This is a good paper with both practical tests and an economic analyse that prove the benefits of frequency support from wind turbines.

Dear Author,
By an advice from the chief editor I have invited a 3 reviewer and he has also engaged his colleges working with the market issues. Please consider the comments from Mattias Persson to make the paper more clearly to the readers and there by more valuable.
When reading your comments of the previous reviews, I agree in most of your comments, but still I think the new review is well done and needs your full attention.
I personally like the paper it gives me a valuable information in a direct and practical way. I am looking forward to read the paper with the improvements suggested in the new review and your comments of the review.

Dear Authors,
I like your work with testes on commercial wind turbines it gives a good knowledge and experience of the control of the turbine and can help the development of the frequency control by wind turbines.
I have seen your last update of the paper and it is good, although I still like to see some small updates.
1. Regarding the comments from the latest review. Figure 2. Have a figure of Type 3 and Type 4 wind turbine and saying they ae different, it give notthing to the reader. Skip this text.
2. I like to see a motivation to your selection of AGC signals in figure 6. One is at rated power the other one around zero, wat what is good with the selection, what should the reader learn.
3. In the same way what are the motivations for perform the specific tests I table 1 ?
4. Page 9 line 3: some words missing?
5. Page 9 line 5: Do not write about a future battery test in this paper, may be in a specific chapter: Future work
6. Page 12 Figure 9: Nice if you could add an error signal in figure 9, as you have done in figure 10.
7. Page 13: Figure 10. Please improve the color for the regulation region, very hard to read. I also suggest that you have a separate scale for the Error, on the right side of the figure, maybe with a factor 4 to be able to read the Error. Alternative have a special figure for the Error. The Error is an important number and need to be readable.

And then a comment to the discussion of electrical torque/power: The electrical power output is set by the control system of the converter of the wind turbine and it can be very fast down to some ms. The pitch controller is used to limit the speed of the turbine by reducing the power input to the turbine. And there by also reducing the incoming loads of the turbine.

Good updates !

I have the pleasant news that your paper is now accepted.
Best regards

Joachim Peinke