Novel Rotated Virtual Synchronous Generator Control for Power-Sharing in Microgrids with Complex Line Impedance

Round 1

Reviewer 1 Report

This paper proposed a rotated VSG control which is based on rotating the conventional reference frame by considering the complex grid condition. The method is compared with the conventional VSG control using the state-space model. the concept is interesting, and the structure is well organized. 

1. In line 3, the first word of this sentence should be capitalized.

2. What are the definitions of F and G in equations (6) and (7). It seems they are the defined new reference frame. Could you please mention it after equations (6) and (7).

3. In line 141, (??) is not correct. Please correct it. The same as line 155.

4. This paper presented a rotated VSG to deal with the grid impedance variation. The adaptive control is proposed in the following reference. Could the authors compare them? 

Mohammed N, Ravanji M H, Zhou W, et al. Online Grid Impedance Estimation-Based Adaptive Control of Virtual Synchronous Generators Considering Strong and Weak Grid Conditions[J]. IEEE Transactions on Sustainable Energy, 2022, 14(1): 673-687.

5. The reviewer admits that from Figs. 3 and 4 it can be observed that the stability of the proposed VSG is better than the conventional VSG. But it can be seen that 1R moves right when grid inductance or reactive power coefficient changes. The reviewer wonders if the eigenvalues can move to the right-half plane if the parameters further increase. Please confirm this.

6. Please clearly show the events in Figs. 5 and 6. The reviewer could not see what happened for each event.

7. Based on the eigenvalues loci in Figs. 3 and 4, could the authors add more simulation and experimental cases where the VSG is unstable (corresponding to the eigenvalues within the right-half plane) and the proposed VSG is stable (corresponding to the eigenvalues within the left-half plane). The oscillation frequency in the verification cases should match the eigenvalues.

8. For the state-space modelling of the VSG, the authors ignored the inner voltage and current control loop, which is alternatively converted in a recent publication as follows,

Xu J, Zhou W, Bahrani B. Small-Signal Modeling and Validation including State-Space and Admittance Models of the Virtual Synchronous Machine[M]//Grid-Forming Power Inverters. CRC Press, 107-130.

The reviewer suggests explaining the advantage of the simplified state space, probably in the section where the model is derived. 

Author Response

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper suggests a novel rotated virtual synchronous generator control for power sharing in microgrids with complex impedance lines, many challenges and worries still exist to the reviewer which requests to be fully addressed and improved.

Comment#1: introduction is too extended along with literature review, therefore, a clear and factual introduction is needed to rewrite and state briefly the purpose of the research which including the principle results and the major conclusions. The gap of this paper in the manuscript should be clearly and briefly clarified. Please point out and rearrange the contribution of your work before state of the art literatures.  

Comment#2: Please provide flowchart for your proposed methodology and how the current technology can be implemented in this work. Since, you utilized various equations, providing nomenclature at the beginning of your paper will be very useful and helpful to track your method.

Comment#3: The authors should explain setting parameters of the proposed method in table.

Comment#4: Please provide comparison table between your proposed method with other techniques and how your method can be verified and implemented for power system.

Comment#5: Authors should explain the process of model implementation and data construction on software platform.

Author Response

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper can be published in its current form.

Reviewer 2 Report

 Thanks for authors.

Regards