Electric Field Distribution on Zinc Oxide Pills in Gapless Surge Arresters Using Finite Element Method and Evolutionary Optimization Algorithms in HVAC Systems
Round 1
Reviewer 1 Report
More context could be put into this work in terms of ageing/aging.
Author Response
We would like to thank the editor and reviewers for their valuable comments and suggestions that helped us to improve the manuscript. We have tried to address all the editor and reviewers’ concerns in the best manner. The modifications on the paper are marked-up in yellow so that they are easy to locate. We hope that following answers are satisfactory.
Detailed responses and discussions are provided as follows.
Reviewer #1
Comment 1. More context could be put into this work in terms of ageing/aging.
Answer: MOAs can be degraded during utilization due to the destructive factors. Degradation of MOAs caused by destructive factors can damage them and thus change the V–I characteristic of surge arresters.
It is supposed that a surge arrester is classified as ‘‘aged’’ if the maximum voltage of V–I characteristic decreases by 10% or so. Therefore the voltage of ZnO block V–I characteristic has been intentionally reduced to study aging effect.
On the other, aging detection of surge arrester is usually carried out by determining the third harmonic component of resistive leakage current.
Therefore, it can be seen that in order to check the aging of the surge arrester, the current and characteristic V-I of the surge arrester are needed, which are usually obtained from laboratory tests.
At the same time, our research team intends to present as a new research work the electrical aging and At the same time, our research team intends to present as a new work the electrical aging and the network outage rate caused by it under pollution conditions in the form of mathematical relations and laboratory tests, which is also mentioned in the conclusion section and highlighted in yellow.
Reviewer 2 Report
This is an interesting paper on a traditional problem of high voltage engineering.
The contribution of the authors is not clear to the reviewer. Some aspects on the core of this work are not clear to the reader and superficially covered by the original document.
Please consider the following comments on the revised manuscript.
- - There is similarity to the following paper:
[R1] “A More Uniform Electric Field Distribution on Surge Arresters through the Optimal Design of Spacer and Fiber Glass Layer” by M.R. Aghaebrahimi et al.
This paper must be included in the reference list; the contribution of the present work with respect to [R1] shall be highlighted.
- This work is relevant to gapless surge arresters; do the authors believe that this research is relevant to externally gapped surge arresters? If no, amend the title. If yes, clarify.
- - Provide an introductory section to the problem of non-uniform distribution of the operating voltage across high-voltage surge arresters. Explain the problem, the fundamental mathematical formulation with appropriate refence to relevant CIGRE Technical Brochures.
[R2] CIGRE Working Group A3. 25, “MO Surge Arresters – Metal Oxide Resistors and Surge Arresters for Emerging System Conditions,” August 2017.
- This work relevant to HVAC systems; do the authors believe that this research is relevant to HVDC systems? If no, amend the title. If yes, clarify.
- Introduction writes “if arresters are not designed properly, they will be burned”. This is not true. This is a mature technology and varistors are isolated in case of overload by internal or external disconnectors [R2], [R3]. Please amend accordingly this statement.
[R3] CIGRE WG C4.30,Use of Surge Arresters for Lightning Protection of Transmission Lines, 2010.
[R4] Z. Topcagic and T. E. Tsovilis, “Varistor Electrical Properties: Microstructural Effects,” Encyclopedia of Materials: Technical Ceramics Glasses, Ed. M. Pomeroy, Elsevier, vol. 3, pp. 254-271, Mar. 2021.
- - You declare in section 2.2 air-breakdown at 2.4 kV/mm and in section 4.1 ZnO εr 150. Why did you select these values? Provide references to justify this selection. Which is the effect of these values on your results? For example according to [R5], apparent relative perimitivity could be up to 1000 – how do your results will change for this value?
[R5] F. Greuter, ZnO varistors: From grain boundaries to power applications, in book “Oxide Electronics,” Ed. A. Ray, Chapter 8, 2021.
- - This work claims contribution to the degradation of surge arresters. Do you refer to partial discharge activity suppression? Do you refer to diminishing of the leakages current? If you refer to leakage current – do you mean the current conduction via ZnO varistors or the current conduction on the surface of the surge arrester? Which is the definition of the leakage current path shown in Fig. 8?
Author Response
We would like to thank the editor and reviewers for their valuable comments and suggestions that helped us to improve the manuscript. We have tried to address all the editor and reviewers’ concerns in the best manner. The modifications on the paper are marked-up in yellow so that they are easy to locate. We hope that following answers are satisfactory.
Detailed responses and discussions are provided as follows.
Reviewer #2
Comment 1. There is similarity to the following paper:
[R1] “A More Uniform Electric Field Distribution on Surge Arresters through the Optimal Design of Spacer and Fiber Glass Layer” by M.R. Aghaebrahimi et al.
This paper must be included in the reference list; the contribution of the present work with respect to [R1] shall be highlighted.
Answer:
In article “A More Uniform Electric Field Distribution on Surge Arresters through the Optimal Design of Spacer and Fiber Glass Layer”, the effect of the dimensions of ZnO tablets on field distribution has been investigated in a simple way, therefore, by changing the dimensions of ZnO tablets, the electrical characteristics of the arrester, including the V-I curve and the ZnO varistor, have changed. Therefore, the studied arrester can no longer be used at the specified voltage level.
While in the new article under your review, various parts of the surge arrester, including the dimensions of the fiberglass layer and the positive and negative spacers, are optimized so as not to affect the electrical characteristics of the surge arrester. Also, a detailed and complete investigation of the factors affecting the distribution of the field on the ZnO column and the external shield of the surge arrester has been done.
Extensive studies have been done on the gradient ring in high voltage insulators, and in this article, as a new work, its precise placement in surge arresters has been studied, which has a significant effect on the distribution of the electric field along the arrester. It should be noted that the appearance design of the gradient ring is a priority of our research team as a future research topic, which will be presented soon.
As a summary, it can be mentioned that manuscript “A More Uniform Electric Field Distribution on Surge Arresters through the Optimal Design of Spacer and Fiber Glass Layer” is only the initial model of this simulation, while the manuscript under review has fully examined the parameters that are effective in the distribution of the field. In such a way, after the optimal design, an electrocution with a higher lifespan can be provided. Therefore, these two manuscripts are similar only in the COMSOL simulation model of surge arrester.
Finally, according to your request, the paper [R1] has been added as a new reference in the introduction section, which is highlighted in yellow.
[Ref.1] M. R. Aghaebrahimi, Reza Shariatinasab, M. Ghayedi and Rozita Gholami, "A More Uniform Electric Field Distribution on Surge Arresters through the Optimal Design of Spacer and Fiber Glass Layer," Research Journal of Applied Sciences, Engineering and Technology vol. 5, 13, p. 7, 15 April 2013, doi: 10.19026/rjaset.5.4496.
Comment 2. This work is relevant to gapless surge arresters; do the authors believe that this research is relevant to externally gapped surge arresters? If no, amend the title. If yes, clarify.
Answer:
No, this research is relevant to gapless surge arresters. Therefore, the title of the manuscript is modified to “Electric Field Distribution on ZnO Pills in gapless Surge Arrester Using FEM and Evolutionary Optimization Algorithms in HVAC systems” (highlighted in yellow).
Comment 3. Provide an introductory section to the problem of non-uniform distribution of the operating voltage across high-voltage surge arresters. Explain the problem, the fundamental mathematical formulation with appropriate refence to relevant CIGRE Technical Brochures.
Answer:
The reasons for the non-uniformity of the field along the high-voltage arresters were presented, which are highlighted in yellow in the introduction. But due to the fact that it is not customary to refer to mathematical relationships in the introduction, we also avoided mentioning mathematical formulas.
"Due to the height of high voltage MOAs and the resulting stray capacitances, it is obvious, that the voltage distribution along a MOAs are not uniform. This means, the upper MO-blocks are more stressed than the lower MO-blocks. Additionally, there are permanent superimposed alternating voltages which have a higher frequency than the grid frequency. Both effects, higher voltages and higher frequencies, lead to superior stress for the MO-blocks because of the increased power dissipation. On the other, in this type of arresters, the pills located at the bottom and the top of the resistor column are subject to more wear and early aging, because of the way they are located in the network and because of the concentration of electric field on them[Ref.2, Ref.2]
Therefore, in order to uniform distribution of the electric field along the arrester, the geometric shape of different parts of the ZnO surge arrester, including the, spacers, fiber glass layer, grading ring and etc., can have a significant effect for this purpose [Ref.1]. "
[Ref.2] ELT_294_2 , "MO surge arresters - Metal oxide resistors and surge arresters for emerging system conditions", ELECTRA, 2017.
[Ref.3] Hippler, C, Leu, C, ANALYSIS OF POWER DISSIPATION BY VARIATION OF FREQUENCY ON HIGH VOLTAGE MET-AL-OXIDE ARRESTER BLOCK, ISH Collection, ISH2015_583, 2015.
Comment 4. This work relevant to HVAC systems; do the authors believe that this research is relevant to HVDC systems? If no, amend the title. If yes, clarify.
Answer:
No, this research is relevant to HVAC systems. Therefore, the title of the manuscript is modified to “Electric Field Distribution on ZnO Pills in gapless Surge Arrester Using FEM and Evolutionary Optimization Algorithms in HVAC systems” (highlighted in yellow).
Comment 5. Introduction writes “if arresters are not designed properly, they will be burned”. This is not true. This is a mature technology and varistors are isolaed in case of overload by internal or external disconnectors [R2], [R3]. Please amend accordingly this statement.
[R3] CIGRE WG C4.30,Use of Surge Arresters for Lightning Protection of Transmission Lines, 2010.
[R4] Z. Topcagic and T. E. Tsovilis, “Varistor Electrical Properties: Microstructural Effects,” Encyclopedia of Materials: Technical Ceramics Glasses, Ed. M. Pomeroy, Elsevier, vol. 3, pp. 254-271, Mar. 2021.
Answer:
You are absolutely right, I meant that if they are not designed properly, they will go out of the circuit. So I replace the following sentence (highlighted in yellow in Introduction section):
If the arresters are not designed correctly, in case of overload on the varistors, they will be isolated by internal or external circuit breakers and the arrester will be removed from the circuit [Ref.4, Ref.5].
[Ref.4] [Ref.4] C. W. G. C. 301, "Use of surge arresters for lightning protection of transmission lines," ed: Technical Brochure 440, CIGRE, Paris, France, 2010.
[Ref.5] Z. Topcagic and T. E. Tsovilis, “Varistor Electrical Properties: Microstructural Effects,” Encyclopedia of Materials: Technical Ceramics Glasses, Ed. M. Pomeroy, Elsevier, vol. 3, pp. 254-271, Mar. 2021.
Comment 6. You declare in section 2.2 air-breakdown at 2.4 kV/mm and in section 4.1 ZnO εr 150. Why did you select these values? Provide references to justify this selection. Which is the effect of these values on your results? For example according to [R5], apparent relative perimitivity could be up to 1000 – how do your results will change for this value?
[R5] F. Greuter, ZnO varistors: From grain boundaries to power applications, in book “Oxide Electronics,” Ed. A. Ray, Chapter 8, 2021.
Answer:
In any geometrical condition, both near the MO arrester (solid dielectric) and standard geometric (plate capacitor), the breakdown voltage is same because both are in the air insulation. Except that the changes of electric field is nonlinear in near the surge arrester specially in near arrester sheds and the air strength fulfill in shorter distance. In other word, the strength per length is same in both conditions (2.4~3 kV/mm). But according variance atmospheric conditions, the magnitude of air strength is different and in order to compare with other papers and to simplify model we try to make simulation in standard conditions in this paper, which value is selected based on references [Ref.6 and Ref.7].
Also, the dielectric coefficient of zinc oxide is defined in a wide range which can be variable even above 2000 based on voltage, temperature and type of metal oxide used [Ref.8 and Ref.9]. On the other hand, according to reference 1, with the increase of the dielectric constant of the ZnO, the electric field decreases, but in this manuscript, due to the large dielectric value of ZnO and the applied voltage, the changes in the Maximum electric field were not noticeable and can be ignored. In addition, the dielectric constant of ZnO used in the manuscript is based on reference [Ref.10], which is mentioned in Table 1.
[Ref.6] A. Srikant and S. C. Pradhan, "Simulation of air breakdown mechanism using different electrodes," 2011.
[Ref.7] M. Valavala, "MEASUREMENT OF AIR BREAKDOWN VOLTAGE USING STANDAD SPHERE GAP METHOD," Journal of Electrical Engineering, vol. 13, pp. 6-6, 2013.
[Ref.8] H. A. Illias, S. Abd Halim, A. H. Abu Bakar, and H. Mokhlis, "Determination of surge arrester discharge energy using finite element analysis method," IET Science, Measurement & Technology, vol. 9, pp. 693-701, 2015.
[Ref.10] B. Vahidi, R. S. Nasab, J. S. Moghani, S. Kashi, and S. Hosseinian, "Three dimensional analyses of electric field and voltage distribution on ZnO surge arrester with broken sheds," in 2005 IEEE/PES Transmission & Distribution Conference & Exposition: Asia and Pacific, 2005, pp. 1-2.
Comment 7. This work claims contribution to the degradation of surge arresters. Do you refer to partial discharge activity suppression? Do you refer to diminishing of the leakages current? If you refer to leakage current – do you mean the current conduction via ZnO varistors or the current conduction on the surface of the surge arrester? Which is the definition of the leakage current path shown in Fig. 8?
Answer:
Partial discharge and leakage current are not mentioned in this article. Therefore, the destruction takes place only by using the non-uniform distribution of the field and electric stresses that enter the ZnO tablets at the beginning and end of the surge arrester. Also, the leak path in Figure 8 refers to the creepage distance of surge arrester shields, which was modified.
Reviewer 3 Report
The manuscript needs to be improved, clarification and completions are necessary.
If possible, you should avoid using abbreviations in the title.
The introduction does not provide an adequate overview of previous research on the topic. The authors should introduce short sentences to explain the relevance of the cited papers with respect to the context in which they are cited.
Values must be accompanied by measure units (Ec.1; Ec.2 ; Table 3; Table 4; Figures 4-6).
The meaning of each symbol in the provided equation needs to be explained the first time it is used.
The mathematical model used is presented quite poor. The methodology should be presented with sufficient information and input data to allow replication of the research.
Author Response
We would like to thank the editor and reviewers for their valuable comments and suggestions that helped us to improve the manuscript. We have tried to address all the editor and reviewers’ concerns in the best manner. The modifications on the paper are marked-up in yellow so that they are easy to locate. We hope that following answers are satisfactory.
Detailed responses and discussions are provided as follows.
Reviewer #3
The manuscript needs to be improved, clarification and completions are necessary.
Comment 1. If possible, you should avoid using abbreviations in the title.
Answer:
The title is modified.
Comment 2. The introduction does not provide an adequate overview of previous research on the topic. The authors should introduce short sentences to explain the relevance of the cited papers with respect to the context in which they are cited.
Answer:
The introduction section is modified.
Comment 3. Values must be accompanied by measure units (Ec.1; Ec.2 ; Table 3; Table 4; Figures 4-6).
Answer:
All requested items are either unitless due to a constant quantity like (NP, F, CR, C1, C2, iteration, and …) or the ratio of two field values (Objective function value), so it does not change.
Comment 4. The meaning of each symbol in the provided equation needs to be explained the first time it is used.
Answer:
The each symbol is explained in section 2.2, highlighted in yellow.
Comment 5. The mathematical model used is presented quite poor. The methodology should be presented with sufficient information and input data to allow replication of the research.
Answer:
We explained the proposed model along with the governing equations in more detail and added three sections to the paper in Section 3, including electric field calculation via finite element method, DE algorithm and PSO algorithm, highlighted in yellow.
Round 2
Reviewer 2 Report
ok - it is improved.
Reviewer 3 Report
The authors improved the presentation of their manuscript.
