Research on Frequency Response Modeling and Frequency Modulation Parameters of the Power System Highly Penetrated by Wind Power

Round 1

Reviewer 1 Report

The work is interesting. The following comments should be incorporated in the revised version of the manuscript:

1. The introduction should be divided into three subsections: 1) Literature review, 2) Research gap and motivation and 3) Contribution and paper organization.
2. The main contributions of this paper should be further summarized and clearly demonstrated. This reviewer suggests the authors exactly mention what is new compared with existing approaches and why the proposed approach is needed to be used instead of the existing methods.
3. Conclusions should be further refined.
4. Comparison with the existing published control methods not provided.
5. Language requires improvement.
6. Literature review is insufficient. More papers should be added and reviewed critically.
7. What are the advantages and drawbacks of the proposed method?
8. Frequency should be shown by ω and not by w. Please check frequency unit Hz or Radian.
9. In Figs. 3-4, Results should be shown by dot, dash, dot-dash and with different line widths so that they can be easily distinguished.
10. IEEE three-machine nine-node simulation system is not a realistic system. Authors should simulate a high bus realistic system.
11. Give reference no in Table 1 and Appendix A.

Author Response

Response to Reviewer 1 Comments

Dear Reviewer

The authors would like to thank the editor and reviewers for their thoughtful comments and suggestions, which certainly helped us improve the quality of this paper. Now the paper has been revised and improved based on the recommendations from the editor and reviewers. All changes made in the revised paper based on the reviewer’s comments are highlighted in red.

Reviewers’ comments:

The work is interesting. The following comments should be incorporated in the revised version of the manuscript:

Response: Thanks for your encouragement of our work. We sincerely appreciate the reviewer for your valuable time to read throughout the paper and indicate these valuable comments to us. The valuable comments helped us improve the quality of our paper.

General questions:

1, The introduction should be divided into three subsections: 1) Literature review, 2) Research gap and motivation and 3) Contribution and paper organization.

Response: Thank you for your suggestions. As shown in this paper, we have divided the introduction into three subsections according to your opinion. This will make the introduction more reasonable and organized.

2, The main contributions of this paper should be further summarized and clearly demonstrated. This reviewer suggests the authors exactly mention what is new compared with existing approaches and why the proposed approach is needed to be used instead of the existing methods.

Response: Thanks for your advice. We have summarized the contributions in section 1.3.1 and 5.1. On the one hand, we analyzed the existing research on SFR model, summarized and analyzed the shortcomings of the existing research in section 1.2. On the other hand, we compared the model proposed this paper with the model and calculation method in existing literature in section 2.2.

Most of the researches only conduct qualitative analysis on the influence of wind power permeability on system frequency. Little researches calculate the DFIG’s frequency modulation parameters that meet the system’s requirements according to the frequency response formula. It is of great engineering significance to improve the existing SFR model and derive the system frequency response formula in combination with the system frequency stability requirements.

The TSFR model in [27] provides a theoretical basis for the analysis of the frequency response of the power system. The model in [20] considers various frequency response strategies of wind power. And this paper draws on two mature virtual response control strategies. The SFR model proposed combines the advantages of models in [19-20] and [22]. Compared with the models in [19] and [22], the model considers not only the permeability of wind power, but also the complex and specific strategies of DFIG. Compared with the model in [20], the model can reflect not only the permeability of the wind power but also the effect about rotor frequency   to the system frequency. Therefore, it can fit the actual power system better than the TSFR.

[19] Li, H., Wang, J., Du, Z., Zhao, F., Liang, H., Zhou, B. Frequency control framework of power system with high wind pene-tration considering demand response and energy storage. The Journal of Engineering 2017, pp. 1153–1158.

[20] Wu, Z., Gao, W., Gao, T., Yan, W., Zhang, H., Yan, S., Wang, X. State-of-the-art review on frequency response of wind power plants in power systems. Journal of Modern Power Systems and Clean Energy 6, 2018, pp. 1–16.

[22] Zhang Jianyun, Li Mingjie. Analysis of the Frequency Characteristic of the Power Systems Highly Penetrated by New Energy Generation, in Proceedings of the Chinese Society of Electrical Engineering 2020, Volume 9, pp.3498-3506.

[27] Kundur P. Power system stability and control. New York：McGraw-Hill,1994,395-428.

3, Conclusions should be further refined.

Response: Thanks for your suggestions. we have adopted the advice, and further simplify and summarize the conclusions in section 5.1.

4, Comparison with the existing published control methods not provided.

Response: we compared the model proposed this paper with the model and calculation method in existing literature in section 2.2. On the one hand, the model is proposed based on the existing researches, and it combined the advantages of different models. On the other hand, another work of this paper is to quantitively calculate the frequency modulation parameters that meet the requirements of system stability.

5, Language requires improvement.

Response: Thanks for your careful review. There are some improper words in this paper. We have checked and corrected them one by one.

6, Literature review is insufficient. More papers should be added and reviewed critically.

Response: Thanks for your comments. We have supplemented a large number of reference and discussed the control strategy of DFIG and the SFR model of the system in section 1.2.

7, What are the advantages and drawbacks of the proposed method?

Response: Thank you for your question. We have added this point in section 5.2. The details are as follows:

The frequency response model proposed in this paper equates all DFIG in the system to one, which cannot reflect the working state of a single fan. The advantage of this method is that the characteristics of the system frequency response are preserved to the greatest extent, while simplifying the calculation. We can use the transfer function to calculate the frequency stability of the system, as the calculations in section 3.

However, in practice, the working state of the wind turbine is different, and the response ability of participating frequency is different. And It only considers two relatively simple frequency response control strategies. When other frequency response control strategies are considered, the calculation will become very complex and there will be the possibility of non-closed loop.

8, Frequency should be shown by ω and not by w. Please check frequency unit Hz or Radian.

Response: Thanks for your remarks. And we have corrected the figures and check the frequency unit in Figure 8,10,11,13.

9, In Figs. 3-4, Results should be shown by dot, dash, dot-dash and with different line widths so that they can be easily distinguished.

Response: Thanks for your remarks. According to your advice, we have changed the line of the Figure 3 and Figure 4 as shown below.

Figure 3. System frequency response under different wind power permeability.

Figure 4. Influence of different control parameters on system frequency.

10, IEEE three-machine nine-node simulation system is not a realistic system. Authors should simulate a high bus realistic system.

Response: Thanks for your pertinent suggestions. The IEEE three-machine nine-node system is to small to reflect the frequency response of the real system. This paper models the IEEE-bus New England test system by DIgSILENT Power Factory. The system structure topology is shown as below.

Figure 6. Diagram of the 39-node system.

Based on the 39-node system, this paper sets the Case 3. Compare the frequency response in the frequency-domain and time-domain to verify the accuracy of the model in large scale system as shown below. Specific case details are analyzed in section 4.4

Figure 13. The results of case 3 system frequency simulation.

11, Give reference no in Table 1 and Appendix A.

Response: Thanks for your careful review. In Appendix A, the generators set, lines and transformer parameters adopt the Simulink’s own parameters. DFIGs and the other parameters are set according to reference [29]. According to the detailed parameters in Appendix A, we can calculate the frequency domain parameters of the SFR model based on the calculation methods in [18]. The frequency domain response parameters are shown in Table 1.

[18] Q. Shi, F. Li and H. Cui, Analytical Method to Aggregate Multi-Machine SFR Model With Applications in Power System Dynamic Studies, in IEEE Transactions on Power Systems 2018, Volume 33, no. 6, pp. 6355-6367.

[29] Hu, B., Tang, F., Liu, D., Li, Y., Wei, X., 2021. A Wind-Storage Combined Frequency Regulation Control Strategy Based on Improved Torque Limit Control. Sustainability 2021, Volume 13, pp. 3765.

 

Thank you again for reviewing the paper. Your valuable comments are of great significance to the thesis of this paper. We hope that the revised paper could show our efforts to the reviewers, and sincerely hope revision can meet the requirement. If there are any suggestions, please tell us.

We wish you all the best and good health.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is about frequency response modelling and simulation in the case of wind energy. It is well presented and shaped with lines 78-80 defining the research gap of this research.

The literature review is very extensive in this topic, albeit the authors cited one of the most significant ones. I invite the authors to provide further literature review to cover widely the research made in this topic.

Minor remarks:

- It is better to include and properly cite author's name in the text when you are referring to their work (e.g: "Margaris et al. analyse that wind" instead of "[18] analyses that wind"

- Figure 1, please define P and the Delta

- equations are sometimes put without clearly explaining their purpose and their link to the followed logic, e.g: equations 27 and 28

- lines 358-363, please define which formula from section 2.2 you are referring to

- if relevant, please consider the two following references dealing with Frequency control framework of power system with high wind penetration. Please define how your model differs from these references,

https://doi.org/10.1049/joe.2017.0510

https://doi.org/10.1007/s40565-017-0315-y

 

Author Response

Response to Reviewer 2 Comments

Dear Reviewer

The authors would like to thank the editor and reviewers for their thoughtful comments and suggestions, which certainly helped us improve the quality of this paper. Now the paper has been revised and improved based on the recommendations from the editor and reviewers. All changes made in the revised paper based on the reviewer’s comments are highlighted in red.

Reviewers’ comments:

The paper is about frequency response modelling and simulation in the case of wind energy. It is well presented and shaped with lines 78-80 defining the research gap of this research.

The literature review is very extensive in this topic, albeit the authors cited one of the most significant ones. I invite the authors to provide further literature review to cover widely the research made in this topic.

Response: Thanks for your recognition and encouragement of our work. We sincerely appreciate the reviewer for your valuable time to read throughout the paper and indicate these valuable comments to us. The valuable comments helped us improve the quality of our paper. At the same time, we have supplemented a large number of reference and discussed the control strategy of DFIG and the SFR model of the system in section 1.2.

Minor remarks:

1, It is better to include and properly cite author's name in the text when you are referring to their work (e.g: "Margaris et al. analyse that wind" instead of "[18] analyses that wind".

Response: Thanks for your careful review. In this paper, we have modified some important references according to your advice. Some references are cited as follows:

Fangxing Li et al propose the calculation method of system equivalent parameters and verify its effectiveness in [18].

2, Figure 1, please define P and the Delta.

Response: Thanks for your careful review, we have explained it in the paper, according to your advice.

Figure 1. The traditional frequency response model of the power system

In Figure 1, ΔP_L is the disturbance power, Δw and are system frequency deviation and reference value respectively; Δw_ref is the turbine coefficient of the turbine generator; T is the equivalent time constant of the turbine; M is the rotor time constant; 1/R is governor gain; D is the frequency response coefficient of the load.

3, Equations are sometimes put without clearly explaining their purpose and their link to the followed logic, e.g: equations 27 and 28.

Response: Thanks for your careful remarks. Some equations including 27 and 28 in the paper are not properly defined and explained. We have corrected them one by one.

4, lines 358-363, please define which formula from section 2.2 you are referring to.

Response: Thank you for your remarks. The equations in lines 358-363 are not from section 2.2. They are from section 3.2. We have corrected it as follows.

Calculate the RoCoF according to the frequency response of the seven different control parameter combinations set, as shown in Figure 12. According to the calculation formula (20) proposed in Section 3.2, when A2 > 2.13, the system meets the maximum frequency change rate requirements. But as shown in Figure 12, when A2 > 2.5, the maximum frequency change rate of the system meets the requirements; When A2 < 1.5, the maximum frequency change rate of the system is greater than 0.5 Hz/s. It shows that the calculation formula proposed in Section 3.2 has errors within the allowable range and verifies the correctness of the theoretical calculation.

5, If relevant, please consider the two following references dealing with Frequency control framework of power system with high wind penetration. Please define how your model differs from these references.

Response: Thanks for your suggestions. We have carefully read these two references, and cited and compared them in the paper.

The TSFR model in [27] provides a theoretical basis for the analysis of the frequency response of the power system. The model in [20] considers various frequency response strategies of wind power. And this paper draws on two mature virtual response control strategies. The SFR model proposed combines the advantages of models in [19-20] and [22]. Compared with the models in [19] and [22], the model considers not only the permeability of wind power, but also the complex and specific strategies of DFIG. Compared with the model in [20], the model can reflect not only the permeability of the wind power but also the effect about rotor frequency   to the system frequency. Therefore, it can fit the actual power system better than the TSFR.

[19] Li, H., Wang, J., Du, Z., Zhao, F., Liang, H., Zhou, B. Frequency control framework of power system with high wind penetration considering demand response and energy storage. The Journal of Engineering 2017, pp. 1153–1158.

[20] Wu, Z., Gao, W., Gao, T., Yan, W., Zhang, H., Yan, S., Wang, X. State-of-the-art review on frequency response of wind power plants in power systems. Journal of Modern Power Systems and Clean Energy 6, 2018, pp. 1–16.

[22] Zhang Jianyun, Li Mingjie. Analysis of the Frequency Characteristic of the Power Systems Highly Penetrated by New Energy Generation, in Proceedings of the Chinese Society of Electrical Engineering 2020, Volume 9, pp.3498-3506.

[27] Kundur P. Power system stability and control. New York：McGraw-Hill,1994,395-428.

 

Thank you again for reviewing the paper. Your valuable comments are of great significance to the thesis of this paper. We hope that the revised paper could show our efforts to the reviewers, and sincerely hope revision can meet the requirement. If there are any suggestions, please tell us.

We wish you all the best and good health.

 

Author Response File: Author Response.docx

Reviewer 3 Report

It is not clear from the paper (up to the case study) whether the frequency response model of the wind power highly penetrated system was created by the authors, or whether it is taken over. After you expressed that it could be obtained in this way (followed by figure 2), you stopped. Here should have been the most important part, namely the more detailed description of the model and what underlies it. The analysis of the effect of the implementation of the model does follow, but it is not enough.
What are the parameters in Table 1 (name of parameters D, T, a, M, R)? Nothing is mentioned about them, not even in Appendix A.
Additional materials from the address specified in line 393 cannot be accessed.
Bibliographic references should be improved with more titles to support the theory and the current stage of development.

Author Response

Response to Reviewer 3 Comments

Dear Reviewer

The authors would like to thank the editor and reviewers for their thoughtful comments and suggestions, which certainly helped us improve the quality of this paper. Now the paper has been revised and improved based on the recommendations from the editor and reviewers. All changes made in the revised paper based on the reviewer’s comments are highlighted in red.

Comments and Suggestions:

1, It is not clear from the paper (up to the case study) whether the frequency response model of the wind power highly penetrated system was created by the authors, or whether it is taken over. After you expressed that it could be obtained in this way (followed by figure 2), you stopped. Here should have been the most important part, namely the more detailed description of the model and what underlies it. The analysis of the effect of the implementation of the model does follow, but it is not enough.

Response: Thanks for your careful review. We have supplemented the relevant analysis in section 2.2 according to your suggestions. We have summarized the contributions in section 1.3.1 and 5.1. On the one hand, we analyzed the existing research on SFR model, summarized and analyzed the shortcomings of the existing research in section 1.2. On the other hand, we compared the model proposed this paper with the model and calculation method in existing literature in section 2.2.

Figure 2. The frequency response model of the wind power highly penetrated system.

As shown in Figure 2, the improved SFR model consists frequency response model of DFIG and the traditional frequency response model. The model is proposed after improvement based on the models in [19-20],[22] and [28]. P_wind can reflects the change of system frequency by the virtual control strategies and wind speed by the MPPT strategy. The wind power permeability is adjusted through K. The calculation of system parameters is the same as that of TSFR [18], and the whole wind farm is equivalent to a DFIG.

The TSFR model in [27] provides a theoretical basis for the analysis of the frequency response of the power system. The model in [20] considers various frequency response strategies of wind power. And this paper draws on two mature virtual response control strategies. The SFR model proposed combines the advantages of models in [19-20] and [22]. Compared with the models in [19] and [22], the model considers not only the permeability of wind power, but also the complex and specific strategies of DFIG. Compared with the model in [20], the model can reflect not only the permeability of the wind power but also the effect about rotor frequency   to the system frequency. Therefore, it can fit the actual power system better than the TSFR.

[19] Li, H., Wang, J., Du, Z., Zhao, F., Liang, H., Zhou, B. Frequency control framework of power system with high wind penetration considering demand response and energy storage. The Journal of Engineering 2017, pp. 1153–1158.

[20] Wu, Z., Gao, W., Gao, T., Yan, W., Zhang, H., Yan, S., Wang, X. State-of-the-art review on frequency response of wind power plants in power systems. Journal of Modern Power Systems and Clean Energy 6, 2018, pp. 1–16.

[22] Zhang Jianyun, Li Mingjie. Analysis of the Frequency Characteristic of the Power Systems Highly Penetrated by New Energy Generation, in Proceedings of the Chinese Society of Electrical Engineering 2020, Volume 9, pp.3498-3506.

[27] Kundur P. Power system stability and control. New York：McGraw-Hill,1994,395-428.

2, What are the parameters in Table 1 (name of parameters D, T, a, M, R)? Nothing is mentioned about them, not even in Appendix A.

Response: Thank you for your suggestions. We have supplemented the relevant references in section 2.1 and section 4.1.1.

Figure 1. The traditional frequency response model of the power system

In Figure 1, ΔP_L is the disturbance power, Δw and Δw_ref are system frequency deviation and reference value respectively; a is the turbine coefficient of the turbine generator; T is the equivalent time constant of the turbine; M is the rotor time constant; 1/R is governor gain; 1/R is the frequency response coefficient of the load. The multimachine system parameters can be equivalent to the single machine system parameters according to [18].

In Appendix A, the generators set, lines and transformer parameters adopt the Simulink’s own parameters. DFIGs and the other parameters are set according to reference [29]. According to the detailed parameters in Appendix A, we can calculate the frequency domain parameters of the SFR model based on the calculation methods in [18]. The frequency domain response parameters are shown in Table 1.

[18] Q. Shi, F. Li and H. Cui, Analytical Method to Aggregate Multi-Machine SFR Model With Applications in Power System Dynamic Studies, in IEEE Transactions on Power Systems 2018, Volume 33, no. 6, pp. 6355-6367.

[29] Hu, B., Tang, F., Liu, D., Li, Y., Wei, X., 2021. A Wind-Storage Combined Frequency Regulation Control Strategy Based on Improved Torque Limit Control. Sustainability 2021, Volume 13, pp. 3765.

3, Additional materials from the address specified in line 393 cannot be accessed.

Response: Thank you for your careful remarks. There is no more materials from the address specified in line 393. And we have deleted it.

4, Bibliographic references should be improved with more titles to support the theory and the current stage of development.

Response: Thanks for your pertinent suggestions. As shown in this paper, we have divided the introduction into three subsections according to your opinion. This will make the introduction more reasonable and organized. At the same time, we have added the Case 3 in section 4.3 to verify the accuracy of the model in large scale system.

 

Thank you again for reviewing the paper. Your valuable comments are of great significance to the thesis of this paper. We hope that the revised paper could show our efforts to the reviewers, and sincerely hope revision can meet the requirement. If there are any suggestions, please tell us.

We wish you all the best and good health.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper may be accepted.