Power Flow Control Strategy and Reliable DC-Link Voltage Restoration for DC Microgrid under Grid Fault Conditions
Round 1
Reviewer 1 Report
It is clearly a high-level comprehensive research work. Both the content and the way that this research is presented demonstrate the importance of the subject. The effectiveness of the control schemes and the developed algorithms is confirmed by simulation and experimental results.
Only minor spell checking is needed in a few cases.
Author Response
Point 1: Comments and Suggestions for Authors
It is clearly a high-level comprehensive research work. Both the content and the way that this research is presented demonstrate the importance of the subject. The effectiveness of the control schemes and the developed algorithms is confirmed by simulation and experimental results.
Only minor spell checking is needed in a few cases.
Response 1: Thank you for your comments. Concerning the reviewer’s comment, the authors carefully reviewed the entire manuscript especially regarding English expressions and spell checking. All the corrections have been highlighted in the revised paper.
Reviewer 2 Report
I agree that too many rules were created in AC, with or without reason, the harmonics are caused by led lamps, laptops, which save a lot of energy (compared to filament, CFL, mainframe), PFC have significant losses and have a risk of HF EMC. Without PFC, voltage spikes are limited, which may be more harmful than harmonics. But we have to take care not to do create too much rules in DC as well.
26 pages is (too) long... or the system too complex?
13 modes, in fact it should influence the cost of the sold electricity: what is exchanged in a battery is much more expensive (in money and CO2 to make the battery) that the original renewable energy. One should be able to stimulate the users to use electricity "as and when the sun shines" or "as and when the wind blows".
A lot of appliances can work on DC, between the extremes of 110Vdc up to 370Vdc, but would be damaged at the proposed 400Vdc.
The fact to use a "central controller" is already a problem for reliability: lightning or ageing. The DC voltage is above 370V: this does not permit using normal equipment in houses, as they are made for an extreme voltage of 370V (240V*1.1*2^0.5, Austrailia). Only equipment which was made for PFC has such a high internal dc voltage.
I put "minor revision" with the purpose to shorten the text: remove weaker parts to strengthen the average? Who will read all the pages?
Author Response
Thank you for your comments.
The authors carefully corrected our manuscript according to the reviewer’ comments and uploaded our replies in attached file.
"Please see the attachment"
Author Response File: 
Author Response.docx
Reviewer 3 Report
In this paper Authors proposed power flow control strategy (PFCS) based on the centralized control method and a reliable DC-link voltage (DCV) restoration algorithm for DC microgrid (DCMG) under grid fault conditions. Authors proposed also DCV restoration algorithm to prevent the system power imbalance in DCMG caused by the delay of grid fault detection. Comprehensive simulations and experiments based on DCMG testbed are carried out to prove the effectiveness of the PFCS and the proposed DCV restoration algorithm. Below I presented some remarks that came to my mind during reading.
Remarks:
1. Line 203: Empty line is unnecessary.
2. Figure 2: Figure and description of the figure should be on one page.
3. Lines 214-234: In my opinion, the symbols should be defined in the description of Figure 2.
4. The discussion needs more details, the observations and future trends. This chapter should be connected with others published papers. From my point of view, it has no justification not conducting a comparison with similar works already published. The lack of such a comparison compromises the significance of the paper.
5. Conclusions should be worded slightly different. Try to emphasize novelty. The Authors should highlight what are the advantages and disadvantages when comparing their devised solution with other solutions from the scientific literature. Put some quantifications, and comment on the limitations. This is a very common way to write conclusions for a learned academic journal. The conclusions should highlight the novelty and advance in understanding presented in the work.
6. The Authors should present the findings also highlighting current limitations of their study, and briefly mention some precise directions that they intend to follow in their future research work.
Author Response
Thank you for your comments.
The authors carefully corrected our manuscript according to the reviewer’ comments and uploaded our replies in attached file.
"Please see the attachment"
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
The comments and corrections made as part of my first review have been addressed. The authors have taken into consideration all my questions and comments. I recommend to accept the new version of the paper.
Author Response
Thank you for your comments and review
