Optimized Universal Droop Control Framework for Enhancing Stability and Resilience in Renewable-Dense Power Grids

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I recommend accepting the manuscript upon resolving the following issues.

(1) The comparison of existing methods (such as DFDC, DNDC, ADC, etc.) in the abstract and introduction is somewhat general. It is recommended to include a quantitative performance comparison with the latest advanced control strategies to clearly demonstrate the unique advantages of UDC in terms of response speed, regulation accuracy, and resource allocation efficiency.

(2) The authors provided a good literature review of the current research progress. However, it should include a discussion on advanced optimization algorithms, such as Harris hawks optimization in few-shot fault diagnosis for machinery using multi-scale perception multi-level feature fusion image quadrant entropy.

(3) There is an issue with the numbering of the paper’s section titles. The authors should revise all title formats to align with the journal’s requirements. For example: “1. Mathematical Modeling” and “A. Grid-Forming Universal Droop Controller (GFM-UDC)”.

(4) It is necessary to supplement the influence analysis experiment of the parameters involved in the proposed model.

(5) The experimental section lacks a comparison with existing state-of-the-art models, which is necessary to highlight the advantages of the proposed framework.

(6) A discussion on whether the computational complexity of the GAMS optimization algorithm meets real-time control requirements should be included.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study proposes an integrated framework aimed at enhancing stability and resilience in power grids with high penetration of renewable energy sources, by designing optimized Universal Droop Controllers (UDCs) tailored for grid-forming operations under high-impact contingencies. These controllers enable real-time fault detection, thereby improving operational reliability. Validation conducted on a distribution network demonstrates that the optimized framework achieves superior voltage and frequency regulation compared to conventional droop-based methods, ensuring optimal resource allocation and sustained load support.

The article is well-structured and clearly written, with coherent arguments and an appropriate motivation for both the introduction and the development of the research. However, the theoretical foundation requires improvement. As currently presented, it lacks clarity, particularly in the mathematical modeling, where the equations do not follow a logical sequence or exhibit clear interrelation with the implementation. The references cited are consistent and up-to-date, encompassing relevant studies within the same research area, which constitutes the main focus of the work. The proposed approach is pertinent, innovative, and demonstrates potential to add significant value to the journal, provided the following corrections and adjustments are implemented:

• Add a concluding paragraph to the Introduction summarizing the content to be covered in the subsequent sections of the manuscript.

• Review all section and subsection titles to comply with the journal’s formatting guidelines, including font size, indentation, and numbering.

• Revise the captions of all figures to ensure they adhere to the journal’s style requirements.

• Eliminate the excessive spacing observed on page 4.

• In line 187, Figure 7 is referenced far before it appears in the text. Relocate the figure closer to its first mention.

• Improve the presentation of the mathematical modeling. The current layout appears disorganized, with equations presented without explicit relationships. Reorganize the mathematical content to follow a clear sequence and logical correlation.

• In line 289, verify whether the correct reference is to Equation (31) instead of Equation (1).

• Standardize the font type and quality of all figures presented in the results section. Axis labels (x and y) in the plots appear to have inconsistent font sizes and styles—revise all figures accordingly.

• In line 393, should the reference be to Figure 17 instead of Figure 15?

• In line 398, should the reference be to Figure 18 instead of Figure 16?

• A critical point: the authors claim that the proposed framework outperforms conventional methods in distribution network validation; however, no comparison is presented in the text. On what basis is this claim made? This comparison must be clearly demonstrated.

• Improve the legibility and size of the numbering in Figure 7. Even at 200% zoom in the PDF, it is not possible to clearly view the content, which hinders interpretation of the results.

• In line 415, is the reference to Figure 19 correct?

• In line 419, should the reference be to Figures 22–27 instead of 20–25?

• In line 432, should the reference be to Figure 28?

• Review all figure citations throughout the text. In several instances, they appear to reference the incorrect figures.

• In the conclusion, include suggestions for future research directions.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1- Clearly state what makes your UDC approach novel compared to existing methods like DFDC, DNDC, or ADC. A separate “Contributions” bullet list in the introduction helps.
2- Discuss real-time applicability of your framework. How fast can the GAMS-MATLAB system respond in actual grid scenarios? Mention solver performance or decision latency.
3- Although your system is largely decentralized, clarify if any minimal communication is needed (for switching or load coordination) — and how the system performs under communication failures.
4- The paper includes many droop and PI parameters. Add a guideline or discussion on how these were chosen (heuristically? via optimization?) and how they affect performance.
5- Even if the current work is simulation-based, mention plans or feasibility for hardware-in-the-loop testing, which adds realism and practical depth.
6- Add quantitative comparisons between your method and at least one baseline, showing improvement in metrics like frequency stability, voltage regulation, and load served.
7- Explicitly state system assumptions (communication-free control, DER behavior, fault types). This improves clarity and allows readers to generalize or adapt your model.
8- Introduce specific metrics (% voltage deviation, frequency recovery time, optimization run-time, load curtailment reduction) in the Results section to support your conclusions.
9- Discuss the limitations of the study, such as assumptions made in the simulation or scalability challenges for larger grids.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I congratulate the authors for making changes to the text that significantly improved the text.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have carefully revised the manuscript, and I consider it ready for publication in the journal.