Extended Equal Area Criterion Revisited: A Direct Method for Fast Transient Stability Analysis
Round 1
Reviewer 1 Report
This paper deals with extended equal area criterion for transient stability analysis.
The conventional extended equal area criterion is well reviewed. In section 5, new contributions are well described.
- This paper has many pages. So, it is difficult to read. Specially, this paper includes many appendix. Some appendix can be replaced as references. If it is not possible, this paper can be divided two papers.
- In the simulation results, please add some figures to build up the advantages of new contribution.
Author Response
Dear Reviewer,
We highly appreciate your valuable comments on our manuscript. We have carefully considered the comments and have addressed them in the revised paper to improve the quality of the work.
In the following, we answer and clarify the points raised by the respected reviewer. The comments are in normal font and our responses are in italics.
We hope you will be satisfied with our responses to the comments.
Best Regards,
On behalf of all authors, Alireza Bahmanyar
ULiége
Email: [email protected]
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Reviewer comments and answers:
This paper deals with extended equal area criterion for transient stability analysis. The conventional extended equal area criterion is well reviewed. In section 5, new contributions are well described.
The authors highly appreciate the time and effort made by the respected reviewer for the detailed review of their paper.
- This paper has many pages. So, it is difficult to read. Specially, this paper includes many appendix. Some appendix can be replaced as references. If it is not possible, this paper can be divided two papers.
The EEAC was proposed years ago as a promising and fast transient stability analysis method. However, from the current literature, it was difficult to obtain a synthetic view of the concept and the key building blocks upon which the EEAC was built. The idea was to clarify the concept and to propose a general full-resolution functional scheme that not only covers all the previous literature on the subject, but also introduces interesting possibilities for several new approaches.
To this end, all the details of EEAC concept and equations are presented in this paper from scratch, to develop a clear basis for the future research on this interesting technique. The main part of the paper is 25 pages in the revised version, and many parts are moved to the appendix to avoid overwhelming the reader. Unfortunately, the details of the equations and the procedure presented in the paper appendix are not presented elsewhere, and it is not possible to replace them as references. We believe that a clear description of the concept and the implementation procedure of the EEAC method can regain the attentions on this interesting but less perceived technique.
- In the simulation results, please add some figures to build up the advantages of new contribution.
In this paper, the functional view proposed, introduces several new possibilities for EEAC approaches. In response to the respected reviewer comment, in the revised version of the manuscript, new simulation results and figures are added to better evaluate these schemes.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article is well written and organized. Besides, it revisited a very critical and important topic in the field of power system operation and control, e.g., Extended Equal Area Criterion and proposed a direct method for transient stability analysis. This reviewer has two minor concerns about the submitted manuscript:
- The quality of the figures should be enhanced. In most cases, the font sizes of texts in the figures are very small and not readable.
- The article has a few grammatical mistakes and typos that should be taken care of before publication.
Overall, the article can be accepted with minor revisions.
Author Response
Dear Reviewer,
We highly appreciate your valuable comments on our manuscript. We have carefully considered the comments and have addressed them in the revised paper to improve the quality of the work.
In the following, we answer and clarify the points raised by the respected reviewer. The comments are in normal font and our responses are in italics.
We hope you will be satisfied with our responses to the comments.
Best Regards,
On behalf of all authors, Alireza Bahmanyar
ULiége
Email: [email protected]
------------------------------------------
Reviewer comments and answers
The article is well written and organized. Besides, it revisited a very critical and important topic in the field of power system operation and control, e.g., Extended Equal Area Criterion and proposed a direct method for transient stability analysis. This reviewer has two minor concerns about the submitted manuscript.
The authors highly appreciate the time and effort made by the respected reviewer for the review of their paper. We hope the responses presented below are satisfactory.
- The quality of the figures should be enhanced. In most cases, the font sizes of texts in the figures are very small and not readable.
In response to the respected reviewers concern, all the figures are redrawn to increase their quality and readability.
- The article has a few grammatical mistakes and typos that should be taken care of before publication.
The revised version has gone through a professional native English editing. We tried to modify the mistakes and typos throughout the paper.
Overall, the article can be accepted with minor revisions.
Author Response File: Author Response.pdf
Reviewer 3 Report
The reviwer could not find any technical contribution in this manuscript. This is because, the problem formulation and solution both are the old problems. So, the reviwer completely disagree to accept this paper.
Author Response
Dear Reviewer,
We highly appreciate your valuable comment on our manuscript. In the following, we answer and clarify the point raised by the respected reviewer. The comment is in normal font and our response is presented in italics.
We hope you will be satisfied with our response to the comment.
Best Regards,
On behalf of all authors, Alireza Bahmanyar
ULiége,
-----------------------------
Reviewer comments and answers
The reviwer could not find any technical contribution in this manuscript. This is because, the problem formulation and solution both are the old problems. So, the reviwer completely disagree to accept this paper.
The authors highly appreciate the time and effort made by the respected reviewer for the review of their paper.
We agree with respected reviewer that the EEAC was proposed years ago. However, from the current literature, it was difficult to obtain a synthetic view of the concept and the key building blocks upon which the EEAC was built. We believe that a clear description of the concept and the implementation procedure of the EEAC method can regain the attentions on this interesting but less perceived technique.
The previous literature were lacking a detailed description of the concept and the equations. The clear description of the concept and the equations in this paper, and the functional view presented, provides a clear basis for the future research on this interesting subject. Moreover, the presented full-resolution functional scheme not only covers all the previous literature on the subject, but also introduces limitless possibilities for several new EEAC approaches. As examples, the approaches referred to as `Refinement 1' and `Refinement 2' in the paper, are not proposed in the previous literature.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
However, still the reviewer has the following concerns before accepting this paper for publication:
- First of all, the presentation of this paper is very poor as it is really hard to follow each section.
- Abstract of this paper needs to improve in view of existing problems and its solution adopting by new methodology.
- Introduction section should be enhanced in the revised version of this paper. The literature review requires improvement along with more recent papers.
- The quality of all figures should be improved.
- The motivation for the suggested method should be more carefully laid out, in particular with respect to previous publications in the area.
- It is required to improve the conclusion part with clear suggestions in bullet points.
Author Response
Dear Reviewer,
We highly appreciate your comments on our manuscript. In the following, we answer and clarify the points raised by the respected reviewer. The comments are in normal font and our responses are presented in italics.
We hope you will be satisfied with our responses to the comments.
Best Regards
On behalf of all authors, Alireza Bahmanyar
ULiége
Email: [email protected]
---------------------------------------
Reviewer comments and answers:
- First of all, the presentation of this paper is very poor as it is really hard to follow each section.
The concept of equal area criterion for a single machine infinite bus model is quite well-known and easy to understand. However, when it comes to a multimachine power system, it soon becomes complex. The Extended Equal Area Criterion (EEAC) was proposed years ago, but the concept behind was not really clarified before, as it is complex and difficult to present. In this paper, we approach the concept in its most general form. We then describe the necessity and the ideas behind the approximate models, and their detailed formulation in the appendix, to not overwhelm the reader. In the next step, we describe the other algorithms required to implement the EEAC, e.g. the critical cluster identifier. The paper presents each algorithm as a function. We believe this functional view will help the reader to realize the connection between the algorithms in software implementations. Moreover, it helps to realize a full resolution scheme of EEAC described in the last sections. The main idea was to describe the complex content of EEAC systematically from the parts to the whole. As the respected reviewer mentioned, this systematic presentation style might seem effortful to follow at the beginning, but it forms the big picture elegantly section by section.
- Abstract of this paper needs to improve in view of existing problems and its solution adopting by new methodology.
In response to the respected reviewers comment, the main contribution of the paper are more highlighted in the abstract of the revised version.
- Introduction section should be enhanced in the revised version of this paper.
The introduction is presented as a story line to serve multiple purposes. It presents the background, starting with transient stability and the evolution of direct methods. It then introduces the paper topic, the EEAC, and gives an overview of the first papers on the subject to the recent ones. It then presents the idea and the reason of revisiting the EEAC to provide a solid foundation and to encourage readers to continue on to the main parts of the paper. At the end of the introductions, the systematic procedure of the paper from the parts to the whole is clearly outlined, and the main contribution are highlighted.
- The literature review requires improvement along with more recent papers.
The EEAC is quite an old method and most of the literature on this subject date back to 1988 to 2000. However, the recent literature on the subject which mainly present the application of the EEAC technique are also reviewed, including the ones published in 2020 and 2021.
- The quality of all figures should be improved.
We agree with the respected reviewer that the quality of the figures had to be improved. During the previous review round, we improved the quality and readability of all the figures.
- The motivation for the suggested method should be more carefully laid out, in particular with respect to previous publications in the area.
This paper is more of a review type that revisits the EEAC concept. It is built on a project to overcome the problems a real TSO is facing these days in the operation of its transmission networks. In introductions, we have presented the motivation of revisiting the EEAC:
These days, power systems are operating closer to their security limits and the uncertainties are increasing. Hence, the list of scenarios to study is increasing substantially. Therefore, though the recent significant reduction, time-domain simulation computational time is still restrictive for the growing list of case studies, calling for fast, transient stability analysis techniques once more. The EEAC, provides the possibility of a quick TSA, on a large number of case studies, to filter the list of critical contingencies. The limited list of critical contingencies can then be investigated in detail with time-domain simulations.
- It is required to improve the conclusion part with clearsuggestions inbullet points.
In conclusions the motivations are presented in the first paragraph and then the contributions are clearly presented:
This paper has revisited the EEAC from scratch. It has presented its very basic concept, the detailed equations, and the idea behind the approximations for fast TSA. New definitions and conditions have been designed to approximate model forward swing and backward swing stabilities. Based on these definitions and conditions, functions were developed for each EEAC building block, together with detailed pseudocodes. The idea was to propose a general full-resolution functional scheme that not only covers all the previous literature on the subject, but also introduces interesting possibilities for several new approaches.
Then, after summarizing the results, the suggestions for future research are presented:
Further studies are required to design result quality indicators to tag cases where EEAC may not perform well. Moreover, the EEAC equations should be developed to consider non-synchronous generation units (e.g., windfarms) and HVDC links.
Author Response File: Author Response.pdf
