Bundle Conductors Research Articles

Development of galloping endurance design for extra large 6-conductor bundle spacers by the experience of the full scale 500 kV test line

Large diameter bundle conductors, which result in lower line inductance is one of the most cost effective methods to gain stable power transfer capability on a long bulk power transmission line. To bring this new type of conductor into practice, since galloping is a major cause of damage to transmission lines in certain regions of Japan, it is essential to grasp the dynamic mechanical loads during the phenomena. New methods for designing several kinds of hardware involved in the new 500 kV bulk transmission facilities utilizing extra large 6 conductor bundles were developed using three years of field experience on a full scale 500 kV testing line. The 769 m test line supported by three full scale supporting structures were constructed on Mt Sanpo (alt 970 m) located 35 km from the Japan sea, where frequent galloping phenomenon was observed. This paper features the methods used in designing the spacers developed from the field studies.

Lightning impulse corona characteristics of conductors and bundles

The paper describes an experimental study and a computational method of estimating the q-u corona characteristics of single and bundle conductors for conductor-plane and conductor-conductor gaps under lightning impulse voltages. Measurements were performed for individual subconductors in a bundle which provided data necessary for an estimation of charge distribution and electric field strength in the streamer zones. A method for calculating q-u curves for any arbitrary bundle configuration for conductor-plane and conductor-conductor gaps is described.

A Special-Case Surface Voltage Gradient Formula

In the electrical design of a high-voltage substation, the designer needs a simple and reliable tool, preferably a closed-form formula, when calculating the surface voltage gradient of line segments within the substation since the surface voltage gradient is the governing parameter of the corona performance. This paper presents a derivation of a closed-form formula for calculation of the maximum surface voltage gradient of a special line configuration, namely a horizontal AC three-phase line configuration with bundle conductors consisting of three sub-conductors in a horizontal arrangement. The formula has been verified against exact calculations and was found to have an error less than 5% for all practical combinations of the conductor radius, the sub-conductor spacing, the phase distance, and the height above earth.

Reduction of audible noise using asymmetrical bundles for 1000 kV transmission lines: full-scale test results of Akagi test line

Long-term tests of asymmetrical bundles which have the potential to suppress corona activity on conductor bundles have been carried out in the Akagi test line, and their corona performance, mainly audible noise, was measured. Asymmetrical bundles generally show good performance; however, the added system, which is classified as an asymmetrical bundle due to the addition of a subconductor at the bottom of regular symmetrical conductor bundles, shows better performance. These reduction techniques can be applied to actual 1000 kV transmission lines because of their good corona-suppressing performance, if problems such as mechanical performance and unbalanced current passing through individual subconductors can be resolved.

Power R&D: more watts, but less to pay

Thousands of kilometers separate the hydroelectric sources on the Amazon from main load centers far to the south. If Brazil is to transmit many megawatts of power over such distances, it must develop technology that is more efficient and less costly than what is in use today. For this and other pressing needs in the power field, the country's federally owned holding company in charge of power generation and transmission, Electrobras, turns to the country's leading power R&D center, Cepel. Both organizations are based in Rio de Janeiro. This paper details four of Cepel's many projects which are of particularly broad interest. One is an optimized design of conductor bundles for AC transmission lines, Another is a test station for DC equipment up to 800 kV. Then there is software for the stability analysis of large transmission systems, which may involve thousands of buses and branches. Fourth and last, an inexpensive electronic ampere-hour meter is being developed for customers with low incomes, who seldom use more than 100 kWh per month.

A special-case surface voltage gradient formula [for substation design

In the electrical design of a high-voltage substation, the designer needs a simple and reliable tool, preferably a closed-form formula, when calculating the surface voltage gradient of line segments within the substation since the surface voltage gradient is the governing parameter of the corona performance. This paper presents a derivation of a closed-form formula for calculation of the maximum surface voltage gradient of a special line configuration, namely a horizontal AC three-phase line configuration with bundle conductors consisting of three sub-conductors in a horizontal arrangement. The formula has been verified against exact calculations and was found to have an error less than 5% for all practical combinations of the conductor radius, the sub-conductor spacing, the phase distance, and the height above earth.

Critical switching impulse breakdown of long bundle-conductor gaps

The paper presents a generalized physical approach to account for the effect of bundle geometry on critical switching impulse strength of long air gaps. The model covers phase-to-ground as well as phase-to-phase insulation. It has been applied to conventional symmetrical bundles as well as to more complex open configurations. The effect of bundle conductors was investigated for the following basic configurations: conductor-plane; conductor-rod; conductor-tower leg; conductor-tower window; and phase-to-phase, within a wide range of clearances. The model is compared with previous analytical approaches as well as to extensive experimental results.

Fundamental characteristics of overhead transmission line galloping determined by simulating calculation using equivalent single‐conductor method

AbstractTheoretical study and phenomenal examination have been ongoing for many years; however, some electric power companies still have instantaneous power failure due to galloping. This study differs from others in that nonlinear three‐dimensional simultaneous equations of conductor movement can be solved directly using numerical calculation. Fundamental characteristics of galloping can be ascertained by changing calculation parameters variously. This time, a method is used in which bundle conductors are changed equivalently to single conductor. It is also clarified that unstable domain becomes wider when rotational movement of conductor occurs.

Macroscopic electric characterization of bundles of conductors

The author explains how the ohmic behaviour of a bundle of conductors can be characterized by a complex resistivity. He provides an analytical expression, explicit and simple, of that resistivity and shows how to optimize an HF transformer, using that formula together with a previously published expression of the macroscopic magnetic permeability. >

On the energy dissipation in spacer dampers in bundled conductors of overhead transmission lines

In high voltage overhead transmission lines, bundles of conductors are used frequently for mechanical and electrical reasons. These bundled conductors are particularly susceptible to wind excited vibrations in the frequency range approximately from 10 to 60 Hz, due to vortex shedding. The usual dampers of the Stockbridge or of a similar type located near the suspension clamp do not lead to pervasive damping of the whole bundle. In recent years self-damping spacers have therefore been used to limit the danger of conductor fatigue due to aeolian vibrations. The numerical treatment of the boundary value problem for bundles equipped with self-damping spacers leads to complicated and poorly conditioned equations. In the present paper, a self-damping spacer is considered in a bundle of four conductors. The energy dissipation associated with the mathematical model for this spacer can be expressed in the form of a symmetric matrix of dimension 16 × 16. By solving the relatively small eigenvalue problem defined by the corresponding 16 × 16 matrix, the spacer damper can be optimized with respect to mechanical energy dissipation by maximizing the smallest real part of its eigenvalues.

Calculating the switching surge critical flashover voltage of phase-to-ground and phase-to-phase bundle conductor gaps

The paper presents a method for calculating the 50% breakdown voltages of conductor-to-plane and conductor-to-conductor air gaps for any bundle design, all the three phases of lines being taken into account. The method is developed for switching impulses with long time front (/spl tau/f=1000-4000 /spl mu/sec) which are the most typical for UHV lines. The results of calculations are extensively compared with previous experimental results for different bundles and over a wide range of gap spacings. The influence of bundle configuration, type of phases displacement (flat, delta or inverted delta) and voltage distribution among phases for UHV lines are analyzed. >

AUTOMATED WIND TUNNEL MEASUREMENTS

It is common practice in power transmission to use bundled overhead electrical conductors because the lower rate of corona discharge, compared with single conductors, makes the bundle attractive for high voltages. However, secondary problems may arise from the vibrations induced by the aerodynamic forces which act on the leeward conductors as a result of their immersion in the wake of a windward conductor. Thus, in addition to possible aeolian and galloping oscillations observed for a single conductor, bundle conductors may also be subjected to wake-induced oscillations. 1,2 Although extensive research has been done on the aeroelastic behavior of single and bundled conductors which are bare, little is known about the galloping or wake oscillation characteristics of given bundle conductors which, depending upon the environmental conditions during the formation of ice, may have five or so representative shaped cross-sections. One important task involves the aerodynamic quasi-static force and moment measurements in a wind tunnel using full scale conductor cross-sections each of which must be rotated through many angles at different spacings. Such measurements are repetitive as well as tediously time consuming and, hence, are beneficially automated. A reliable, accurate and inexpensive automated apparatus is described in this paper which permits the aerodynamic measurements to be performed efficiently and without intervention. Most importantly, it relieves the operator of the usual responsibility for manually controlling the separation and orientation of the sections as well as the need to manually compensate fluctuations in the free stream air speed. For simplicity, the apparatus is detailed in the context of a twin bundle conductor.

A new charge-simulation-based method for analysis of monopolar Poissonian fields

The charge-simulation technique is applied to solve the Poissonian field problem, which is governed by Poisson's equation, the equation for current density, and the current continuity condition in transmission line arrangements. These include the coaxial cylinder arrangement, the monopolar line with single and bundle conductors, and the homopolar line with single conductors. The surface charge on the stressed conductor as well as the charge in the space around it are represented by a discrete set of unknown infinite line charges. Satisfying properly chosen boundary conditions at the transmission line conductors results in a system of algebraic equations whose iterative solution evaluates the unknown line charges. Having determined these unknowns, the potential, electric field and volume charge density can be calculated everywhere between the stressed conductor and the ground plane. The I-V characteristic was evaluated for the investigated arrangements and agreed satisfactorily with those reported earlier.

Modélisation magnétique macroscopique des faisceaux de conducteurs

This paper deals with the macroscopic magnetic characterization of the bundles of conductors, regarded as composite materials. We get by calculation (homogenization) an analytical expression, explicit and simple, for the macroscopic magnetic permeabilities. The study is achieved in the frequency domain. Numeric results are compared with results of computation using finite elements.

Mechanical characteristics related to fault currents in bundle conductors

AbstractThe flow of fault currents in bundled conductors induces an electromagnetic attraction between subconductors and thereby the bus conductor system to an extremely high level of tension. This tension, which is the most important factor in designing the mechanical strength of the system, is determined by a large number of parameters—the magnitude of the fault current, the size and number of the subconductors, spacer interval, the spring of the structure, and so on.Full‐scale 63‐kA class fault current tests were carried out on eight types of bus conductors used in 275‐and 500‐kV subconductors, and measurements of fluctuation in tension were used to clarify the relationship between the various parameters and maximum tension at fault time.A method also was devised for calculating maximum tension at fault time on the basis of the various parameters, and it has been applied in the mechanical strength design of the bus conductor system.

多導体母線の短絡電流に対する機械的特性

多導体母線の短絡電流に対する機械的特性

Computer analysis of the effects of asymmetries of a two-conductor bundle upon its aeolian vibration

A brief description of VIBEOL, a new computer model for the analysis of aeolian vibrations of bundled conductors, is given. Its main characteristics include the capability to treat, in the same span, different spacer-dampers, subconductors, and dampers and a calculation scheme based on the random behavior of aeolian vibrations. In addition, the model can take into account the flexural rigidity of the conductor, thus yielding more accurate estimates of conductor strains and allowing for the moments of inertia and angular stiffness of spacers, dampers and other special types of line equipment. The model has been used to investigate the effects of asymmetries of a twin ASCR conductor bundle equipped with Hydro-Quebec spacer-dampers. While differences in the rigidity of the spacer-damper articulation did not affect the control of aeolian vibration, tension differentials and bundle twist were shown to have a large influence on the reduction of vibration levels. >

A prediction method of audible noise and radio noise generated from HVDC transmission line with 4×3.84 cm conductor bundles

Electrical Engineering in JapanVolume 111, Issue 7 p. 68-77 Article A prediction method of audible noise and radio noise generated from HVDC transmission line with 4×3.84 cm conductor bundles Yukio Nakano, CRIEPI Joined Central Research Institute of Electric Power Industry in April 1981 after obtaining a Master's degree from Nagoya University. His interest is in the electrical environmental problems of overhead lines and infrared ray heating. He is a member of I.E.E.E., and of the Infrared Ray Technology Association.Search for more papers by this authorYoshitaka Sunaga, CRIEPI Joined Central Research Institute of Electric Power Industry in April 1970 after obtaining a Master's degree from Kobe University. His main interest is in corona discharge, partial discharge of insulators, and ionic flows generated from the HVDC line.Search for more papers by this author Yukio Nakano, CRIEPI Joined Central Research Institute of Electric Power Industry in April 1981 after obtaining a Master's degree from Nagoya University. His interest is in the electrical environmental problems of overhead lines and infrared ray heating. He is a member of I.E.E.E., and of the Infrared Ray Technology Association.Search for more papers by this authorYoshitaka Sunaga, CRIEPI Joined Central Research Institute of Electric Power Industry in April 1970 after obtaining a Master's degree from Kobe University. His main interest is in corona discharge, partial discharge of insulators, and ionic flows generated from the HVDC line.Search for more papers by this author First published: 1991 https://doi.org/10.1002/eej.4391110708 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Volume111, Issue71991Pages 68-77 RelatedInformation

AC SR 810mm<sup>2</sup>4導体方式直流送電線のコロナ騒音およびラジオ雑音の予測法

This paper describes a general prediction method of audible noise and radio noise generated from HVDC transmission lines with 4×3.84cm conductor bundles. This method is based on the longterm test results of audible noise and radio noise arranged by the maximum conductor surface gradient in the presence of space charge. The feature of the method is as follows:(i) It is applicable to 4×3.84cm DC transmission lines with any line configuration and any polarity arrangement.(ii) It has a high prediction accuracy because it is confirmed by a large quantity of measured data.

Hum noise performance of 6, 8, 10 conductor bundles for 1000 kV transmission lines at the Akagi test site: a comparative study with cage data

The hum noise performance of 6, 8, 10 conductor bundles (subconductor diameter: 3.84 cm) for 1000 kV transmission lines was measured at the Akagi test site and the results were compared with cage data. In general, hum noise levels calculated with cage data were higher than the long-term test results. It was found that the differences between calculated and measured levels were formulated with the maximum surface gradient. Based on this relationship a new prediction method for hum noise near AC transmission lines is proposed. >