Effect of elevated temperature operation on the tensile strength of overhead conductors

Morgan, V.T.

doi:10.1109/61.484034

Cited by 58 publications

(19 citation statements)

References 8 publications

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“…Manuscript If software is to be employed to continuously monitor the cumulative loss of tensile strength of conductors operating at elevated temperatures, it is essential that a reliable annealing model be used. In particular, the effect of reduction of wire diameter during drawing should be taken into account [5]. What is the wire diameter in Fig.…”

Section: Discussion Of "High Temperature Sag Model For Overhead Condumentioning

confidence: 99%

Closure on "high temperature sag model for overhead conductors"

Chen¹,

Black²,

Fancher³

2003

IEEE Trans. Power Delivery

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former. This is then a function of the current and voltage, which are both a function of the frequency. Therefore, the conversion factor for the transformer leakage impedance, in Ohms, should theoretically be 1.2. To confirm this relationship with test, the corresponding impedance voltage, which would result in full load current in the winding, should be used and resulting impedances in Ohms, 60 versus 50 Hz, compared. 2) Correct. 3) Yes, the flux density was the same in each comparison. The sound level conversion factor was developed from both measured data and from information available with major power transformer manufacturers who have had a significant database for both 50-and 60-Hz noise level measurements. The analysis in the paper used 16 sets of measurements, which was a fairly large sample size that covered the range of megavolt-amperes, core steel materials, and inductions used in the industry. Data that were outside of the expected range could be attributed to mechanical resonance or testing error. With reference to Table 1, the two manufacturers with a lot of experience in building units for the 50-and 60-Hz market used conversion factors of 3.0 and 3.5 dB, respectively, which closely matched the calculated conversion factor. Thus, the authors are confident that the calculated value matches the experience seen by the industry and is a correct and practical value to use. REFERENCES[1] R. S. Girgis, B. Beaster, and E. G. teNyenhuis, "Proposed standards for frequency conversion factors of transformer performance parameters," inThe authors [1] imply that their combined ampacity/sag computer program is the first of its kind. The program Calculation of Overhead Line Thermal, Electrical and Mechanical Properties (COOLTEMP) has been described previously [2]. Besides calculating the surface temperature and the sag of a conductor, this unified model also calculates the radial temperature and current distributions, tension, stresses, creep, cumulative loss of tensile strength, complex permeability of the steel core, if present, ac resistance, core loss, and total loss.It is surprising that the authors have used a graphical method in their program to calculate sag, rather than a program such as STESS [3]. Was the effect of creep taken into account? It is stated that a unique aspect of their program is the high operating temperature limit. However, other codes have been validated for conductor temperatures up to 275 C, for example [4].

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Section: Discussion Of "High Temperature Sag Model For Overhead Condumentioning

confidence: 99%

Closure on "high temperature sag model for overhead conductors"

Chen¹,

Black²,

Fancher³

2003

IEEE Trans. Power Delivery

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“…To deal with this deficiency, a strength reduction coefficient W i , t is introduced in the outage model of the proposed method to reflect the amount of strength reduction of conductors. The conventional way to estimate the amount of conductor strength reduction is to build a model by analyzing the mechanism of strength reduction . However, the strength reduction of overhead conductors is a complicated process in reality and is affected by many factors, which makes it difficult to build an accurate model representing the strength reduction process.…”

Section: Outage Rate Estimation Methods For Overhead Transmission Linementioning

confidence: 99%

“…Since the strength reduction of conductors is a slow process during stable operating period , the strength reduction coefficient of a transmission line can be assumed to be a constant within a certain time period, such as 2 years. Thus, if the performance of line i under wind storms is recorded during the last 2 years, the strength reduction coefficient W i , t within this time period is constant and can represent the present value of conductor strength of this line as shown below:

W_{i, t \in T} = W_{i}

where T is the set of time intervals with wind storms occurring in the predefined time period T , and W i is the present value of the strength reduction coefficient of line i .…”

Section: Outage Rate Estimation Methods For Overhead Transmission Linementioning

confidence: 99%

Overhead transmission line outage rate estimation under wind storms

Liu

Lei

Hou

2018

IEEJ Transactions Elec Engng

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Wind storms such as hurricanes increase the outage rate of overhead transmission lines and hence can seriously affect the security of power systems. Therefore, it is very important to estimate the overhead transmission line outage rate for a power system that might be jeopardized by wind storms. In this paper, we propose a new method for estimating the outage rate of overhead transmission lines, with two primary advantages. First, the proposed method describes the relationship between the outage rate and the weather factors by a fragility curve customized for overhead transmission lines to ensure that the relationship is precisely represented. Second, the proposed method takes the conductor strength reduction and different physical properties of overhead transmission lines into consideration to increase outage rate estimation accuracy. We test the proposed method by estimating the outage rate of overhead transmission lines in a regional power system based on both historical and simulated wind storms. The test results show that the proposed method generates a more accurate estimation than the conventional approaches. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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“…Prior pursuits have examined the long-term physical impact of violating the thermal limits of conductors. These studies focus on the physical aspects of aluminum-conductor steel-reinforced (ACSR) conductors such as loss of strength and sagging [16]- [19].…”

Section: Introductionmentioning

confidence: 99%

Impacts of Constraint Relaxations on Power System Operational Security

Salloum

Al-Abdullah

Vittal

et al. 2016

IEEE Power Energy Technol. Syst. J.

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Constraint relaxations by definition mean that certain constraints are allowed to be violated in energy market models for a pre-determined penalty price. System operators utilize this mechanism in an effort to impose a price-cap on shadow prices in the markets. In addition, constraint relaxations can serve as corrective approximations that help to reduce the occurrence of infeasible or extreme solutions in market models. This work aims to capture the impact constraint relaxations have on AC operating conditions. Moreover, this analysis also provides a better understanding of the correlation between DC market models and AC systems and analyzes how relaxations in market models propagate to system operations. This information can be used to assess the risk associated with constraint relaxations. The practice of constraint relaxations was replicated in this work using a test case and a real-life large-scale system, while capturing both energy market aspects and AC system performance. System performance investigation included static and dynamic security analysis for base-case and post-contingency conditions. Index Terms-Optimal power flow, power generation dispatch, power system economics, power system security, power system simulation, power system stability.

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Effect of elevated temperature operation on the tensile strength of overhead conductors

Cited by 58 publications

References 8 publications

Closure on "high temperature sag model for overhead conductors"

Closure on "high temperature sag model for overhead conductors"

Overhead transmission line outage rate estimation under wind storms

Impacts of Constraint Relaxations on Power System Operational Security

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