System, method and computer readable recording medium for measuring partial discharge using acoustic camera and reference signal generator

Abstract

A partial discharge measurement system is disclosed. The system includes a reference signal generator located in real space that outputs a reference signal for phase correction, and an acoustic camera that measures partial discharge based on a partial discharge acoustic signal generated from a measurement target. The acoustic camera includes an acoustic signal receiver that receives a partial discharge acoustic signal generated from a measurement target, and a data processing unit that generates partial discharge acoustic data for the partial discharge acoustic signal and generates phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between a reference signal and the partial discharge acoustic signal.

Description

Technology Field

[0001] The present invention relates to a technology for performing phase calibration of partial discharge acoustic data collected by an acoustic camera using a reference signal of a reference signal generating device, and analyzing Phase Resolved Partial Discharge (PRPD) based on the phase-calibrated partial discharge acoustic data. Background Technology

[0002] Partial Discharge (PD) is a localized discharge phenomenon occurring within an electrical insulation system; it is an electrical discharge that occurs in a localized area without destroying the insulation of the entire system.

[0003] In general, partial discharges can be classified into external discharge, internal discharge, surface discharge, floating discharge, etc.

[0004] External discharge includes arc discharge, a type of dielectric breakdown that occurs continuously in the gas between electrodes when a potential difference is generated between the electrodes, and corona discharge, a discharge phenomenon that occurs when gas particles on the electrode surface are ionized by the high voltage when a high voltage is applied between two electrodes.

[0005] Internal discharge is the discharge that occurs most frequently when there is a defect in the solid insulation of cables, bushings, and GIS joint insulators.

[0006] Surface discharge is the most dangerous type of discharge, occurring on the surface of an insulator when the voltage applied to the dielectric surface exceeds a certain value as the voltage applied to the dielectric increases.

[0007] Floating discharge is a partial discharge that occurs when there is a conductor with a floating potential, such as in a state where the potential is uneven due to poor grounding, poor connections, or insulation cracks.

[0008] As an example of the partial discharge described above, power equipment deteriorates as it is used while exposed outdoors for a long period of time. In particular, as the deterioration progresses, cracks develop inside the insulators of the power equipment. Moisture penetrates into these cracks, and as the wet and dry states repeat, contaminants penetrate inside, creating conductive paths. As the electric field concentrates in these conductive paths, partial discharge occurs.

[0009] Since partial discharge induces electrical and mechanical vibrations to release discharge energy in the form of electromagnetic waves, ultrasound, and sound, detecting discharge energy in power equipment allows for the diagnosis of equipment deterioration.

[0010] Conventionally, there existed acoustic cameras that determined the presence or type of partial discharge by measuring the ultrasound generated at the time of partial discharge.

[0011] These acoustic cameras provide a Phase Resolved Partial Discharge Graph (hereinafter referred to as PRPD graph) for partial discharge analysis, and in order to generate the PRPD graph from the acoustic camera, ① synchronization information of the power line frequency (typically 50Hz or 60Hz) of the measurement target equipment and the AC voltage signal applied to the equipment in operation, and ② time-domain sound pressure data are essential.

[0012] In this case, the reason for knowing the commercial frequency of the measurement target equipment is to perform Phase Lock. The PRPD graph displays a constant signal as points by decomposing it into phases ranging from 0 to 360 degrees; without performing Phase Lock, it is difficult to obtain an accurate PRPD graph.

[0013] Figure 25 is a diagram showing PRPD graphs according to Poor Phase Lock and Good Phase Lock, respectively. In the PRPD graph, the X-axis represents the phase value (degree) in the range of 0 to 360 degrees, the Y-axis represents the partial discharge magnitude, and the color / density of the points on the graph represents the number of partial discharge occurrences.

[0014] If the PRPD graph is visualized without obtaining accurate phase information, a PRPD graph may be drawn in which the points of the graph are distributed across the entire phase rather than concentrated in a specific phase, as in the Poor Phase Lock example shown in Fig. 24(a), making it impossible to distinguish what type of partial discharge it is. However, if the PRPD graph is visualized with accurate phase information, a PRPD graph may be drawn in which the points of the graph are concentrated in a specific phase, as in the Good Phase Lock example shown in Fig. 24(b), making it possible to distinguish what type of partial discharge it is.

[0015] Conventional HFCT sensors or TEV sensors that measure partial discharge using electromagnetic waves can measure the commercial frequency and phase of equipment in operation, so it is possible to calculate an accurate PRPD graph.

[0016] However, since it is difficult for acoustic cameras to accurately measure the commercial frequency and phase information of the equipment, the reality is that PRPD graphs are plotted after setting the commercial frequency and phase to arbitrary values; consequently, there was a problem in that conventional acoustic cameras found it difficult to produce accurate PRPD graphs.

[0017] In addition, there was a problem in that conventional inaccurate PRPD graphs led to inaccurate partial discharge analysis results for users of acoustic cameras. The problem to be solved

[0018] The present invention has been devised in accordance with the aforementioned necessity, and the objective of the present invention is to provide a partial discharge measurement method, a partial discharge measurement system, and a computer-readable recording medium that enable an acoustic camera to accurately measure commercial frequency and phase information of a measurement target using a reference signal output from a reference signal generating device.

[0019] The objective of the present invention is to provide a partial discharge measurement method, a partial discharge measurement system, and a computer-readable recording medium that generate phase-corrected partial discharge acoustic data by phase-correcting partial discharge acoustic data collected by an acoustic camera using a reference signal of a reference signal generating device.

[0020] In addition, the objective of the present invention is to provide a partial discharge measurement method, a partial discharge measurement system, and a computer-readable recording medium for generating a PRPD graph based on phase-corrected partial discharge acoustic data. means of solving the problem

[0021] A partial discharge measurement system according to one embodiment of the present invention for achieving the above-described purpose comprises a reference signal generating device located in real space that outputs a reference signal for phase correction and an acoustic camera that measures partial discharge based on a partial discharge acoustic signal generated from a measurement target, wherein the acoustic camera comprises an acoustic signal receiving unit that receives the partial discharge acoustic signal generated from the measurement target and a data processing unit that generates partial discharge acoustic data for the partial discharge acoustic signal and phase corrects the partial discharge acoustic data based on the phase difference between the reference signal and the partial discharge acoustic signal to generate phase-corrected partial discharge acoustic data.

[0022] In addition, the reference signal generating device may include a power supply unit connected to an external power source in the same environment as the environment where the measurement target is located.

[0023] In addition, the reference signal generating device can generate and output a signal synchronized with the AC voltage signal applied through the power supply.

[0024] In addition, the reference signal generating device may include a phase detection unit that detects a predetermined phase position of an AC voltage signal applied through the power supply unit, and a reference signal output unit that generates a predetermined pulse at the detected phase position and outputs it as the reference signal.

[0025] In addition, the reference signal may include at least one of an RF (Radio Frequency) signal and an ultrasonic acoustic signal.

[0026] And, if the above reference signal is an ultrasonic reference signal, the above reference signal output unit can adjust at least one of the period and number of times the ultrasonic reference signal is output.

[0027] In addition, the data processing unit can calculate the phase difference between the reference signal and the partial discharge acoustic signal, convert the calculated phase difference into a number of samples, and correct the acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data.

[0028] In addition, the data processing unit can calculate a phase-resolved partial discharge (PRPD) graph using phase-corrected partial discharge acoustic data.

[0029] In addition, it may further include an output unit that outputs the phase-resolved partial discharge graph.

[0030] In addition, the reference signal generating device may be located within a predetermined distance from the measurement target or within a predetermined distance from the acoustic camera.

[0031] Meanwhile, in a partial discharge measurement method according to an embodiment of the present invention for achieving the above-mentioned purpose, a reference signal generating device is located in real space and includes the step of outputting a reference signal for phase correction, and an acoustic camera includes the steps of receiving a partial discharge acoustic signal generated from a measurement target, generating partial discharge acoustic data for the partial discharge acoustic signal, and generating phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the reference signal and the partial discharge acoustic signal.

[0032] In addition, the power supply unit of the reference signal generating device may further include a step of being connected to an external power source in the same environment as the environment where the measurement target is located, and the step of outputting the reference signal may generate and output a signal synchronized with the AC voltage signal applied through the power supply unit.

[0033] In addition, the reference signal may include at least one of an RF reference signal and an ultrasonic reference signal.

[0034] And, in the case of the RF reference signal, the step of generating the phase-corrected partial discharge acoustic data may include the step of calculating the phase difference between the RF reference signal and the partial discharge acoustic signal, the step of converting the calculated phase difference into a number of samples, and the step of correcting the partial discharge acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data.

[0035] Additionally, in the case of the ultrasonic reference signal, the step of generating the phase-corrected partial discharge acoustic data may include: distinguishing the ultrasonic reference acoustic data corresponding to the ultrasonic reference signal from the partial discharge acoustic data; calculating the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal; converting the calculated phase difference into a number of samples; and correcting the partial discharge acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data.

[0036] Meanwhile, an acoustic camera according to one embodiment of the present invention for achieving the above-mentioned purpose may include an acoustic receiving unit that receives a partial discharge acoustic signal generated from a measurement target and an ultrasonic reference signal generated from a reference signal generating device that outputs a reference signal for phase correction, and a data processing unit that generates phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal.

[0037] Additionally, an acoustic camera according to one embodiment of the present invention for achieving the above-mentioned purpose includes an acoustic receiver that receives a partial discharge acoustic signal generated from a measurement target, an RF receiver that receives an RF reference signal generated from a reference signal generating device that outputs a reference signal for phase correction, and a data processing unit that generates phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the RF reference signal and the partial discharge acoustic signal.

[0038] In addition, a computer-readable recording medium according to one embodiment of the present invention for achieving the above-described purpose may have a program recorded thereon for executing the above-described partial discharge measurement method.

[0039] In addition, a computer program stored on a computer-readable recording medium according to one embodiment of the present invention for achieving the above-described purpose may include program code for executing the above-described partial discharge measurement method. Effects of the invention

[0040] According to various embodiments of the present invention, by generating phase-corrected partial discharge acoustic data by correcting the phase of partial discharge acoustic data collected by an acoustic camera using a reference signal of a reference signal generating device, an accurate PRPD graph can be drawn through Phase Lock.

[0041] In addition, according to various embodiments of the present invention, accurate partial discharge analysis by a user of an acoustic camera can be made possible through an accurate PRPD graph. Brief explanation of the drawing

[0042] FIG. 1 is a conceptual diagram showing a partial discharge measurement system according to one embodiment of the present invention. FIG. 2 is a block diagram showing a partial discharge measurement system according to one embodiment of the present invention. FIG. 3 is a block diagram showing an RF reference signal generating device that generates an RF reference signal according to one embodiment of the present invention. FIG. 4 is a diagram showing an AC voltage signal in an environment where a measurement target is installed according to one embodiment of the present invention and an RF reference signal generated by a reference signal generating device. FIG. 5 is a block diagram showing an ultrasonic reference signal generating device that generates an ultrasonic reference signal according to one embodiment of the present invention. FIG. 6 is a diagram illustrating the operation of a phase detection unit and an ultrasonic reference signal output unit according to an embodiment of the present invention. FIG. 7 is a diagram showing an example of controlling at least one of the period and number of times an ultrasonic reference signal is output according to an embodiment of the present invention. FIG. 8 is a block diagram showing a reference signal generating device that generates an ultrasonic reference signal and an RF reference signal according to one embodiment of the present invention. FIG. 9 is a drawing showing an example of an implementation of a reference signal generating device according to an embodiment of the present invention. FIG. 10 is a block diagram showing an acoustic camera according to one embodiment of the present invention. FIG. 11 is a flowchart illustrating a method for generating acoustic data through beam forming according to an embodiment of the present invention. FIG. 12 is a diagram illustrating a method for time alignment and synthesis of acoustic signals according to one embodiment of the present invention. FIG. 13 is a flowchart illustrating a method for phase correction of partial discharge acoustic data using an ultrasonic reference signal according to one embodiment of the present invention. FIG. 14 is a drawing illustrating a phase difference calculation and phase correction method according to an embodiment of the present invention. FIG. 15 is a drawing illustrating a partial discharge acoustic data phase correction method according to one embodiment of the present invention. FIG. 16 is a block diagram showing an acoustic camera according to another embodiment of the present invention. FIG. 17 is a flowchart illustrating a method for phase correction of partial discharge acoustic data using an RF reference signal according to one embodiment of the present invention. FIG. 18 is a drawing showing an example of an implementation of an acoustic camera according to an embodiment of the present invention. FIG. 19 is a conceptual diagram illustrating a scenario in which a reference signal generator is installed close to a measurement target to measure partial discharge of the measurement target. FIG. 20 is a conceptual diagram showing a scenario in which a reference signal generator is installed close to an acoustic camera to measure partial discharge of a measurement target. FIG. 21 is a flowchart showing the operation of a system when implemented as an ultrasonic reference signal generator in the example of FIG. 19. FIG. 22 is a flowchart showing the operation of a system when implemented as an ultrasonic reference signal generator in the example of FIG. 20. FIG. 23 is a flowchart showing the operation of a system when implemented as an RF reference signal generator in the example of FIG. 19. FIG. 24 is a flowchart showing the operation of a system when implemented as an RF reference signal generator in the example of FIG. 20. Figure 25 is a diagram showing PRPD graphs according to bad phase lock and good phase lock, respectively. FIG. 26 is a diagram showing a PRPD graph of corona discharge according to one embodiment of the present invention. FIG. 27 is a drawing showing an optical-acoustic coupled image according to one embodiment of the present invention. FIG. 28 is a block diagram showing the configuration of a data processing unit according to one embodiment of the present invention. Specific details for implementing the invention

[0043] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, this is merely illustrative and the present invention is not limited thereto.

[0044] In describing the embodiments of the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions may unnecessarily obscure the essence of the invention. Furthermore, the terms described below are defined considering their functions in the present invention, and these definitions may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0045] The terms used in the detailed description are merely for describing embodiments of the invention and should not be limiting in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0046] In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0047] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are used merely to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the terms used.

[0049] FIG. 1 is a conceptual diagram showing a partial discharge measurement system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a partial discharge measurement system according to an embodiment of the present invention. Referring to FIG. 1 and 2, the partial discharge measurement system (1000) includes a reference signal generating device (100), an acoustic camera (200), and a measurement target (300).

[0050] A reference signal generating device (100) is a device that outputs a reference signal for phase correction and may include a power supply unit (110) and a reference signal generating unit (120, 130).

[0051] The power supply unit (110) can be connected to an external power source (102) in the same environment as the environment where the measurement target (300) is located. The external power source may be a ground power source, and an alternating current (AC) voltage of commercial frequency may be applied through the ground power source.

[0052] Commercial frequency refers to the frequency of alternating current supplied by a power company, and it can be 50Hz or 60Hz. For reference, the commercial frequency in Korea is 60Hz, and the commercial frequency in Germany is 50Hz.

[0053] The reference signal generator (120, 130) can generate and output a signal synchronized with an AC voltage signal applied through the power supply (110). At this time, the reference signal (101) may include at least one of an RF (Radio Frequency) signal and an ultrasonic acoustic signal.

[0054] The measurement target (300) is a device, apparatus, or equipment that is subject to partial discharge measurement, such as external discharge, internal discharge, surface discharge, floating discharge, etc. According to an example not limited to the present invention, the measurement target (300) may be power equipment such as a high-voltage cable, transformer, motor, insulator, bushing, capacitor, reactor, etc.

[0055] The measurement target (300) can emit a partial discharge acoustic signal (301) when partially discharged. Here, the partial discharge acoustic signal may be an ultrasonic acoustic signal.

[0056] The acoustic camera (200) receives a partial discharge acoustic signal (301) generated when a measurement target (300) partially discharges, generates partial discharge acoustic data, and can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between a reference signal and the partial discharge acoustic signal. Here, the acoustic camera (200) may include a signal receiving unit (210, 220), a data processing unit (230), and an output unit (240).

[0057] Here, the reference signal generating device (100) may be installed at a close distance from the measurement target (300) or the reference signal generating device (100) may be installed at a close distance from the acoustic camera (200). At this time, the close distance may preferably be within a radius of 1 meter from the measurement target (300) or the acoustic camera (200), but is not limited thereto.

[0058] As previously explained, in order to calculate an accurate PRPD graph using the collected data of the acoustic camera (200), it is necessary to know the synchronization information of the commercial frequency of the measurement target (300) and the AC voltage signal applied to the operating equipment. The present invention enables accurate PRPD analysis by the reference signal generating device (100) generating a reference signal including the synchronization information of the commercial frequency of the measurement target (300) and the AC voltage signal applied to the operating equipment and transmitting it to the acoustic camera (200).

[0060] FIG. 3 is a block diagram showing an RF reference signal generating device that generates an RF reference signal according to an embodiment of the present invention. Referring to FIG. 3, the RF reference signal generating device (100-1) includes a power supply unit (110) and an RF reference signal generating unit (120).

[0061] The power supply unit (110) can be connected to an external power source in the same environment as the environment where the measurement target (300) is located. The external power source may be a ground power source, and an alternating current (AC) voltage of commercial frequency may be applied through the ground power source.

[0062] Additionally, the power supply unit (110) may include an internal power source, such as a battery, for the operation of the device in situations where it is not possible to connect to an external power source.

[0063] The RF reference signal generation unit (120) includes a phase detection unit (121) and an RF reference signal output unit (122). The phase detection unit (121) can detect a predetermined phase position of an AC voltage signal applied through the power supply unit (110). For example, the phase detection unit (121) can be implemented as a zero-cross detector that detects the zero point of the AC voltage signal applied through the power supply as a phase position of 180 degrees and 360 degrees. And, the RF reference signal output unit (122) can generate a predetermined pulse at the phase position of the detected point and output it as an RF reference signal.

[0064] At this time, the generated RF reference signal is an electromagnetic wave signal, and the frequency of the RF reference signal can be determined by synchronizing with the commercial frequency of the power supply grounded in the environment where the measurement target (300) is located. In addition, the generated RF reference signal can be synchronized with the AC voltage signal applied through the power supply unit (110).

[0066] FIG. 4 is a diagram showing an AC voltage signal in an environment where a measurement target is installed according to an embodiment of the present invention and an RF reference signal generated by a reference signal generating device. FIG. 4(a) shows the case where the commercial frequency of the AC voltage signal in an environment where a measurement target (300) is installed is 60Hz. Referring to FIG. 4(a), the phase detection unit (121) can detect the 180-degree phase position (41-1, 41-3, 41-5) and the 360-degree phase position (41-2, 41-4), which are zero-cross points of the AC voltage signal.

[0067] Also, FIG. 4(b) represents an RF reference signal. Referring to FIG. 4(b), the RF reference signal output unit (122) can generate a predetermined pulse (42-1, 42-2, 42-3, 42-4, 42-5) at the detected 180-degree phase positions (41-1, 41-3, 41-5) and 360-degree phase positions (41-2, 41-4) and output it as an RF reference signal. For example, since the commercial frequency of the grounded power supply in the environment where the measurement target (300) is installed is 60Hz, the pulse period at the 180-degree phase positions (41-1, 41-3, 41-5) and 360-degree phase positions (41-2, 41-4) may be 8.35ms. The RF reference signal generating device (100-1) can output an RF reference signal in which periodic peaks occur at 180-degree and 360-degree phase positions.

[0069] FIG. 5 is a block diagram showing an ultrasonic reference signal generating device that generates an ultrasonic reference signal according to an embodiment of the present invention. Referring to FIG. 5, the ultrasonic reference signal generating device (100-2) includes a power supply unit (110) and an ultrasonic reference signal generating unit (130).

[0070] Here, the function of the power supply unit (110) is the same as that previously described in FIG. 3, so a detailed description thereof is omitted.

[0071] The ultrasonic reference signal generation unit (130) includes a phase detection unit (131) and an ultrasonic reference signal output unit (132). For example, the phase detection unit (131) can detect a predetermined phase position of an AC voltage signal applied through the power supply unit (110). For example, the phase detection unit (131) can be implemented to detect the phase of the point of maximum magnitude of the AC voltage signal applied through the power supply, for example, a 90-degree phase position. And, the ultrasonic reference signal output unit (132) can generate a predetermined pulse at the phase position of the detected point and output it as an ultrasonic reference signal.

[0072] At this time, the generated ultrasonic reference signal is an acoustic signal, and the frequency of the ultrasonic reference signal can be determined by synchronizing with the commercial frequency of the power supply grounded in the environment where the measurement target (300) is located. In addition, the generated ultrasonic reference signal can be synchronized with an alternating voltage signal applied through the power supply unit (110).

[0073] FIG. 6 is a diagram showing an ultrasonic reference signal according to an embodiment of the present invention. Referring to FIG. 6(a), when the commercial frequency of the grounded power supply in the environment where the measurement target (300) is installed is 60Hz, the phase detection unit (131) detects the position of the 90-degree phase, which is the point of maximum magnitude of the AC voltage signal (61), and the ultrasonic reference signal output unit (132) can generate an ultrasonic reference signal (62) by creating a constant pulse at the detected 90-degree phase position and output the generated ultrasonic reference signal. For example, when the commercial frequency of the grounded power supply in the environment where the measurement target (300) is installed is 60Hz, one cycle of the AC voltage signal (61) may be 0.0167 seconds, and the ultrasonic reference signal generating device (100-2) may output an ultrasonic reference signal (62) in which a periodic peak occurs at the 90-degree phase position.

[0074] Referring to FIG. 6(b), when the commercial frequency of the grounded power supply in the environment where the measurement target (300) is installed is 50 Hz, one cycle of the alternating current signal (63) may be 0.02 seconds, and the ultrasonic reference signal generating device (100-2) may output an ultrasonic reference signal (64) in which a periodic peak occurs at a 90-degree phase position.

[0075] Meanwhile, in the examples of FIGS. 3 to 6 described above, the phase detection unit (121) of the RF reference signal generator (120) is described as detecting a zero-crossing point, and the phase detection unit (131) of the ultrasonic reference signal generator (130) is described as detecting the phase of the point of maximum magnitude of the AC voltage signal; however, this is merely one example of implementation and is not limited thereto. According to another embodiment of the present invention, each phase detection unit (121, 131) may be implemented to detect a phase position different from that described above.

[0076] In addition, in the examples of FIGS. 3 to 6 described above, an impulse-shaped reference signal having a peak value at a detected phase position was described as an example, but it is not limited thereto. According to another embodiment of the present invention, the reference signal generating unit (120, 130) may be implemented to generate a pulse having a value of "0" in the zero-cross phase position range of 0 to 180 degrees and a predetermined value (e.g., a value of "1") in the range of 180 to 360 degrees.

[0078] Meanwhile, the partial discharge acoustic signal generated when the measurement target (300) partially discharges and the ultrasonic reference signal generated by the ultrasonic reference signal generating device (100-2) are both acoustic signals in the ultrasonic band, so a method is required to enable the acoustic camera (200) receiving them to distinguish between the partial discharge acoustic signal and the ultrasonic reference signal. Accordingly, the ultrasonic reference signal generating device (100-2) according to the present invention can adjust at least one of the period and number of times the ultrasonic reference signal is output to enable the acoustic camera (200) receiving them to distinguish between the partial discharge acoustic signal and the ultrasonic reference signal.

[0079] FIG. 7 is a diagram illustrating an example of controlling the output cycle of an ultrasonic reference signal according to an embodiment of the present invention. FIG. 7(a) is an example in which the output cycle of the ultrasonic reference signal generator (100-2) is operated to be the same as the commercial frequency of 60 Hz, and it can be seen that during 0.167 seconds, which is 10 cycles, the ultrasonic reference signal generator (100-2) generates an ultrasonic reference signal in which a total of 10 peaks occur periodically at a 90-degree phase position. However, in this case, the timing of the partial discharge acoustic signal generated when the measurement target (300) partially discharges and the ultrasonic reference signal generated by the ultrasonic reference signal generator (100-2) may be the same, and it may be difficult to distinguish between the partial discharge acoustic signal and the ultrasonic reference signal from the side of the acoustic camera (200).

[0080] FIG. 7(b) shows that by setting the output cycle of the ultrasonic reference signal generator (100-2) to 10%, the ultrasonic reference signal generator (100-2) generates an ultrasonic reference signal in which a total of one peak occurs periodically at a 90-degree phase position during 0.167 seconds, which is 10 cycles. In this case, the timing of the partial discharge acoustic signal generated when the measurement target (300) partially discharges and the ultrasonic reference signal generated by the ultrasonic reference signal generator (100-2) are different, so it is easy to distinguish between the partial discharge acoustic signal and the ultrasonic reference signal from the acoustic camera (200).

[0082] Meanwhile, the reference signal generating device (100-3) described above may be implemented to include both an RF reference signal generating unit (120) and an ultrasonic reference signal generating unit (130). FIG. 8 is a block diagram showing a reference signal generating device that generates an ultrasonic reference signal and an RF reference signal according to an embodiment of the present invention. Here, since the functions of the power supply unit (110), the RF reference signal generating unit (120), and the ultrasonic reference signal generating unit (130) are the same as those previously described in FIG. 3 and 5, a detailed description thereof is omitted.

[0083] The switching unit (140) can select one of generating and outputting an RF reference signal through the RF reference signal generator (120) or generating and outputting an ultrasonic reference signal through the ultrasonic reference signal generator (130) depending on the location of the measurement target (300) or the measurement environment.

[0084] In the case of the RF method, since the acoustic camera (200) can receive a constant reference signal with relatively little delay in an environment where a line of sight is secured regardless of the measurement distance, it may be desirable to select and operate the RF reference signal generator (120) in such an environment.

[0085] In the case of the ultrasonic method, since calibration must be performed at a relatively short distance, it may be desirable to select and operate the ultrasonic reference signal generator (130) in that environment.

[0086] Meanwhile, the reference signal generating device (100-3) may be implemented to simultaneously emit an RF reference signal and an ultrasonic reference signal for distance estimation. In this case, the acoustic camera (200), which will be described later, can calculate the distance between the acoustic camera (200) and the reference signal generating device (100-3) by using the time difference between the received RF reference signal and the ultrasonic reference signal.

[0088] FIG. 9 is a diagram illustrating an example of an implementation of a reference signal generating device according to an embodiment of the present invention. The reference signal generating device (100) may include a speaker (132) that outputs an ultrasonic reference signal generated by an ultrasonic reference signal generating unit (130), a volume knob (151) for adjusting the size of the ultrasonic reference signal, a power supply unit (110) that receives power from an external power source through a power connection line (111) for connecting to a ground power source of an external power source, and a mode selection switch (152). Although not shown in FIG. 9, the reference signal generating device (100) may include an RF reference signal generating unit (120) internally.

[0089] Here, the mode selection switch (152) is a switch for selecting the frequency of the reference signal output from the reference signal generating device (100), and the user can select an operation mode through the switch (152) to at least one of "frequency 50Hz mode", "frequency 60Hz mode" and "external power connection mode".

[0090] "50Hz frequency mode" is a mode selected when the reference signal generator (100) is not connected to an external power line (111) and operates on its own using an internal power source such as a battery, and the reference signal generator (100) can generate and output an RF reference signal of 50Hz and / or an ultrasonic reference signal of 50Hz. However, since the AC voltage of commercial frequency is not applied from the external power source in "50Hz frequency mode," the reference signal generated in "50Hz frequency mode" is a signal that is not synchronized with the AC voltage signal of the external power source.

[0091] "Frequency 60Hz mode" is a mode selected when the reference signal generator (100) is not connected to an external power line (111) and operates on its own using an internal power source such as a battery, and the reference signal generator (100) can generate and output an RF reference signal of 60Hz and / or an ultrasonic reference signal of 60Hz. However, since the AC voltage of commercial frequency is not applied from the external power source in "Frequency 60Hz mode," the reference signal generated in "Frequency 60Hz mode" is a signal that is not synchronized with the AC voltage signal of the external power source.

[0092] "External power connection mode" is a mode selected when the reference signal generator (100) is connected to a power connection line (111) and operates with an external power source. The reference signal generator (100-3) has a frequency equal to the commercial frequency of 50Hz or 60Hz of the AC voltage signal applied from the external power source (111), and can generate and output an RF reference signal and / or an ultrasonic reference signal synchronized with the AC voltage signal.

[0093] The aforementioned "frequency 50Hz mode" and "frequency 60Hz mode" may be suitable for a usage environment in which the reference signal generator (100) cannot be connected to an external power source and the user checks the commercial frequency (e.g., 60Hz in Korea, 50Hz in Germany) and directly sets the frequency to operate. However, in the "frequency 50Hz mode" and "frequency 60Hz mode," the reference signal output from the reference signal generator (100) is not synchronized with the AC voltage signal applied to the measurement target (300). Therefore, while the accuracy of PRPD analysis can be improved compared to the case where there is no reference signal generator (100), there is a limitation in that accurate PRPD analysis is difficult compared to the case where an external power source is connected to the power supply unit (110).

[0094] However, the aforementioned "external power connection mode" may be suitable for an environment where the reference signal generator (100) can be connected to an external power source. In this case, since the reference signal output from the reference signal generator (100) is synchronized with the AC voltage signal applied to the measurement target (300), accurate PRPD analysis may be possible.

[0096] FIG. 10 is a block diagram showing an acoustic camera according to an embodiment of the present invention. The acoustic camera (200-1) shown in FIG. 10 is an embodiment that includes only an acoustic signal receiver (210) without an RF signal receiver, and can be used to measure partial discharge of a measurement target (300) in conjunction with an ultrasonic reference signal generator (100-2) shown in FIG. 5, which has an ultrasonic signal generator (130), or an RF and ultrasonic reference signal generator (100-3) shown in FIG. 8.

[0097] Referring to FIG. 10, the acoustic camera (200) may include an acoustic signal receiving unit (210), an optical signal receiving unit (220), a data processing unit (230), and an output unit (240).

[0098] The acoustic signal receiving unit (210) can receive an acoustic signal from an acoustic scene and may be configured as an acoustic sensor array in which a plurality of acoustic sensors (210-1, 210-2, ..., 210-n) are arranged in a structured or unstructured manner. In this case, the acoustic sensors (210-1, 210-2, ..., 210-n) may be implemented as MEMS (Micro-Electro-Mechanical Systems) microphones.

[0099] The acoustic scene may be a space in the real world where a sound source generating sound is located. That is, the acoustic scene may be a scene in the real space (or real world) where the measurement target (300) and the reference signal generating device (100-2, 100-3) are located.

[0100] Here, the acoustic signal of the acoustic scene may include audible sound, ultrasound, infrasound, etc. Accordingly, the acoustic signal may include an audible acoustic signal in the range of 20 Hz to 20 kHz, which is the frequency of sound waves that can be heard by the human ear, and an inaudible acoustic signal in a band outside the audible range (e.g., ultrasound band).

[0101] Accordingly, when a partial discharge acoustic signal is generated according to partial discharge at a measurement target (300) located in an acoustic scene, the acoustic signal receiver (210) can receive the partial discharge acoustic signal generated at the measurement target (300). Additionally, when an ultrasonic reference signal is generated at a reference signal generating device (100-2, 100-3) located in an acoustic scene, the acoustic signal receiver (210) can receive the ultrasonic reference signal generated at the reference signal generating device (100-2, 100-3).

[0102] And, the acoustic signal receiving unit (210) can transmit the received partial discharge acoustic signal and ultrasonic reference signal to the data processing unit (230).

[0103] The optical signal receiving unit (220) may be implemented as an optical camera composed of a lens and an image sensor, etc. Specifically, the optical signal receiving unit (220) may receive an optical signal from an optical scene. Here, the optical scene may be a scene in real space (or real world) where the measurement target (300) and the reference signal generating device (100-2, 100-3) are located, just like the acoustic scene.

[0104] And, the optical signal receiving unit (220) can transmit the optical signal to the data processing unit (230).

[0105] The data processing unit (230) can generate partial discharge acoustic data for a partial discharge acoustic signal and ultrasonic reference acoustic data for an ultrasonic reference signal. Additionally, the data processing unit (230) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal. The operation of this data processing unit (230) will be explained in detail later with reference to the drawings.

[0106] The output unit (240) can display at least one of the partial discharge status, partial discharge location, and type of partial discharge (corona discharge, surface discharge, floating discharge, etc.) of the measurement target (300) through an optical-acoustic combined image. Specifically, the data processing unit (230) can generate an acoustic image through beamforming of the partial discharge acoustic signal, generate an optical image for the optical signal received from the optical signal receiving unit (220), and generate an optical-acoustic combined image by combining the optical image and the acoustic image. An optical-acoustic combined image is an image that visualizes the partial discharge status and partial discharge location by combining acoustic information with an optical image. Such an optical-acoustic combined image may be expressed as an acoustic map, an acoustic spectrum image, an acoustic heatmap, an acoustic beamforming visualization, etc.

[0107] Additionally, the output unit (240) can output the PRPD graph calculated by the data processing unit (230).

[0109] FIG. 11 is a flowchart illustrating a method for generating acoustic data through beamforming according to an embodiment of the present invention. Here, beamforming is a signal processing technique that utilizes a microphone array to enhance acoustic signals generated from a specific direction and suppresses unnecessary noise to increase the signal-to-noise ratio (SNR).

[0110] Referring to FIG. 11, the data processing unit (230) can receive an acoustic signal from the acoustic signal receiving unit (210) (S1001). In the case of the acoustic camera (200-1) shown in FIG. 10, the data processing unit (230) can receive a partial discharge acoustic signal and an ultrasonic reference signal from the acoustic signal receiving unit (210).

[0111] And, the data processing unit (230) can remove noise from the acoustic signal by setting a frequency detection band of a predetermined range (S1002).

[0112] Additionally, the data processing unit (230) can perform time alignment and synthesis of acoustic signals (S1003). Since the time at which acoustic signals coming from a specific direction reach each microphone is different, it is necessary to calculate the time difference for the arrival of acoustic signals at each microphone and perform delay compensation to time-align the ultrasonic acoustic signals. This will be explained in detail with reference to FIG. 12.

[0113] FIG. 12 is a diagram illustrating a method for time alignment and synthesis of acoustic signals according to one embodiment of the present invention. The data processing unit (230) calculates distances between the acoustic sensors (210-1, 210-2, ..., 210-n) and virtual plane points (410-1, 410-2, ..., 410-n) using the coordinates (Xs, Ys) of each acoustic sensor (210-1, 210-2, ..., 210-n) constituting the acoustic signal receiving unit (210), the coordinates (Xg, Yg) of a virtual plane (Source surface) set in a real-world acoustic scene, and the distance (L) between the acoustic sensor array plane (Array surface) and the virtual plane (Source surface); calculates delay distances for each virtual plane point (410-1, 410-2, ..., 410-n) based on the calculated distances; applies time delay correction to each acoustic signal using the calculated delay distances; calculates the sound source value for each virtual plane point (410-1, 410-2, ..., 410-n) by summing them; and the calculated The sound source value can be divided by the number of acoustic sensors (210-1, 210-2, ..., 210-n) constituting the acoustic signal receiver (210) to calculate the sound pressure level of each of the virtual plane points (410-1, 410-2, ..., 410-n).

[0114] Here, a virtual plane is a virtual space in which sound pressure levels are calculated in a real-world acoustic scene, and at least one such plane can be established. Additionally, the size of the virtual plane may vary depending on the beamforming angle of view.

[0115] In this way, the data processing unit (230) can receive only the acoustic signal generated at the beamforming angle through beamforming and remove the acoustic signal generated in the area outside the beamforming angle. Through this, the data processing unit (230) can intensively capture the ultrasonic acoustic signal generated from each of the measurement target (300) and the ultrasonic reference signal generating device (100-2, 100-3) and remove the unwanted ultrasonic acoustic signal.

[0116] Referring to FIG. 11, the data processing unit (230) can generate acoustic data corresponding to an acoustic signal (S1004). In the case of the acoustic camera (200-1) shown in FIG. 10, the data processing unit (230) can generate partial discharge acoustic data corresponding to a partial discharge acoustic signal and ultrasonic reference acoustic data corresponding to an ultrasonic reference signal.

[0118] FIG. 13 is a flowchart illustrating a method for phase correction of partial discharge acoustic data using an ultrasonic reference signal according to one embodiment of the present invention.

[0119] Referring to FIG. 13, the data processing unit (230) can distinguish between ultrasonic reference acoustic data and partial discharge acoustic data (S110). Unlike the RF method, in the ultrasonic method, the module receiving the ultrasonic reference signal and the module receiving the partial discharge acoustic signal are both the same as the acoustic signal receiving unit (210), so an algorithm for distinguishing between the ultrasonic reference signal and the partial discharge acoustic signal must be additionally provided. The ultrasonic reference signal generating unit (130) can adjust at least one of the period and number of times the ultrasonic reference signal is output, and the data processing unit (230) can distinguish between the ultrasonic reference acoustic data and the partial discharge acoustic data based on at least one of the information regarding the period and number of times.

[0120] The data processing unit (230) can calculate the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal (S120).

[0121] FIG. 14 is a diagram illustrating a method for calculating a phase difference and correcting a phase according to an embodiment of the present invention. FIG. 14(a) shows a partial discharge acoustic signal before phase correction. Referring to FIG. 14(a), the pulse of the reference signal (73) is located at a 90-degree phase position of the AC voltage signal (71) in the environment where the measurement target (300) is installed, while the pulse of the partial discharge acoustic signal (72) is located at a phase position of approximately 200 degrees, so it can be confirmed that there is a phase difference between the reference signal (73) and the acoustic signal (72). At this time, the phase difference may be expressed as a delay time.

[0122] As shown in Fig. 14(a), if a PRPD graph is calculated based on partial discharge acoustic data in a situation where a phase difference exists, an accurate PRPD graph cannot be calculated.

[0123] The data processing unit (230) according to the present invention can calculate the phase difference between a reference signal (73) and a partial discharge acoustic signal (72) as in FIG. 14(a), and correct the phase of the partial discharge acoustic data based on the calculated phase difference to generate phase-corrected partial discharge acoustic data. At this time, the phase-corrected partial discharge acoustic signal corresponding to the phase-corrected partial discharge acoustic data may be as in FIG. 14(b).

[0124] To this end, the data processing unit (230) can convert the calculated phase difference into the number of samples (S130). Then, the data processing unit (230) can correct the partial discharge acoustic data by the converted number of samples to generate phase-corrected partial discharge acoustic data (S140).

[0125] FIG. 15 is a diagram illustrating a partial discharge acoustic data phase correction method according to an embodiment of the present invention. FIG. 15(a) is partial discharge acoustic data before phase correction, and FIG. 15(b) is ultrasonic reference acoustic data. Referring to FIG. 15(a) and (b), it can be seen that there is a phase difference (delay time) between the partial discharge acoustic signal and the ultrasonic reference signal before phase correction.

[0126] In this case, the data processing unit (230) can convert the phase difference into the number of samples (81) of the partial discharge acoustic data before phase correction as shown in FIG. 15(c), and generate phase-corrected acoustic data by cutting the partial discharge acoustic data by the converted number of samples. At this time, data collection / analysis is performed by advancing or delaying the timing by the number of samples (81) according to the correction (e.g., adding or cutting data) of the partial discharge acoustic data by the number of samples, and the peak position of the phase-corrected partial discharge acoustic signal can be located at the pulse of the reference signal.

[0127] As described above, after performing phase correction once using the reference signal generating device (100) in the environment where the measurement target (300) according to the present invention is located, the AC voltage signal in which the measurement target (300) operates in that environment and the partial discharge acoustic signal collected by the acoustic camera (200) are mutually synchronized, so subsequent phase correction may be unnecessary unless the measurement location or measurement environment changes.

[0128] Meanwhile, the data processing unit (230) can calculate a PRPD graph using phase-corrected acoustic data (S150). Then, the data processing unit (230) can output the calculated PRPD graph through the output unit (240).

[0129] This data processing unit (230) may be installed inside the acoustic camera (200-1). However, the installation location is merely an example of implementation, and it may also be implemented as being installed outside the acoustic camera (200-1).

[0131] FIG. 16 is a block diagram showing an acoustic camera according to another embodiment of the present invention. The acoustic camera (200-2) shown in FIG. 16 is an embodiment that includes both an RF signal receiver (250) and an acoustic signal receiver (210), and can be used to measure partial discharge of a measurement target (300) in conjunction with an RF reference signal generator (100-1) shown in FIG. 3 or an ultrasonic and RF reference signal generator (100-3) shown in FIG. 8.

[0132] Referring to FIG. 16, the acoustic camera (200-2) may include an acoustic signal receiving unit (210), an optical signal receiving unit (220), a data processing unit (230), an output unit (240), and an RF receiving unit (250). Here, the function of the acoustic camera (200-2) shown in FIG. 16 differs from the acoustic camera (200-1) shown in FIG. 10 in that it receives and utilizes an RF reference signal generated by an RF reference signal generating device (100-1, 100-3) through the RF signal receiving unit (250) for phase correction of a partial discharge acoustic signal generated from a measurement target (300). Therefore, in describing FIG. 16, content that overlaps with FIG. 10 will be omitted, and the explanation will focus on the differences.

[0133] In the case of the RF method, the RF receiver (250) receiving the RF reference signal and the acoustic receiver (210) receiving the partial discharge acoustic signal can be separated into different modules, and accordingly, the step of distinguishing between the RF reference signal and the partial discharge acoustic signal may be unnecessary.

[0134] The RF receiver (250) can receive an RF reference signal generated by an RF reference signal generating device (100-1, 100-3).

[0135] The data processing unit (230) can generate partial discharge acoustic data for a partial discharge acoustic signal. Additionally, the data processing unit (230) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the RF reference signal and the partial discharge acoustic signal.

[0136] Additionally, the data processing unit (230) can receive the RF reference signal and the ultrasonic reference signal emitted from the RF and ultrasonic reference signal generating unit (200-3) to the RF signal receiving unit (250) and the acoustic signal receiving unit (210), respectively, and calculate the distance between the acoustic camera (200-2) and the reference signal generating unit (200-3).

[0137] Specifically, since the RF reference signal travels at the speed of light, it will be received almost immediately at the RF signal receiver (250), whereas the ultrasonic reference signal travels much slower than the RF reference signal, so it takes time to arrive at the acoustic signal receiver (210). The data processing unit (230) can calculate the time difference between the reception time of the RF reference signal and the reception time of the ultrasonic reference signal, and calculate the distance between the acoustic camera (200-2) and the reference signal generating device (200-3) by multiplying the calculated time difference by the speed of the ultrasonic signal (for example, the speed of the ultrasonic signal passing through air is about 340 m / s).

[0138] FIG. 17 is a flowchart illustrating a method for phase correction of partial discharge acoustic data using an RF reference signal according to one embodiment of the present invention.

[0139] Referring to FIG. 17, the data processing unit (230) can calculate the phase difference between the RF reference signal and the partial discharge acoustic signal (S210). Here, the process of calculating the phase difference of the processor (230) can be easily derived by a person skilled in the art based on FIG. 14, so a detailed explanation thereof will be omitted.

[0140] And, the data processing unit (230) can convert the calculated phase difference into the number of samples (S220). And, the data processing unit (230) can correct the partial discharge acoustic data by the converted number of samples to generate phase-corrected partial discharge acoustic data (S230).

[0141] And, the data processing unit (230) can calculate a PRPD graph using phase-corrected acoustic data (S240). Here, the acoustic data phase correction process of the data processing unit (230) can be easily derived by a person skilled in the art based on FIG. 15, so a detailed description thereof will be omitted.

[0143] FIG. 18 is a drawing illustrating an example of an implementation of an acoustic camera according to an embodiment of the present invention. Referring to FIG. 18, the acoustic camera can be implemented as a portable acoustic camera that is portable by a user. FIG. 18(a) shows the front of the acoustic camera, and grip portions (260) for user gripping are formed on both sides of the acoustic camera, and an acoustic signal receiving portion (210) can be formed on the front of the acoustic camera. The acoustic receiving portion (210) has an acoustic wave inlet hole (211) for sound wave inflow and a microphone array can be formed inside.

[0144] FIG. 18(b) shows the rear of the acoustic camera, and an output unit (240) for user verification may be formed on the rear of the acoustic camera.

[0145] Meanwhile, although FIG. 18 describes an example in which the acoustic camera is implemented as a portable type, it is not limited thereto. According to another embodiment of the present invention, the acoustic camera may be implemented as a fixed acoustic camera fixedly installed at a predetermined point, or as a fixed acoustic camera that operates in conjunction with a CCTV fixedly installed at a predetermined point. Alternatively, according to another embodiment of the present invention, the acoustic camera may be implemented as a mobile acoustic camera installed on a mobile platform capable of autonomous or non-autonomous driving (e.g., a robot, a vehicle, a motorcycle, etc.).

[0147] Below, a partial discharge measurement scenario of a partial discharge measurement system (1000) composed of a reference signal generating device (100), an acoustic camera (200), and a measurement target (300) will be described in detail.

[0148] FIG. 19 is a conceptual diagram illustrating a scenario in which a reference signal generator is installed close to a measurement target to measure partial discharge of the measurement target. FIG. 19 is a scenario in which a user can access the measurement target (300), and the reference signal generator (100) may be installed at a close distance from the measurement target (300). In this case, according to an unlimited embodiment of the close distance, it may be within 1 meter from the measurement target (300).

[0149] FIG. 20 is a conceptual diagram illustrating a scenario in which a reference signal generator is installed close to an acoustic camera to measure partial discharge of a measurement target. FIG. 20 is a scenario in which it is difficult for a user to access the measurement target (300), and the reference signal generator (100) may be installed at a close distance from the acoustic camera (200). In this case, according to an unlimited embodiment of the close distance, it may be within 1 meter from the acoustic camera (200).

[0150] FIG. 21 is a flowchart illustrating the operation of a system implemented as an ultrasonic reference signal generator in the example of FIG. 19. Referring to FIG. 21, the reference signal generator (100-2, 100-3) can be installed at a close distance from the measurement target (300) as in the implementation example of FIG. 19 (S11), and the reference signal generator (100-2, 100-3) can be connected to an external power source (102). In this case, the reference signal generator (100-2, 100-3) can output an ultrasonic reference signal (101).

[0151] And, the acoustic camera (200-1) can receive the ultrasonic reference signal (101) (S14).

[0152] Additionally, when a partial discharge acoustic signal is output according to the partial discharge of the measurement target (300) (S15), the acoustic camera (200-1) can receive the partial discharge acoustic signal (S16).

[0153] And, the acoustic camera (200-1) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal (S17).

[0154] And, the acoustic camera (200-1) can perform phase-resolved partial discharge analysis using phase-corrected acoustic data to produce a PRPD graph (S18). And, the acoustic camera (200-1) can output the produced PRPD graph (S19).

[0155] In the example of FIG. 21, since the reference signal generator (100-2, 100-3) and the measurement target (300) are located adjacent to each other, the first distance between the acoustic camera (200-1) and the reference signal generator (100-2, 100-3) and the second distance between the acoustic camera (200-1) and the measurement target (300) are nearly identical. Furthermore, both the ultrasonic reference signal (101), which is the output of the reference signal generator (100-2, 100-3), and the partial discharge acoustic signal generated by the partial discharge of the measurement target (300) are sound waves having the same physical characteristics. Therefore, in the scenario of FIG. 21, the acoustic camera (200-1) does not need to perform distance correction considering the signal delay due to the difference between the first distance and the second distance.

[0157] FIG. 22 is a flowchart illustrating the operation of a system implemented as an ultrasonic reference signal generator in the example of FIG. 20. Referring to FIG. 22, the reference signal generator (100-2, 100-3) can be installed at a close distance from the acoustic camera (200) as in the example of FIG. 20 (S41), and the reference signal generator (100-2, 100-3) can be connected to an external power source (102) (S42). In this case, the reference signal generator (100-2, 100-3) can output an ultrasonic reference signal (101) (S43).

[0158] And, the acoustic camera (200-1) can receive the ultrasonic reference signal (101) (S44).

[0159] Additionally, when a partial discharge acoustic signal is output according to the partial discharge of the measurement target (300) (S45), the acoustic camera (200-1) can receive the partial discharge acoustic signal (S46).

[0160] And, the acoustic camera (200-1) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal (S47).

[0161] Meanwhile, in the example of FIG. 22, since the reference signal generating device (100-2, 100-3) is located adjacent to the acoustic camera (200-1), there is a significant difference between the first distance between the acoustic camera (200-1) and the reference signal generating device (100-2, 100-3) and the second distance between the acoustic camera (200-1) and the measurement target (300). Therefore, in the scenario of FIG. 22, distance correction is required to account for the signal delay due to the distance difference.

[0162] To this end, the acoustic camera (200-1) can measure the distance between the acoustic camera (200-1) and the measurement target (300) (S48).

[0163] And, the acoustic camera (200-1) can apply distance correction to the phase-corrected partial discharge acoustic data after calculating the delay according to the distance (S49). Here, the sample delay for distance correction can be calculated based on the following mathematical formula 1.

[0164] [Mathematical Formula 1]

[0165] Sample delay for distance correction = (Distance between acoustic camera and measurement target) / (Transmission speed of the sound source of the measurement target)

[0166] In addition, distance correction can be applied by converting the sample delay into the number of samples as shown in the example of FIG. 15 described above, and correcting the phase-corrected partial discharge acoustic data by the converted number of samples. At this time, if the distance between the acoustic camera (200-1) and the measurement target (300) changes, the distance correction described above must be performed again.

[0167] And, the acoustic camera (200-1) can perform phase-resolved partial discharge analysis using phase-corrected acoustic data to produce a PRPD graph (S18). And, the acoustic camera (200-1) can output the produced PRPD graph.

[0169] FIG. 23 is a flowchart illustrating the operation of a system implemented as an RF reference signal generator in the example of FIG. 19. Referring to FIG. 23, the reference signal generator (100-1, 100-3) can be installed at a short distance from the measurement target (300) as in the implementation example of FIG. 19 (S21), and the reference signal generator (100-1, 100-3) can be connected to an external power source (102) (S22). In this case, the reference signal generator (100-1, 100-3) can output an RF reference signal (101) (S23).

[0170] And, the acoustic camera (200-2) can receive the RF reference signal (101) (S24).

[0171] Additionally, when a partial discharge acoustic signal is output according to the partial discharge of the measurement target (300) (S25), the acoustic camera (200-2) can receive the partial discharge acoustic signal (S26).

[0172] And, the acoustic camera (200-2) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the RF reference signal and the partial discharge acoustic signal (S27).

[0173] Meanwhile, in the example of FIG. 23, the physical characteristics of the RF reference signal (101), which is the output of the reference signal generating device (100-1, 100-3), are electromagnetic waves, and the physical characteristics of the partial discharge acoustic signal generated by the partial discharge of the measurement target (300) are sound waves, which are different from each other. Therefore, in the scenario of FIG. 23, distance correction is required to account for the signal delay due to the difference in the physical characteristics of the signals.

[0174] To this end, the acoustic camera (200-2) can measure the distance between the acoustic camera (200-2) and the measurement target (300) (S28). Then, the acoustic camera (200-2) can calculate a delay based on the distance and apply a distance correction to the phase-corrected partial discharge acoustic data (S29). Here, the sample delay for distance correction can be calculated based on the above-described mathematical formula 1.

[0175] And, the acoustic camera (200-2) can perform phase-resolved partial discharge analysis using phase-corrected partial discharge acoustic data to produce a PRPD graph (S30). And, the acoustic camera (200-2) can output the produced PRPD graph (S31).

[0177] FIG. 24 is a flowchart illustrating the operation of a system when implemented as an RF reference signal generator in the example of FIG. 20. Referring to FIG. 24, the reference signal generator (100-1, 100-3) can be installed at a close distance from the acoustic camera (200-2) as in the implementation example of FIG. 20 (S61), and the reference signal generator (100-1, 100-3) can be connected to an external power source (102) (S62). In this case, the reference signal generator (100-1, 100-3) can output an RF reference signal (101) (S63).

[0178] And, the acoustic camera (200-2) can receive the RF reference signal (101) (S64).

[0179] Additionally, when a partial discharge acoustic signal is output according to the partial discharge of the measurement target (300) (S65), the acoustic camera (200-2) can receive the partial discharge acoustic signal (S66).

[0180] And, the acoustic camera (200-2) can generate phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the RF reference signal and the partial discharge acoustic signal (S67).

[0181] Meanwhile, in the example of FIG. 24, the physical characteristics of the RF reference signal (101), which is the output of the reference signal generating device (100-1, 100-3), are electromagnetic waves, and the physical characteristics of the partial discharge acoustic signal generated by the partial discharge of the measurement target (300) are sound waves, which are different from each other. Therefore, in the scenario of FIG. 24, distance correction is required to account for the signal delay due to the difference in the physical characteristics of the signals.

[0182] To this end, the acoustic camera (200-2) can measure the distance between the acoustic camera (200-2) and the measurement target (300) (S68). Then, the acoustic camera (200-2) can apply distance correction to the phase-corrected partial discharge acoustic data after calculating the delay according to the distance (S69). Here, the sample delay for distance correction can be calculated based on the above-described mathematical formula 1.

[0183] And, the acoustic camera (200-2) can perform phase-resolved partial discharge analysis using phase-corrected partial discharge acoustic data to produce a PRPD graph (S70). And, the acoustic camera (200-2) can output the produced PRPD graph (S71).

[0185] FIG. 26 is a diagram showing a PRPD graph of corona discharge according to an embodiment of the present invention. Referring to FIG. 26, by using a reference signal of a reference signal generating device (100) to phase-correct the partial discharge acoustic data collected by an acoustic camera and generating phase-corrected partial discharge acoustic data, an accurate PRPD graph can be drawn through Phase Lock.

[0186] Through this, users of acoustic cameras can perform accurate partial discharge analysis by checking the PRPD graph.

[0188] FIG. 27 is a drawing showing an optical-acoustic combined image according to an embodiment of the present invention. Referring to FIG. 27, the output unit (240) can display at least one of an acoustic map (2701) indicating whether partial discharge occurs and the location of partial discharge, and a phase-corrected PRPD graph (2702), through an optical-acoustic combined image.

[0189] Through this, a user of an acoustic camera can easily check at least one of whether there is partial discharge, the location of the partial discharge, and the type of partial discharge (corona discharge, surface discharge, floating discharge, etc.).

[0191] FIG. 28 is a block diagram showing the configuration of a data processing unit according to an embodiment of the present invention. Referring to FIG. 28, the data processing unit (230) may include a processor (234), an input / output I / O (231), a memory (232), an interface (233), and a bus (235). The processor (234), the input / output device (231), the memory (232), and / or the interface (233) may be connected to each other through the bus (235). The bus (235) corresponds to a path through which data is moved.

[0192] Specifically, the processor (234) may include at least one of a CPU (Central Processing Unit), MPU (Micro Processor Unit), MCU (Micro Controller Unit), GPU (Graphic Processing Unit), microprocessor, digital signal processor, microcontroller, application processor (AP), and logic elements capable of performing similar functions.

[0193] The input / output device (231) may include at least one of a keypad, a keyboard, a touchscreen, and a display device. The memory device (122) may store data and / or programs, etc.

[0194] The interface (233) can perform the function of transmitting data to a communication network or receiving data from a communication network. The interface (233) may be wired or wireless. For example, the interface (233) may include an antenna or a wired / wireless transceiver, etc. The memory (232) enhances the operation of the processor (234) and, as a volatile operational memory, may further include high-speed DRAM and / or SRAM, etc.

[0195] Additionally, the memory (234) stores programming and data configurations that provide the functions of some or all of the modules described herein. For example, it may include logic that enables the execution of selected modes of the method described above.

[0196] A program or application is loaded as a set of instructions containing each step of performing the aforementioned method stored in memory (232), and the processor (234) is enabled to perform each step.

[0197] The present invention has been described so far with reference to its preferred embodiments. All embodiments and conditional examples disclosed herein are intended to help readers of the art who have ordinary knowledge in the technical field of the present invention to understand the principles and concepts of the present invention, and those of the art will understand that the present invention may be implemented in modified forms without departing from the essential characteristics of the present invention.

[0198] Therefore, the disclosed embodiments should be considered in an illustrative rather than a limiting sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

[0199] Meanwhile, the method of the various embodiments of the present invention described above may be implemented as a program and provided to servers or devices. Accordingly, each device may connect to a server or device where the program is stored and download the program.

[0200] In addition, the method according to the various embodiments of the present invention described above may be implemented as a program and provided by being stored on various non-transitory computer-readable media. A non-transitory computer-readable medium refers to a medium that stores data semi-permanently and is readable by a device, rather than a medium that stores data for a short period of time, such as a register, cache, or memory. Specifically, the various applications or programs described above may be provided by being stored on non-transitory computer-readable media such as CDs, DVDs, hard disks, Blu-ray discs, USBs, memory cards, ROMs, etc.

[0201] Furthermore, although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. It is understood that various modifications can be made by those skilled in the art without departing from the essence of the invention as claimed in the claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0202] 100: Reference signal generator 200: Acoustic camera 300 : Measurement target

Claims

Claim 1 A partial discharge measurement system comprising: a reference signal generator located in a real space and outputting a reference signal for phase correction; and an acoustic camera that measures partial discharge based on a partial discharge acoustic signal generated from a measurement target; wherein the acoustic camera comprises: an acoustic signal receiver that receives the partial discharge acoustic signal generated from the measurement target; and a data processing unit that generates partial discharge acoustic data for the partial discharge acoustic signal and phase-corrects the partial discharge acoustic data based on the phase difference between the reference signal and the partial discharge acoustic signal to generate phase-corrected partial discharge acoustic data; and wherein the reference signal generator comprises a power supply unit connected to an external power source in the same environment as the environment in which the measurement target is located. Claim 2 delete Claim 3 A partial discharge measurement system according to claim 1, wherein the reference signal generating device generates and outputs a signal synchronized with an AC voltage signal applied through the power supply. Claim 4 A partial discharge measurement system according to claim 1, wherein the reference signal generating device comprises: a phase detection unit that detects a predetermined phase position of an AC voltage signal applied through the power supply unit; and a reference signal output unit that generates a predetermined pulse at the detected phase position and outputs it as the reference signal. Claim 5 A partial discharge measurement system according to claim 4, wherein the reference signal comprises at least one of an RF (Radio Frequency) signal and an ultrasonic acoustic signal. Claim 6 A partial discharge measurement system according to claim 5, wherein, when the reference signal is an ultrasonic reference signal, the reference signal output unit controls at least one of the period and number of times the ultrasonic reference signal is output. Claim 7 A partial discharge measurement system according to claim 1, wherein the data processing unit calculates the phase difference between the reference signal and the partial discharge acoustic signal, converts the calculated phase difference into a number of samples, and corrects the acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data. Claim 8 A partial discharge measurement system according to claim 1, wherein the data processing unit calculates a phase-resolved partial discharge (PRPD) graph using phase-corrected partial discharge acoustic data. Claim 9 A partial discharge measurement system characterized by further including, in claim 8, an output unit that outputs the phase-resolved partial discharge graph. Claim 10 A partial discharge measurement system according to claim 1, characterized in that the reference signal generating device is located within a predetermined distance from the measurement target or within a predetermined distance from the acoustic camera. Claim 11 A partial discharge measurement method comprising: a reference signal generating device located in real space and outputting a reference signal for phase correction; an acoustic camera comprising: receiving a partial discharge acoustic signal generated from a measurement target; generating partial discharge acoustic data for the partial discharge acoustic signal and generating phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the reference signal and the partial discharge acoustic signal; and further comprising: a step in which the power supply of the reference signal generating device is connected to an external power source in the same environment as the environment in which the measurement target is located. Claim 12 A partial discharge measurement method according to claim 11, wherein the step of outputting the reference signal generates and outputs a signal synchronized with an AC voltage signal applied through the power supply. Claim 13 A partial discharge measurement method according to claim 11, wherein the reference signal comprises at least one of an RF reference signal and an ultrasonic reference signal. Claim 14 A partial discharge measurement method according to claim 13, wherein, in the case of the RF reference signal, the step of generating the phase-corrected partial discharge acoustic data comprises: a step of calculating the phase difference between the RF reference signal and the partial discharge acoustic signal; a step of converting the calculated phase difference into a number of samples; and a step of correcting the partial discharge acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data. Claim 15 A partial discharge measurement method according to claim 13, wherein, in the case of the ultrasonic reference signal, the step of generating the phase-corrected partial discharge acoustic data comprises: a step of distinguishing between the ultrasonic reference acoustic data corresponding to the ultrasonic reference signal and the partial discharge acoustic data; a step of calculating the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal; a step of converting the calculated phase difference into a number of samples; and a step of correcting the partial discharge acoustic data by the converted number of samples to generate the phase-corrected partial discharge acoustic data. Claim 16 An acoustic camera comprising: an acoustic receiver that receives a partial discharge acoustic signal generated from a measurement target and an ultrasonic reference signal generated from a reference signal generator that outputs a reference signal for phase correction; and a data processing unit that generates phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the ultrasonic reference signal and the partial discharge acoustic signal, wherein the reference signal generator comprises a power supply unit connected to an external power source in the same environment as the environment in which the measurement target is located. Claim 17 An acoustic camera comprising: an acoustic receiver for receiving a partial discharge acoustic signal generated from a measurement target; an RF receiver for receiving an RF reference signal generated from a reference signal generator for outputting a reference signal for phase correction; and a data processing unit for generating phase-corrected partial discharge acoustic data by phase-correcting the partial discharge acoustic data based on the phase difference between the RF reference signal and the partial discharge acoustic signal, wherein the reference signal generator comprises a power supply unit connected to an external power source in the same environment as the environment in which the measurement target is located. Claim 18 A computer-readable recording medium having a program recorded thereon for executing the partial discharge measurement method described in any one of paragraphs 11 to 15. Claim 19 A computer program stored on a computer-readable recording medium containing program code for executing a partial discharge measurement method described in any one of claims 11 to 15.

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