Optical type corona discharge detection system

Abstract

To optically detect a corona discharge.SOLUTION: A discharge detection device is configured to provide: a parabola 111 that reflects a discharge sound generated by a corona discharge; and a detection unit 113 in the vicinity of a focus point of the parabola. In the detection unit 113, a light emitting unit is configured to irradiate a laser beam in a direction orthogonal to an incidence direction of the discharge sound, and receive the laser beam by a light reception unit provided in a facing side. When the discharge sound exists, the laser beam is diffracted by an impact of the existence of the discharge sound, and thus, diffraction light is detected by the light reception unit. Therefore, presence or absence of the discharge sound can be determined without using a microphone and the like. In such a way, a sound collection of the discharge sound by the parabola 111 enables improving sensitivity. Also, the microphone and the like are not needed in a front of the parabola 111, which in turn the discharge sound can be detected without rendering these microphone and the like as shielding members.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a technique for detecting corona discharge occurring in electrical equipment such as power cables. [Background technology]

[0002] In high-voltage electrical equipment such as power cables, the exterior and various other parts of the power cable are insulated by insulating materials as appropriate. If the insulating material deteriorates or becomes damaged over time, or if the wires are cut or loosened, electric field concentration occurs, resulting in corona discharge. It is known that corona discharge is accompanied by a discharge sound called corona noise, which includes irregular components such as a buzzing or rustling sound, and regular components such as a buzzing sound. Therefore, by detecting this discharge sound, it is possible to detect deterioration or damage of the power cable. Non-Patent Document 1 discloses a technology for detecting discharge sounds using a light wave microphone. In this technology, diffracted light caused by phase modulation when a sound wave hits a laser is detected by an optical Fourier transform on the light receiving lens side. [Prior art documents] [Patent documents]

[0003] [Non-Patent Document 1] Fumiaki Mitsuki et al., "Measurement and Analysis of Surface Discharge Sound Using an Optical Microphone," Laser Research, May 2009, p.379-383 Summary of the Invention [Problem to be solved by the invention]

[0004] Non-Patent Document 1 assumes that the discharge sound is collected by a microphone, and if it is to be detected in an actual power cable, it is necessary to approach the power cable by about 5 to 10 m, which is not practical. In order to improve sensitivity, a method of collecting sound using a parabola is also conceivable, but this method requires the placement of a microphone at the focal position in front of the parabola, which creates the problem that the microphone itself becomes a shield against the incoming discharge sound. In addition, the method of collecting sound with a single microphone using a parabola has a narrow sound collection range, making it difficult to detect even the slightest deviation in the search direction relative to the sound source, and it takes a long time when searching a wide area. The present invention has been made in view of the above problems, and has an object to make it possible to detect corona discharges efficiently and with high sensitivity over a wide range. [Means for solving the problem]

[0005] The present invention provides a discharge detection device for optically detecting corona discharge, comprising: A sound collecting section having a concave curved surface shape that reflects the discharge sound generated by the corona discharge so as to collect the discharge sound; a light emitting unit that irradiates a laser beam near a portion where the discharge sound is collected; The discharge detection device may further include a detection unit that detects diffracted light produced by diffracting the laser due to the discharge sound.

[0006] According to the present invention, the sound collecting section can collect the incident discharge sound by reflecting it on the concave curved surface, thereby improving the sensitivity. Also, the discharge sound is detected by irradiating a laser and detecting the diffracted light, rather than by a microphone, so the detection section can be configured without placing a shield that blocks the discharge sound in front of the sound collecting section. Therefore, according to the present invention, multiple detection sections can be arranged arbitrarily, making it possible to detect the discharge sound with good sensitivity over a wide range.

[0007] In the present invention, the sound collecting section may have various concave shapes. It is preferable that the discharge sound can be collected at one point, but this is not necessarily limited to this. In addition, the area where the sound is collected may vary depending on the incident direction of the discharge sound. It is preferable to irradiate the laser in a direction in which diffraction due to the discharge sound is likely to occur. From this viewpoint, it is preferable to irradiate in a direction perpendicular to the discharge sound incident on or reflected from the sound collecting section. Since the discharge sound may be incident from various directions, it is sufficient to determine that the front of the sound collecting section, i.e., the direction in which the projected area is maximum, is set as the representative direction and that the laser is irradiated in a direction perpendicular to this. Known methods for detecting diffracted light by a laser include the so-called Schlieren method, light wave microphone, etc. The detection unit of the present invention can adopt a configuration that realizes these methods. Other configurations that can detect diffracted light may also be adopted. In addition, since the area where the sound is collected may move depending on the direction in which the discharge sound is incident, a mechanism for scanning the area on the front side of the concave curved surface with a laser may be provided.

[0008] In the present invention, The concave curved surface shape is a parabolic shape, The laser may be irradiated near a focal point of a parabola shape in a direction perpendicular to an axis of symmetry of the parabola shape.

[0009] The parabolic shape allows the discharge sound incident from the front to be collected toward the focal point, and also makes it possible to collect the discharge sound incident from an oblique direction at one of the points.

[0010] In the present invention, The light emitting section may emit a plurality of parallel laser beams.

[0011] In this way, even if the location where the sound is collected varies depending on the direction of incidence of the discharge sound, the sound can be detected by any one of the multiple lasers without scanning the laser. In the above-mentioned aspect, the number and intervals of the lasers can be determined arbitrarily.

[0012] In the above aspect, The detection unit may use a line sensor in which a plurality of optical sensors are arranged in order to detect the diffracted light.

[0013] In this way, the diffracted light from a plurality of lasers can be detected with a simple configuration. The configuration for detecting the diffracted light of the multiple lasers is not limited to the above embodiment. For example, the multiple detectors may be provided at positions where the diffracted light of the multiple lasers can be detected. Also, the detectors may be moved to positions where the diffracted light of the multiple lasers can be detected.

[0014] In the present invention, The light emitting section may emit a plurality of intersecting laser beams.

[0015] This makes it possible to detect the discharge sound from multiple directions. At the point where the lasers intersect, it becomes possible to detect diffracted light from both the first-direction laser and the second-direction laser, improving the detection accuracy of the discharge sound. In the above-mentioned aspect, the number of lasers in the first direction and the second direction intersecting with each other can be determined arbitrarily. It is not necessary that the numbers are the same, and there may be only one first direction or one second direction. If multiple first directions and multiple second directions are prepared, multiple intersections between the two directions are also generated, which has the advantage that the detection accuracy can be improved even if the part where the discharge sound is collected moves.

[0016] In the present invention, The detection unit is an optical sensor for detecting the diffracted light; and a circular shield that blocks the non-diffracted laser beam from entering the optical sensor.

[0017] As explained above, known methods for detecting diffracted light include the Schlieren method and light wave microphones. When using the Schlieren method, a mechanism called a knife edge is usually installed on the optical path to block the non-diffracted main light beam. However, when using a knife edge, fine adjustment of its position is required, which makes it less practical. In contrast, in the above embodiment, a circular shield that blocks the main light beam is used instead of the knife edge. This makes it possible to effectively block the main light beam and improve the detection accuracy of the diffracted light. In addition, a circular shield can be easily fixed by, for example, attaching it to the front of the optical sensor, and has the advantage of being able to stabilize the position. The size of the circular shield can be set arbitrarily. It is not necessary to block all of the main beam. Since diffracted light occurs in a ring shape around the main beam, it is sufficient to block the main beam to an extent that the diffracted light can be detected.

[0018] In the present invention, A plurality of sound collecting units each having a different range for collecting the discharge sound; A plurality of light emitting units and detecting units may be provided, each corresponding to one of the sound collecting units.

[0019] In this way, it is possible to detect the discharge sound over a wide range. The sound collecting units etc. may be arranged, for example, in a line or two-dimensional array facing the same direction. In this way, it is possible to widen the detection range of the discharge sound. Also, the sound collecting units may be installed facing various directions. In this way, it is possible to detect the discharge sound from various incident directions.

[0020] In the present invention, the discharge detection device may be further attached to a drone, an aircraft, a vehicle, a ship, or other moving object. Generally, power cables are installed at high places, but according to this embodiment, it becomes possible to relatively easily inspect the power cables.

[0021] The present invention relates to 1. A discharge detection system for optically detecting a corona discharge, comprising: The discharge detection device according to any one of the above aspects, The discharge detection system may further include an analysis device that analyzes the occurrence of the corona discharge based on the output of the discharge detection device.

[0022] In this way, it becomes possible to detect the occurrence of corona discharge based on the presence or absence of diffracted light. Examples of the analysis include a process to suppress the effects of various noises contained in the detection result of the diffracted light, and a process to determine whether the sound is due to discharge sound based on the frequency of the diffracted light contained in the detection result or other factors. In the above-mentioned aspect, the discharge detection device and the analysis device may be configured as an integrated unit or may be configured as separate units. For example, the discharge detection device may be mounted on a moving body, and the analysis device may acquire the detection result via communication or a medium and perform analysis. When the discharge detection device and the analysis device are separate devices, for example, a plurality of discharge detection devices may be associated with one analysis device.

[0023] When the discharge detection device and the analysis device are separate, The output of the discharge detection device may be wirelessly communicated to the analysis device.

[0024] This eliminates the need to wire the two together, improving practicality. When performing wireless communication, a configuration for limiting the amount of information communicated may be provided in order to reduce power consumption and traffic.

[0025] In the present invention, it is not necessary to have all of the various features described above, and some of them may be omitted or combined as appropriate. In the present invention, what is detected is not limited to discharge sounds, but may be used for wide-range detection of sound sources in general. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of a discharge detection system. [Diagram 2] FIG. 2 is an explanatory diagram showing the configuration of a discharge detection device. [Diagram 3] FIG. 2 is an explanatory diagram showing the principle of detecting a discharge by the Schlieren method. [Figure 4] FIG. 2 is an explanatory diagram showing the principle of detecting a discharge by a light wave microphone. [Diagram 5] 3 is an explanatory diagram showing an example of the configuration of a light emitting unit and a light receiving unit; FIG. [Figure 6] 4 is a flowchart of a discharge detection process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described by taking as an example a system for detecting corona discharge occurring in a power cable as power equipment. Fig. 1 is an explanatory diagram showing the configuration of a discharge detection system. This system detects discharge sound NZ caused by corona discharge that occurs when deterioration or damage occurs in a power cable for carrying high-voltage power, as shown in the lower part of the figure. The electric discharge detection system includes a mobile body 100 equipped with an electric discharge detection device, and an analysis device 200. In this embodiment, a drone is used as the mobile body 100, but various types of vehicles such as airplanes, ships, and vehicles may also be used. In addition, the electric discharge detection device may be used without being mounted on the mobile body, for example, by fixing it to a steel tower of a power cable.

[0028] The mobile object 100 is provided with the functions shown in the figure. The discharge detector 110 is a device for optically detecting the discharge sound accompanying the corona discharge, as will be described later. The location information acquisition unit 102 acquires location information of the moving object 100. For example, a GPS or the like can be used. The detection result storage unit 103 stores the detection result detected by the discharge detection device 110 in association with the position information. The transmitting / receiving unit 101 transmits information such as detection results to the analysis device 200, and also transmits and receives various information to and from the analysis device 200. In this embodiment, the transmission and reception is performed by connecting to a network NE such as the Internet via wireless communication. Other methods may be used. The communication between the mobile body 100 and the analysis device 200 may be constant or intermittent. Furthermore, the means for transmitting information such as detection results to the analysis device 200 does not necessarily have to be by communication. For example, the detection results may be recorded on a medium and the medium may be read by the analysis device 200.

[0029] Analysis device 200 is constructed in software form by installing a program that realizes each of the functions shown in the figure on a server. Some or all of the functions may be constructed in hardware form. Each of the functions shown in the figure will be explained below. The transceiver unit 201 performs the function of transmitting and receiving signals to and from the mobile object 100 via the network NE. The discharge detection unit 202 analyzes whether or not the detection result obtained by the discharge detection device 110 corresponds to a corona discharge. The alert unit 203 outputs an alert when a corona discharge is detected and it is determined that there is an abnormality in the power cable. The alert can be output in various ways, for example, by sending an email to a predetermined notification destination.

[0030] The sensor database 204 is a database that stores information about the electric discharge detection device 110. In this embodiment, one analysis device 200 is capable of handling a plurality of moving objects 100. Since information about each moving object 100 is registered in the sensor database 204, by referring to this, it is possible to manage the operation history of each moving object 100, manage the detection accuracy of corona discharge, and the like. The detection log storage unit 205 stores past detection results by the discharge detection device. By storing past detection results, for example, it is possible to check how frequently corona discharge occurs, and to analyze or predict the presence or absence of an abnormality in the power cable. The partial discharge detection system can have various configurations, not limited to the configuration shown in Fig. 1. Functions other than those shown in the figure may be added.

[0031] Fig. 2 is an explanatory diagram showing the configuration of the discharge detection device, with Fig. 2(a) showing a schematic front view and Fig. 2(b) showing a schematic side view. As shown in FIG. 2(b), the discharge detection device 110 has a parabola 111 that reflects and collects incident sound waves. When sound waves that are incident parallel to the symmetrical axis direction are reflected by the parabola 111, they are collected at the focal point of the parabola 111, as shown by the dashed line in the figure. In this embodiment, the sound waves are collected and then detected, so that the sensitivity can be improved. Other concave curved surfaces may be used instead of the parabola 111. Also, a multi-axis parabola that can collect sound from various incident directions at a common focal point may be used.

[0032] A detection unit 113 for detecting the discharge sound is installed near the focal point. In the detection unit 113, a laser is irradiated from one side to the other as shown by the arrow in the figure. When a discharge sound is present, this laser is diffracted along with the sound wave. Therefore, the discharge sound can be detected by detecting the presence or absence of this diffraction.

[0033] The discharge detection device thus optically detects the discharge sound by utilizing a laser. Therefore, it is possible to configure the device so that there is nothing blocking the incidence of sound in front of the parabola 111. As a result, there is an advantage in that the discharge sound can be sufficiently captured over a wide range and detected with high sensitivity.

[0034] The front view is shown in Figure 2(a). The main body of detection unit 113 is configured as a hollow rectangular frame as shown in the figure. The size of the rectangular frame can be determined arbitrarily, but is set to a size that can almost cover parabola 111. When the incident direction of the discharge sound deviates from the symmetry axis of parabola 111, the discharge sound will be reflected so as to gather at a location other than the focus. However, as in this embodiment, if a rectangular frame that almost covers parabola 111 is prepared, it will be possible to detect the discharge sound even if the location where it gathers is shifted from the focus. In this embodiment, the detection unit 113 is formed with a rectangular frame, but the frame is not limited to this and may have various shapes such as a circular shape.

[0035] Detection unit 113 can be irradiated with multiple lasers in parallel between opposing sides of a rectangular frame, and the lasers can be irradiated in a lattice pattern overall. The area where the sound reflected by parabola 111 gathers varies depending on the incident direction of the radiated sound, but by irradiating multiple lasers in parallel, it becomes possible to detect the radiated sound over a wide range of detection unit 113. In addition, while there is a risk of reduced detection sensitivity in the gaps when only a one-way laser is used, irradiating the laser in a grid pattern in two directions increases the number of areas that can be detected by either laser, improving overall detection sensitivity. Furthermore, at grid points, discharge sounds can be detected by irradiating the laser in two directions, reducing the possibility of false detection and improving detection accuracy.

[0036] Next, the principle of detecting the discharge sound will be described. Figure 3 is an explanatory diagram showing the principle of detecting discharge using the Schlieren method. The Schlieren method is a method for visualizing sound waves by capturing the phenomenon in which light is diffracted by changes in air density accompanying sound waves. The figure shows a schematic diagram of the configuration of one laser of the light detection unit. In this figure, the sound wave of the discharge sound and the parabola 111 are drawn vertically. On the left side, a laser light emitter 120 is shown. The light emitter 120 is provided with a light source 121 that emits a laser, a lens 122 for focusing the laser light, and a slit 123. As long as it is possible to emit a laser with high directivity that is focused to an extent that diffracted light can be detected, the lens 122 and the slit 123 may have various structures or may be omitted. On the right side, the structure of the light receiving unit 130 is shown. The light receiving unit 130 is equipped with a knife edge 131 and a lens 132 for blocking the laser light when not diffracted, i.e., the main light beam, and an optical sensor 133 for detecting the light.

[0037] According to the above configuration, when no discharge sound is generated, the laser emitted from the light-emitting unit 120 is not diffracted but enters the light-receiving unit 130 and is blocked by the knife edge 131 provided in the light-receiving unit 130. Therefore, at this time, the optical sensor 133 does not detect any light. When a discharge sound is being generated, the laser emitted from the light emitting unit 120 is diffracted and enters the light receiving unit 130. As a result, the laser is not blocked by the knife edge 131 and enters the optical sensor 133. In this way, it becomes possible to detect the presence or absence of a discharge sound based on the detection result by the optical sensor 133. In reality, the detection result by the optical sensor 133 is affected by noise and sound waves other than the discharge sound, so analysis is required to determine the presence or absence, frequency, strength, etc. of the discharge sound based on the detection result.

[0038] When the Schlieren method is applied, a disk 131a may be used instead of the knife edge 131. The disk 131a is a circular shield that blocks the main light beam. The disk 131a can be attached by a method of adhering it to the lens 132, a method of adhering it to the surface of the optical sensor 133, a method of supporting it above the main light beam separately from the lens 132, etc., or the like. In this case, too, if there is no discharge sound, the main light beam is blocked by the disk 131a, and so no light is detected by the optical sensor 133. As shown in the lower part of the figure, the detection result of the optical sensor 133 is a dot P where nothing is detected in the part corresponding to the disk 131a. On the other hand, when a discharge sound is present, diffracted light is generated, and the light that is not blocked by the disk 131a reaches the light sensor 133. As a result, as shown in the figure, an area a where the diffracted light reaches is generated around the dot P corresponding to the main light beam. If the optical sensor 133 is formed from a single element, the presence or absence of region a will be analyzed according to the intensity of the detection signal from the optical sensor 133. Alternatively, multiple optical sensors 133 may be prepared with a resolution sufficient to distinguish the dot P and region a shown at the bottom of the figure, and the presence or absence of region a may be determined.

[0039] The discharge sound may be detected by using a light wave microphone instead of the Schlieren method. Fig. 4 is an explanatory diagram showing the principle of detecting a discharge by a light wave microphone, and is shown in the same schematic diagram as Fig. 3. The left side of the figure shows the structure of the light emitting section 120. This structure is similar to that described in FIG. The structure of the light receiving unit 135 is shown on the right side of the figure. When a lightwave microphone is used, a lens group 136 is provided that performs an optical Fourier transform on the light incident on the light receiving unit 135. In other words, when a discharge sound is generated, the light undergoes a phase transformation, causing a fluctuation in the frequency of the light. The lens group 136 makes it possible to detect such frequency fluctuations by optical Fourier transform. As a result, it becomes possible to detect the presence or absence of diffracted light based on the results of the optical Fourier transform.

[0040] The discharge sound may be detected by selectively using either the Schlieren method or the method using a light wave microphone, or by combining the two. For example, a configuration may be considered in which the Schlieren method is applied to the laser in the first direction, and the method using a light wave microphone is applied to the laser in the second direction. It is also possible to apply a method other than the Schlieren method or the method using a light wave microphone.

[0041] FIG. 5 is an explanatory diagram showing an example of the configuration of a light emitting section and a light receiving section. FIG. 5(a) shows an example in which multiple light-emitting units 120 and light-receiving units 130 are arranged. Specifically, light-emitting units 120[1]-120[6] and light-receiving units 130[1]-130“6” are arranged in the vertical direction of the figure, and light-emitting units 120[1]-120[6] and light-receiving units 130[1]-130“6” are arranged in the horizontal direction of the figure. In this way, six lasers are irradiated on each of the top, bottom, left, and right, and discharge sound can be detected from each. The number of lasers on each of the top, bottom, left, and right can be selected arbitrarily, and the number of lasers on each of the top, bottom, left, and right may be different.

[0042] Fig. 5(b) shows a modified configuration. A light source 121A[1] is provided to irradiate lasers in the vertical direction, and a lens 122A[1] is provided to separate the light into multiple lasers. Similarly, the light from the light source 121A[2] is separated by the lens 122A[2] on the left and right. This reduces the number of light sources 121A[1], and allows multiple laser irradiation to be achieved with a simple configuration. In addition, the vertical light receiving section 130A[1] and the horizontal light receiving section 130A[2] each use a line sensor. This allows the light receiving sections 130A[1] and 130A[2] to have a simple configuration. The light emitting section and the light receiving section can have various configurations, for example, a plurality of light emitting sections may be used as shown in Fig. 5(a) and then the light receiving section 130A shown in Fig. 5(b) may be used. Conversely, the light emitting section in Fig. 5(b) may be used and the light receiving section in Fig. 5(a) may be used.

[0043] 6 is a flowchart of the discharge detection process, which is performed by the analysis device 200. When the process starts, the analysis device 200 receives a detection signal (step S10) and determines whether or not a discharge has occurred (step S11). The method of determining whether or not a discharge has occurred is shown in the figure. When the light undergoes a phase shift due to the discharge sound, the intensity of the light is detected according to the frequency, as shown in the figure. If the intensity of the region f corresponding to the frequency of the discharge sound to be detected exceeds a predetermined threshold, it is determined that a discharge sound is occurring, and if not, it is determined that no discharge sound is occurring. In this case, even if the threshold value is exceeded at frequencies f1, f2, f3, etc. outside the region f, it will be determined that this is due to noise or other influences and is not a discharge sound. The region f is not limited to one, but may cover a plurality of possible frequencies of the discharge sound. When the Schlieren method is applied, the presence or absence of discharge sound can be determined based on whether or not the intensity of the detected diffraction exceeds a predetermined threshold value. The method for determining whether or not there is a discharge sound is not limited to the above-mentioned method, and various other methods can be used.

[0044] When the discharge sound is not detected (step S12), the discharge detection process ends. When a discharge sound is detected (step S12), the analysis device 200 reads past detection logs (step S13) and outputs an alert based on a determination of whether an alert is necessary (step S14). Whether an alert is necessary can be determined, for example, based on the number of times corona discharges have been detected in the past, the detection frequency, etc. The alert can be output, for example, by sending an email to a predetermined notification destination. The process of step S13 may be omitted.

[0045] According to the discharge detection device and partial discharge detection system of the embodiment described above, it is possible to detect corona discharge occurring in a power cable or the like with high sensitivity and high accuracy.

[0046] It is not necessary that all of the various features described in the embodiments are provided, and some of them may be omitted or combined as appropriate. The present invention is not limited to application to power cables, but can also be applied to switchboards and various other types of power equipment. In the embodiment, a plurality of laser beams are used for irradiation, but a single laser beam may be used for scanning. [Industrial Applicability]

[0047] The present invention can be utilized to detect corona discharges occurring in electrical equipment. [Explanation of symbols]

[0048] 100 Mobile 101 Transmitter / receiver 102 Location information acquisition unit 103 Detection result storage unit 110 Discharge detection device 111 Parabola 113 Detection Unit 120 Light emitting part 121, 121A light source 122, 122A Lenses 123 Slit 130, 130A light receiving section 131 Knife Edge 131a Disk 132 Lens 133 Optical Sensor 135 Light receiving part 136 Lens Group 200 Analysis equipment 201 Transmitter / receiver 202 Discharge detection unit 203 Alert Department 204 Sensor Database 205 Detection log storage unit

Claims

1. A discharge detection device for optically detecting corona discharge, comprising: A sound collecting section having a concave curved surface shape that reflects the discharge sound generated by the corona discharge so as to collect the discharge sound; a light emitting unit that irradiates a laser beam near a portion where the discharge sound is collected; a detector that detects diffracted light produced when the laser is diffracted by the discharge sound.

2. The discharge detection device according to claim 1, The concave curved surface shape is a parabolic shape, The laser is irradiated near the focal point of the parabola in a direction perpendicular to the axis of symmetry of the parabola. Discharge detection device.

3. The discharge detection device according to claim 1, The light emitting unit is a discharge detection device that irradiates multiple parallel laser beams.

4. The discharge detection device according to claim 3, The detection unit is a discharge detection device that uses a line sensor in which a plurality of optical sensors are arranged to detect the diffracted light.

5. The discharge detection device according to claim 1, The light emitting unit is a discharge detection device that irradiates a plurality of intersecting laser beams.

6. The discharge detection device according to claim 1, The detection unit is an optical sensor for detecting the diffracted light; a circular shield that blocks the non-diffracted laser beam from entering the optical sensor.

7. The discharge detection device according to claim 1, A plurality of sound collecting units each having a different range for collecting the discharge sound; The discharge detection device includes a plurality of light emitting units and detection units each corresponding to a respective sound collecting unit.

8. 1. A discharge detection system for optically detecting a corona discharge, comprising: The discharge detection device according to any one of claims 1 to 7, and an analysis device that analyzes the occurrence of the corona discharge based on an output of the discharge detection device.

9. 9. The discharge detection system according to claim 8, An electric discharge detection system in which an output of the electric discharge detection device is wirelessly communicated to the analysis device.

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