Review of Power Control Methods for a Variable Average Power Load Model Designed for a Microgrid with Non-Controllable Renewable Energy Sources
Round 1
Reviewer 1 Report (Previous Reviewer 1)
All my previous comments have been properly addressed in the revised manuscript. Therefore, the latter can be accepted for publication in the Sustainability .
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report (Previous Reviewer 3)
The paper reviews average power control methods to control the excess power in a system using a variable average power load which was proposed in reference [1] by the authors.
1. Figure 1 is copied and pasted from reference [1]. Even though reference [1] is written by the same authors, it is required to at least cite the reference in the caption or create a new figure specific to this article. Moreover, why are both off-grid and grid-tied inverters connected to the grid through the battery in the figure?
2. Figure 6 does not add any value to the paper as it is not explained what exact scenario is displayed here. Please provide the details of this experiment.
3. How do the authors measure versatility? What is the exact definition? This should be clearly clarified.
4. Four methods are compared in Table 2, but the THD of only two of them are compared in Figure 7. Can you improve Figure 7 by adding the other methods' THD performance?
5. In section 2, please add subsections for each method for better clarity.
The authors have improved the quality of work compared to the last submission. However, there is till room for further improvement.
The authors use the term "renewables" to describe renewable-energy power plants. This can be clarified or improved in the paper.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report (New Reviewer)
The paper reviews power control methods for microgrids with non-controllable renewable energy sources. After reviewing the paper, here are some comments that should be considered to improve it:
1. The abstract is unclear. It should provide a clear overview of the research objectives and key findings.
2. The main goal of the paper in line 19-21 should be revised to align with the title of a review paper. For example: "The main goal of this study is to review power control methods for the VAPL device and provide guidance to researchers in selecting the most suitable method for controlling excess power." This will make it sound more like a review paper. The same applies to the Introduction section.
3. Section 2 should provide a brief description of the VAPL device, including its structure, operating principle, control function, and location within the microgrid. Please provide pseudocode of the solving algorithms and explain how they were used to solve the problem.
4. The same comments apply to the four control methods discussed in Section 2. Please provide a brief description of the structure, operating principle, and control function of each method.
5. Since this is a review paper, it would be helpful to create a table listing the references that utilize the control methods, along with the objectives and benefits of using each control method.
6. Are there any other control methods that haven't been mentioned in this paper? If so, please add them and explain why they weren't considered in depth.
7. Please explain why versatility, cost-efficiency, and non-filtering are the most important criteria used to compare these methods.
8. The information in Section 3 is very vague, and there isn't enough data to accurately compare the methods. To provide a more accurate comparison, it is important to perform a test model to check the parameters instead of solely citing information from other papers.
9. Due to the lack of clarity in Section 3, it's difficult for reviewers to evaluate the discussion and conclusion.
Please consider addressing these comments to enhance the clarity and quality of the paper.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report (Previous Reviewer 3)
My concerns have been addressed.
Authors improved the paper significantly. It is recommended that MDPI review and edit the paper in terms of reading comprehension, formatting, and consistency before publication.
Figure 6 is not properly introduced or discussed in the text.
All references should be formatted based on the template, consistently.
Author Response
Dear Reviewer,
Authors are thankful for the comments.
Authors have had a description of Figure 6 in the text, however, there were no directions to Figure 6, article modified according to the recommendation.
Authors have modified reference list according to the recommendation.
Reviewer 3 Report (New Reviewer)
The authors have revised the paper as per the majority of my comments. I do not have any further comments at this time.
Author Response
Dear Reviewer,
Authors are thankful for the received comments.
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 author proposed that when designing a microgrid system there are lots of various combinations to connect generating units and different brand inverters to a system, but all the system must be set up in a way it would work in balance. Example of not balanced microgrid system is given in an article with the main issue of a system being non-predictive excess power which causes frequency rise and faulty conditions in the system. Overall, the results are interesting and the manuscript is well organized. I would like to recommend publishing in Sustainability after some minor revisions.
1. Highlights can be improved.
2. I think the abstract should be rewritten and highlights the novelty.
3.The format of the article, especially the recently 3 years reference.
4. The introduction should be improved and tell the differences compared with others.
5. The authors may discuss New computational methodology development based upon artificial intelligence (AI) for the future materials and devices. Therefore, the introduction of recent progress of novel materials and novel devices may attract broader readership. For example: DOI: 10.3390/en16041599 and so on.
6. The figure and table caption should be more informative, and I suggest the author added more tables.
7.What’s the innvotion of this article? The author should explain.
8. Why the title is Variable Average Power Load Model Designed For Microgrid should explain, and I think the author should improve the title.
9. English should be improved.
10.In the experimental section, the analysis of the experimental curve is too brief, please conduct in-depth analysis.
In short, in its current form, the paper is not suitable for acceptance. The paper needs rewriting, by addressing the above-mentioned comments.
Author Response
Dear Reviewer,
Authors thank you for the comments and please find attached document with the answers to the comments and suggestions. We believe your comments have helped us to improve the quality of the article.
Author Response File: Author Response.pdf
Reviewer 2 Report
The paper compares four different method of variable average power load methods. In my opinion it is not a review paper and only a comparison between four methods are presented. The paper is well written, but I think it lacks sufficient contribution for the publication.
Author Response
Dear Reviewer,
Authors thank you for the comments and please find attached document with the answers to the comments and suggestions. We believe your comments have helped us to improve the quality of the article.
Author Response File: Author Response.pdf
Reviewer 3 Report
1. The writing of the article needs comprehensive proofreading by a professional editor and/or a native English speaker. There are numerous sentences that are not clear.
e.g. "There are lots of simple options to control excess power in a microgrid system, but none of these methods does not solve an issue permanently or it affects the solution affects the accumulated system`s energy – battery SOC level."
There are many examples. A thorough editing is a must.
2. All the abbreviations like state of charge (SOC) and vehicle to grid (V2G) need to be elaborated first time they appear in the text.
3. Is VAPL a device or a method? This was not clear from the abstract. Overall, the abstract was not very clear on what to expect in the paper and how to model the variable average power load, and how the paper solves the excess power and imbalance problem in microgrids.
4. Please avoid using run-on sentences (extending beyond 2 lines) like the one here: "As one of such a system example is shown in Figure 1, where battery inverters with off-grid type photovoltaic inverter are communicating, but the third inverter which is grid-tied type and different brand is not communicating with the rest of a system."
They are confusing and hard to read.
5. Inverter need PLL to synchronize. What do you mean by different-brand inverters communicating? Can you please elaborate on the power imbalance issue in Figure 1?
6. In line 54, to cross reference an article you do not need to repeat the name of the article. The following sentence needs to be rewritten: "Due to the excess power utilization, there was found a solution in the article “A Grid-Tied Inverter with Renewable Energy Source Integration in an Off-Grid System with a 55 Functional Experimental Prototype” [1]."
7. The reference list should be formatted according to the template. The reference list is not consistent. Please edit.
8. What are the main novelties of this paper compared to your previous work (reference [1])? It seems that VAPL was already suggested and examined in that paper.
9. The explanation provided in section 2 is not clear. I had to read the whole section twice to understand what the authors are trying to introduce in this chapter. It should be clearly mentioned that the paper compares 4 different method: 1. Burst Control, 2. Phase-Delay Control, 3. PWM AC-Side Control, and 4. PWM DC-Side Control.
Each method needs to be introduced, and their performance efficiencies and drawbacks should be analyzed comparatively.
10. My main comment is the lack of extensive study on the four compared methods. Most of the comparison are qualitative.
Different scenarios need to be studied and compared quantitatively.
11. The experimental validation does not exist.
12. I feel the amount of simulation and analysis done in this paper is not sufficient .
Author Response
Dear Reviewer,
Authors thank you for the comments and please find attached document with the answers to the comments and suggestions. We believe your comments have helped us to improve the quality of the article.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
My main comment similar to the last revision is regarding the lack of extensive study on the four compared methods. Most of the comparison are qualitative. I understand that this is a review article which means that there should be more focus on extensive comparison of different control methods and different aspects of it. I feel the amount of simulation and analysis done in this paper is minimal. Figures 1-5 are good but trivial for the researchers in this topic. The only quantitative analysis is on THD of two different control methods which is measured by MATLAB's THD block.
Editing comment: First row of Table 2 needs to be formatted (the heading for the second column can be "Versatile" and for the 4th column "Filtering Needed?" (or something else, shorter than what they are right now)
Author Response
please see the attachment
Author Response File: Author Response.pdf
