Topological Optimization of an Offshore-Wind-Farm Power Collection System Based on a Hybrid Optimization Methodology

Round 1

Reviewer 1 Report

The paper is the interesting contribution of Authors to the development  of the novel hybrid optimization methods of structure of offshore wind farm power collection systems. The paper can find interests in works connected with optimal placing of offshore wind farm power collection systems.

The paper has proper form and  scientific level.  But it requires the knowledge of modern optimization methods for understanding the presented issues.

There are only some detailed remarks of the reviewer, that are listed below:

1.    For the most of presented equations in the paper, there are any citations of the references. It is not stated, that these equations were developed by the Authors.

2.    Not all terms and components used in equations were properly explained. For instance it is not clear for Eq.(4) what is wind condition and what is the number Kn of wind conditions. How is this number determined and in what period of time. What is the lifetime T of wind farm ? The wind farm is complex system with wind turbine, gearbox,  electrical generator, power electronic converters, switches and other devices. The individual elements have different lifetimes of operation. How is the global  lifetime T determined.

3.    P.4, L.131-132 – The part of the sentence with: “cosj is the power factor of the wind turbine” is not precise. The wind turbine is mechanical device and cosj is only determined for AC electrical devices. In wind farm we have two possible values of cosj: for electrical generator and fin the system with converters for circuits at the grid side.

4.    In Eq.(6) the component with penalty term can have very large value and influence the final form of the relationship. How this term is optimal determined ?

5.    In the presented cost analysis, the considered costs are given in yuans. For this reason the obtained results are proper for China country. Will it be possible to develop more general conditions of analysis.

6.    The list of References  in the paper is quite short. It is not possible to download many of references by using European versions of browsers: Google and Google Scholar. Some Reference data  are not proper – for the given data it is not possible to find cited article (for example Ref.5). The List of References should be checked and verified.

7.    There are some editorial mistakes in the article:

a)   In some places the cited references are presented by using index form, but not normal form;

b)   P.2, L.47-48  - The sentence is not complete;

c)    In Eq.(6) the denotation pe is used, but in the line below the Eq.(6) the denotation Pe is used.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

 

1. The reference citing on the first page is different than in the rest of the paper (the literature number is written in superscript). This mistake is repeated also throughout the paper for some references.

2. In row 47 sentence ˝In terms of cost modeling and optimization variable selection.˝ is vague.

3. In Table 1 some terms that are used are unusual - for example, cut to the wind speed - usually, the term is cut-in wind speed and cut out of the wind speed - usually, the term is cut-out wind speed

4.  What was the criterion for cable selection? The only ampacity of the cable? What with the short-circuit current?

5. Authors proof the advantages of hybridization of PSO and Ao but what are the performances of the proposed methodology compared to some other intelligent algorithms such as genetic algorithm?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript refers to the process of optimizing the topological structure of an offshore wind harvesting system. The authors focused on developing a detailed cost model for the energy harvesting system, which was identified as the main optimization problem. The research took into account the cost of investment in the cable, the cost of construction, and energy losses. A method for grouping wind turbines has been proposed, where each group is initialized separately by the Prim algorithm. In this area, it is an optimization process done correctly, unfortunately, without a clear own contribution.

It is not clear whether the hybrid algorithm based on PSO and AO described in the paper is a proprietary solution. Improving search patterns when solving a complex multimodal problem concerning the topological structure of an offshore wind farm energy harvesting system is basically nothing new. Therefore, I think the authors should better emphasize their own contribution, shown in the work and clearly indicate how it differs from other methods described in the literature. It also requires a combination of benefits and possibly losses that result from the adopted optimization strategy. Such lists would be good to present to the reader in a compact form, e.g., tabular.

 In equation (6), p_e has a different designation from that in the following paragraph (P_e). Also, explain what a "penalty term" is and what is the reason for the 10^10 multiplier?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Thank you for the comprehensive explanations introduced in the manuscript. I believe that in its present form, the article has been sufficiently improved and is worth publishing. Congratulations on the hard work and the results obtained.