Round 1

Reviewer 1 Report (New Reviewer)

The author presented an energy management scheme for a microgrid with EVs and PVs connected. The critical comments are summarized bellowed:

1) In the abstract section, the author should clearly describe the scheduling strategy applied with its novelty highlighted. It is also suggested to add some quantitive results to prove the superiority of the proposed energy management scheme.

2) In section 2.1, the author presented a Simulink model for a microgrid. However, it needs to be made clear how each subsystem is constructed. For example, what is the applied circuit topology of the V2G charger and how the PV system is modelled?

3) How the scope subsystem in Figure 2 is related to the other sections?

4) The diversity and uncertainty of EV charging behaviours are not fully exploited in the paper. For example, EVs of different types can exhibit distinctive charging demands. This will definitely affect the energy charging schemes.

5) The proposed operational strategy is oversimplified and lacks of concerns about the EV charging requirements. For example, the EV charging duration, EV charging power, and the EV users' willingness to participate in the V2G service should be fully considered in the energy management scheme. Neglecting the above factors makes the proposed strategy infeasible.

6) The coordination between EV chargers needs to be considered. 

 

The writing style should be further polished.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Dear Authors,

 

 

General Comment: the subject is under intense debate, and the new research effort is welcome but the concept is not new.

 

"In our future work, we propose the optimal driving profile for V2G technology to be always beneficial."

 

The cost – It’s a problem. The Authors admit that the project has significant flaws. I would add the problem of "ageing" of li-ion batteries and photovoltaic panels. Their operational parameters are getting weaker.

 

Authors should include a list of abbreviations.

 

The references aren’t in English.

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Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

In the manuscript, the authors simulated the energy system that consists of a photovoltaic generator and an electric vehicle's battery connected to the microgrid. The EV battery will discharge to the grid during peak hours when the price of electricity is high, and charge during off-peak hours when the energy cost is low. Two cases with different driving profiles (whether to charge the battery at work) are compared. The results show that the photovoltaic generator will contribute 100% to cover the load requirements in one day in April, and it provides higher injection power to the grid using V2G technology. Revision is required before publication. A list of specific comments is as follows:

 

1. The resolution of Figure 2 needs to be improved to make the words readable.

2. It will be clearer to use hours as the unit instead of seconds when plotting parameters vs. time in Figures 5-12.

3. Figure 7 needs to be double-checked. It looks the same as in Figure 9.

4. In Tables 2 and 3, the numbers of power after 6 pm (7 pm) before 8 am (10 am) and the contribution of the EV battery need to be added.

5. In the discussion section, the comparison of the cost for the two cases needs to be explained more clearly. Is the cost of the charging at work in case 2 considered? How are the percentages of 5.65% and 6.53% calculated?

 

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Thank you for the efforts in making the modifications,

My main concern is the feasibility of the proposed energy management strategy (EMS). The further comments are summarized below:

1) How the peak hours are defined in Figure 3？ Why it is assumed to be 6:00 om? For example, the load consumption can be quite different between weekdays and weekends. 

2) The control objective is not mathematically defined in the paper. How to ensure that the minimum operation cost can be ensured by the EMS in Figure 3? Is there any optimisation technique applied ? 

3) In the abstract, the author mentioned that the energy cost can be reduced by the proposed EMS. However, the proposed EMS (Figure 3) does not consider the energy price at all.

4) The proposed EMS will prohibit EV charging after 6 pm, and this will sacrifice the charging flexibility.

5) When there are multiple EVs integrated into the microgrid, the proposed EMS can result in charging congestion.

 

 

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Thank you for the revision and responses. There are still concerns about the discussion of the results. 

 

1. Case one used 15.4 kWh for driving, and case two used 15.4+5.5-9.9 kWh = 11 kWh for driving. The contribution percentages are not comparable in these two cases, and they cannot be used to prove the strategy is beneficial.

 

2. There might be benefits in the cost, but it was not compared clearly. The injection power is the power injected into the main grid in off-peak hours and consumed during peak hours, then what is the cost for (361.30 kWh x 1.2467 DH/kWh = 450.43 DH)? The price differences before and after 6 pm should be considered when calculating the price for extraction power.

 

3. There is more power load during peak hours after 7 pm, and what is the power of extraction after 7 pm? Why are they not included in the calculation?

 

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

1.     Line number 153: ‘i.e.’ to be replaced by ‘if’.

2.     Line number 159: ‘are’ to be replaced by ‘will be’.

3.     Line number 182-183: The description of Figure 5 is not stated correctly.

4.     For all the figures: (a) x-axis and y-axis labelling is missing.

(b) Why x-axis is not considered in terms of hours? Present scaling is not easy to understand.

5.     Figure 8 and 10: The scaling of x-axis also need to be proper. How SoC is straight line i.e from 0.2 to 0.9 vertical at charging when connected to V2G terminal? Similarly at the discharged condition.

6.     Citation of figure in line numbers 200, 207, 249, 250, 277, 280 are not as per template of MDPI.

7.     The notation of unit of energy is different at each time. It should be same and as per standard ‘kWh’. ( correction needed in Table 2, Table 3 and all the sections)

8.     Line number 249: The values of SoC to be corrected as it is written ‘0,20’ and ‘0,2’ instead of ‘0.20’ and ’0.2’. Need to correct it.

9.     In Section 4: Case (ii): The calculation should also consider cost of energy consumption (DH/kWh) during the charging of EV at working hours because due to good SoC value only (0.65), the EV is able to inject the energy to grid at peak hours after reaching to home which is somewhat benefiting.   

Author Response

 "Please see the attachment." 

Author Response File: Author Response.docx

Reviewer 2 Report

No structure in the presentation of the methodology in this article.

Figure 1 exists in the MATLAB library, it is not a model developed by the authors.

What is the originality of this article?

The figures are of poor quality.

Which algorithm was used for the energy management strategy?

What percentage of the energy stored in the battery has been injected into the grid?

What is the MPPT algorithm used in this study?

What is the impact study of V2G on the grid during peak shaving and what is the saving impact?

The references are very poor and references 6 and 7 represent nothing.

The authors can use the articles below to improve their article.

-        Grid of Hybrid AC/DC Microgrids: A New Paradigm for Smart City of Tomorrow, IEEE-SOSE2020

-        Vehicle to grid technology: A review, 2015 34th Chinese Control Conference (CCC)

-        A smart cyber physical multi-source energy system for an electric vehicle prototype, ELSEVIER2020- Journal of systems architecture.

-        V2G and Wireless V2G concepts: State of the Art and Current Challenges, 2019 International Conference on Wireless Technologies, Embedded and Intelligent Systems (WITS)

The authors must seriously improve their article.

Author Response

 "Please see the attachment."