The Efficacy of Multi-Period Long-Term Power Transmission Network Expansion Model with Penetration of Renewable Sources
Round 1
Reviewer 1 Report
Dear Authors,
I have some comments on your article:
1. Literature should be checked if there are no newer items. Especially from the last 18 months.
2. All indexes in symbols in text and equations should be checked carefully.
3. Please note minor editorial errors. E.g. line 168 where the dot at the end of the sentence is missing.
4. Please write something more about the usefulness of the analyzes carried out.
5. In the Conclusions section, please add information on how to apply the research contained in the article in practice.
Author Response
Good day reviewer,
Thank you very much for the in-depth review of the paper. Your comments and inputs have contributed immensely to new look of the paper.
Our answers to your comments and concerns are found in the attached word document.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper presents the study about efficacy of multi-period long-term power transmission network expansion with penetration of renewable sources. Authors say, that increase in energy demand introduces challenge in power system. The penetration of renewable energy has evolved rapidly in the past three decades. However, the grid system has to be well planned ahead to accommodate such increase in energy demand in the long run. Authors propose a TNEP model that minimizes the network reinforcements, operational costs and costs of renewable energy penetrations, while satisfying the increase in demand. Obtained results show the efficacy of the developed model in solving the TNEP problem with a reduced and acceptable computation time even for large power grid system.
Dear author, thank you very much for interesting paper about problem of electric transmission and distribution grid in situation of renewable sources of energy. I put some comments and question.
Comments:
1. The introduction is well organized and planned. Authors presented motivation and reviewed all literature where results of many researchers are presented. Anyway, I did not find description of problems, which are generated by many small sources of renewable energy, such as frequency and voltage stabilization, the increase of voltage, the change of structure of power grid, which generates extra costs. Please complete if possible.
2. Formulas 1, 2, 3, …, please describe all parameters in presented equations.
3. Fig.1. what was the source of the information presented on the figure? National grid or other? I ask because I did not see the references. Please complete the information.
4. Similar information as 3 is for next figures. Please complete the information.
5. Summarizing, I think the paper is very value. I ask the authors to complete some information. obtained results try to solve some problem, which is generated by many small renewable sources of energy. It is very universal problem for each country, which change the electric power grid.
Author Response
Good day reviewer,
Thank you very much for the in-depth review of the paper. Your comments and inputs have contributed immensely to new look of the paper.
Our answers to your comments and concerns are found in the attached word document.
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript addresses the problem of transmission network expansion planning and presents the mathematical model to resolve the problem. The novelty of the model, according to the authors, is that each year of the planning period is considered, and decisions for electricity network expansion are considered for each year. The authors stated that they formulated the problem as a mixed integer linear programming problem. The developed model has been tested in several IEEE test systems in multi-period scenarios.
There are the following comments to the manuscript:
1. The title of the manuscript should be changed with the introduction of the word “model”, for example “The Efficacy of Multi-Period Long-Term Power Transmission Network Expansion Model with Penetration of Renewable Sources”, because the authors main contribution is the development of the model.
2. The verbal description of the developed model does not fully correspond to the mathematical description. For example, as can be concluded from the lines 155-157, 164-166, 265-266 expansion of generating sources is also optimized by the model. Same time, as can be seen from the mathematical description of the model, transmission expansion is optimized by the model (since the capital costs of transmission are optimized in the model).
3. Tables 3, 5, 7, 8, 9 contain results on “optimal” generating capacities. It’s not clear what does mean “optimal” here, because in the model there are only operating costs of generation and not capital cost of generation. If we optimize expansion of generation using just operation costs, we obtain wrong decisions.
4. It is inconvenient when explanations of variables, constants and constraints are given only in the end of the manuscript and are absent right after the equations.
5. All introduced parameters, like Cg1, CR1, etc., should be explained, and readers should not guess what do they mean.
6. It’s not clear why AC and DC models are considered, if the latter is used for the calculations. It should be explained when each model should be applied.
7. Why after the reference to the Table 2 (line 286) there is a reference to the Table 10 (line 293), etc.
8. It should be clearly explained what successive consideration of 6, 9, 24, 39, 200 bus systems gives.
9. Numerous tables should be removed from Conclusions and placed, for example, in Appendix B.
10. The main inference (lines 386-389) looks quite obvious.
Author Response
Good day reviewer,
Thank you very much for the in-depth review of the paper. Your comments and inputs have contributed immensely to new look of the paper.
Our answers to your comments and concerns are found in the attached word doc.
Thanks
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors,
Thank you very much for introducing changes that have improved the quality of the article. I have no more comments.
Reviewer 3 Report
I have no additional comments to the manuscript.
