A Rotor Winding Internal Short-Circuit Fault Protection Method for Variable-Speed Pumped Storage Units

Round 1

Reviewer 1 Report

A rotor windings’ internal short-circuit fault protection method based on the harmonic characteristics of the circulating current between stator branches is proposed in the paper.

There are following remarks

1.Methods of diagnosing short circuits in the rotor by harmonic analysis of stator currents are well known. It is necessary to explain the advantages of the proposed method.

2.The turbine rotor does not contain windings. The windings are in the rotors of an electric machine driven by a turbine.

3.It is necessary to explain why the harmonic spectrum of the currents in different branches of the stator winding during a short circuit in the rotor is different (Fig. 3).

4.It should be «Substitute Eq. (4) into Eq. (1)» instead  «Substitute Eq. (4) into Eq. (2)» in the line 119.

5.The term «simulation modeling» is not clear (line 163).

6. There should be 0 instead of spaces in the matrix of Eq. 9.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

 

The title of the article is A Rotor Windings’ Internal Short-circuit Fault Protection Method for Variable-speed Pumped Storage Units. It's about multi-Loop fault analysis method for protection elements. I have some questions and comments in the attached file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Review of

 A Rotor Windings’ Internal Short-circuit Fault Protection 2 Method for Variable-speed Pumped Storage Units

This is a very well written, understandable article.  There are a number of grammatical suggestions that are marked on the manuscript.  The biggest difficulty in understanding this work is in missing information in figures and a few definitions.

Required changes.

1.       On page 6 define TPY

2.       Page 7, figure 3.  What is the current normalized to?  Also, the abscissa needs to be labeled (time in sec) and the fact that the fault occurred at 35 sec in branch A2 in th figure caption

3.       Page 8., figure 4 the axes need to be labeled again and state fault occurred in branch A at t=35.0 seconds. 

4.       Page 8 Figure 5.  Is the amplitude of the 50 Hz fundamental 1?  So these are normalized amplitudes?

5.       Page 10.  A p.u. needs to be defined. What are good values and bad values?

6.       Page 11.  You state the minimum protection action value is .0473 p.u.  How was this determined and what is an acceptable p.u. value?

7.       Page 12 Figure 9 and following figures.  What does the red number indicate?  Also what is the arrow about?  (It looked like a slope at first.)  If say in figure 9a the minimum value was 0.1678 then it would be helpful to have the arrow pointed in the opposite direction and maybe label the number as (1, 0.1678) and explain this.   The density shading is good.  On parts where these is a large (approximately 2-orders of magnitude variation) would a log scale for the ordinate help?

The paper is informative, interesting, and timely.  It should be published subject to these changes.  I will rereview if desired. 

Comments for author File: Comments.docx

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

 

In my opinion the authors have answered all the questions and have improved the article whose title is:

A Rotor Windings’ Internal Short-circuit Fault Protection Method for Variable-speed Pumped Storage Units.

 

Thank you very much