A Comparative Study of Supercapacitor-Based STATCOM in a Grid-Connected Photovoltaic System for Regulating Power Quality Issues

Round 1

Reviewer 1 Report

Described investigation of Supercapacitor based STATCOM  does not bring anything new. The research shows some basic schemes and pseudo-research at a very low level. 

Author Response

We greatly appreciate the reviewer’s efforts to carefully review the manuscript Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Article presents the problem of cooperation of STATCOM type devices based on supercapacitors with the power grid and loads. The problem is difficult and current.

The article begins with a very extensive recognition of the topic and analysis of available literature. In my opinion, the selection of literature is correct and the publications cited are actual. Introducing the reader in the subject of the article is correct and understandable, it contains many mathematical relationships describing STATCOM type devices. The authors also present the test environment.

The main part of the article is a comparative analysis of STATCOM systems based on supercapacitors and batteries, taking into account additional interference from the source of energy (irradiance). The analysis is complete and detailed, although in my opinion the conclusions drawn from it should be expanded. The authors focus mainly on presenting time courses of selected quantities.

The thesis presents a very high substantive level and in my opinion it needs to be supplemented only with slightly more extensive conclusions, which I would like to ask for.

I would like to thank the Authors and congratulations for undertaking such a difficult topic and wish them further successes in research and scientific work.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The topic of this work is interesting. The authors provide a pretty detailed study of supercapacitor based STATCOM. Some extended works need to be done before the manuscript is accepted. Below are some detailed issues with this manuscript:

1. In section 2 (“Proposed design”), the authors simply describe the design of STATCOM. However, why do they choose to design like these? What are the advantages?
2. The authors don’t need to show all mathematical procedures of how they got the grid voltages, STATCOM, and load currents. Please pick some important ones from equation (4) – (40) and put the others in the supplementary section.
3. In section 4 (“Results and Comparison of …”), the authors demonstrated and compared all the results. However, they didn’t provide discussions regarding these results: what do these results represent? Which parameters play an important role?
4. The figures in section 4 are terribly prepared:

• Figure 8, 21, 22, 23, and 24: cannot see the spectrograms in the sub-figure; cannot tell the differences among the three phases (should use different colors or divide them with dash-lines);
• Figure 9, 11, and 15: lack of zoom-in diagrams for Phase 1 and 3; Figure 15 lacks the vertical axis title;
• Figure 10: the zoom-in diagrams should be in the same step, for example, every 0.02 second;
• Figure 12 and 13 should be combined together;
• Figure 14: the authors should emphasize the difference between SCESS/STATCOM and BESS/STATCOM since the reviewer hardly see any difference between Figure 14(a) and 14(b); cannot see the spectrograms in Figure 14(b);
• Figure 16(b) and 17(b): it is easier to understand the diagram without the zoom-in diagrams;
• Figure 18: the diagrams should be in the same range to compare: 0~3 seconds;
• Figure 19 and 20 should be combined together;
• Figure 25: cannot see the spectrograms in Figure 25(a); Figure 25(b) and 26(b) are so redundant, should just zoom-in once.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I am still confused about the statcom controller design and the diagram of the system. 

For example, You have connected the statcom with the grid through thyristor and you have a controller for the thyristor, at this figure could you please explain what is a statcom? 

Figure 2, could you please explain the connection of filter with the solar system and the connection point of statcom? As from figure 1, it seems you are controlling the current Iac through the statcom controller while there is no connection in figure 2.  

 

From figure 5, it is not clear if you are designing a statcom or a power quality condenser for the system, please explain.

 

To identify the contribution of your work you have explained the necessity of such a device, however, how did you differentiate the dynamic characters of a battery or capacitor with supercapacitor need to be explained. In this case, a dynamic stability analysis can be helpful. 

As you claim "This design of supercapacitor based STATCOM is being used for a grid-connected solar power plant in which the main source of the power supply is solar and is very rare in literature". I would like to have a justification for your design on how it will be economically viable while you are increasing complexity in the designed controller.  

 

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

The reviewer is satisfied with the responses the authors provided. 

Author Response

Thanks for reviewing our research article your suggestion really improved the quality of this reseach