Impact of Electric Vehicles on Energy Efficiency with Energy Boosters in Coordination for Sustainable Energy in Smart Cities
Round 1
Reviewer 1 Report
The article has a good approach and a logical sequence that is favorable for reading, but some points still deserve attention:
1- The objective must be clear in the abstract.
2- Include the main contributions and/or conclusions of the article in the abstract.
3- The authors do a good job in the introduction, indicating several previous studies, however it would be interesting to put the practical contributions of this article.
4- At the end of the introduction, indicate the structure of the article.
5- Why was the Harmony Search Algorithm used?
6- There are only a few arrows in Fig 2, it would be interesting to place the arrows on the other lines clearly indicating the flow.
7- Fig 3 is illegible.
8- Indicate the limitations of the research and indications for future research at the end of the conclusion.
Author Response
Response to the reviewer’s comments
REVIEWER-1: The article has a good approach and a logical sequence that is favourable for reading, but some points still deserve attention:
Response: Authors are thankful to the renowned reviewer for his/her appreciation and valuable observation.
Comment-1: The objective must be clear in the abstract.
Response: Thank you for the suggestion. In the revised version of the manuscript, the abstract has been revised.
Comment-2: Include the main contributions and/or conclusions of the article in the abstract.
Response: The abstract has been revised thoroughly.
Comment-3: The authors do a good job in the introduction, indicating several previous studies; however, it would be interesting to put the practical contributions of this article.
Response: In response to the practical contribution of the article, here, the authors would like to convey that in the proposed approach, a 33-node radial distribution system is considered. In this network, along with one substation at node 1, there are 32 load points, 4 EV stations and 3DGs. In this scenario, developing a practical model is costly and infeasible. Therefore, for such a network, we can perform simulations on developing mathematical models in different software like Simulink, MATLAB etc...
However, in practice, the network performance needs to be evaluated based on several parameters under different operating constraints, and the proposed approach is a multi-objective formulation where,
- Improvement in loadability allows the maximum number of customers to be connected at a particular node.
- Improvement in voltage profile allows operating the power devices near to their nominal voltage, which reduces the current drawn by them, e.g. Induction motor draws more current at reduced voltage.
- Margin of Reliability is the measure of the reliability of supplying power to the consumer with fewer interruptions and for less duration.
- The reduction in power loss improves the overall system performance.
Also, a detailed explanation of the EEP parameter is given in table 1 in the manuscript.
Comment-4: At the end of the introduction, indicate the structure of the article.
Response: As per the suggestion, the structure of the article is now added to the revised version.
Comment-5: Why was the Harmony Search Algorithm used?
Response: The critical feature of HSA is that it can independently consider each component variable in a single solution vector while it generates a new vector. With this feature, the convergence rate of the HS algorithm can be accelerated by imposing constraints in the process of harmony improvisation (i.e. pitch adjustment, memory consideration and random selection) for selecting a new decision variable. In HSA, discrete and continuous variables are managed together.
In addition, HSA includes the structure of several heuristic approaches. Similar to Tabu Search, it preserves the history of past vectors, and like Simulated Annealing, it can vary the adaptation rate from the beginning to the end of the computation. It can manage several vectors together like GA. However, in HSA, a new vector is generated from all the existing vectors, while GA makes the new vector only from two existing vectors (i.e. parents). In HSA, the representation of the decision variable in a single solution vector, while generating a new vector, makes it a multi-purpose algorithm which can be customized on case bases, whereas in GA, it is not possible since it has to maintain the structure of a gene [2, 3, 35-38].
Comment-6: There are only a few arrows in Fig 2; it would be interesting to place the arrows on the other lines clearly indicating the flow.
Response: As per the suggestion, figure 2 is redrawn.
Comment-7: Fig 3 is illegible.
Response: Figure 3 is redrawn for clarity.
Comment-8: Indicate the limitations of the research and indications for future research at the end of the conclusion.
Response: As per the suggestion, the limitations and the directions for future research are mentioned at the end of the conclusions
Author Response File: 
Author Response.docx
Reviewer 2 Report
The full text is fluent in language and rich in content，however, there are some problems that need to be adjusted and improved.
1. In the Test results and discussions section, the result data of each case is very rich and complete, but it is necessary to point out which key data is in the article, analyze and integrate these data in detail, and then draw corresponding conclusions. Compared with listing data and conclusions, it lacks the process of extracting, analyzing and integrating data, and does not emphasize key data.
2. The introduction of the process and algorithm steps in the Proposed algorithm and flowchart is very specific, but it lacks a summary of the core content and innovations of the entire algorithm.
Author Response
REVIEWER-2: The full text is fluent in language and rich in content, however, there are some problems that need to be adjusted and improved.
Response: Authors are thankful to the learned reviewer for his/her appreciation and valuable comments.
Comment-1: In the test results and discussions section, the result data of each case is very rich and complete, but it is necessary to point out which key data is in the article, analyze and integrate these data in detail, and then draw corresponding conclusions. Compared with listing data and conclusions, it lacks the process of extracting, analyzing and integrating data and does not emphasize key data.
Response: Authors are thankful to the learned reviewer for the appreciation. In this work, five different cases are considered for energy-efficient power distribution system operation; therefore, the results for all five cases have their significant contribution under different operating conditions.
Several parameters, including voltage profile, ladability, supply reliability, and power losses, have been considered for energy efficiency in power delivery. In the revised manuscript version, the results discussion has been thoroughly revised, as per the suggestion, and section 6.6 (new) is introduced in the last.
Comment-3: The introduction of the process and algorithm steps in the Proposed algorithm and flowchart is very specific, but it lacks a summary of the core content and innovations of the entire algorithm.
Response: With due regard, in response to this critical observation, the authors would like to convey that algorithm describes the generalized steps for network reconfiguration and identification of DG location and EV stations under different operating conditions. Therefore, the innovation in the proposed approach is derived once we have the results for the network under consideration. The algorithm, in this case, involves the constraints under which energy-efficient operation of the radial network is obtained during the identification of DG allocation along with the EV station. Therefore, to avoid duplicity of the text, the algorithm presents the generalized steps only.
Author Response File: Author Response.docx
Reviewer 3 Report
Dear Authors,
thank you very much for the opportunity to review your research paper. The discussed topic is extremely important due to, inter alia, the development of metropolitan organisms (smart or smart cities), which inevitably involves the reduction of harmful substances emitted into the atmosphere and thus the growing trend of electrification of the vehicle fleet in these cities.
However, I would have a few comments for your work, the implementation of which I would personally consider:
- the abstract is factual and concise, however, it lacked (and for the potential reader) information regarding the link between the subject of the work with the title of the article - I would advise you to encourage the reader by adding a short information on embedding the work in the subject of sustainable development and smart cities (as the title states);
- similarly, in the extended "introduction" section, I would advise to add a paragraph devoted to sustainable development and smart cities in order to further emphasize the relevance and topicality of the issues raised (preferably before initiating the concepts of EEP, PEBs / AEBs or ESS). The current advancement of the concepts regarding SD / smart cities does not match the title of the work and is not sufficiently grounded in the literature. You can consider changing the title, focusing more on aspects related to electricity / energy processes, however, I advise you to develop the context of this work more based on SD / smart cities, because a more multidisciplinary approach in this case may expand the group of potential recipients of this work;
- I am glad that the literature setting (epistemological) regarding technical aspects (electrical and energy) is good enough - it deserves praise and motivates the selection of methodology in the practical part of the work;
- I also have no objections to the part related to mathematical formulas (load models and patterns, analysis of energy efficiency, etc.);
- I have a minor objection to the "harmony search algorithm" section - although the methodology has been described correctly, however, I missed a larger development here on the wide application of this metaheuristics - for this purpose, I encourage you to read the articles available at these addresses: https://doi.org/10.1155/2021/5594267 and https://doi.org/10.1109/ACCESS.2019.2893662 (these are systematic reviews on HSA) and, above all, quoting the article presenting this metaheuristics: https://doi.org/10.1177/003754970107600201
- the algorithm you proposed was very skillfully presented;
- I also have no objections to chapter 5 (but please improve the resolution of Figure 3, which is currently low) - however, I suggest adding a summary sentence both under Figure 3 and under Table 5 to briefly present the essence of these segments (in the case of the summary sentence under Table 5, I suggest using the phrase that the sentences commenting on these results are presented in sections 6.1 - 6.5);
- personally, I think that the discussion itself is too little extensive, because the largest part of chapter 6 is the description of the results of case studies - I believe that the discussion should be further developed and a separate "full" chapter should be devoted to it (i.e. chapter 7, while the summary chapter should be marked number 8);
- the summary does not contain limitations, practical implications or directions for further research - such paragraphs should be found here, which would constitute an open end to this article and would give room for development on this topic for stakeholders from public sectors (such as city authorities or public network managers) energy) and private (such as charging station operators);
- please adjust the style of citation (bibliography) to the requirements set by the journal - currently they do not meet them.
Summing up, I think the article is interesting and very well developed. The methodology used in the research is correct, and the results can be a field for the development of this topic. I believe that after taking into account the comments raised by me, the article is suitable for publication. Thank you for your cooperation.
Author Response
REVIEWER-3: Thank you very much for the opportunity to review your research paper. The discussed topic is extremely important due to, inter alia, the development of metropolitan organisms (smart or smart cities), which inevitably involves the reduction of harmful substances emitted into the atmosphere and thus the growing trend of electrification of the vehicle fleet in these cities.
Response: Authors are very thankful to the renowned reviewer for the appreciation and praise.
Comment-1: However, I would have a few comments for your work, the implementation of which I would personally consider:
- the abstract is factual and concise; however, it lacked (and for the potential reader) information regarding the link between the subject of the work with the title of the article - I would advise you to encourage the reader by adding a short information on embedding the work in the subject of sustainable development and smart cities (as the title states);
Response: As per the suggestions, the abstract has been revised thoroughly.
Comment-2: Similarly, in the extended "introduction" section, I would advise to add a paragraph devoted to sustainable development and smart cities in order to further emphasize the relevance and topicality of the issues raised (preferably before initiating the concepts of EEP, PEBs / AEBs or ESS). The current advancement of the concepts regarding SD / smart cities does not match the title of the work and is not sufficiently grounded in the literature. You can consider changing the title, focusing more on aspects related to electricity / energy processes, however, I advise you to develop the context of this work more based on SD / smart cities, because a more multidisciplinary approach in this case may expand the group of potential recipients of this work;
Response: Thank you for the valuable comments and observations. As suggested, a new paragraph explaining the smart energy system and its significance in the proposed work is added.
Comment-3: I am glad that the literature setting (epistemological) regarding technical aspects (electrical and energy) is good enough - it deserves praise and motivates the selection of methodology in the practical part of the work;
- I also have no objections to the part related to mathematical formulas (load models and patterns, analysis of energy efficiency, etc.);
Response: Thank you for your appreciation and praise.
Comment-4: I have a minor objection to the "harmony search algorithm" section - although the methodology has been described correctly; however, I missed a larger development here on the wide application of this metaheuristics - for this purpose, I encourage you to read the articles available at these addresses: https://doi.org/10.1155/2021/5594267 and https://doi.org/10.1109/ACCESS.2019.2893662 (these are systematic reviews on HSA) and, above all, quoting the article presenting these metaheuristics: https://doi.org/10.1177/003754970107600201.
Response: In response to this critical observation, the authors would like to submit here that the efficiency of the heuristic and/or meta-heuristic approaches are judged based on their computation time. Instead, it depends on multiple factors such as the operator’s experience, objective function and the imposed constraints. The fact is that the above is true for any heuristic and/or meta-heuristic method. This is because operating strategies depend upon the operating constraints. It further depends upon the type of load, like Residential, Commercial and Industrial, and the new load, such as EVs. Hence, in this paper, several parameters are considered, and the results are found to improve as compared to the existing approach under the same operating conditions.
Therefore, the testing of the algorithm is not in the scope of this work, and it is believed that the results of different algorithms will be the same, and the only difference may occur in the computational times, which in this case has no significance.
Also, the harmony search algorithm has been extensively explored by the researchers in the literature and the authors in their previous articles [2] [3]. However, the authors are thankful to the renowned reviewer for their valuable concern. The reviewer’s concern is well received, and the suggestion will be considered for future reference.
Comment-5: The algorithm you proposed was very skillfully presented;
- I also have no objections to chapter 5 (but please improve the resolution of Figure 3, which is currently low) - however, I suggest adding a summary sentence both under Figure 3 and under Table 5 to briefly present the essence of these segments (in the case of the summary sentence under Table 5, I suggest using the phrase that the sentences commenting on these results are presented in sections 6.1 - 6.5);
Response: In section 5, the text has been revised in the manuscript, as per the suggestions.
Comment-6: Personally, I think that the discussion itself is too little extensive, because the largest part of chapter 6 is the description of the results of case studies - I believe that the discussion should be further developed and a separate "full" chapter should be devoted to it (i.e. chapter 7, while the summary chapter should be marked number 8);
Response: As per the suggestion, a new section no 6.6 is added to summerize the results of case studies.
Comment-7: The summary does not contain limitations, practical implications or directions for further research - such paragraphs should be found here, which would constitute an open end to this article and would give room for development on this topic for stakeholders from public sectors (such as city authorities or public network managers) energy) and private (such as charging station operators);
Response: The future work of the proposed approach is now described in revised version (chapter 7) under conclusions.
Comment-8: Please adjust the style of citation (bibliography) to the requirements set by the journal - currently they do not meet them.
Response: The reference section has been improved as per the suggestions.
Comment-9: Summing up, I think the article is interesting and very well developed. The methodology used in the research is correct, and the results can be a field for the development of this topic. I believe that after taking into account the comments raised by me, the article is suitable for publication. Thank you for your cooperation.
Response: Authors believe that the comments raised by the learned reviewer reflect a deep understanding of the proposed approach. Therefore, the authors are very thankful to the learned reviewer, as the valuable comments he raised to bridge the gap between the present form of the manuscript and the scope of improving it. Also, as per the suggestions, the authors tried to improve the manuscript up to the level of the learned reviewer’s expectations.
Again, the authors thank the reviewers for devoting precious time to improving the manuscript by raising their valuable comments.
Author Response File: Author Response.docx
Reviewer 4 Report
Summary: The paper presents an extensive mathematical background to support an original approach to determine the EEP of an electric system under various hypothetical scenarios. The results section, details the values obtained under these scenarios with high accuracy. Still the conclusions seem to be far too general.
General comments: The load scenarios have no specific correlation to real-life load conditions. At least some specific computations on a certain smart city (e.g. some city from India, Croatia) would have been nice to have in order to support the theoretical scenarios.
In the same tone, a set of controls are not provided to confirm the soundness of the specific test cases that were considered throughout the paper.
I'm also in an measure to say that I cannot reproduce the obtained results based on the amount of information detailed in the paper. So from this perspective it is difficult if not impossible for a peer to test the results in his/her own environment.
Author Response
Reviewer- 4: Response to the comments
Comment-1: Summary: The paper presents an extensive mathematical background to support an original approach to determine the EEP of an electric system under various hypothetical scenarios. The results section, details the values obtained under these scenarios with high accuracy. Still the conclusions seem to be far too general.
Response: Authors thank the renowned reviewer for their appreciation and valuable observation. The conclusion section has been revised in the manuscript.
Comment-2: General comments: The load scenarios have no specific correlation to real-life load conditions. At least some specific computations on a certain smart city (e.g. some city from India, Croatia) would have been nice to have in order to support the theoretical scenarios.
Response: In response to this critical observation, the authors would like to convey that the loads in practical scenario varies at random and follows no fixed pattern. The load demand and the type of load in the morning hours may not be the same in the evening hours. Therefore, an accurate loading pattern cannot be determined, matching the practical scenario. This requires developing a near-about scenario with different load combinations and their weightage in the mathematical formulations. Because of that, in this work, three different load models are presented and formulated with a random distribution function to show the loading pattern that can vary between a minimum and maximum values. The proposed load models are tested on a standard IEEE 33-node radial distribution system. The researcher has extensively studied this network, explaining the test results under the same operating conditions. In this work, out of different cases described in section 5 in Table 5, case 1 is similar to the existing approaches where test results are matched for original and reconfigured networks.
Therefore, the results are believed to be reliable and implementable to the practical system with little modification of the load modelling due to changes in voltage exponents and the contribution of different types of loads.
Comment-3: In the same tone, a set of controls are not provided to confirm the soundness of the specific test cases that were considered throughout the paper.
Response: In the proposed work, five different cases are considered to present the extensive review of energy efficiency performance of a distribution system where energy-efficient operation depends upon several parameters, and compromising one parameter over the other optimal operation can be achieved.
In addition, in the proposed work, integrating ESS with the existing system as a load or source can significantly affect the loading patterns. Therefore, EEP of the distribution network needs to be realized at the planning stage to identify the most economical, may not be optimal, location for EV stations. This aspect has been realized through four different cases (i.e. case 2 to 5) where EEP is evaluated with PEBs and AEBs while ESS works exclusively as a load or source. In these cases, the optimal location of DGs and the ESS differ. Here, some locations are found repeatedly across different LMs in case-4 and 5. From across four cases, the optimal location of ESS is identified, such as; node 18 for 1EV, nodes 2 and 19 for 2EVs, nodes 2, 19 and 23 for 3EVs, and nodes 2, 19, 23 and 30 for 4EVs when ESS works as a load. On the other hand, the optimal location of EV stations when ESS works as a source is node 32 for 1EV, nodes 18 and 32 for 2EVs, nodes 17, 18, 32 for 3EVs and nodes 17, 18, 30, and 32 for 4EVs. This has been explained in the revised manuscript under section 6.6 (new).
Considering the above, the network's performance is evaluated under a fixed loading scenario, as shown in Table 11. Also, the results are compared with the existing approach under the same operating conditions for the robustness of the proposed approach.
Comment-4: I'm also in an measure to say that I cannot reproduce the obtained results based on the amount of information detailed in the paper. So from this perspective it is difficult if not impossible for a peer to test the results in his/her own environment.
Response: Authors fully agree with the renowned reviewer that the test result cannot be reproduced, but this is because the loading pattern in this work is formulated in view of the practical scenario where loads are not of a similar type all the time. The load profile varies with the improvement in voltage profile and differently in different configurations and with DG allocations. The random variation in the loading pattern is modelled with a random distribution function where the load pattern changes with increased iterations in the load flow solution. However, the result obtained under LM-1 in table 1 can be reproduced because, in that case, the loading pattern is fixed, and the results are obtained in the absence of ESS throughout the load flow solution.
Author Response File: Author Response.docx
Reviewer 5 Report
n.a
Author Response
REVIEWER-5: Comments and Suggestions for Authors
n.a
Response: Authors are very thankful to the renowned reviewer for the appreciation and praise.
Thank you to the reviewer 5 since he has not any comments.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors did a great job of reviewing this article and followed this reviewer's suggestions, responding appropriately. Based on this, I consider that the article is ready to be published.
Reviewer 4 Report
No further comments
