A Hierarchical Voltage Control Strategy for Distribution Networks Using Distributed Energy Storage

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The abstract lacks quantitative results or performance metrics.
2. The phrase "address voltage violations through the coordinated operation of distributed energy storage systems (DESSs)" is slightly verbose. Consider rephrasing for conciseness (e.g., "coordinate DESSs to mitigate voltage violations").
3. The references cited are insufficient and fail to adequately represent the latest research achievements in this field.
4. Figure 1 titled "Process of the proposed two-layer control scheme," the current diagram does not effectively illustrate the structure of the controller constructed in this paper. It is recommended to revise the figure to more clearly depict the architectural components and interactions within the proposed two-layer control scheme. This will enhance the clarity and comprehensibility of the paper for readers.
5. In the simulation section, it is hoped that the author can add some comparison result graphs between the control method proposed in this paper and existing control methods.
6. In the simulation section, tables displaying specific result data should be added, as this will make the results more intuitive.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors describe current problems with voltage regulation in modern distribution networks, taking into account the impact of DER and the limitations of classical methods (e.g. OLTC).
The selection of the test system, DESS configuration and taking into account the variability of PV generation confirm the adequacy of the project to the set goals.
For full repeatability, more details on the implementation of the algorithms (e.g. MPC parameters, QP solver) would be useful, but the main scheme of the procedure is clear.
The illustrations are clear and well-chosen, and the analysis of the results is consistent with the objectives of the study.

The conclusions are adequate to the presented results.

It would be useful to add more information on the numerical tools. This comment should be addressed.

Although two-layer control is not completely new, the proposed combination of MPC with broadcast-based control and its application taking into account communication constraints is a new, well-justified contribution. This comment should be addressed.

The article does not provide information on the QP solver used, the computation time or the hardware characteristics of the simulation environment. This limits the possibility of assessing the real performance of the algorithm. This comment should be addressed.

No analysis of communication costs. Although broadcast-based control is supposed to reduce the dependence on P2P communication, no quantitative analysis regarding the actual load on the communication network is presented. This comment should be addressed.

The DistFlow model used is a linear approximation, and the accuracy of this approximation has not been assessed. The authors mention "minor transient deviations" but do not analyze them in detail. This comment should be addressed.

The simulations were performed on a single version of the IEEE 34-bus feeder. It is not known how well the method scales to larger, irregular or asymmetric systems. This comment should be addressed.

There is no comparison of the control quality with other known approaches (e.g. in the comparison table), which makes it difficult to assess the relative advantage of the proposed method. This comment should be addressed.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript addresses a highly relevant topic in smart grid voltage regulation, proposing a two-layer control strategy that combines model predictive control (MPC) with a broadcast-based lower-layer controller for distributed energy storage systems (DESSs). The hierarchical architecture is novel and well motivated, and the authors support their method with solid mathematical modeling and simulation results using the IEEE 34-bus feeder.

The manuscript presents a well-structured and original control strategy with solid theoretical foundations and practical validation. However, several language, structural, and technical clarity issues must be addressed. It requires language polishing, clearer figure integration, and slight structural tightening to improve readability and impact. In particular, some items that should be improved are the following:

1.- The manuscript title is informative but could benefit from simplification: consider “A Hierarchical Voltage Control Strategy for Distribution Networks Using Distributed Energy Storage”.

2.- In Line 13, “aggregated active power reference trajectories” is slightly technical; perhaps “optimal power dispatch trajectories” is clearer for the reader.

3.- In the abstract, please, add one or two lines summarizing the simulation results more quantitatively (e.g., percentage of voltage violations reduced) to see the advantages of the control strategy proposed in the manuscript.

4.- Good context is given regarding DERs, voltage regulation challenges, and limitations of conventional approaches. However, the list of drawbacks (presented in lines 52-57) of distributed methods is strong, but could be improved with clearer sentence construction. For example: “Firstly, their dependence on peer-to-peer communication increases vulnerability to cyber-physical threats…”

5.- Use consistent notation throughout. For instance, sometimes “DESSs” is used, sometimes “ESS”.

6.- “Broadcast-based controller” is repeatedly introduced; consider abbreviating it as BBC after first definition for readability.

7.- In Figures 1 to 3, please, add brief captions under each figure explaining what is being illustrated. E.g., for Figure 3: “Schematic of the hierarchical voltage control structure with upper-layer MPC and lower-layer broadcast control loop.”

8.- On equation formatting, notice that Eq. (7) has missing clarity on dimensions of vectors and matrices. Notice that, for instance, a notation table would help.

9.- In Eq. (24), there is a formatting issue with the Lagrangian; please, use clear subscript notation and define dual variables upon introduction.

10.- Notice that Figures 6–11 need clearer axis labels, consistent units (p.u., kW, etc.), and legends. Please, notice that the quality and resolution of the different traces tend to lead to confusion. Please, improve the plots of these figures.

11.- In Section 4 (A Case Study), please, consider summarizing key outcomes numerically in a table (e.g., number of buses with voltage violations before/after, average deviation, etc.).

12.- Add more narrative explaining why certain buses were chosen (e.g., Bus 33), and how PV variability was simulated.

13.- Communication loss analysis is quite interesting. However, consider extending this to include packet delay scenarios.

14.- Grammar and flow need work in several places. Examples: Line 58: in “to achieve voltage regulation for distribution networks with massive distributed ESSs”, consider “to ensure voltage regulation in networks with large-scale DESS deployment”. Line 273: in “showing the proposed strategy maintains voltages…”, consider “demonstrating that the proposed strategy maintains voltages…”.

15.- Reference [5] is duplicated (also appears as [2]); consolidate.

16.- Consider adding citations from recent works (years 2023 and 2024) on decentralized voltage regulation via reinforcement learning or consensus-based methods.

 

Comments on the Quality of English Language

The English should be improved to more clearly express the research.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has carefully revised the manuscript in accordance with the reviewers' comments from the initial review and hereby grants consent for the publication of the article.

Author Response

Comments 1: The author has carefully revised the manuscript in accordance with the reviewers' comments from the initial review and hereby grants consent for the publication of the article.

Response 1: Thank you for your efforts in evaluating our paper.

Reviewer 2 Report

Comments and Suggestions for Authors

Good corrections. Good luck.

Author Response

Comments 1: Good corrections. Good luck.

Response 1: Thank you for your efforts in evaluating our paper.

Reviewer 3 Report

Comments and Suggestions for Authors

The technical and scientific improvements included in this new version of the manuscruipt are considered. However, notice that the quality of the presentation in very poor; for instante, there is some figure not included in the paper or missing information.

It's necessary to have tha final manuscript in the Journal template.

 

Author Response

Comments 1: The technical and scientific improvements included in this new version of the manuscruipt are considered. However, notice that the quality of the presentation in very poor; for instante, there is some figure not included in the paper or missing information.

Response 1: Thank you for your corrections. We have thoroughly addressed the issue of missing figures and incomplete information by ensuring that all references are now correctly inserted and fully annotated to improve clarity.

Comments 2: It's necessary to have tha final manuscript in the Journal template.

Response 2: Thank you for your suggestions. We have obtained the official template for the journal and are scrutinizing each section, including the title page, abstract, body, equations, figures, tables, and references to ensure strict adherence to the template.

 

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

In the reviewer's opinion, the technical and scientific improvements included in this new version of the manuscruipt are enough to consider it for publication in the Journal.

However, notice that the quality of some figures could be improved to see plots and labels with good resolution. It is the case of Figs. 1, 3, 5(b), etc.