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Frequency Characteristics and Transient Response of Transmission Lines with Longitudinally Varying Ambient Temperature
Abstract
This paper addresses the steady state, the frequency characteristics and the transient response of power lines in the presence of longitudinally varying ambient temperature. This variation will lead to location-dependent line circuit parameters and to a changing equivalent circuit. The derived models, which are based on the exact long line theory, can incorporate the impact of the different patterns of the temperature distribution in terms of location and magnitude. Several case studies of the resulting non-uniform lines are investigated. The results include the steady-state response at any frequency, the transient voltage and current distributions and the line's input impedance under various loading conditions.
This paper addresses the effect of the conductor sag on the electromagnetic transients in high voltage
lines. A time-domain model for their simulation is presented. It yields a set of simultaneous partial
differential equations governing the voltage and current distributions in terms of both the time and
location, as well as the corresponding initial and boundary conditions. An efficient Mathematica code
is suggested for their numerical solution. The presented model and the corresponding computer
program are validated via discussing the results of their application to several case studies.
This paper discusses system-level impacts of temperature-dependent transmission line models based on given ambient temperature profiles. In order to capture nonuniformity of line parameters caused by ambient temperature gradients, a line model characterized by multiple nonuniform segments is used. An automated tool has been developed to obtain appropriate system models, given a set of temperature measurements and their locations along each system branch. Using these models, the impacts of temperature variations are investigated with respect to line terminal behavior (bus voltage) and maximum power transfer characteristics. Results for the IEEE 30-bus test system are presented.
First, a new method for numerical inversion of the Laplace transform is proposed. The essential point of this method is to approximate the exponential function in the Bromwich integral by the function Eec(s, a) d= exp (a)/2 cosh (a – s). With this we can get an infinite series which gives a good approximation to the inverse transform. In practice, we accelerate the convergence of the series by the Euler transformation. Thus in ordinary cases, only twenty to thirty terms give satisfactory results, and even a $100 pocket calculator can solve practical problems which are not so easy by the usual method. Second, the wave propagation in dispersive media is studied by using the above method. This problem has been investigated analytically by many authors. The problem is so difficult that there has been no detailed solution available other than asymptotic expressions. Some detailed numerical results by our method are given for the transient phenomena in a waveguide and the medium discussed by Sommerfeld and Brillouin. Our numerical results show that Brillouin's results should not be taken quantitatively except the first forerunner whose approximate variation is predicted by Sommerfeld correctly.
This paper discusses a transmission-line modeling ap- proach that incorporates available ambient temperature informa- tion. Several proposed line modeling techniques are studied and includedistributedandlumpedparametermodels.Inordertocap- ture the nonuniformity of line parameters caused by temperature gradients, a model with multiple nonuniform segments is also pro- posed.Anautomatedtoolhasbeendevelopedtoobtainappropriate line model segmentation and parameter values of each segment, given a set of temperature measurements and their locations along the line.
The principles of this paper is to teach students and engineers the fundamentals of electrical transients and equip them with the skills to recognize and solve transient problems in power networks and components--- also guide this second edition. While the text continues to stress the physical aspects of the phenomena involved in these problems, it also broadens and updates the computational treatment of transients. This paper addresses the subject of modeling, and models for most types of equipment are discussed. The adequacy of the models, their validation, and the relationship between model and the physical entity it represents are also examined.
This paper addresses the achievable advantage of the dynamic rating of overhead power lines based on the continuous monitoring of the ambient temperature and wind speed. Starting from their measured profiles on a typical summer day, the corresponding possible current loading of the line could be determined over the 24 hours. It is then compared with the conventional line rating calculated using the maximum daily temperature and the typically assumed value of 0.6 m/s for the wind speed. The additional daily transmitted energy resulting from the dynamic line rating (DLR) could be found. The procedure is applied to lines of different conductor radii. Results indicate an achievable increase in the daily transmitted energy of about 40%. Copyright © 2007 John Wiley & Sons, Ltd.
Conductor temperature monitors were installed on a four-mile-long
section of 115 kV transmission line and served as the basis for the
dynamic thermal rating of the line during June and December of 1985. A
method of detecting temperature monitor measuring errors is described,
and a method to correct the thermal rating of the line is given. Of the
four spans containing temperature monitors, no one span was consistently
the hottest, but for each month, one span was hottest more than half the
time. By accounting for variations in span orientation along the test
line section, it was found that the weather data from a single weather
station as far as 20 miles away could be used to predict the statistical
distribution of thermal ratings for the test line. The dynamic thermal
rating of the test line was above the line's static rating some 80% to
90% of the time, being 15% to 30% higher 50% of the time. The
correlation of peak contingency loading and peak dynamic thermal rating
is identified as a major factor in evaluating the use of dynamic rating
methods in line uprating
Power System Analysis
- J Grainger
- Stevenson
J Grainger, WD Stevenson. Power System
Analysis. Noida: McGraw-Hill, Inc.; 1994.
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Chapter 9. and Transient Response of Transmission Lines with Longitudinally Varying Ambient Temperature
- A Greenwood
A Greenwood. Electrical Transients in
Power Systems. New Delhi: John Wiley &
Sons. Inc.; 1999. Chapter 9.
and Transient Response of
Transmission Lines with Longitudinally
Varying Ambient Temperature. Journal of
Power Electronics & Power Systems.
2019; 9(3): 19-30p.
Frequency Characteristics and Transient Response of Transmission Lines with Longitudinally Varying Ambient Temperature
Cite this Article
Mohamed
M.
Saied.
Frequency
Characteristics and Transient Response of
Transmission Lines with Longitudinally
Varying Ambient Temperature. Journal of
Power Electronics & Power Systems.
2019; 9(3): 19-30p.