Monte Carlo analysis of a transposed overhead line

International Journal of Electrical Engineering Education, Oct 2000 by Indulkar, C S

Abstract In this paper the Monte Carlo simulation method is introduced for evaluating the receiving-end voltage and powers for changes in parameters of a transmission line, such as length, spacing, height and frequency for given sending-and voltage and powers.

Keywords Monte Carlo simulation; software tools; tolerance design; transmission line analysis

The performance of overhead lines depends on a number of parameters that may not remain constant over a period, and the contributions of each add to the performance in a complex manner. The mathematical model of the line requires the assignment of average values to conductor height and conductor spacing that may vary considerably along the line. Some parameters are known with good accuracy and may be taken as constant, whereas there are others which are affected by errors of evaluation and may be variable along the line. The usual interest consists in evaluating the receiving-end voltage and powers with respect to these variable parameters for given sending-end voltage and powers. Many approaches are available for considering these parameter changes including worst-case analysis, sensitivity analysis, and Monte Carlo simulation. The author in a previous paper1 has performed sensitivity analysis of a transposed overhead line. Worst-case analysis is difficult to perform. A statistical model based on Monte Carlo simulation is introduced in this paper in order to estimate the influence of the variable parameters on the line performance. Monte Carlo simulation allows several parameters to be varied, revealing the interaction between them. Monte Carlo simulation may be carried out efficiently with the help of a computer, providing more information on the overall line performance for given simultaneous parameter variations. The results of Monte Carlo simulation should be of interest to engineers responsible for transmission line operation and to students as an introduction to the method. Recently, Hamann et al.2 have used Monte Carlo simulations to introduce tolerance design to undergraduates. Earlier Sadiku3 introduced the method in an electromagnetics course,3 and Distler4 described the Monte Carlo analysis of system tolerance.

Conclusions

The paper presents a Monte Carlo-based approach for evaluating the transmission line receiving-end voltage and powers for the given sending-end quantities. The expected values and the variances of the receiving-end quantities are calculated. The statistical model proposed in this paper provides a generalised, powerful tool of wide-ranging applicability for analysing the performance of a transmission line. Since appropriate software tools are now readily available, Monte Carlo simulation can be easily taught to undergraduate students. There are many other power system problems which can also benefit from the introduction of Monte Carlo analysis in the power area.

References

I C. S. Indulkar, 'Sensitivity analysis of a transposed overhead line', Int. J. Elect. Enging Educ., 18(1981), 251-256.

2 J. C. Hamann, J. W. Pierre, S. F. Legowski and F. M. Long, `Using Monte Carlo simulation to introduce tolerance design to undergraduates', IEEE Trans. Educ., 42(1) (1999), 1-7.

3 M. N. O. Sadiku, 'Monte Carlo methods in an introductory electromagnetic course', IEEE Trans. Educ., 33 (1990), 73-80.

4 R. J. Distler, 'Monte Carlo analysis of system tolerance', IEEE Trans. Educ., 20 (1977), 98-101.

5 C. S. Indulkar and M. S. Thomas, 'Statistical evaluation of peak switching overvoltages in EHV underground cables', Int. J. Power Energy Syst., 14(1) (1994), 34-38.

C. S. Indulkar

Department of Electrical and Communication Engineering, PNG University of Technology, Lae, Papua New Guinea

E-mail. C.Indulkar@ieee.org