Multiple-Zone Synchronous Voltage Regulation and Loss Reduction Optimization of Distribution Networks Based on a Dual Rotary Phase-Shifting Transformer

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The scientific article titled "Multi-zone synchronous voltage regulation and optimization of loss reduction in distribution networks based on a double-phase transformer with a rotating winding" presents an innovative approach to the problem of voltage regulation in distribution networks with a high share of renewable energy. The authors of the article focused on the development and verification of the operation of a double-phase transformer with rotating winding (DRPST), which enables bidirectional voltage regulation while being characterized by high reliability and low costs. The research methodology presented in the article is solid and well thought out. The authors describe in detail the topology, working principle and equivalent circuit of DRPST, which allows for a deeper understanding of the proposed method. The simplified circuit model of the transformer, which was established for the analysis, is adequately constructed and allows for an effective assessment of the impact of DRPST on the network. distribution. The discussion of the results is reliable and comprehensive. The authors focus on the analysis of the causes of exceeding the permissible voltage values ​​in distribution networks and present how DRPST can contribute to solving this problem. The proposal of a real-time two-layer optimization strategy based on DRPST is novel and constitutes an important contribution to the development of voltage regulation technology. The form of presentation of the results is transparent and understandable. The authors use clear charts and tables that help the reader follow the reasoning and research results. Appropriate use of illustrations and examples contributes to a better understanding of the presented content. The scientific article is a valuable contribution to the field of voltage regulation in distribution networks using renewable energy. Solid methodology, exhaustive discussion and transparent form of presentation of results make this work worth recommending to scientists and engineers. dealing with this topic.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study introduces a series-type dual rotary phase-shifting transformer (DRPST) employing phase volume synthesis principles. The transformer facilitates bidirectional voltage regulation, displaying high reliability and cost-effectiveness. It introduces the DRPST's topology, operating principles, and its simplified circuit model. The study analyzes the causes of voltage limit exceedance and devises an active distribution network model integrating the DRPST. A two-layer optimization strategy is proposed, employing multi-objective particle swarm optimization to minimize voltage deviation and line loss. The solution is optimized using a fuzzy subordinate degree function method. After reading the manuscript several times, the reviewer found the following major points need to be revised to make the paper qualified to be published in Frontiers in MDPI Sustainability:

 

1. The draft emphasizes 'low cost' as an advantage of the DRPST, but the details supporting this assertion are inadequately disclosed. It would be beneficial to elaborate on how the implementation of the DRPST influences manufacturing, operational, and maintenance costs. A comprehensive examination of these cost aspects would significantly enhance the understanding of the economic advantages associated with the DRPST technology.

 

2. Regarding the discussion on steady-state regulation characteristics, Figures 9 and 10 are addressed collectively. Would it be feasible to consolidate these figures into a single composite figure for a more cohesive presentation?

 

3. The author asserts that the experimental results validate the effectiveness and accuracy of the proposed DRPST topology and its control strategy. To further bolster the credibility of the findings, it would be beneficial to include references from recent publications for comparative purposes. A comparative analysis would enhance the demonstration of the effectiveness and robustness of the results presented in this work.

 

 

4. The formatting of the references lacks consistency.

Comments on the Quality of English Language

The overall clarity and coherence of the text are quite good.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Editing notes

Figure 4 – please insert some space before and after the figure, at present the drawing collides with the text (Eq.(9)).

Line 134-136 – please insert an extra space below figure caption.

Line 168 – it should be “kV”, not “kv”.

Line 203 – symbol “bird”_si (corresponding to weight of the load at particular node) is not used in Eq.12.

Between references and Appendix A some empty space should be left. Same between Appendix A and Appendix B.

Figure B1 – please consider enlarging this figure, it is not very clear to the reader.

References: Editing style should be consistent throughout, please pay attention to use of capital letters in some authors’ names.

Figure 12 -  is too small, details in photos are not easily discernible.

 

Notes on subject matter

The subject matter is very up-to-date and of great interest, as the problem of increase in power line voltage due to “injection” of RES power is becoming more and more serious. The solution proposed by the authors, i.e. a rotary transformer connected in series with the line instead of traditional OLTC or some power electronics device seems relatively simple and reliable. The problem of setting the rotation of DRPST is solved by application of PSO algorithm. Interesting point about the calculations is that authors have chosen two objectives: apart from lowest voltage deviation (which seems to be the prime objective in other works), they have also considered the minimum line loss. The regulated quantity is rotor angle of the DRPST.

The authors have run some simulations using MATLAB environment, but they have also verified the proposed algorithm experimentally. However, results of real-life experiments shown in Figs. 13 and 14 are not discussed in detail. I feel that some supplemental description is needed here.

Figure 2 seems unnecessary – wiring connections are clearly shown in Figure 1.

Vector diagram in Fig.4 – surely “d” i “q” axes are unnecessary? The component voltages/currents/voltage drops are not split into d-q components, as in Park transformation, the vectors represent real quantities (magnitudes and phase angles)! Please justify this approach or else rework the diagram.

Figure 5  - it should be stressed that it is just an example of distribution network, not general view.

 Lines 500-502: The authors have written: “As can be seen from the attached Figure B1, compared with the traditional MOPSO, the dynamic parameter design of inertia weights and acceleration factors in the solution process can effectively improve the solution speed and meet the online operation requirements”. Actually, when these three figures (a,b and c) are compared, there is virtually no difference between them! It seems that the solution time is exactly the same for all three cases. Please discuss this or else amend the figures.

As for giving the parameters of MOPSO algorithm and details of solution in the form of appendixes: these appendixes are very short, very concise. In fact, this data could be easily included in the body text of the article and I recommend it.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

Author Response File: Author Response.pdf