative conductors for overhead lines with enhanced performances with respect to the traditional ones would bring benefits in terms of energy efficiency increases in transmission and distribution grids without requiring the substitution of the existing towers. The project CALAJOULE (the genesis of the acronym comes from the union of the Italian verb “calare”-to decrease-to the third person singular, namely “cala” i.e., decreases, and of Joule, obvious reference to the active losses), cofinanced by the Italian Ministry of Economic Development in the framework of the “Ricerca di Sistema” program, aims at proposing innovative solutions for overhead line conductors for the containment of Joule power losses. In this paper, starting from the state-of-the-art of the currently adopted conductors, the main innovative solutions resulting from the project are presented and compared with the traditional ones to evaluate the achievable reduction in Joule losses. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessArticle
Influence of DC Electric Fields on Pollution of HVDC Composite Insulator Short Samples with Different Environmental Parameters
Energies 2019, 12(12), 2304; https://doi.org/10.3390/en12122304 - 17 Jun 2019
Abstract
Pollution-induced flashover is a serious threat to the safe operation of power systems. With the development of High Voltage Direct Current (HVDC), it is necessary to study insulator contamination in DC electric fields. In this paper, the energized wind tunnel contamination test was [...] Read more.
Pollution-induced flashover is a serious threat to the safe operation of power systems. With the development of High Voltage Direct Current (HVDC), it is necessary to study insulator contamination in DC electric fields. In this paper, the energized wind tunnel contamination test was conducted in order to systematically study the pollution ratio, k (ratio of non-soluble deposit density (NSDD) of a DC-energized condition to a non-energized condition), under different environmental parameters. Later, a two-dimensional contamination model of short samples of an HVDC composite insulator was established. The particle motion characteristics under different environmental parameters were then analyzed by the finite element method (FEM). The research results showed that—the DC electric field had an influence on particle motion but in different environments, the degree of influence was different. In addition, k was found to largely vary, with a variation in the environmental parameters. When the electrical stress (Es) increased from 0 to 70 kV/m, k increased gradually. However, when the wind speed (ws) increased, k experienced a decreasing trend. Finally, as the particle diameter (dp) decreased, k increased at first, followed by a decrease, and then again showed an increase. The results of the pollution ratio, k, for different environmental parameters are of great importance for guiding anti-pollution work in power systems. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessFeature PaperArticle
Improving Angle Stability by Switching Shunt Reactors in Mixed Overhead Cable Lines. An Italian 400 kV Case Study
Energies 2019, 12(7), 1187; https://doi.org/10.3390/en12071187 - 27 Mar 2019
Abstract
Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems [...] Read more.
Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems in the operation of the electrical system, both during steady-state and transient conditions. In particular, the system stability is one of the main concerns when analyzing the dynamic response of power systems. In this paper, the study of angular stability of a system containing a mixed line is presented: a specific control logic applied to the shunt reactors of the mixed line is proposed as improvement of the overall system stability. The proposed switching logic is first discussed from a theoretical point of view and validated with two different testing systems. Then, the existing overhead-cable lines connecting Sicily to the rest of continental Europe 400 kV power system are taken as case study for the application of the proposed switching strategy. Several simulations are performed in the power system analysis software NEPLAN360: the results show the fundamental role of the timing of the control actions applied on the shunt reactors in helping the system to keep the stability. The proposed control proves to be an effective support to the system subjected to critical contingencies, contributing decisively to avoid the angular separation between areas and therefore to preserve the stability of the system. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessArticle
A Non-Uniform Transmission Line Model of the ±1100 kV UHV Tower
Energies 2019, 12(3), 445; https://doi.org/10.3390/en12030445 - 30 Jan 2019
Cited by 1
Abstract
The modeling of the Ultra-High Voltage (UHV) tower plays an important role in lightning protection analysis of transmission lines because the model used will directly affect the reliability of the results. Moreover, the higher the voltage level is, the more prominent the impact [...] Read more.
The modeling of the Ultra-High Voltage (UHV) tower plays an important role in lightning protection analysis of transmission lines because the model used will directly affect the reliability of the results. Moreover, the higher the voltage level is, the more prominent the impact becomes. This paper first analyzes the inapplicability of the Hara multi-segment multi-surge impedance model for the ±1100 kV UHV towers, and then builds a non-uniform transmission line model of the tower. Secondly, the multi-segment multi-surge impedance model is used to study the influence of the tower’s spatial structure changes on its electromagnetic transient characteristics. It is concluded that the more accurately the nominal height of the tower is modeled, the more accurately its electromagnetic transient response is reflected. Finally, the lightning electromagnetic transient responses of the tower with the non-uniform transmission line model and with the multi-segment multi-surge impedance model are compared and analyzed, which shows that the non-uniform transmission line model is more in line with the actual situation under the lightning strikes. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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Open AccessArticle
Transient Temperature Calculation and Multi-Parameter Thermal Protection of Overhead Transmission Lines Based on an Equivalent Thermal Network
Energies 2019, 12(1), 67; https://doi.org/10.3390/en12010067 - 26 Dec 2018
Abstract
The overload degree of a transmission line is represented by currents in traditional overload protection, which cannot reflect its safety condition accurately. The sudden rise in transmission line current may lead to cascading tripping under traditional protection during power flow transfer in a [...] Read more.
The overload degree of a transmission line is represented by currents in traditional overload protection, which cannot reflect its safety condition accurately. The sudden rise in transmission line current may lead to cascading tripping under traditional protection during power flow transfer in a power system. Therefore, timely and accurate analysis of the transient temperature rise of overhead transmission lines, revealing their overload endurance capability under the premise of ensuring safety, and coordination with power system controls can effectively eliminate overloading. This paper presents a transient temperature calculation method for overhead transmission lines based on an equivalent thermal network. This method can fully consider the temperature-dependent characteristics with material properties, convective heat resistance, and radiation heat and can accurately calculate the gradient distribution and response of the conductor cross-section temperature. The validity and accuracy of the proposed calculation method are verified by a test platform. In addition, a multi-parameter thermal protection strategy is proposed on the basis of the abovementioned calculation method. The protection can adequately explore the maximum overload capability of the line, and prevent from unnecessary tripping to avoid the expansion of accidents. Finally, the validity of the proposed protection is verified by the modified 29-bus system. Full article
(This article belongs to the Special Issue DC and AC Overhead Transmission Lines from Low to Extra-High Voltages)
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