Review Reports - Design of a New Busbar for VFTO Suppression and Analysis of the Suppression Effect

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is interesting for the readers to suppress the VFTO in GIS.

Followings are comments.

L20 be-tween → between

L66 meth-od →　method

L98 . is missing after figure 2

Eq.(2) Is τ complex number? Add the comment about Z1 and Z2 is real number.

Figure 4 The size of caption is too small an unclear.

L182 (17)→(18)

Eq.(19) <- →　>-

L192 What is τg?

L331-332 high-frequency frequency →high-frequency

L333 com-ponent →component

Author Response

Dear editors and reviewers,

Thank you for your letter and the reviewers’ comments concerning our manuscript (electronics-3567413). We appreciate to you and the reviewers for your effort to review our manuscript. The comments are valuable and very helpful. We have read through comments carefully and have made corrections. Here are responses to the reviewer comments:

Question

1) L20 be-tween → between. L65 meth-od →method.

Answer: Thank you for your valuable advice. In the revised manuscript we found problems with the spelling of words. We change the L20 be-tween to between, change the L65 meth-od to method. According to the experts' opinions, the authors have revised the manuscript, and the number of lines where the contents of the original manuscript need to be revised and the numbering of charts and graphs have been changed. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

2) L98 . is missing after figure 2.

Answer: Thank you for your valuable advice. In the revised manuscript we have added “.” in the L98 after figure 2. According to the experts' opinions, the authors have revised the manuscript, and the number of lines where the contents of the original manuscript need to be revised and the numbering of charts and graphs have been changed. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

3) The Eq.(2) is τ complex number? Add the comment about Z1 and Z2 is real number.

Answer: Thank you for your valuable advice. In the revised manuscript the τ represents for time, it not a complex number. In the revised manuscript we add the comment about Z₁and Z₂ is real number in the L115-116. According to the experts' opinions, the authors have revised the manuscript, and the number of lines where the contents of the original manuscript need to be revised and the numbering of charts and graphs have been changed. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

4) The Figure 4 The size of caption is too small an unclear.

Answer: Thank you for your valuable advice. In the revised manuscript we enlarged the size of caption of the figure 4 to make it clearer. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

5) L182 (17)→(18)

Answer: Thank you for your valuable advice. We found that the numbering of the Eq. 18 was incorrectly labeled as 17, which we have corrected in the manuscript. According to the experts' opinions, the authors have revised the manuscript, and the number of lines where the contents of the original manuscript need to be revised and the numbering of charts and graphs have been changed. The change part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

6) (19) <- →　>-.

Answer: Thank you for your valuable advice. In the revised manuscript we modify the in Eq. 19 to . The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

7) The L192 What is τ_g.

Answer: Thank you for your valuable advice. In the revised manuscript the τ_g denotes the breakdown time of the gap. The footnote for τ in Eq. 19 is omitted. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

8) The L331-332 high-frequency frequency →high-frequency.

Answer: Thank you for your valuable advice. In the revised manuscript we modified the high-frequency frequency to high-frequency. The issue was a result of a clerical error. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

9) The L333 com-ponent →component.

Thank you for your valuable advice. In the revised manuscript we found problems with the spelling of words. We change the L33 com-ponent to component. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

Reviewer 2 Report

Comments and Suggestions for Authors

The interesting paper shows a practical application of the damping bus attenuating transients in 550 kV systems.

The paper is written well however the results presented in Figures 13, 14 and 15 are obtained in unspecified circuit. From the text it is known that the test circuit is shown in picture from Figure 12. however it is not given in the form of schematic. Please, show the schematic of the test circuit to provide more detials on the performance of the proposed daming bus.

In lines 199 (table 1) there is (pH) unit - is it picohenry? Below the table there is a note 1 however it is not clear if it is applied to this table. Word "famous" seem to be strange, maybe "not listed" is better. However there is strange pH which should be corrected or explained.

Provide also some discussion if the proposed damping busbar can be applied in other voltage systems and what specific parameters of this busbar must be changed. This would be interesting for readers.

I claimed my remarks as minor, however if they are considered definitely the manuscript will gain value.

In Figure 15 presents transient response of two cases where voltages are given in p.u. system however the spectrum shown in 15.c shows voltages given in numbers not corresponding to p.u system. This should be consistent and if not put "kV" as an unit for amplitudes in Figure 15.c. Figure 15 should have also different description because the spectrum is only shown in 15.c.

Author Response

Dear editors and reviewers,

Question

1) The results presented in Figures 13, 14 and 15 are obtained in unspecified circuit. From the text it is known that the test circuit is shown in picture from Figure 12. However, it is not given in the form of schematic. Please, show the schematic of the test circuit to provide more details on the performance of the proposed damming bus.

Answer: Thank you for your valuable advice. In the revised manuscript we added the circuit schematic for the damped bus test rig, shown in the figure 12. The description of each equipment component within the schematic is provided. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

2) In lines 199 (table 1) there is (pH) unit - is it picohenry? Below the table there is a note 1 however it is not clear if it is applied to this table. Word "famous" seem to be strange, maybe "not listed" is better. However, there is strange pH which should be corrected or explained.

Answer: Thank you for your valuable advice. In the revised manuscript we change the unit for L_e0 in table 1 from pH to μH. The original unit was misspelled due to a clerical error. We change the “famous” to “not listed”. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

3) Provide also some discussion if the proposed damping busbar can be applied in other voltage systems and what specific parameters of this busbar must be changed. This would be interesting for readers.

Answer: Thank you for your valuable advice. In the revised manuscript we have added key parameters and considerations at the end of the summary regarding the need to modify the damped busbar for applications in other voltage systems. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

4) In Figure 15 presents transient response of two cases where voltages are given in p.u. system however the spectrum shown in 15.c shows voltages given in numbers not corresponding to p.u. system. This should be consistent and if not put "kV" as a unit for amplitudes in Figure 15.c. Figure 15 should have also different description because the spectrum is only shown in 15.c.

Answer: Thank you for your valuable advice. In the revised manuscript we modified the vertical coordinates in Fig. 15(c) by changing the units to kV. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper addresses the equipment insulation issues caused by the very fast transient overvoltage (VFTO) in gas-insulated switchgear (GIS), proposes a novel design of a damping busbar with a "inductor + resistor" structure, and verifies its suppression effect through simulations and experiments. The research topic has strong engineering practical value and innovation. The model establishment is relatively systematic, the testing methods are detailed, and the data support is sufficient. My comments are as follows:

There are repetitions and jumps in the overall logic of the article. For example, some contents in Chapter 2 and Chapter 3 overlap. It is recommended to make the structural design, parameter modeling, and simulation analysis into independent subsections respectively to enhance the logical coherence.

In Section 2.2 of the article, the derivation of the equivalent circuit and wave impedance (Formulas 1 to 13) lacks sufficient intermediate derivation steps, and the meanings of some formulas are unclear. Especially for the formulas related to "wave impedance synthesis" and "voltage steepness", the explanations of physical meanings and engineering backgrounds should be supplemented.

The quality of Figures 13 to 15 is too poor. It is recommended to redraw the charts and add unified figure captions to enhance the readability of the data.

There are a large number of grammatical errors and misuses of technical terms (for example, "skeletonization" is repeatedly used but not defined, and the expression "non-obvious high-frequency frequency" is redundant). It is recommended to ask a native English speaker to polish the article or use professional language editing services to improve the language quality.

Although multiple VFTO suppression technologies are listed in the article, the advantages and disadvantages of these technologies and the relative advantages of the research method in this paper are not compared. It is recommended to add a performance comparison analysis with typical methods such as metal oxide arresters, damping resistors, and magnetic ring schemes.

In the experimental part, only the waveform and data of a single test are shown, and the repeatability of the test and the error range are not reflected. Also, the measurement accuracy and error sources of the test system are not explained. It is recommended to supplement the error analysis and verify with the results of multiple sets of experiments.

It is recommended to supplement the following literature (not written by me): 10.1109/TCSI.2024.3523339, 10.1109/TII.2024.3495785.

Author Response

Dear editors and reviewers,

Question

1) There are repetitions and jumps in the overall logic of the article. For example, some contents in Chapter 2 and Chapter 3 overlap. It is recommended to make the structural design, parameter modeling, and simulation analysis into independent subsections respectively to enhance the logical coherence.

Answer: Thank you for your valuable advice. In the revised manuscript we found that there were duplications and jumps in the overall logic of the manuscript, and made adjustments to the manuscript chapters, including modifying the chapter names as well as deleting repetitive research content. After modification, the second chapter of the manuscript mainly carries out the design of damping bus structure, and analyzes through simulation that the configuration of inductance and resistance parameters of damping bus will have an impact on the VFTO suppression effect. The third chapter of the manuscript mainly carries out the optimization design of damping bus structure, and takes the actual bus length used in 550kV actual voltage level as the limitation, compares the influence of the turn spacing and the number of turns on the inductance of the bus, and provides technical support for maximizing the effect of the damping bus on VFTO suppression. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

2) In Section 2.2 of the article, the derivation of the equivalent circuit and wave impedance (Formulas 1 to 13) lacks sufficient intermediate derivation steps, and the meanings of some formulas are unclear. Especially for the formulas related to "wave impedance synthesis" and "voltage steepness", the explanations of physical meanings and engineering backgrounds should be supplemented.

Answer: Thank you for your valuable advice. In the revised manuscript we have added a schematic diagram of the wave propagation process across the inductor before Eq. (1), describing the variation of voltage and wavefront steepness at point A. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

3) The quality of Figures 13 to 15 is too poor. It is recommended to redraw the charts and add unified figure captions to enhance the readability of the data.

Answer: Thank you for your valuable advice. In the revised manuscript we redrew Figures 13 to 15 (the serial numbers change to 15-17 here because of the addition of other figures earlier in the article) and standardized the formatting of the various types of captions in the figures. According to the experts' opinions, the authors have revised the manuscript, and the number of lines where the contents of the original manuscript need to be revised and the numbering of charts and graphs have been changed. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

4) There are a large number of grammatical errors and misuses of technical terms (for example, "skeletonization" is repeatedly used but not defined, and the expression "non-obvious high-frequency frequency" is redundant). It is recommended to ask a native English speaker to polish the article or use professional language editing services to improve the language quality.

Answer: Thank you for your valuable advice. In the revised manuscript we have made modifications and deletions to lots of vocabulary and sentences, such as “skeletonization”, “non-obvious high-frequency frequenc” and so on. We understand the importance of clear and precise language in academic writing, so our team found an English major to polish the paper. However, the English major we found lacked background knowledge in the field of electricity. Therefore, even though we proofread the manuscript carefully and made revisions, including correcting grammatical errors, poor word choice, and improving sentence structure. However, the manuscript may still not be up to the level of professional writing by native English speakers. Thank you again for your good suggestion.

5) Although multiple VFTO suppression technologies are listed in the article, the advantages and disadvantages of these technologies and the relative advantages of the research method in this paper are not compared. It is recommended to add a performance comparison analysis with typical methods such as metal oxide arresters, damping resistors, and magnetic ring schemes.

Answer: Thank you for your valuable advice. We add the comparison of the advantages and disadvantages of metal oxide arresters, damping resistors, and magnetic ring schemes in chapter 1, forming the table 1. The change part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

6) In the experimental part, only the waveform and data of a single test are shown, and the repeatability of the test and the error range are not reflected. Also, the measurement accuracy and error sources of the test system are not explained. It is recommended to supplement the error analysis and verify with the results of multiple sets of experiments.

Answer: Thank you for your valuable advice. We carried out several tests. In the manuscript we added the statistics of the VFTO amplitude collected from several tripping operations before and after the damping bus was installed, as shown in Fig. 18. In the measurement system, we give the measurement accuracy of the three-part device of the measurement system. In this technical study, we have done many tests on both the breaking operation and the closing operation etc. Considering the length of the paper, we have analyzed only the breaking state in this manuscript. The following are some of the test data we have done and the graphs we have drawn. The revised part has been marked yellow in the revised manuscript. Thank you again for your good suggestion.

(1) Disconnect switch open, not pre-charged with DC voltage

The magnitude statistics of the high-frequency overvoltage are shown in Table 1, and Table 2 shows the mean values of the high-frequency overvoltage before and after the installation of the suppression conductors, the standard deviation, the degree of reduction (%) of the mean values of the magnitudes before and after the addition of the conductors, and the results of the calculation of the analysis of variance (ANOVA). After arranging the amplitude values from largest to smallest, they are plotted in Figure 1. According to the data, it can be seen that the difference in the mean values is very significant, indicating that the magnitude of the HF overvoltage is not due to the randomness of the HF overvoltage generation, but that the damping bus makes the VFTO magnitude decrease by 20.05% on average.

Table 1

Number of tests	pre-installation（p.u.）	post-installation（p.u.）
1	1.57	1.19
2	1.52	1.29
3	1.48	1.19
4	1.43	1.27
5	1.48	1.17
6	1.56	1.09
7	1.48	1.17
8	1.72	1.33
9	1.62	1.24
10	1.53	1.26
11	1.50	1.22
12	1.56	1.1
13	1.61	1.16
14	1.51	1.16
15	1.28	1.24
16	1.26	1.12
17	1.62	1.28
18	1.36	1.23
19	1.53	1.16
20	1.49	1.21

Table 2

mode	Average voltage（p.u.）	standard deviation	F-value	Average reduction in amplitude (%)
pre-installation	1.505	0.111	1.196***	20.05%
post-installation	1.204	0.065	1.196***	20.05%

“***” means the p<0.001

Figure 1

(2) voltage Disconnect switch closed, not pre-charged with DC voltage

The magnitude statistics of high frequency overvoltage are shown in Table 3. Table 4 shows the mean value of high-frequency overvoltage before and after the installation of the damping bus, standard deviation, the degree of reduction (%) of the mean value of the amplitude before and after the addition, and the results of the calculation of the analysis of variance (ANOVA). After arranging the amplitude values from largest to smallest, they are plotted as shown in Figure 2. Based on the data, it can be seen that the damping bus reduces the average value of VFTO amplitude by 31.16%.

Table 3

Number of tests	pre-installation（p.u.）	post-installation（p.u.）
1	2.38	1.12
2	2.02	1.17
3	1.42	1.29
4	2.09	1.14
5	1.39	1.24
6	1.66	1.23
7	1.92	1.27
8	1.83	1.38
9	2.06	1.31
10	1.87	1.33
11	2.02	1.21
12	1.96	1.33
13	1.79	1.33
14	1.72	1.4
15	1.74	1.44

Table 4

mode	Average voltage（p.u.）	standard deviation	F-value	Average reduction in amplitude (%)
pre-installation	1.858	0.256	7.354***	31.16%
post-installation	1.279	0.944	7.354***	31.16%

“***” means the p<0.001

Figure 2

(3) Disconnecting switch breaking, pre-charging DC voltage

The statistics of the magnitude of the high frequency overvoltage of the disconnecting switch tripping and pre-charging DC voltage are shown in Table 5. Table 6 shows the mean value of the high-frequency overvoltage before and after the installation of the damping busbar, the standard deviation, the degree of reduction (%) of the mean value of the amplitude before and after the addition, and the results of the calculation of the analysis of variance (ANOVA). After arranging the amplitude values from largest to smallest, they are plotted as shown in Figure 3. According to the data, it can be seen that the difference in the mean value is significant, and the suppression of the conductor reduces the mean value of the amplitude by 17.12%.

Table 5

Number of tests	pre-installation（p.u.）	post-installation（p.u.）
1	1.53	1.19
2	1.39	1.22
3	1.37	1.2
4	1.58	1.22
5	1.38	1.24
6	1.41	1.25
7	1.56	1.16

Table 6

mode	Average voltage（p.u.）	standard deviation	F-value	Average reduction in amplitude (%)
pre-installation	1.46	0.924	30.423***	17.12%
post-installation	1.21	0.308	30.423***	17.12%

“***” means the p<0.001

Figure 3

(4) Disconnect switch closing, pre-charged DC voltage

The statistics of the magnitude of the high frequency overvoltage of the disconnecting switch tripping and pre-charging DC voltage are shown in Table 7. Table 8 shows the mean value of the high-frequency overvoltage before and after the installation of the damping busbar, the standard deviation, the degree of reduction (%) of the mean value of the amplitude before and after the addition, and the results of the calculation of the analysis of variance (ANOVA). After arranging the amplitude values from largest to smallest, they are plotted as shown in Figure 4. According to the data, it can be seen that the difference in the mean value is significant, and the suppression of the conductor reduces the mean value of the amplitude by 37.25%.

Table 7

Number of tests	pre-installation（p.u.）	post-installation（p.u.）
1	2.42	1.49
2	2.4	1.72
3	2.49	1.45
4	2.52	1.73
5	2.56	1.72
6	2.54	1.56
7	2.61	1.43
8	2.51	1.52
9	2.61	1.44
10	2.57	1.77

Table 8

mode	Average voltage（p.u.）	standard deviation	F-value	Average reduction in amplitude (%)
pre-installation	2.523	0.538	10.876**	37.25%
post-installation	1.583	0.369	10.876**	37.25%