Methodology Approbation for the Overhead Power Lines Sag Determining by the Period of Conductor Owned Oscillations

Round 1

Reviewer 1 Report

The paper tackles an interesting topic of sag monitoring (or in a broader sense, cable/wire monitoring or grid infrastructure monitoring). The idea is useful but there are some questions on the paper that the reviewer has, which, when answered, can make the paper stronger.

First, the method presented in this paper requires sensors in the form of accelerometers installed on the power lines. So the question is how many such sensors are needed per section or per line. How are the lines segmented and how many segments can be monitored by one line?

Next, methods to determine sags are presented in this paper. But the solution to the detected problem is missing. While this may be out of scope for this paper, the solution to the detected problem could indicate how useful the presented methods are and what resolution of sag determination is required to be achieved. Therefore, adding this piece could not only provide context to the work presented in this paper but also enable us to understand the solution. 

Comparison with state of the art appears incomplete. For example, trivial solutions, like, monitoring weather, which is widely available, can also indicate the probability of impact of power line distortion. Why are such solutions not applicable?

 

Author Response

Response to Reviewer 1 Comments:

Point 1: First, the method presented in this paper requires sensors in the form of accelerometers installed on the power lines. So the question is how many such sensors are needed per section or per line. How are the lines segmented and how many segments can be monitored by one line?

Response 1: the device allows you to control one wire in one span. The device must have at least one three-axis accelerometer.

Point 2: Next, methods to determine sags are presented in this paper. But the solution to the detected problem is missing. While this may be out of scope for this paper, the solution to the detected problem could indicate how useful the presented methods are and what resolution of sag determination is required to be achieved. Therefore, adding this piece could not only provide context to the work presented in this paper but also enable us to understand the solution.

Response 2:This question is beyond the scope of the presented article. In this article, the correlation between the change in the temperature of the wire and the frequency of its natural oscillations at different harmonics is estimated. Thus, the possibility of using the frequency of natural oscillations of the wire at higher harmonics to determine the boom of the wire sag is evaluated. The results of research on determining the arrows of wire sag based on the higher harmonics of its oscillations are expected to be published in the future.

Point 3: Comparison with state of the art appears incomplete. For example, trivial solutions, like, monitoring weather, which is widely available, can also indicate the probability of impact of power line distortion. Why are such solutions not applicable?

Response 3: Using only the temperature of the wire to evaluate the boom of its sag is unacceptable. Answer: Using only the temperature of the wire to evaluate the boom of its sag is unacceptable. For example,the suspension points of the wire can shift, thereby changing the geometry of the wire, which will not be noticeable by its temperature. Weather monitoring (air temperature and humidity, wind speed, wire temperature) allows you to find out the time of the beginning of the formation of icy-frost deposits, but not the current mechanical loads.

 

Reviewer 2 Report

1, All kinds of existing transmission line sag detection methods should be introduced, as well as the shortcomings of these methods.

2, Conductor sag is related to its temperature. Wouldn't it be more convenient for us to measure sag directly by temperature rather than by vibrating the conductor?

3, In line 59, the meaning of the letters in the formula is not stated.

4, In Figure 1, what causes the wire to vibrate? Is the wind?

5, How is the conductor oscillation frequency obtained using the accelerometer?

6, What kind of test conditions does experimental results correspond to?

7, The influencing factors include wind speed, height difference between the suspension points and so on, which need to be discussed.

Author Response

Response to Reviewer 2 Comments:

Point 1: All kinds of existing transmission line sag detection methods should be introduced, as well as the shortcomings of these methods.

Response 1: The introduction of the article has been expanded. Information added.

Point 2: Conductor sag is related to its temperature. Wouldn't it be more convenient for us to measure sag directly by temperature rather than by vibrating the conductor?

Response 2: Using only the temperature of the wire to evaluate the boom of its sag is unacceptable. The suspension points of the wire can shift, thereby changing the geometry of the wire, which will not be noticeable by its temperature. Weather monitoring (air temperature and humidity, wind speed, wire temperature) allows you to forecast find out the time of the beginning of the formation of ice-frost deposits, but not the current mechanical loads.

Point 3: In line 59, the meaning of the letters in the formula is not stated.

Response 3: The notation of the formula is explained.

Point 4: In Figure 1, what causes the wire to vibrate? Is the wind?

Response 4:  Yes, the vibration is caused by the wind. To register fluctuations, a very insignificant flow of air masses, which is available in any weather, is sufficient.

Point 5: How is the conductor oscillation frequency obtained using the accelerometer?

Response 5: The accelerometer sends signals about a change in its position in space with a sampling frequency of 1000 Hz. Using the melon signals, you can determine the frequency of vibrations of the wire (the accelerometer is rigidly fixed on the wire).

Point 6: What kind of test conditions does experimental results correspond to?

Response 6: the suspension points of the wire are fixed. The wire was in the open air. The temperature of the wire varied from -16.5 to 0 degrees Celsius, wind speed up to 5.5 m/s.

Point 7: The influencing factors include wind speed, height difference between the suspension points and so on, which need to be discussed.

Response 7: at any wind speed, the wire will oscillate at the fundamental frequency of its own oscillations and its harmonics. The height between the suspension points is planned to be taken into account in the future. In this work, the height difference between the suspension points was 0 m.

Round 2

Reviewer 1 Report

The authors have addressed all comments.