Advanced Energy Management System for Generator–Battery Hybrid Power System in Ships: A Novel Approach with Optimal Control Algorithms
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsREVIEW REPORT jmse-3203181
Manuscript title
Advanced Energy Management System of Generator-Battery Hybrid Power System in Ship: A Novel Approach with Optimal Control Algorithms
Authors
Eunbae Choi, Heemoon Kim
In the manuscript, a novel management system for the consumption of generated energy available on a target vessel is proposed. Consequently, a control method was developed that integrates a battery system with an efficiency-based algorithm to optimize the overall performance of the system. The new method performs control operations based on the characteristics of the power generation source and adjusts controls according to the state of charge of the battery.
Using Matlab-Simulink features, an original algorithm was developed to control the operation mode of the generator-battery hybrid system at the optimal efficiency point, according to the fuel consumption characteristics, related to the power output of the diesel generator.
Even if the work deals with a current topic in the field of energy consumption efficiency on systems installed on ships, from a conceptual point of view, its structure could be improved, so that it becomes clearer. However, some recommendations are required, as follows.
1. It should be explained how the optimal operating point of the engine has been inferred.
2. How the optimal operating point (𝐷𝐺𝑜𝑝𝑡) for efficient operation was selected ?
3. The discussion section should be completed with an in-depth analysis of the results.
4. The conclusion paragraph should be improved with statement of application perspective.
5. Marginal recommendation: the text annotation on the Figure 7 is almost illegible.
6. Marginal recommendation: the manuscript must be modified to meet the requirements of the JMSE template, at this moment there are multiple mistakes related to editing, such as the sequences of blank lines after each paragraph from the introduction, non-compliance with the template for tables and formulas.
Finally, I appreciate that the manuscript could be considered for publication in JMSE, after major revision.
Author Response
Comments 1: It should be explained how the optimal operating point of the engine has been inferred.
Response 1: Thank you for your comments. The optimal operating point of the engine, based on SFOC data, shows the lowest SFOC at 100% load, indicating the highest efficiency point. However, operating the engine generator at 100% load poses a risk of a blackout due to additional power load. To mitigate this risk, when the engine generator load exceeds 85%, the Power Management System's load-dependent start function activates the standby generator to reduce the load and ensure safety. Therefore, this paper designates 85% load as the point of highest efficiency with safety assured. The related content has been added to 2. Methodology - Step 1. Thank you.
Comments 2:How the optimal operating point (?????) for efficient operation was selected ?
Response 2: Thank you for your comments. As previously mentioned, while the optimal efficiency point of the diesel generator for the target ship in this paper is 100%, we have selected 85% as the optimal point to ensure safety and prevent blackouts by incorporating the PMS's load-dependent start function. Thank you.
Comments 3: The discussion section should be completed with an in-depth analysis of the results.
Response 3:Thank you for your valuable comments on the key points. I have reviewed the entire discussion section and created separate chapters for each topic, adding further analysis where necessary. Thank you again.
Comments 4: The conclusion paragraph should be improved with statement of application perspective.
Response 4:Thank you for your comments. As you suggested, I have thoroughly reviewed the conclusion section and revised both the format and content to make it easier for readers to understand. Thank you.
Comments 5: Marginal recommendation: the text annotation on the Figure 7 is almost illegible.
Response 5: Thank you for your detailed review, and I agree that the text annotations in the figures were difficult to read. I have thoroughly reviewed and revised the figure files to improve their quality and readability, and the updated versions have been incorporated into the revised manuscript. Thank you.
Comments 6: Marginal recommendation: the manuscript must be modified to meet the requirements of the JMSE template, at this moment there are multiple mistakes related to editing, such as the sequences of blank lines after each paragraph from the introduction, non-compliance with the template for tables and formulas.
Response 6: I fully agree with your observation regarding the formatting errors that did not adhere to the template standards, and I appreciate your comments. I have reviewed and revised the entire manuscript, starting from the introduction, to meet the requirements of the JMSE template, enhancing both the quality and readability. Thank you again.
Reviewer 2 Report
Comments and Suggestions for AuthorsPlease, find reviewer's comments in the attached file.
Comments for author File: 
Comments.pdf
English is fine but minor editing could benefit the quality of the paper.
Author Response
Comments 1: While the Introduction section seems fine, it is advised to make a more fluent text. At the moment, the section looks like an addition of ideas in many small paragraphs.
Response 1: Thank you for your detailed review of the introduction section. As you suggested, I have revised the text to make it more natural and fluent, and additionally had it reviewed by a professional English editing service. Thank you.
Comments 2: When, in line 140, the authors talk about determining the optimal operating point of the diesel generator it sounds like they did a previous work. I believe this point is given by the manufacturer. Please explain and correct the text so it does not lead to confusion.
Response 2: Thank you for your thorough comments. I have re-examined the areas you pointed out and revised any ambiguous expressions that may cause confusion. Thank you.
Comments 3: Adding a 1500 kW battery system to a vessel is not a minor conversion.
Price, weight of the battery bank and safety in case of fire should be looked into carefully. If the authors conduct following research, to calculate the payback of installing batteries a number of factors similar to the above mentioned should be taken into account.
Response 3: Thank you for your careful review aimed at improving this paper. I agree with your points, and have incorporated the relevant details into the Limitations and Future Research sections. In future studies, I will consider factors such as CAPEX, OPEX, and other elements related to battery integration to improve the research. Thank you.
Comments 4: Similar to comment #2, in line 183 the authors stated that optimal operating point was selected at 85% load. While this is a reasonable point, I do not see what procedure followed the authors to select that point and not any other like, for example, 75% load.
Response 4: Thank you for your comments. The optimal operating point of the engine, based on SFOC data, shows the lowest SFOC at 100% load, indicating the highest efficiency point. However, operating the engine generator at 100% load poses a risk of a blackout due to additional power load. To mitigate this risk, when the engine generator load exceeds 85%, the Power Management System's load-dependent start function activates the standby generator to reduce the load and ensure safety. Therefore, this paper designates 85% load as the point of highest efficiency with safety assured. The related content has been added to 2. Methodology - Step 1. Thank you.
Comments 5: I believe that, below Eq 1., DG stop, min, opt and max are repeated from line 183.
Response 5: Thank you for your detailed comments. I agree with your suggestions and have revised the redundant sections accordingly. Thank you.
Comments 6: For the statement made in lines 197 to 199: “correlation between generator… operational state”. Please provide a further explanation.
Response 6: Thank you for your comments. Upon thorough review, I found that the relevant logic is already explained in Table 3 and the text below, so I have deleted the redundant sentence to avoid confusion. Thank you.
Comments 7: Please, consider to add colors and larger font size to Figures 2 and 3.
Response 7: I fully agree with your suggestions to improve the quality of the paper. As mentioned, I have added color to the figures and adjusted the font size. Thank you.
Comments 8: In lines 238 and 239 I am of the opinion that it would be better to use hours instead of days with decimal numbers.
Response 8: I fully agree with your suggestions to improve the paper's quality. As indicated, I have corrected the units. Thank you.
Comments 9: Please, enlarge Figure 5.
Response 9: Thank you for your comments. As you suggested, I have enlarged the figure text to make it more legible. Thank you.
Comments 10: In Figure 7, it would be interesting to see the “PMS Block” and “Dynamic Load VI Mea” inner configurations.
Response 10: Thank you for your detailed comments. The PMS block you mentioned is coded within the function block. Additionally, it was developed using the 'Dynamic Load VI Mea' Matlab/Simulink commercial library. Please refer to this. Thank you.
Comments 11: The results obtained do not account for Power Factor and this is important as alternators will vary it with the help of the AVR but batteries do not have that flexibility. How will the authors deal with this?
Response 11: Thank you for your careful comments. The simulation model proposed in this paper focuses on long time-scale simulations, and it does not account for transient-state simulations, such as those including AVR. This will be considered in future research, and I have mentioned this in the Limitations and Future Research sections. Thank you.
Comments 12: The sentence in lines 310 to 312 “The remaining load…” seems to be difficult to understand. Please rewrite or provide a further explanation.
Response 12: I fully agree with your suggestions for improving the paper's quality. I have carefully reviewed the relevant sections and revised them to make the content easier for readers to understand. Thank you.
Comments 13: The work is interesting and by knowing the fuel consumption reduction when applying the different control strategies and the fuel Emission Factors they could deduce the savings in CO2 emissions easily. EF for marine fuels can be found in International Maritime Organization’s Resolution MEPC.364(79).
Response 13: Thank you for your thorough comments. I believe that the research areas that can be expanded upon from this paper are vast. I will consider conducting future studies on fuel emission factors and CO2 reduction, as you suggested, and have mentioned this in the Limitations and Future Research sections. Thank you.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have responded in detail to my comments and have made the corresponding revisions to the manuscript.
