Review Reports - Fault Location on Three-Terminal Transmission Lines Without Utilizing Line Parameters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper presents a method of estimating faults in a three-terminal transmission line.

Comments/suggestions to authors:

- Figure 7 - the quality of the figure is very bad, please fix;
- Please explain fault type abbreviations AG, AB, ABG, ABC in Table 1;
- Section 1 at the end - some formatting issues in lines 78 - 81;
- Lines 103, 104 - equation contain i.x2 and i.x4. If "." is a multiplication symbol, it has to be properly presented. All equations seem to have the same issue with multiplication sign (ex. (5)...);
- Explain in more detail what the S, T and R in Figure 1 is, as well as provide practical examples of where this type of connection can be found in practical use. Currently it seems, as if 3 pcs. of AC sources are shorted into a single power line, while being connected to different places...
- It would be correct to compare the accuracy of the proposed fault detection method to what is currently available or has been proposed by others. This comparison might also include a broader view on the pros and cons of existing methods compared to the proposed one;
- The conclusions could be improved by more clearly defining the advantages of the proposed method compared to others;

Author Response

Dear Reviewer!

Thank you very much for taking the time to review this manuscript. We appreciate so much the inputs of you and the reviewers on our manuscript (electricity-3696998) with the title of " Fault Location on Three-terminal Transmission Lines without Utilizing Line Parameters ". Your comments help us to improve the quality of our study. We agree with all the reviewers' comments. And we have revised our manuscript according to your suggestions. In this letter, we will describe our revision in detail. The comments and opinions of the reviewers will be shown in the black colour Font. The modified part of our manuscript will be shown in red colour font. Below is our reply to the reviewers.

Thank you for your consideration. I look forward to hearing from you.

Sincerely,

Le Minh Tri Nguyen et al.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article deals with the important issue of locating faults in transmission lines (power lines) based on synchronous voltage and current measurements. Unfortunately, the manuscript contains many factual, linguistic, and editorial errors and does not consider significant achievements in this field available in the world literature.

Is the manuscript clear, relevant for the field and presented in a well-structured manner?

The manuscript addresses the current problem of identifying faults in power transmission lines. Although the authors emphasize that climatic conditions and aging processes change the parameters of the lines, they mainly focus on locating faults in a three-terminal line. The research is based on analytical relationships and verified exclusively by simulation. The structure of the work is appropriate, but the work contains many shortcomings.

Are the cited references mostly recent publications (within the last 5 years) and relevant? Does it include an excessive number of self-citations?

Of the 20 works cited, eight were published after 2020. There are no instances of self-citations in the bibliography. However, the selection of sources raises some concerns. Many of the cited works are not generally available or are published in Chinese in journals that are not well-known globally. Where available, the ‘doi’ of the articles should be provided. On the other hand, many works on similar topics that the authors should cited in the paper are missing. Against this background, the authors should demonstrate the advantages of their proposal. Below are selected works that, in the reviewer's opinion, should be included in the revised version of the manuscript.

Mahyar Abasi, Arash Rohani, Farhad Hatami, Mahmood Joorabian, Gevork B. Gharehpetian, “Fault location determination in three-terminal transmission lines connected to industrial microgrids without requiring fault classification data and independent of line parameters,” International Journal of Electrical Power & Energy Systems, Volume 131, 2021, 107044, doi.org/10.1016/j.ijepes.2021.107044.
M. Davoudi, J. Sadeh and E. Kamyab, "Transient-Based Fault Location on Three-Terminal and Tapped Transmission Lines Not Requiring Line Parameters," in IEEE Transactions on Power Delivery, vol. 33, no. 1, pp. 179-188, Feb. 2018, doi: 10.1109/TPWRD.2017.2695653.
Poudineh-Ebrahimi, Farhad & Ghazizadeh-Ahsaee, Mahdi. (2022). Accurate fault location algorithm for three-terminal lines without time synchronization considering unknown and different parameters of sections. Electric Power Systems Research. 211. 108057. 10.1016/j.epsr.2022.108057.
Badran, Osama & Rizk, Moh & Abulanwar, Sayed. (2023). Comprehensive fault reporting for three-terminal transmission line using adaptive estimation of line parameters. Electric Power Systems Research. 223. 10.1016/j.epsr.2023.109536.
Abu-Siada, A., Mosaad, M.I. and Mir, S. (2020), Voltage–current technique to identify fault location within long transmission lines. IET Gener. Transm. Distrib., 14: 5588-5596. https://doi.org/10.1049/iet-gtd.2020.1012
Zahra Shafiei Chafi, Hossein Afrakhte, “Wide area fault location on transmission systems using synchronized/unsynchronized voltage/current measurements,” Electric Power Systems Research, Volume 197, 2021, 107285, doi.org/10.1016/j.epsr.2021.107285.
Izykowski, Jan “Fault location on power transmission lines” , Wroclaw, 2008, https://www.dbc.wroc.pl/dlibra/publication/2583/edition/2599/content.
Özdemir, Ö.; Köker, R.; Pamuk, N. Fault Classification and Precise Fault Location Detection in 400 kV High-Voltage Power Transmission Lines Using Machine Learning Algorithms. Processes 2025, 13, 527. https://doi.org/10.3390/pr13020527

Is the manuscript scientifically sound and is the experimental design appropriate to test the hypothesis?

The article contains theoretical foundations and analytical derivations of five equations that form the basis of the method for identifying parameters and locating faults. The methodology is correct, but there are quite a few errors in the derivations themselves (perhaps arising during the editing process). Still, these must be removed in the revised version of the manuscript. In addition, fonts in the text, formulas, and figures should be standardized, and mathematical functions and zero should be written in a simple font. Wherever the multiplication sign is used in the text, it should be moved to the center of the line (or, in some cases, removed). It should also be emphasized that all currents and voltages are in the form of phasors.

Below is a list of errors and typos that I have noticed.

Line 93 - instead of RJ, it should be TJ.
Lines 103, 104 – 1,2,3,4 should be indexes.
(5) - there should be a minus sign before the last term.
Line 113 - the statement is incorrect. You cannot substitute (7) into (3) because Ij does not appear in formula (3).
The part from eq. (18) to the end of line 142 is a copy of the part from eq. (13) to the end of line 128. Other dependencies related to EQ2 and the appropriate comment should appear here.
Lines 146,151 - the order of the drawings should be reversed
(20) - “l - d” should be in parentheses.
(26) - instead of indexes 1b, there should be 2b.
Line 164 - the statement is incorrect. You cannot substitute (21) into (26).
Line 164 and eq. (31) - Figure 4 does not show Vr, Vt, Ir, and It.
Equations (39), (41) - “l - d” should be in parentheses.
Equations (40), (42) - the incorrect equations may be due to the lack of parentheses covering certain components. Only the products of matrix elements are present without multiplication by currents/voltages. In addition, the last current is mismarked.
Since the current direction notation used in Figures 2 and 4 is different to facilitate verification of formulas (40) and (42), it would be beneficial to provide figures similar to Figure 4 instead of Figures 5 and 6.
Lines 209-210 are a copy of lines 179-180 and do not refer to the case under discussion.
Equations (43)- (45) - missing parentheses.
Equation (45) should be under line 221.
One set of equations is missing for the SJ segment using equation (3).
Line 219 - no information is provided on the method used to solve the system of nonlinear equations.
Lines 223-228 - 1, 2, 3, 4, and 5 should be written as indexes.
Lines 245-247 - more details should be provided, including an explanation of which parts of the transmission line correspond to which unit parameters and what the phases mean. Units should be written in standard font.
How does measurement uncertainty affect the results and what are the requirements for practical implementation? Were reasonable measurement conditions in terms of accuracy assumed in the simulation?
Some terms are quite incorrect, e.g., trust domain and artistic intelligence.

Are the manuscript’s results reproducible based on the details given in the methods section?

Although the methodology is transparent, the results presented in the manuscript are challenging to reproduce due to numerous errors in the text and formulas and gaps in specific data.

Are the figures/tables/images/schemes appropriate? Do they properly show the data? Are they easy to interpret and understand? Is the data interpreted appropriately and consistently throughout the manuscript? Please include details regarding the statistical analysis or data acquired from specific databases.

Some tables and figures require correction or supplementation. Figures 4 and 6 should be enlarged. In Figures 5 and 6, db and dc should be written as in the text. In Figure 7, the lower description should be corrected (impedance instead of influence, the line propagation constant gamma instead of the propagation constant of gamma lines. The ei notation and damage types in the tables should be explained. The tables provided illustrate well how the method works under the assumptions made.

Are the conclusions consistent with the evidence and arguments presented?

The conclusions summarize the results achieved under the assumptions made. However, no information exists about the impedance and propagation constant determined according to the algorithm shown in Figure 7. The authors focus only on the location of faults with specific values.

Please evaluate the ethics statements and data availability statements to ensure they are adequate.

There are no statements regarding ethics and data availability in the attached manuscript.

Comments on the Quality of English Language

Due to numerous linguistic and grammatical errors, the reviewer suggests using the help of appropriate services or a native speaker.

Author Response

Dear Reviewer!

Thank you for your consideration. I look forward to hearing from you.

Sincerely,

Le Minh Tri Nguyen et al.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the corrections, no additional comments.

Author Response

Dear Reviewer!

Thank you for your consideration.

Sincerely,

Le Minh Tri Nguyen et al.

Reviewer 2 Report

Comments and Suggestions for Authors

The reviewer would like to thank the authors for their corrections and additions. The current version of the article is significantly improved in both content and form. Unfortunately, it still contains some errors (probably editorial errors in the formulas). It, therefore, requires corrections, primarily in the formulas, which the reader may misinterpret.

1. The authors added the suggested references but limited themselves to replacing the existing references in the original manuscript version. When reading the introduction in the new version of the manuscript, apart from linguistic corrections and formal changes in the order of references, there are no apparent differences in content, which may be surprising in light of the addition of new works. The works refer to similar issues, and the authors should demonstrate the advantages of their proposal in comparison with them.

2. Although the methodology is correct and the authors have fixed many errors, there are still numerous mistakes in the formulas. Even so, the authors claim in their response to the reviewer that the errors have been corrected; they are still present in the version of the manuscript received by the reviewer. It may be the result of mistakes made during the editing of the text, but the authors must remove these errors in the final version of the manuscript. Below are the errors and editing mistakes that were noticed

- Mathematical functions, e.g., cosh, should be written in a plain font

- Equation (5) is still incorrect. The minus sign should appear before DcI2c, not before I1b.

- Eqs. (20), (38), and (41) - “l - d” should be in parentheses.

- Eqs. (18), (19), (40), (42)-(46) - add parentheses in the appropriate places.

- Lines 140-145 - the description contains symbols that are not present in the formulas. Furthermore, not all symbols in the formulas are explained.

- Lines 240-241 - It should be ‘j’ instead of ‘i’.

- Lines 261-262 - The phase notation is unclear; it should be stated that the initial phase of phase A is 0 degrees, phase B is 20 degrees, and phase C is 40 degrees.

3. The quality of the illustrations 5 and 7 is poor.

Author Response

Dear Reviewer!

Thank you for your consideration. I look forward to hearing from you.

Sincerely,

Le Minh Tri Nguyen et al.

Author Response File: Author Response.pdf