Alleviation of Power Quality Issues in MVF-DEANF-PLL Based Solar PV Systems under Polluted Grid Conditions

Round 1

Reviewer 1 Report

The authors have designed a control scheme for grid-integrated solar photovoltaic system to overcome the power quality issues with unbalanced and non-linear loading conditions along with the MPPT control. The paper provides extensive information about the subject matter; however, the reviewer has following observations, which need to be address.

1.      Add in the abstract, the problem and motivation to justify the proposed work.

2.      The power sharing between solar PV and grid is ambiguous. The authors need to explain how this power-sharing ratio is set between two mentioned sources.

3.      Since there are two control schemes acting simultaneously i.e, MPPT for achieving maximum power point tracking while the  MVF-DEANF-PLL based approach is adopted to compensate the harmonics due to non-linear load. However, it is quite hard to achieve IGBTs triggering at the same time since the real operating points (current, voltage and power) would change once a set of IGBTs are switched, so how exactly authors have synchronized both control loops at the same time? 

4.      In section 4.5, authors need to quantify the referred “extremely non-linear load condition”.

5.      The authors need to mention how many cycles of voltage and current are selected for evaluation of harmonics content.

6.      Provide a more comprehensive introduction to the topic. Clearly state the motivation behind developing MVF-DEANF-PLL control and its potential advantages over conventional available techniques. Include a brief overview of previous research in the area and contextualize the novelty and significance of your work. Identify, clear research gap?

7.      Majority of references should be from 2018 to 2023. For now they are old.

8.      In my opinion, the simulation results have to be analyzed by the authors in more detail. The quality of figures presented in results section is poor. They are a bit pale. For example in Figure 10, the time Vs current values are not clear and prominent. Also, only show number of cycles, which are important.      

9.  In conclusion section, quantify the improvement made by the proposed controller compared to the conventional controller. Rewrite the conclusion, emphasizing its contribution and results.

Author Response

The authors have designed a control scheme for grid-integrated solar photovoltaic system to overcome the power quality issues with unbalanced and non-linear loading conditions along with the MPPT control. The paper provides extensive information about the subject matter; however, the reviewer has following observations, which need to be address.

1. Add in the abstract, the problem and motivation to justify the proposed work.

Answer: The problem and motivation of the proposed work have been added to the abstract of the revised manuscript.

2. The power sharing between solar PV and grid is ambiguous. The authors need to explain how this power-sharing ratio is set between two mentioned sources.

Answer: In the proposed work, the grid, load, and VSC (fed by solar PV) are connected at the common coupling point (CCP). The total capacity of the load is higher than the solar PV system's capacity in the suggested work. Hence, during SPV hours, the total power generated by the solar PV power is supplied to the load, and the remaining required load power is met by the grid supply. During non-SPV hours, the entire load's active power will be supplied from the grid supply. The power-sharing between solar PV and the grid is done in this way.

3. Since there are two control schemes acting simultaneously i.e, MPPT for achieving maximum power point tracking while the MVF-DEANF-PLL based approach is adopted to compensate the harmonics due to non-linear load. However, it is quite hard to achieve IGBTs triggering at the same time since the real operating points (current, voltage and power) would change once a set of IGBTs are switched, so how exactly authors have synchronized both control loops at the same time?

Answer: In the proposed work, the MPPT control scheme is designed in a way to maintain DC link capacitor voltage at a reference value of  by the duty ratio control of the boost converter. The VSC is also linked with the DC link capacitor. The VSC control scheme performs load compensation effectively until the DC link voltage is maintained at its reference. The solar power generated is also shared with VSC through the DC link capacitor. Hence, by maintaining the DC link voltage at its reference and utilizing energy stored in the DC link capacitor, both control schemes are synchronized without any interference between them.

4. In section 4.5, authors need to quantify the referred “extremely non-linear load condition”.

Answer: The word “extremely” has been replaced with “purely” in the revised manuscript (section – 4.5).

5. The authors need to mention how many cycles of voltage and current are selected for evaluation of harmonics content.

Answer: The number of cycles considered for the evaluation of harmonics content in voltage/current is "5 cycles". (from Line 309 – 310)

6. Provide a more comprehensive introduction to the topic. Clearly state the motivation behind developing MVF-DEANF-PLL control and its potential advantages over conventional available techniques. Include a brief overview of previous research in the area and contextualize the novelty and significance of your work. Identify, clear research gap?

Answer: The introduction section has been completely revised which has potential disadvantages of conventional methods, novelty/merits of the proposed strategy and significance of the proposed work.

7. Majority of references should be from 2018 to 2023. For now they are old.

Answer: The references section has been revised with the latest articles in the revised manuscript.

8. In my opinion, the simulation results have to be analyzed by the authors in more detail. The quality of figures presented in results section is poor. They are a bit pale. For example in Figure 10, the time Vs current values are not clear and prominent. Also, only show number of cycles, which are important.

Answer: A detailed analysis of the results has been done in the revised manuscript. All the figures are replaced with new high-quality images in the revised manuscript.

9. In conclusion section, quantify the improvement made by the proposed controller compared to the conventional controller. Rewrite the conclusion, emphasizing its contribution and results.

Answer: The conclusion section has been completely revised with the addition of numerical values of results which emphasize the proposed work’s contribution.

Reviewer 2 Report

Literature Review Section: Add new, updated references and cite them appropriately in the literature review section. Clearly highlight the main contribution(s) of the study based on the reviewed literature.

Methodology: Provide a detailed and clear explanation of the methodology used in the study.

 include information about the PI controller parameters utilized, and identify any missing parameters or variables that were crucial in the research.

Conclusion and Abstract: Enhance the conclusion section by incorporating numeric values or statistical information to reinforce the findings.

in the abstract, add specific numerical data or results to provide a concise overview of the study.

Figures: Improve the quality of the figures by ensuring they are clear, and if necessary, provide higher resolution images for better visualization

good

Author Response

1. Literature Review Section: Add new, updated references and cite them appropriately in the literature review section. Clearly highlight the main contribution(s) of the study based on the reviewed literature.

Answer: The introduction/literature review section has been completely reviewed in the revised manuscript, which highlights the main contributions of the study based on the reviewed literature.

2. Methodology: Provide a detailed and clear explanation of the methodology used in the study

Answer: A brief introduction about the proposed strategy has been added in the introduction section (lines 101 – 120) of the revised manuscript. A detailed explanation of the methodology is given in sections 3.1, 3.3, 3.4, 3.5 and 3.6 of the revised manuscript.

3. Include information about the PI controller parameters utilized, and identify any missing parameters or variables that were crucial in the research.

Answer: PI controller and other crucial parameters are added in the Appendix of the revised manuscript.

4. Conclusion and Abstract: Enhance the conclusion section by incorporating numeric values or statistical information to reinforce the findings.

Answer: Both the Conclusion and Abstract sections have been completely revised with the addition of numerical values of results which reinforce the proposed work’s contribution.

5. In the abstract, add specific numerical data or results to provide a concise overview of the study.

Answer: The Abstract sections have been completely revised with the addition of numerical values of results to provide a concise overview of the proposed study.

6. Figures: Improve the quality of the figures by ensuring they are clear, and if necessary, provide higher resolution images for better visualization

Answer: All the figures are replaced with new high-quality images in the revised manuscript.

Reviewer 3 Report

The article is well prepared in terms of organization and writing, and its scientific content is acceptable in terms of both method and presentation. However, clarification of major points presented below will be useful for understanding the manuscript.

1- A descriptive keywords without abbreviations are suggested. It should encompass the novelty involved.
2- Highlights are missing. It should be written in concise way.
3- The paper contains a language formulation problem and many conceptual, grammatical, type, format, and spelling errors. A comprehensive proofreading must be conducted for the text of the manuscript by a technical native person
4- Revise the abstract and include important findings. Some numerical data is required.
5- The symbols used in equations should be defined following the equation and they should be provided in the Nomenclature together with respective SI units.
6- The exiting of the first sub-section in the beginning of Introduction "1.1 Research motivation and innovation" is not right.
7- In the review section;. I would recommend strengthening your introduction and literature review by adding recent papers studying PV innovative strategies based on machine learning algorithms such as https://doi.org/10.1016/j.csite.2022.101797 and https://doi.org/10.1016/j.tsep.2023.102051
8- The limitations of the related previous studies based PV power allocation strategies in the summarized literature should be further deeply discussed. Please explain to highlight the novelty of the paper.
9- It is necessary to deeply discuss the methods' pros and cons of the applied  flexible step-size incremental conductance (FSSINC) maximum power point tracking (MPPT) technique compared to other relevant previous models.
10- An detailed flow chart is also highly needed to show the solution method of the system modeling indicating inputs, constraints, and operative, and design variables (at the end of section system modeling section
11- The formatting of the equations is wrong, the variables in the text should be in italics as they appear in the equations.
12- It is very important to discuss every figure or table by adding citations from other researchers. By citing several references in the results and discussion section.
13- At the end of the discussion section, is that possible to include reference results where the traditional methods involved smart control PV systems are used to further highlight the effectiveness of the current system proposed? The comparison may help the readers immediately find the merit of the proposal.
14- The conclusions are listed is very short and quite messy. It must be improved in a scientific way, clarifying the objectives of the study first, the research methods used, and then the most important results and outputs in clear points, one by one.

Comments for author File: Comments.pdf

Author Response

1. A descriptive keyword without abbreviations are suggested. It should encompass the novelty involved.

Answer: The descriptive keywords which encompass the novelty of the proposed work are included in the revised manuscript.

2. Highlights are missing. It should be written in concise way.

Answer: A brief introduction highlighting the proposed strategy has been added in the introduction section (lines 101 – 120) of the revised manuscript.

3. The paper contains a language formulation problem and many conceptual, grammatical, type, format, and spelling errors. A comprehensive proofreading must be conducted for the text of the manuscript by a technical native person

Answer: The manuscript has been thoroughly reviewed and corrected for conceptual, grammatical, type, format, and spelling errors.

4. Revise the abstract and include important findings. Some numerical data is required.

Answer: The Abstract sections have been completely revised with the addition of numerical values of results to provide a concise overview of the proposed study.

5. The symbols used in equations should be defined following the equation and they should be provided in the Nomenclature together with respective SI units.

Answer: All the symbols used in equations have been defined following the equation in the revised manuscript. Nomenclature section has been added at the end of the revised manuscript.

6. The exiting of the first sub-section in the beginning of Introduction "1.1 Research motivation and innovation" is not right.

Answer: The introduction section has been completely reviewed in the revised manuscript with research motivation and innovation.

7. In the review section;. I would recommend strengthening your introduction and literature review by adding recent papers studying PV innovative strategies based on machine learning algorithms such as https://doi.org/10.1016/j.csite.2022.101797 and https://doi.org/10.1016/j.tsep.2023.102051

Answer: The introduction/literature review section has been completely revised with a recent literature study.

8. The limitations of the related previous studies based PV power allocation strategies in the summarized literature should be further deeply discussed. Please explain to highlight the novelty of the paper.

Answer: In the revised manuscript, the limitations of the related previous studies have been explained in detail in the introduction section.

9. It is necessary to deeply discuss the methods' pros and cons of the applied flexible step-size incremental conductance (FSSINC) maximum power point tracking (MPPT) technique compared to other relevant previous models.

Answer: In the revised manuscript, the pros and cons of the FSSINC MPPT technique are compared to other relevant previous literature articles. (lines 45 – 53 and 133 – 143)

10. An detailed flow chart is also highly needed to show the solution method of the system modeling indicating inputs, constraints, and operative, and design variables (at the end of section system modeling section)

Answer: The proposed control strategy involves coordinated control of two different control schemes such as MPPT for peak power extraction and VSC control for PQ alleviation. The reader may experience confusion due to the utilization of a single flowchart to depict the coordinated control. Hence, both the control schemes are separately explained in different sections of the revised manuscript.

11. The formatting of the equations is wrong, the variables in the text should be in italics as they appear in the equations.

Answer: In the revised manuscript, the formatting of the equations and the appearance of variables in the text are corrected.

12. It is very important to discuss every figure or table by adding citations from other researchers. By citing several references in the results and discussion section.

Answer: In the revised manuscript, appropriate figures are explained by adding citations from other researchers. (lines 324 – 332, 380 – 381, 480 – 483 and 497 – 500)

13. At the end of the discussion section, is that possible to include reference results where the traditional methods involved smart control PV systems are used to further highlight the effectiveness of the current system proposed? The comparison may help the readers immediately find the merit of the proposal.

Answer: In the revised manuscript, the traditional methods reference results have been discussed in the sections 4.1, 4.3, 5.1, and 5.2. Also, the results discussion and comparison of traditional SRF-PLL method has been done in sections 4.6 and 5.3.

14. The conclusions are listed is very short and quite messy. It must be improved in a scientific way, clarifying the objectives of the study first, the research methods used, and then the most important results and outputs in clear points, one by one.

Answer: In the revised manuscript, the conclusion section has been completely revised with the addition of numerical values of results which emphasize the proposed work’s contribution.

Round 2

Reviewer 1 Report

The quality of the manuscript increased significantly.

Reviewer 2 Report

My comments are fully considered. 

Reviewer 3 Report

Accept. No further comments are required

Accept. No further comments are required