Impact Analysis of High-Altitude Electromagnetic Pulse Coupling Effects on Power Grid Protection Relays

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

1. The reasons for impedance analyze is neglected. Is it for the input parameter s of FEKO simulation? The overall paragraphs have to be revised for the need of the impedance analyze

2. Fig. 1 contains figures from the reference. Reviewer wonder whether the authors has copyrights of using presented figures.

3. Paragraph in line 77, the background of utilizing E1 source is neglected. In common, previous reports say E3 is coupled to the transmission line, and it is also described in the paragraph line 59. 

4. Reviewer suggested to include what will happen when the protection relays malfunction paragraph in line 77 with the reference. It will help the reader to understand the importance of the relay.

5. Paragraph in line 93, IEC number is missing. Please note the exact number.

6. Paragraph in line 139, IEEE number is missing. Please note the exact number.

7. Figure 4 (c) and (d) should not include sub-title. Please unify the editing style.

8. Figure 5 (b) does not include mark '(b)' in Figure 5.

9. About Figure 6 (b), please include rise time and FWHM of the pulse in the relating paragraph.

10. Figure 8 is confusing to understand. Please divide as (a) and (b), and revised the following description.

11. In 5.4 Evaluation, 6. Conclusion,  the scientific analyze is insufficient. Reviewer can read the result of the experiments, but the mechanism or the reason why the result happen is insufficient. Please reinforce to improve the journal. 

Author Response

We would like to express our sincere gratitude for the time and effort the reviewer has dedicated to evaluating our manuscript. We highly appreciate the insightful suggestions provided.

In response to these suggestions, we have prepared a detailed document summarizing our responses to each point raised. Furthermore, we have made several modifications to the manuscript in accordance with the feedback received. All changes in the revised manuscript are highlighted in red for ease of identification and review.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The article is right written even if the interest of Feko simulation is not clear. Unfortunately, it cannot be accepted in this state. In fact, the method can be interesting but is used with VNA impedance measurements. These measurements are "small signals" measurements which are very different of under voltage measurement (non linear components). With no injection experimental result on tested equipement, this article is very basic and very contestable. I propose you to perform experiments to compare to calculations. With these experiments, the article will be a real interest for the community.

Author Response

We would like to express our sincere gratitude for the time and effort the reviewer has dedicated to evaluating our manuscript. We highly appreciate the insightful suggestions provided.

In response to these suggestions, we have prepared a detailed document summarizing our responses to each point raised. Furthermore, we have made several modifications to the manuscript in accordance with the feedback received. All changes in the revised manuscript are highlighted in red for ease of identification and review.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

However, all your method is based on VNA (or impedance analyzer) measurement. These measurement are good on the frequency range, no problem on this point. But, VNA measurements are "small signals" measurements which are very different of under voltage measurement (non linear components). You have performed measurement on a control power port or 48VDC output port, these equipment include several non linear components (it is an active equipment). Therefore, the real impedance in operation is very different than the "small signals" VNA measurement. Therefore, the simulation results performed with VNA measurement are false and not permit to predict the impact of HEMP on these equipment. If tested impedances were passive component such as capacitor, the simulation results based on VNA measurement would be good. The high difficult in your work and the real interest for the community is to measure correctly impedances of operational equipment connected to the mains. This is the started point to predict the HEMP impact on equipment using FEKO simulations.

Author Response

Thanks to the reviewer for the insightful feedback and for highlighting the critical concerns regarding the measurement uncertainty of the VNA instrument again. We acknowledge the significance of the impact that nonlinear components can have on our measurements and have consequently revised our measuring and analysis methodologies in response.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

Thank you for your answer and the adding of impedances measurement under powered-on operational conditions.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents the impact analysis of high altitude electromagnetic pulse coupling effects on power grid protection relays. However, some descriptions are not clear. Some revisions are necessary in the manuscript.

1: Please further elaborate the main innovations and significance of the article.

2: Please further explain how the PCI and FEKO methods are used?

3: Please further describe the port impedance measurement approach and the de-embedding process of the fixture.

4: Please briefly describe how to test the level with sine and double exponential waves.
5: In the paper, authors have focused on the relay protection of the power grid, and can compare and analyze the management methods of different power systems to show your advantages, which can refer to：

[a] IEEE Transactions on Industrial Informatics, vol. 18, no. 2, pp. 835-846, 2022

[b] IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 8, no. 2, pp. 1034-1049, June 2020

Comments on the Quality of English Language

A proofreading is needed.