Stability and Distributed Optimization for AC Microgrid Considering Line Losses and Time Delay

Round 1

Reviewer 1 Report (Previous Reviewer 2)

1. Why is the active power mismatch, shown in Figure 6(a), incresing with increase in active power outputs of DGs as well as with the increase in the incremental cost (lambda)? This is NOT Correct.

2. Similiarly, the active power mismatch should be practically close to 0, while in Figure 6(a), it reaches upto even 600 W. This means that the active load demand has not been completely fulfilled. This is in turn means, that the Economic Load Dispatch has not been strategy properly designed.

3. The author claim that, "In Case 4, the fourth DG joins at t = 5s". But surprisingly the power output of DG 4 is not zero during t=1-to-5 s, which is WRONG. Likewise, "the fourth DG exists at t = 15s", but again surprisingly the power output of DG4 is not zero beyond t=15s. These matters are very much SUSPICIOUS.

Moreover, when a DG is out of service, its incremental cost must go to zero, but it is NOT HAPPENING. Why?

4. When a DG is out of service, why is it still contributing towards the Total Cost as depicted in Figure 6(b)? This is NOT CORRECT.

Author Response

Dear Editor and Reviewers:

Thank you for comments concerning our manuscript entitled “Stability and Distributed Optimization for AC microgrid Considering Line Losses and Time Delay”. All those comments are valuable and very helpful for revising and improving the quality and presentation of our paper. All of their comments have been taken into account and the paper has been revised accordingly (revised portions in revised manuscript have been marked in green color). We sincerely hope the paper in its present form will be acceptable for publication. Our specific reply to the specific comment is in the attachment. 

Please see the attachment. 

With best wishes.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 1)

The responses to my previous comments are satisfactory except the missing flowchart/pseudocode. 

 

 

Author Response

We have added the flowchart of the proposed method in Fig.2 (b). 

Reviewer 3 Report (Previous Reviewer 3)

The manuscript is acceptable in its present form as the author improved the manuscript significantly. 

 

Author Response

Thanks for your comments. They greatly improve the quality of the manuscript. 

Reviewer 4 Report (Previous Reviewer 4)

Great improvements. Authors have addressed the concerns very well and I recommend this manuscript for the next stage of acceptance.

Author Response

Thanks for your comments. They greatly improve the quality of the manuscript. 

Round 2

Reviewer 1 Report (Previous Reviewer 2)

I have no more questions to ask.

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

The article "Stability and Distributed Optimization for AC microgrid Considering Line Losses and Time Delay" is very interesting and explains a very necessary topic. In general, it is a good article. However, I have the following minor suggestions.

1.  Various topologies (centralized, decentralized, and distributed) are in discussion and in practice for a long time. The content in the introduction seems very brief overview of the extensively available information about this. However, it lags behind an overview of the modern methods that address specific issues of loss minimization (the key goal of this work). Similarly, the optimal output from the DGs has been discussed in numerous articles using many new and efficient methods. On this ground, I would suggest the authors please work on these sides in your introduction section. The following articles may be explored for such goals. 

- https://doi.org/10.1109/ICIT.2016.7474797

- https://doi.org/10.3390/su14105757

- https://doi.org/10.3390/en14061744

- https://doi.org/10.5755/j02.eie.28917

- https://doi.org/10.3390/app112411840

- https://doi.org/10.1109/ICOMET.2019.8673418

2. The advantages mentioned in lines 145 - 148 seem contradictory because at once it is said that the method does not need any communication but to realize optimal dispatch and frequency recovery "if the communication is normal". Please explain in the article.

3. It seems that in figure 1. it should be V_L*e^(j*theta_L).

4. Does dp_load/dp_i=0 mean that the variation in load is zero? If yes, can this be treated as the practical scenario in microgrids where the load can be constantly varying? Please explain.

5. I would suggest to please include some pseudocode and/or flowchart of your method mentioning the relevant equation numbers at various steps/blocks so that the readers can follow the work better.

6. Referring back to point 2 above, the cases considered for simulation do not contain any communication failure. How can the claims in the contributions and advantages mentioned in the article be verified?

7. Please review the figures (2 - 5). The time axis should be Time (s) instead of Time/s, y-axis labels are missing, and follow inconsistent styling. It should be case 3 for Figure 4(a).

8. Despite the fact that the frequency is within permissible limits but is deteriorating with time in case 3, which is not the case in cases 1 and 2. What can be the reasons? How can it be said that the frequency will not deteriorate further if the variations at 5, 10 and 15 seconds are bigger and continue after 20s time?

9. The explanation for the results is very limited. Please elaborate on the results with discussion.

10. Conclusion section should highlight the key achievements of this article. Currently, it is very short.

11. English proofreading and styling are needed.

Thanks

Reviewer 2 Report

1. The article doesn't report any plug-and-play cability for DGs. Does the proposed strategy supports the plug-and-play feature of DGs? If yes, include supporting results. 

2. The article doesn't report any microgrid testbed specifications, that is, specification of filters, transmission lines, capacities of DGs etc. This makes thing very suspicious to me. So, the authors must describe the complete specifications of the test microgrid.

3. The authors have ignored the impact of parametric uncertainties on the performance of the proposed method. So, the impact of parametric uncertainties must be considered while evaluating the performance of the proposed method.

4. Plot the active power mismatches in each case (i.e., the difference between the total power demanded and the total power dispatched). 

5. Plot the total cost of generation for each case.

6. The econmic or optimal dispatch, using the distributed cooperative control strategies, has already been reported in few recent articles, such as: https://doi.org/10.3390/en14248408 and https://doi.org/10.1109/ACCESS.2022.3183635. Compare your proposed method with the stated methods and describe your noventies/improvements.  

7. The literature review in the introduction section is not quite strong enough. The authors are advised to have an in-depth review of more articles. For example have a look at the following articles: https://doi.org/10.1109/TSTE.2019.2946740, https://doi.org/10.3390/en14102936, and https://doi.org/10.1109/TII.2017.2749424 

Reviewer 3 Report

Lack of comparative analysis.

Objective functions and main applications are not clear.

Main contribution and novelty not highlighted.

Writing and figure quality could have been much better.

Literature review must have been better in pointing out the main drawbacks. Some related papers have been suggested to follow:

[1]          M. F. Ishraque et al., "Optimal sizing and assessment of a renewable rich standalone hybrid microgrid considering conventional dispatch methodologies," Sustainability, vol. 13, no. 22, p. 12734, 2021.

[2]          M. M. Rana et al., "A Comparative Analysis of Peak Load Shaving Strategies for Isolated Microgrid Using Actual Data," Energies, vol. 15, no. 1, p. 330, 2022.

[3]          S. Shezan et al., "Technological Analysis of a Solar-Wind-Battery-Diesel Hybrid Energy System with Fuzzy Logic Controller," International Journal of Research in Engineering and Science (IJRES), vol. 4, no. 4, pp. 46-57, 2016.

 

[4]          S. Shezan and C. Y. Lai, "Optimization of hybrid wind-diesel-battery energy system for remote areas of Malaysia," in 2017 Australasian Universities Power Engineering Conference (AUPEC), 2017: IEEE, pp. 1-6.

 

 

Reviewer 4 Report

The similarity index in the introduction section is very high which is not a good practice. 

 

Related work section should be added as a separate section where authors must cover the shortcomings because shortcoming or challenges in previous work is not mentioned. If the previous work is free of challenges and there is no issue then what motivated the authors to propose this study? It inculcates that authors should revise the literature review and critically highlight the problems in the previous study and compare the proposed solution and tells how the proposed solution is best fitted. 

 

What is the outcome of Ve shown in "Figure 1. The equivalent topology of the microgrid with n DGs and one load."?

 

In Eq37, if M2 becomes independent what impact on output can be seen?

 

A critical analysis of the finding, which is the most important part, is missing. This would help the readers to further improve the study.

 

Go for a thorough proofread of the paper to rectify several existing typos and grammatical mistakes to improve the written quality of the paper. If necessary take the help of a native English speaker to improve the language of the paper.

 

While reviewing the references, I observed that cited references are outdated whereas more work already has been done in the proposed study. The cited references are neither sufficient nor suitable and therefore must extend the list and focus only on the papers from the recent 3 years. The following references may be added to supersede the outdated ones for the authors' convenience.

https://doi.org/10.26634/jwcn.8.3.17310