KR20150037288A - Apparatus and method for estimating partial discharge - Google Patents

Abstract

The present invention relates to an apparatus and method for estimating partial discharge correctly when a partial discharge occurs in an electrical utility. To this end, an apparatus for estimating partial discharge according to the present invention comprises: an integrated sensor part for sensing electromagnetic signals and ultrasonic signals generated at a partial discharge position in an electrical utility; a calculating part for acquiring a time difference pattern of electromagnetic signals and ultrasonic signals and calculating estimated range of partial discharge position; and an outside sensor part for sensing ultrasonic signals in an estimation range, wherein the calculating part calculates partial discharge position by using the result of sensing of the outside sensor part.

Description

[0001] APPARATUS AND METHOD FOR ESTIMATING PARTIAL DISCHARGE [0002]

The present invention relates to an apparatus and method for estimating a partial discharge position, and more particularly, to an apparatus and method for accurately estimating a position of a partial discharge within a power plant when the partial discharge occurs.

Conventionally, when there is an internal defect due to a partial discharge in a power facility, for example, a gas insulated switchgear (GIS), a UHF (Ultra-High Frequency) electromagnetic wave signal generated by a partial discharge and an arc is used And the position of the defect was estimated by TOA (Time of arrival) method. Also, when there is an internal defect due to partial discharge inside the transformer, the partial discharge signal and the arc signal are estimated by the T.O.A method using an ultrasonic sensor installed in the transformer enclosure.

However, in the case of a gas insulated switchgear, the long-distance gas insulated line (GIL) and the gas insulated bus (GIB) of the switch-yard of the power plant are not equipped with a UHF built- There is a problem that it is difficult to estimate the position because the sensor can not be installed to estimate the internal defect position.

In addition, in the case of a long-distance gas insulated transmission line (GIL), a group velocity position estimation method using one sensor is recently used. However, in this case, when the intensity of the partial discharge signal is weak, there is a disadvantage that the application area is limited because it is difficult to perform analysis by TEM (Transverse ElectroMagnetic), TE (Transverse Electric) and TM (Transverse Magnetic) modes.

In this regard, Korean Patent Laid-Open Publication No. 2003-0001945, entitled " Ultrasonic On-Line Monitoring Device for Measuring Partial Discharge in a Transformer, "

An object of the present invention is to provide an apparatus and a method for accurately estimating a position where a partial discharge occurs in a power plant.

According to an aspect of the present invention, there is provided an apparatus for estimating a partial discharge position, comprising: an integrated sensor unit for sensing an electromagnetic wave signal and an ultrasonic signal generated at a partial discharge position in a power facility; A calculation unit for obtaining a time difference pattern between the electromagnetic wave signal and the ultrasonic signal and calculating an estimation range for the partial discharge position using the time difference pattern; And an external sensor unit for sensing the ultrasonic signal in the estimated range, and the calculation unit calculates the partial discharge position using the sensing result of the external sensor unit.

In addition, the integrated sensor section may be located in the spacer if the power plant is a gas insulated switchgear.

In addition, the integrated sensor section may be located in the upper and lower drain valves when the power plant is a transformer or a reactor.

Further, the calculation unit may calculate an average value and a standard deviation by applying a normal distribution function to the time difference pattern, and determine a position corresponding to the calculated average value as the estimated position.

Further, the calculation unit can derive the estimated range by calculating the upper limit value and the lower limit value for the time difference pattern based on the standard deviation.

The calculation unit may calculate the partial discharge position by comparing the time difference between the ultrasonic signals detected at the estimated position and the limit positions and the ultrasonic signal detected by the integrated sensor unit and the difference between the time difference patterns and the standard deviation have.

Also, the external sensor unit may be positioned corresponding to the user's setting or automatically the estimated range, and may sense the ultrasonic signal with respect to the estimated range.

According to an aspect of the present invention, there is provided a method for estimating a partial discharge position of an object, comprising: sensing an electromagnetic wave signal and an ultrasonic signal generated at a partial discharge position inside a power facility by an integrated sensor unit; Obtaining a time difference pattern between the electromagnetic wave signal and the ultrasonic signal by the calculation unit and calculating an estimated range for the partial discharge position using the time difference pattern; And sensing the ultrasonic signal in the estimated range by the external sensor unit and calculating the partial discharge position using the sensing result in the step of sensing the ultrasonic signal in the estimation range by the calculation unit .

In addition, the step of sensing the electromagnetic wave signal and the ultrasonic signal may be performed by the integrated sensor part in the spacer when the power equipment is a gas insulated switchgear.

In addition, the step of sensing the electromagnetic wave signal and the ultrasonic signal may be performed by the integrated sensor unit in the upper and lower drain valves when the power equipment is a transformer or a reactor.

The step of calculating the estimated range for the partial discharge position may include calculating a mean value and a standard deviation by applying a normal distribution function to the time difference pattern, and determining a position corresponding to the calculated mean value as the estimated position.

Further, the step of calculating the estimated range for the partial discharge position can derive the estimated range by calculating the upper limit value and the lower limit value with respect to the time difference pattern based on the standard deviation.

The calculating of the partial discharge position may include comparing the time difference between the ultrasonic signals detected at the estimated position and the limit positions and the ultrasonic signal detected by the integrated sensor unit and the difference between the time difference patterns and the standard deviation The partial discharge position can be calculated.

Further, in the step of sensing the ultrasonic signal in the estimation range, the external sensor unit may be positioned corresponding to the user's setting or automatically the estimation range, and may sense the ultrasonic signal with respect to the estimated range.

According to the apparatus and method for estimating a partial discharge position of the present invention, it is possible to provide an electric power facility in which the partial discharge sensor can not be installed, for example, in the case of a gas insulated switchgear, It is possible to accurately calculate the position where the partial discharge occurs in the discharge, the transformer, and the reactor.

1 is a view of a gas insulated switchgear to which the partial discharge position estimating apparatus of the present invention is applied.
2 is a view of a transformer to which the partial discharge position estimating apparatus of the present invention is applied.
3 is a block diagram of a calculation unit included in the partial discharge position estimation apparatus of the present invention.
4 is a diagram illustrating an example of an ultrasonic signal sensed by an integrated sensor unit included in the partial discharge position estimating apparatus of the present invention.
5 is a diagram of a normal distribution used by a calculation unit included in the partial discharge position estimation apparatus of the present invention.
6 is a flowchart of a partial discharge position estimation method of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, a partial discharge position device according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a view of a gas insulated switchgear 10 to which the partial discharge position estimation apparatus 100 of the present invention is applied. The partial discharge position estimation apparatus 100 of the present invention includes an integrated sensor unit 110, an external sensor unit 120, a calculation unit 130, and an output unit 140. The description of each configuration included in the partial discharge position estimation apparatus 100 of the present invention is as follows.

In the example of FIG. 1, the electric power facility represents the case of a gas insulated switchgear (GIS). More specifically, this example shows the case of the gas insulated transmission line (GIL) of the gas insulated switchgear (GIS) and the substation gas insulated bus bar (GIB).

The integrated sensor unit 110 senses an electromagnetic wave signal and an ultrasonic signal generated at the partial discharge position 12 in the electric power facility. The integrated sensor unit 110 may be mounted on the spacer 11 as shown in FIG. The integrated sensor unit 110 may include a UHF electromagnetic wave sensor and an ultrasonic sensor to sense an electromagnetic wave signal and an ultrasonic signal.

The external sensor unit 120 functions to sense the ultrasonic signal in the estimated range. Here, the estimation range indicates a range in which the partial discharge position is estimated to exist through the calculation unit 130, as described below. Specifically, the external sensor unit 120 functions to sense ultrasonic signals at the estimated positions and the limit positions, which will be described below. Here, the description of the term estimated position and the limit positions will be described in detail below, so that description thereof is omitted for clarity of description. The external sensor unit 120 is positioned corresponding to the user's setting or automatically the estimated range. Accordingly, the external sensor unit 120 can sense the ultrasonic signal corresponding to the estimated range. The external sensor unit 120 may further include an amplification module capable of amplifying the ultrasonic signal. Accordingly, the external sensor unit 120 can measure an ultrasonic signal generated in the electric power facility from the outside.

The calculation unit 130 repeatedly acquires the electromagnetic wave signal and the ultrasonic signal sensed by the integrated sensor unit 110. [ Then, the calculation unit 130 calculates the time differences between the electromagnetic wave signal and the ultrasonic signal in the time-domain of the ultrasonic signal using the repeatedly sensed data. Here, the process of repeatedly acquiring the electromagnetic wave signal and the ultrasonic signal to calculate the time difference is repeated a predetermined number of times. It is to be understood that the number of times in this example is assumed to be 100, but is not limited thereto.

Thereafter, the calculation unit 130 calculates a time difference pattern based on the time differences collected in the time-enabled area of the ultrasonic signal. At this time, the calculation unit 130 sets the electromagnetic wave signal acquired from the integrated sensor unit 110 as a trigger signal. Here, the time-enabling area is an area determined based on the length of the gas insulated transmission line (GIL) and the substation gas insulated bus bar (GIB) (see FIG. 4). Specifically, the time-enabled area is calculated by the following equation (1).

In Equation (1),? T denotes a time-enabled area. And v1 represents the propagation speed of the electromagnetic wave signal, that is, 3 * 10 ⁸ m / s. And v2 represents the transmission speed of the ultrasonic signal, that is, 1.4 m / ms. And L represents the length of the gas insulated transmission line (GIL).

The calculation unit 130 calculates the estimated range for the partial discharge position 12 using the time difference pattern acquired through the repetitive measurement. More specifically, the calculation unit 130 calculates a mean value and a standard deviation by applying a normal distribution function to the time difference pattern (see FIG. 5). Thereafter, the calculation unit 130 determines the position corresponding to the calculated average value as the estimated position. Then, the calculation unit 130 defines the limit positions and calculates the estimated range using the upper limit value and the lower limit value calculated through the mean value + standard deviation value.

Also, the calculation unit 130 acquires the sensing result of the ultrasonic signal with respect to the estimated position and the limit positions using the external sensor unit 120 described above. At this time, the calculation unit 130 sets the estimated position and the limit positions as trigger signals. Here, as described above, the external sensor unit 120 performs sensing by being positioned or automatically corresponding to the estimated range of the user. Then, the calculation unit 130 calculates time differences between the detected ultrasonic signals, i.e., the ultrasonic signals detected at the estimated position and the limit positions, and the ultrasonic signal detected by the integrated sensor unit 110. [ Then, the calculation unit 130 calculates an error between the respective time differences and the time differences derived through the integrated sensor unit 110. [ Here, the calculation unit 130 calculates the partial discharge position by comparing the error and the standard deviation. That is, when the error is less than the standard deviation, it is estimated as the partial discharge occurrence position. Otherwise, the calculation unit 130 repeats the above processes and recalculates the partial discharge generation position.

The output unit 140 outputs the calculation result in the calculation unit 130, verifies the verification result within the error range, and outputs the estimated position to the user or the manager. To this end, the output unit 140 may include a display module and a speaker module.

Also, although not shown in the figure, the partial discharge position estimation apparatus 100 of the present invention may further include a power supply unit to supply power to the integrated sensor unit 110 and the external sensor unit 120.

2 is a view of a transformer 20 to which the partial discharge position estimating apparatus 200 of the present invention is applied. 1, the partial discharge position estimating apparatus 200 of the present invention includes an integrated sensor unit 210, an external sensor unit 220, a calculation unit 230, and an output unit 240 . The partial discharge position estimating apparatus 200 referred to in the description of FIG. 2 has the same configuration as that described above with reference to FIG. That is, in the case of FIG. 1, the partial discharge position estimating apparatus of the present invention is located in the spacer, and the description of FIG. 2 shows an example of being located in the upper and lower drain valves 21 of the transformer. Therefore, in the following description, the matters overlapping with those mentioned with reference to FIG. 1 are omitted for clarity of description.

The integrated sensor unit 210 functions to repeatedly sense the electromagnetic wave signal and the ultrasonic signal generated at the partial discharge position in the electric power facility. For this, the integrated sensor unit 210 may include a UHF electromagnetic wave sensor and an ultrasonic sensor.

The external sensor unit 220 functions to sense an ultrasonic signal in an estimated range. The external sensor unit may sense the ultrasonic signal at the estimated position and the limit positions as described above. In addition, the external sensor unit 220 is located in correspondence with the user's setting or automatically estimated range.

The calculation unit 230 acquires a time difference pattern between the electromagnetic wave signal and the ultrasonic signal using the electromagnetic wave signal and the ultrasonic signal sensed by the integrated sensor unit 210. At this time, the calculation unit 230 can set the first acquired signal among the electromagnetic wave signals acquired by the integrated sensor unit 210 as a trigger signal. Further, when obtaining the time difference pattern, the calculation unit acquires the time difference pattern in the time-enabled area of the ultrasonic signal that is limited by the size of the transformer.

Similar to the one described in FIG. 1, the time-enabled area calculates the transmission time difference between the three-dimensional electromagnetic wave signal and the ultrasonic signal based on the size of the substation to be measured. This time difference is calculated using the propagation speed of electromagnetic waves of 3 * 10 ⁸ m / s and the propagation speed of ultrasonic signals of 1.4 m / ms. The details of this are described with reference to FIG. 1, and are omitted here.

Thereafter, the calculation unit 230 calculates the estimated range for the partial discharge position using the time difference pattern acquired through the repetitive measurement. More specifically, the calculation unit 230 calculates an average value and a standard deviation using the normal distribution function of the obtained time difference pattern. Similar to the example of FIG. 1, the calculation unit 230 may calculate the estimated range for the partial discharge position on the three-dimensional image of the substation using the calculated average value and the standard deviation, and determine the estimated position and the limit positions.

Then, the calculation unit 230 acquires the sensing result of the ultrasonic signal with respect to the estimated position and the limit positions using the external sensor unit 220 described above. 1, a time difference between the ultrasonic signal sensed at the estimated position and the limit positions and the ultrasonic signal sensed by the integrated sensor unit 210 is calculated. Here, the trigger signal uses the estimated position and the limit positions. Then, the calculation unit 230 calculates an error between the respective time differences and the time difference derived through the integrated sensor unit 210, and calculates the partial discharge position by comparing the error and the standard deviation.

The output unit 240 outputs the calculation result in the calculation unit 230, verifies the verification result within the error range, and outputs the estimated position to the user or the manager. To this end, the output unit 240 may include a display module and a speaker module.

Further, as another embodiment, the ultrasonic sensor may be installed on each side of the enclosure of the transformer 20 to sense the ultrasonic waves generated at the partial discharge position to perform the partial discharge position estimation described above. That is, in this example, the signals sensed by the integrated sensor unit 210 and the four ultrasonic sensors are collected. Here, using the acquired electromagnetic wave signal and ultrasonic signal, it is possible to derive the time difference pattern using the arrival time difference on the basis of the earliest electromagnetic wave signal. The partial discharge position estimating apparatus of the present invention calculates the estimated range using the time difference pattern. Thereafter, the external sensor unit may be attached to the transformer enclosure closest to the partial discharge generating position to perform the calculation of the partial discharge position referring to FIGS. 1 and 2. FIG.

Conventionally, a plurality of ultrasonic sensors have been required in the substation apparatus for sensing ultrasonic signals through the embodiment of FIG. 2. However, the present invention has an advantage that an ultrasonic signal can be sensed by only one external sensor unit. This has the advantage of cost saving when estimating the partial discharge position.

Hereinafter, with reference to FIG. 3, the calculation unit 330 included in the partial discharge position estimation apparatus of the present invention will be further described. 3 is a block diagram of a calculation unit 330 included in the partial discharge position estimation apparatus of the present invention. The calculation unit 330 included in the partial discharge position estimation apparatus of the present invention may include a filter module 331, a conversion module 332, a calculation module 333, and a storage module 334.

The filter module 331 performs filtering on signals sensed by the integrated sensor unit and the external signal unit. For this purpose, the filter module 331 may include a high pass filter (HPF) and a low pass filter (LPF). Here, it should be understood that the types of filters included in the filter module 331 are not limited thereto.

The conversion module 332 functions to convert a signal filtered by the filter module 331, that is, an analog signal, into a digital signal. Thus, the partial discharge position estimating apparatus of the present invention can derive more accurate results than processing using an analog signal.

The operation module 333 functions to perform various operations mentioned with reference to FIG. 1 and FIG. That is, the calculation module 333 calculates the time difference using the electromagnetic wave signal and the ultrasonic signal, calculates the time difference pattern, and calculates the estimated range using the normal distribution function in the time difference pattern. In addition, the partial discharge position can be calculated by comparing the calculated error with the standard deviation derived by using the normal distribution function through the error calculation described above.

The storage module 334 stores data necessary for the operation in the operation module 333 or stores necessary information from the operation module 333. [

Hereinafter, with reference to FIG. 6, a partial discharge position estimation method of the present invention will be described. 6 is a flowchart of a partial discharge position estimation method of the present invention. In the following description, the elements overlapping with the partial discharge position estimating apparatus described with reference to Figs. 1 to 5 are omitted for clarity of description.

First, a step S610 of sensing an electromagnetic wave signal and an ultrasonic signal generated at a partial discharge position inside the electric power facility is performed by the integrated sensor unit. As referred to with reference to Figs. 1 and 2, when the electric power facility is a gas insulated switchgear, the integrated sensor portion is located in the spacer to perform sensing. In addition, when the electric power facility is a transformer or a reactor, the integrated sensor unit can be placed in the drain valve to perform sensing. As mentioned above, the integrated sensor unit may be configured to include a UHF electromagnetic wave sensor and an ultrasonic sensor to sense an electromagnetic wave signal and an ultrasonic signal.

Thereafter, step S620 of obtaining the time difference pattern between the electromagnetic wave signal and the ultrasonic signal is performed by the calculation unit. For this, in step S620, the ultrasonic signal and the electromagnetic wave signal sensed in step S610 are repeatedly collected. In step S620, the time differences of the electromagnetic wave signals and the ultrasonic signals collected repeatedly are repeatedly calculated, and the time difference pattern is calculated using the calculated time difference.

Thereafter, a calculation step (S630) of calculating an estimation range for the partial discharge position using the time difference pattern is performed by the calculation unit. In step S630, the estimation range is calculated using the normal distribution function for the time difference pattern calculated in step S620. That is, in step S630, the estimated position corresponding to the standard value and the limit positions corresponding to the upper limit value and the lower limit value calculated using the standard deviation are calculated through the normal distribution function. The description thereof has already been described in detail in Fig. 1 and Fig. 2, and is omitted here for clarity of description.

Thereafter, step S640 of sensing the ultrasonic signal in the estimated range is performed by the external sensor unit. Here, the external sensor unit may be set by the user or automatically positioned corresponding to the estimated range, and may sense the ultrasonic signal with respect to the estimated range.

Thereafter, the calculating unit calculates the partial discharge position (S650) by using the sensing result in step S640. That is, in operation S650, a partial discharge position is calculated by comparing the time difference between the ultrasonic signals detected at the estimated position and the limit positions and the ultrasonic signal detected at the step S610, the error between the time difference patterns, and the standard deviation . That is, in step S650, if the error is equal to or less than the standard deviation, it is estimated as the partial discharge occurrence position. Otherwise, the step S650 is repeated to calculate the partial discharge generation position again.

The teachings of the principles of the present invention may be implemented as a combination of hardware and software. In addition, the software can be implemented as an application program that is actually implemented on the program storage unit. The application program can be uploaded to and executed by a machine that includes any suitable architecture. Advantageously, the machine may be implemented on a computer platform having hardware such as one or more central processing units (CPUs), a computer processor, a random access memory (RAM), and input / output (I / . In addition, the computer platform may include an operating system and microinstruction code. The various processes and functions described herein may be part of microcommand codes or a portion of an application program, or any combination thereof, and they may be executed by various processing devices including a CPU. In addition, various other peripheral devices such as additional data storage and printers may be connected to the computer platform.

It is to be understood that the actual connections between system components or process functional blocks may vary depending on how the principles of the present invention are programmed, as some of the constituent system components and methods illustrated in the accompanying drawings are preferably implemented in software It should be further understood. Given the teachings herein, those skilled in the relevant art (s) will be able to contemplate these and similar implementations or configurations of the principles of the invention.

While the exemplary embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the principles of the invention are not limited to these precise embodiments, and that various changes and modifications may be effected within the spirit and scope of the invention It is to be understood that the invention may be practiced by those skilled in the art. All such modifications and variations are intended to be included within the scope of the inventive principles as set forth in the appended claims.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: partial discharge position estimating device 110:
120: external sensor unit 130: calculation unit
140:

Claims (14)

An integrated sensor unit for sensing an electromagnetic wave signal and an ultrasonic signal generated at a partial discharge position in a power facility;
A calculation unit for obtaining a time difference pattern between the electromagnetic wave signal and the ultrasonic signal and calculating an estimation range for the partial discharge position using the time difference pattern; And
And an external sensor unit for sensing an ultrasonic signal in the estimated range,
Wherein the calculation unit calculates the partial discharge position using the sensing result of the external sensor unit. The method according to claim 1,
The integrated sensor unit includes:
Wherein the power plant is located in a spacer when the power plant is a gas insulated switchgear. The method according to claim 1,
The integrated sensor unit includes:
And wherein the partial discharge position estimating device is located at the up-and-down drain valve when the electric power facility is a transformer or a reactor. The method according to claim 1,
The calculation unit may calculate,
Calculating a mean value and a standard deviation by applying a normal distribution function to the time difference pattern, and determining a position corresponding to the calculated mean value as the estimated position. 5. The method of claim 4,
The calculation unit may calculate,
And calculates an upper limit value and a lower limit value for the time difference pattern based on the standard deviation to derive the estimated range. 6. The method of claim 5,
The calculation unit may calculate,
And comparing the estimated position, the time difference between the ultrasonic signals detected at the limit positions corresponding to the upper limit value and the lower limit value and the ultrasonic signal detected by the integrated sensor unit, and the difference between the time difference patterns, Wherein the partial discharge position calculating means calculates the partial discharge position. The method according to claim 1,
Wherein the external sensor unit comprises:
Wherein the partial discharge position estimating device is located in correspondence with the user's setting or automatically the estimated range, and senses the ultrasonic signal for the estimated range. Sensing an electromagnetic wave signal and an ultrasonic signal generated at a partial discharge position inside the electric power facility by the integrated sensor unit;
Acquiring a time difference pattern between the electromagnetic wave signal and the ultrasonic signal by a calculation unit and calculating an estimation range for the partial discharge position using the time difference pattern; And
Sensing an ultrasonic signal in the estimated range by an external sensor unit,
Further comprising the step of calculating the partial discharge position using the sensing result in the step of sensing the ultrasonic signal in the estimation range by the calculation unit. 9. The method of claim 8,
Sensing the electromagnetic wave signal and the ultrasonic signal,
Wherein the integrated sensor portion is located in a spacer when the power plant is a gas insulated switchgear. 9. The method of claim 8,
Sensing the electromagnetic wave signal and the ultrasonic signal,
Wherein the integrated sensor part is positioned on the upper and lower drain valves when the power plant is a transformer or a reactor. 9. The method of claim 8,
Wherein the step of calculating the estimated range for the partial discharge position comprises:
Calculating a mean value and a standard deviation by applying a normal distribution function to the time difference pattern, and determining a position corresponding to the calculated mean value as the estimated position. 12. The method of claim 11,
Wherein the step of calculating the estimated range for the partial discharge position comprises:
And calculating an upper limit value and a lower limit value for the time difference pattern based on the standard deviation to derive the estimated range. 13. The method of claim 12,
The step of calculating the partial discharge position includes:
A comparison between the estimated position and an error between the time difference and the time difference between the ultrasonic signals detected at the limit positions corresponding to the upper limit value and the lower limit value and the ultrasonic signal detected by the integrated sensor unit, Wherein the partial discharge position is calculated through the calculation of the partial discharge position. 14. The method of claim 13,
In the step of sensing the ultrasonic signal in the estimation range,
Wherein the external sensor unit is positioned in correspondence with the setting range of the user or automatically to sense the ultrasonic signal for the estimated range.

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