Partial discharge monitoring device for gas insulated switchgear

Abstract

Provided is a partial discharge monitoring device capable of determining the cause of partial discharge. A partial discharge monitoring device (10) for a gas insulated switchgear (1) connected to an external device via an insulated adapter (4) and an insulated bus (5), comprising: a voltage detector (7) connected between an insulated adapter housing ground layer (43) and an insulated bus housing ground layer (53) and detecting a voltage pulse caused by a partial discharge and a phase of a system voltage and a partial discharge analyzer (8). A partial discharge analyzer is provided with: a partial discharge occurrence position determination unit for determining the occurrence position of partial discharge; and a partial discharge occurrence cause determination unit for determining the occurrence cause of the partial discharge on the basis of the [phi]-q-n pattern shape of the partial discharge and the occurrence position of the partial discharge.

Description

Technical Field

[0001] The present application relates to a partial discharge monitoring device for a gas insulated switchgear. Background Art

[0002] As a power distribution equipment installed in substations, factories, buildings, etc., there is a cabinet-type gas-insulated switchgear. In this gas-insulated switchgear, equipment such as circuit breakers and isolators are contained in a metal sealed container, and the interior of the sealed container is filled with insulating gas. In this gas-insulated switchgear, if the insulation performance is reduced during operation due to leakage of insulating gas, deterioration of solid insulating components constituting the equipment, and generation of metallic foreign matter accompanying the operation of the equipment, partial discharge may sometimes occur due to local insulation damage. This partial discharge is a precursor to failure. By monitoring this partial discharge, failure of the gas-insulated switchgear can be prevented before it occurs.

[0003] In a conventional partial discharge monitoring device for a gas insulated switchgear, a grounding layer is provided on the outer surface of the insulating material of a main circuit device molded from an insulating material, and partial discharge is detected by measuring the current flowing between the grounding layer and the ground potential. In this case, the partial discharge monitoring device determines the location where partial discharge occurs in the direction of current flow (for example, refer to Patent Document 1). Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-168489 Summary of the invention Technical problem to be solved by the invention

[0005] However, in the conventional partial discharge monitoring device for a gas insulated switchgear, although the occurrence position of the partial discharge can be determined, there is a problem that the cause of the occurrence of the partial discharge cannot be determined.

[0006] The present application is proposed to solve the above-mentioned problems, and its object is to provide a partial discharge monitoring device for a gas insulated switchgear, which can determine the cause of occurrence of partial discharge. Technical means for solving technical problems

[0007] The partial discharge monitoring device of the gas insulated switchgear of the present application is a partial discharge monitoring device of the gas insulated switchgear connected to an external device via an insulating adapter and an insulating busbar, comprising: a voltage detector, which is connected between the shell grounding layer of the insulating adapter and the shell grounding layer of the insulating busbar and detects the voltage pulse caused by partial discharge and the phase of the system voltage of the gas insulated switchgear; and a partial discharge analyzer, which analyzes the partial discharge based on the voltage pulse detected by the voltage detector, the partial discharge analyzer comprising: a partial discharge occurrence position determination unit, which determines the occurrence position of the partial discharge based on the polarity of the voltage pulse; and a partial discharge occurrence cause determination unit, which determines the occurrence cause of the partial discharge based on the φ-qn mode shape of the partial discharge and the occurrence position of the partial discharge determined by the partial discharge occurrence position determination unit when the phase of the system voltage at the timing of the voltage pulse generation is set to φ, the intensity of the voltage pulse is set to q, and the occurrence frequency of the voltage pulse is set to n. Effects of the Invention

[0008] The partial discharge monitoring device of the gas insulated switchgear of the present application includes a partial discharge cause determination unit that determines the cause of partial discharge based on the φ-qn mode shape of partial discharge and the location of partial discharge determined by the partial discharge location determination unit, thereby being able to determine the cause of partial discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a configuration diagram of a partial discharge monitoring device of a gas insulated switchgear according to the first embodiment. Figure 2 This is a configuration diagram of the partial discharge analyzer according to the first embodiment. Figure 3 This is an explanatory diagram showing the relationship between the occurrence position of partial discharge and the polarity of the voltage pulse in the gas insulated switchgear according to the first embodiment. Figure 4 This is an explanatory diagram showing the relationship between the occurrence position of partial discharge and the polarity of the voltage pulse in the gas insulated switchgear according to the first embodiment. Figure 5 It is an explanatory diagram of the φ-qn mode shape of partial discharge in the gas insulated switchgear according to the first embodiment. Figure 6 It is an explanatory diagram of the φ-qn mode shape of partial discharge in the gas insulated switchgear according to the first embodiment. Figure 7 It is an explanatory diagram of the φ-qn mode shape of partial discharge in the gas insulated switchgear according to the first embodiment. Figure 8It is an explanatory diagram of the φ-qn mode shape of partial discharge in the gas insulated switchgear according to the first embodiment. Fig. 9 This is a flowchart showing a method of determining the cause of occurrence of a partial discharge in the partial discharge occurrence cause determination unit according to the first embodiment. Fig.10 It is a configuration diagram of a partial discharge monitoring device for a gas insulated switchgear according to the third embodiment. Fig.11 This is a diagram showing a hardware configuration for realizing a partial discharge occurrence determination unit, a partial discharge occurrence position determination unit, and a partial discharge occurrence cause determination unit according to the first to third embodiments. DETAILED DESCRIPTION

[0010] Hereinafter, a partial discharge monitoring device for a gas insulated switchgear according to an embodiment of the present application will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals in the drawings indicate the same or corresponding parts.

[0011] Implementation method 1. Figure 1 This is a structural diagram of a partial discharge monitoring device of a gas insulated switchgear according to Embodiment 1. The gas insulated switchgear 1 of this embodiment includes a metal container 2, which accommodates a circuit breaker, an isolator, etc., which are not shown in the figure. The interior of the metal container 2 is filled with an insulating gas such as sulfur hexafluoride (SF6). The gas insulated switchgear 1 is electrically connected to an external transformer, etc., which are not shown in the figure, via a bushing 3, an insulating adapter 4, and an insulating busbar 5. The voltage applied to the gas insulated switchgear 1 is called a system voltage. The insulating busbar mentioned here is a busbar that insulates the busbar as a conductor. A busbar that is insulated with an insulating gas around the busbar is called a gas insulated busbar, and a busbar covered with a solid insulating material such as silicone rubber around the busbar is called a solid insulated busbar.

[0012] The bushing 3 is composed of a central conductor 31 and an insulating member 32 covering the outer periphery of the central conductor 31. The bushing 3 is inserted into the metal container 2 in an airtight manner. The central conductor 31 on the inner side of the metal container 2 is electrically connected to a circuit breaker, an isolator, etc. housed inside the metal container 2.

[0013] The insulating adapter 4 includes an insulating container 41 and a contactor 42. An insulating adapter housing grounding layer 43 is provided on the outside of the insulating container 41. The insulating adapter housing grounding layer 43 is set to a ground potential. The portion of the bushing 3 exposed from the metal container 2 is inserted into the insulating adapter 4. In the insulating adapter 4, a conductive cover 44 is provided on the side opposite to the side where the bushing 3 is inserted. The contactor 42 is connected to the bushing 3 and the insulating busbar 5. After the contactor 42 is provided, the conductive cover 44 and the insulating member 45 provided inside thereof are inserted into the insulating adapter 4 and fixed.

[0014] The insulating busbar 5 includes a central conductor 51, an insulating member 52 covering the outer periphery of the central conductor 51, and an insulating busbar housing grounding layer 53 covering the outer periphery of the insulating member 52. The insulating busbar housing grounding layer 53 is set to a ground potential. The insulating busbar 5 is inserted into the insulating adapter 4. An insulating tube 6 is provided between the insulating busbar 5 and the insulating adapter 4. The insulating adapter housing grounding layer 43 and the insulating busbar housing grounding layer 53 are electrically insulated by the insulating tube 6. The central conductor 31 of the bushing 3 inserted into the insulating adapter 4 and one end of the central conductor 51 of the insulating busbar 5 inserted into the insulating adapter 4 are electrically connected through the contactor 42. The other end of the central conductor 51 of the insulating busbar 5 is electrically connected to an external device such as a transformer.

[0015] The insulating adapter grounding terminal 46 is provided at a portion of the insulating adapter housing grounding layer 43. In addition, the insulating busbar grounding terminal 54 is provided at a portion of the insulating busbar housing grounding layer 53. The voltage detector 7 is connected between the insulating adapter grounding terminal 46 and the insulating busbar grounding terminal 54. When partial discharge occurs in the gas insulated switchgear 1 or an external device connected thereto, a voltage pulse is generated between the insulating adapter grounding terminal 46 and the insulating busbar grounding terminal 54. The voltage detector 7 can detect this voltage pulse caused by the partial discharge. In addition, the voltage detector 7 can measure the phase of the system voltage by measuring the voltage caused by the induced current induced by the system voltage and flowing between the insulating adapter grounding terminal 46 and the insulating busbar grounding terminal 54.

[0016] The partial discharge analyzer 8 is connected to the voltage detector 7. The voltage pulse caused by the partial discharge detected by the voltage detector 7 and the phase of the system voltage are input to the partial discharge analyzer 8. For example, a voltage probe can be used as the voltage detector 7. The partial discharge analyzer 8 can analyze the input voltage pulse to determine whether partial discharge occurs, the location of partial discharge, and the cause of partial discharge. The partial discharge monitoring device 10 of the gas insulated switchgear of this embodiment includes the voltage detector 7 and the partial discharge analyzer 8.

[0017] Figure 2: is a structural diagram of a partial discharge analyzer of the present embodiment. The partial discharge analyzer 8 of the present embodiment includes an overvoltage protection circuit unit 81, an amplifier 82, a filter unit 83, an analog-to-digital conversion unit (hereinafter referred to as an AD conversion unit) 84, a partial discharge occurrence determination unit 85, a partial discharge occurrence position determination unit 86, and a partial discharge occurrence cause determination unit 87. The overvoltage protection circuit unit 81 removes the overvoltage component contained in the voltage pulse input from the voltage detector 7. The amplifier 82 amplifies the voltage pulse from which the overvoltage component is removed. The filter unit 83 removes the noise component having a frequency different from that of the system voltage contained in the voltage pulse. The AD conversion unit 84 converts the voltage pulse from which the noise component is removed from analog to digital. The partial discharge occurrence determination unit 85, the partial discharge occurrence position determination unit 86, and the partial discharge occurrence cause determination unit 87 analyze the digitally converted voltage pulse to determine whether partial discharge occurs, the location of partial discharge, and the cause of partial discharge.

[0018] If the intensity of the voltage pulse is above a preset threshold, the partial discharge occurrence determination unit 85 determines that partial discharge has occurred. In addition, the overvoltage protection circuit unit 81, the amplifier unit 82, the filter unit 83, the AD converter unit 84 and the partial discharge occurrence determination unit 85 may be provided in the voltage detector 7 instead of in the partial discharge analyzer 8.

[0019] Figure 3 and Figure 4 1 is an explanatory diagram showing the relationship between the occurrence position of partial discharge and the polarity of the voltage pulse in the gas insulated switchgear of the present embodiment. Figure 3 As shown in the upper part of FIG. 1 , when partial discharge occurs on the left side of the insulating tube 6, that is, on the insulating adapter 4 side, the current flowing through the voltage detector 7 flows from the insulating adapter housing grounding layer 43 to the insulating busbar housing grounding layer 53 as shown by the white arrow. Figure 3 As shown in the lower part of , a voltage pulse having the same polarity as the voltage phase of the system voltage flowing through the center conductor 51 is detected. Figure 4 As shown in the upper part of FIG. 1 , when partial discharge occurs on the right side of the insulating tube 6, i.e., the insulating bus 5 side, the current flowing through the voltage detector 7 flows from the insulating bus housing grounding layer 53 to the insulating adapter housing grounding layer 43 as shown by the white arrow. Figure 4 As shown in the lower part of , a voltage pulse having a polarity opposite to the voltage phase of the system voltage flowing through the center conductor 51 is detected. In addition, hereinafter, the voltage pulse caused by partial discharge is simply expressed as a partial discharge pulse.

[0020] The partial discharge occurrence position determination unit 86 extracts a component that matches the frequency of the system voltage from the signal of the voltage pulse using frequency analysis, thereby grasping the polarity of the system voltage at the timing of the occurrence of partial discharge. As a frequency analysis method, for example, the FFT method (Fast Fourier Transform) can be cited. Similarly, the partial discharge occurrence position determination unit 86 grasps the polarity of the partial discharge pulse on the basis of extracting the partial discharge pulse using frequency analysis. Based on the polarity of the system voltage and the polarity of the partial discharge pulse, the partial discharge occurrence position determination unit 86 determines whether the position where the partial discharge occurred is on the insulation adapter 4 side or the insulation bus 5 side relative to the insulation tube 6.

[0021] The partial discharge occurrence cause determination unit 87 determines the cause of the partial discharge based on the phase of the system voltage at the timing of the partial discharge occurrence extracted by the partial discharge occurrence position determination unit 86 using frequency analysis, the polarity of the partial discharge pulse, the intensity of the partial discharge pulse, the occurrence frequency of the partial discharge pulse, and the occurrence position of the partial discharge determined by the partial discharge occurrence position determination unit 86. Next, a method of determining the cause of partial discharge occurrence in the partial discharge occurrence determining unit 87 will be described.

[0022] The occurrence characteristics of partial discharge are related to its cause. The intensity of the partial discharge pulse is q, the occurrence frequency is n, and the phase of the system voltage at the timing of the partial discharge pulse is φ. The cause of partial discharge can be determined by the φ-qn mode shape. Figures 5 to 8 This is an illustration of the shape of the φ-qn mode of partial discharge. Figures 5 to 8 In the figure, the horizontal axis represents the phase φ of the system voltage, and the vertical axis represents the voltage. Figures 5 to 8 In the figure, the sine wave is the waveform of the system voltage, and the black dots represent the occurrence frequency n of partial discharge. That is, the so-called φ-qn mode of partial discharge is Figures 5 to 8 In FIG. 1 , the horizontal axis position of the black dots corresponds to the phase φ of the system voltage when the partial discharge occurs, the vertical axis position of the black dots corresponds to the intensity q, and the lightness and darkness of the black dots correspond to the occurrence frequency n. The φ-qn pattern of the partial discharge can be obtained from the phase of the system voltage at the timing of the partial discharge occurrence extracted by the partial discharge occurrence position determination unit 86, the intensity of the partial discharge pulse, and the occurrence frequency of the partial discharge pulse.

[0023] Here, in Figures 5 to 8 In the waveform of the system voltage shown, the positions of the maximum and minimum values ​​of the waveform are called peaks, and the position of the waveform where the voltage becomes zero is called the zero crossing position. Figures 5 to 8 The characteristics shown show the characteristics when the cause of occurrence of local discharge is known in advance.

[0024] right Figures 5 to 8The φ-qn mode shapes of the respective partial discharges shown are explained. In the following description, it is assumed that the transformer is connected to the gas insulated switchgear 1 of the present embodiment via the insulating busbar 5. The transformer uses mineral oil as the insulating oil. In the present embodiment, the partial discharge generated inside the gas insulated switchgear 1 occurs in the SF6 filled in the metal container 2. The partial discharge generated inside the transformer occurs in the mineral oil. In addition, the gas insulated switchgear is hereinafter referred to as GIS (Gas Insulation Switchgear).

[0025] The causes of partial discharge are classified into four categories: floating electrodes, conductor protrusions, surface foreign matter, and voids in insulating components. Floating electrodes refer to a state in which a metal component such as a bolt used to fix the conductor inside the GIS is not conducting with the conductor and is at a floating potential. Conductor protrusions refer to a state in which protrusions exist on the surface of a conductor such as an electrode or a central conductor. Surface foreign matter refers to a state in which foreign matter adheres to the surface of an insulating component. Voids in insulating components refer to a state in which voids exist in an insulating component. When this state occurs, the electric field concentrates on that part, which becomes the starting point of partial discharge. Figures 5 to 8 As shown, the φ-qn pattern of partial discharge differs depending on the cause of occurrence of partial discharge.

[0026] Figure 5 The cause of partial discharge is the φ-qn mode shape of partial discharge when the electrode is floating. Floating electrodes occur in both transformers and GIS. Figure 5 As shown in the upper part of , when floating electrodes occur in the transformer, partial discharge occurs with a constant intensity near the zero crossing. At the same time, noise is generated with a smaller intensity regardless of the phase relationship with the system voltage. Figure 5 As shown in the lower part of , when floating electrodes occur in GIS, partial discharge occurs with a constant intensity near the zero crossing. At the same time, a weaker partial discharge occurs near the zero crossing. In the case of floating electrodes, if the weaker partial discharge is removed, there is no big difference in the φ-qn mode of partial discharge in the transformer and GIS, forming a mode shape that is widely distributed with a constant intensity centered on the zero crossing. This mode shape is called a "floating cloud".

[0027] Figure 6 The φ-qn mode of partial discharge is caused by conductor protrusion. Conductor protrusion occurs in both transformers and GIS. Figure 6 As shown in the upper part of , when a conductor protrusion occurs in the transformer, partial discharge occurs with a constant intensity near the negative peak of the system voltage. At the same time, noise is generated with a smaller intensity regardless of the phase relationship with the system voltage. Figure 6As shown in the lower part of the diagram, when a conductor protrusion occurs in the GIS, the following partial discharge occurs: After the partial discharge is delayed to the zero crossing, the intensity of the partial discharge rises in accordance with the change in the system voltage, and then there is a deviation in the intensity near the peak. At the same time, regardless of the relationship with the phase of the system voltage, noise is generated with a smaller intensity. When removing the weaker partial discharge, Figure 6 The φ-qn mode of partial discharge in the transformer shown in the upper part is a mode shape that is widely distributed with the peak as the center. This mode shape is also called a "floating cloud" mode shape. On the other hand, when removing the weaker partial discharge, Figure 6 The φ-qn mode of partial discharge in the GIS shown in the lower part is a mode shape in which the intensity of the partial discharge rises after crossing the zero position and then the intensity deviates near the peak value. This mode shape is called a "rabbit".

[0028] Figure 7 The φ-qn mode shape of partial discharge when the cause of partial discharge is foreign matter along the surface. Foreign matter along the surface can occur in both the transformer and GIS. Figure 7 As shown in the upper part of the figure, when a foreign object is generated in the transformer, partial discharge occurs in the following manner: there is a deviation in the intensity of the partial discharge between the zero crossing and the peak value. At the same time, regardless of the relationship with the phase of the system voltage, noise is generated with a smaller intensity. Figure 7 As shown in the lower part of , when foreign matter is generated along the surface of GIS, partial discharge occurs in the following manner: the intensity of the partial discharge rises near the zero crossing, and then there is a deviation in intensity until it reaches the peak. At the same time, regardless of the relationship with the phase of the system voltage, noise is generated at a smaller intensity. When foreign matter is generated along the surface of the transformer, it becomes a mode in which the intensity deviates between the zero crossing and the peak. This mode shape is called a "turtle". When foreign matter is generated along the surface of GIS, partial discharge occurs in the following manner: the intensity of the partial discharge rises near the zero crossing, and then there is a deviation in intensity until it reaches the peak. This mode shape is different from the "turtle" and is a mode shape called a "rabbit".

[0029] Figure 8 This is the φ-qn mode shape of partial discharge when the cause of partial discharge is voids in the insulating member. The voids in the insulating member are generated only in the GIS. Figure 8As shown in FIG. 1 , when there is a gap in the insulating member in the GIS, partial discharge occurs in the following manner: there is a deviation in the intensity of the partial discharge between the zero crossing and the peak. At the same time, noise is generated with a smaller intensity regardless of the phase relationship with the system voltage. When the weaker partial discharge is removed, the φ-qn mode in the case of a gap in the insulating member has a mode shape in which the intensity is deviated between the zero crossing and the peak. This mode shape is a mode shape called a "turtle".

[0030] Fig. 9 1 is a flowchart showing a method of determining the cause of partial discharge in partial discharge cause determination unit 87. Partial discharge cause determination unit 87 determines the cause of partial discharge based on the phase relationship with the system voltage when partial discharge occurs, the φ-qn mode shape, and the location of partial discharge occurrence.

[0031] In step S01, the partial discharge occurrence cause determination unit 87 acquires the φ-qn pattern obtained by the partial discharge occurrence position determination unit 86. In step S02, the partial discharge occurrence cause determination unit 87 determines whether the position of the phase of the partial discharge is near the peak. In step S02, if it is determined that the position of the phase of the partial discharge is near the peak (yes), the partial discharge occurrence cause determination unit 87 proceeds to step S03. In step S03, the partial discharge occurrence cause determination unit 87 analyzes the φ-qn pattern and determines whether the φ-qn pattern shape is "cloud". In step S03, when it is determined that the φ-qn pattern shape is "cloud" (yes), the partial discharge occurrence cause determination unit 87 determines that the cause of the partial discharge is the conductor protrusion inside the transformer. In step S03, when it is determined that the φ-qn pattern shape is not "cloud" (no), the partial discharge occurrence cause determination unit 87 determines that the cause of the partial discharge is the conductor protrusion inside the GIS.

[0032] In step S02, when it is determined that the position of the phase of the partial discharge is not near the peak (No), the partial discharge occurrence cause determination unit 87 proceeds to step S04. In step S04, the partial discharge occurrence cause determination unit 87 analyzes the φ-qn mode and determines whether the φ-qn mode shape is "cloud". In step S04, when it is determined that the φ-qn mode shape is "cloud" (Yes), the partial discharge occurrence cause determination unit 87 proceeds to step S05. In step S05, the partial discharge occurrence cause determination unit 87 determines whether the occurrence position of the partial discharge is on the GIS side. Here, the occurrence position of the discharge on the GIS side refers to the case where the occurrence position of the partial discharge determined by the partial discharge occurrence position determination unit 86 is located on the insulation adapter 4 side relative to the insulation tube 6. In addition, when the occurrence position of the partial discharge determined by the partial discharge occurrence position determination unit 86 is located on the insulation bus 5 side relative to the insulation tube 6, the occurrence position of the discharge is located on the transformer side. In step S05, when it is determined that the occurrence position of the partial discharge is on the GIS side (Yes), the partial discharge occurrence cause determination unit 87 determines that the occurrence cause of the partial discharge is the floating electrode inside the GIS. In step S05, when it is determined that the occurrence position of the partial discharge is not on the GIS side (No), the partial discharge occurrence cause determination unit 87 determines that the occurrence cause of the partial discharge is the floating electrode inside the transformer.

[0033] In step S04, when it is determined that the φ-qn mode shape is not a "cloud" (No), the partial discharge occurrence cause determination unit 87 proceeds to step S06. In step S06, the partial discharge occurrence cause determination unit 87 analyzes the φ-qn mode and determines whether the φ-qn mode shape is a "turtle". In step S06, when it is determined that the φ-qn mode shape is a "turtle" (Yes), the partial discharge occurrence cause determination unit 87 proceeds to step S07. In step S07, the partial discharge occurrence cause determination unit 87 determines whether the occurrence position of the partial discharge is on the GIS side. In step S07, when it is determined that the occurrence position of the partial discharge is on the GIS side (Yes), the partial discharge occurrence cause determination unit 87 determines that the occurrence cause of the partial discharge is a gap in the insulating member inside the GIS. In step S07, when it is determined that the occurrence position of the partial discharge is not on the GIS side (No), the partial discharge occurrence cause determination unit 87 determines that the occurrence cause of the partial discharge is a creeping foreign body inside the transformer.

[0034] In step S06 , when it is determined that the φ-qn mode shape is not a “turtle” (No), the partial discharge occurrence cause determination unit 87 determines that the cause of the partial discharge is a creeping foreign object inside the GIS.

[0035] Fig. 9The determination of whether the φ-qn mode shape of the partial discharge shown in the flowchart is a "cloud" or a "turtle" can be made by Figures 5 to 8 The φ-qn mode shape of partial discharge shown is recognized as an image shape and is performed using artificial intelligence technology (AI technology: Artificial Intelligence technology). Specifically, judgment using correlation coefficients, judgment using machine learning algorithms such as convolutional neural networks (CNN: Convolutional Neural Network) and support vector machines (SVM: Support Vector Machine) can be used.

[0036] The partial discharge monitoring device for a gas insulated switchgear configured in this manner can determine the cause of partial discharge by using the partial discharge φ-qn mode shape when partial discharge occurs and the location where partial discharge occurs.

[0037] Implementation method 2. The gas insulated switchgear of the second embodiment is a device in which an instrument current transformer (CT: Current Transformer) is used as the voltage detector 7 in the partial discharge monitoring device of the gas insulated switchgear described in the first embodiment. The structure of the partial discharge monitoring device of the gas insulated switchgear of this embodiment is the same as the structure of the partial discharge monitoring device of the gas insulated switchgear described in the first embodiment except for the voltage detector 7. The instrument current transformer is composed of an input side primary coil for detecting voltage, an output side secondary coil, and a core body for magnetically coupling the primary coil and the secondary coil. The primary coil and the secondary coil are electrically insulated.

[0038] Similar to the partial discharge monitoring device of the gas insulated switchgear of the first embodiment, the partial discharge monitoring device of the gas insulated switchgear of the present embodiment can determine the cause of the partial discharge using the φ-qn mode of the partial discharge and the location of the partial discharge. In addition, since the instrument current transformer is used for the voltage detector 7, the measurement accuracy can be improved compared with the voltage measurement performed by connecting the voltage probe between the insulation adapter ground terminal 46 and the insulation bus ground terminal 54. This is because the instrument current transformer can easily reduce the influence of the impedance of the measuring instrument on the measured system.

[0039] Implementation method 3. Fig.10 : is a structural diagram of a partial discharge monitoring device of a gas insulated switchgear according to Embodiment 3. In the gas insulated switchgear described in Embodiment 1, the electric field relaxation electrode 47 is provided inside the insulation adapter 4. Usually, the electric field relaxation electrode 47 is electrically connected to the conductive cover 44. And the electric field relaxation electrode 47 is set to the ground potential via the conductive cover 44. Fig.10 As shown, in the gas insulated switchgear of the present embodiment, the electric field relaxation electrode 47 is electrically disconnected from the conductive cover 44 and is set to a floating potential. The voltage detector 7 is also connected to the electric field relaxation electrode 47 set to a floating potential, and the voltage of the electric field relaxation electrode 47 is also measured. The structure of the partial discharge monitoring device of the gas insulated switchgear of the present embodiment is the same as the structure of the partial discharge monitoring device of the gas insulated switchgear described in Embodiment 1, except that the voltage detector 7 is connected to the electric field relaxation electrode 47 set to a floating potential.

[0040] The electric field relaxation electrode 47 set to a floating potential has a potential induced by the system voltage. Therefore, the phase of the system voltage can be measured by measuring the voltage of the electric field relaxation electrode 47. In the partial discharge monitoring device of the gas insulated switchgear of Embodiment 1, the phase of the system voltage is measured by measuring the voltage caused by the induced current induced by the system voltage and flowing between the insulating adapter ground terminal 46 and the insulating busbar ground terminal 54. However, when the resistance of the insulating adapter housing ground layer 43 and the insulating busbar housing ground layer 53 is large, the phase of the induced current sometimes lags behind the phase of the actual system voltage. As a result, a deviation may occur between the phase of the partial discharge pulse described in Embodiment 1 and the phase of the system voltage, and an error may occur when determining the φ-qn mode.

[0041] The phase of the voltage of the electric field relaxation electrode 47 induced by the system voltage is slightly different from the phase of the system voltage. In the gas insulated switchgear of the present embodiment, the phase of the system voltage is measured by measuring the voltage of the electric field relaxation electrode 47 induced by the system voltage. Therefore, in the partial discharge monitoring device of the gas insulated switchgear of the present embodiment, the phase of the partial discharge pulse is less different from the phase of the system voltage, and an error can be prevented from occurring when determining the φ-qn mode.

[0042] In addition, if Fig.11 As shown in the figure, an example of the hardware of the partial discharge occurrence determination unit 85, the partial discharge occurrence position determination unit 86 and the partial discharge occurrence cause determination unit 87 is composed of a processor 100 and a storage device 101. Although not shown in the figure, the storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. In addition, an auxiliary storage device such as a hard disk may be provided instead of the flash memory. The processor 100 executes a program input from the storage device 101. In this case, the program is input from the auxiliary storage device to the processor 100 via the volatile storage device. In addition, the processor 100 can output data such as the calculation result to the volatile storage device of the storage device 101, and can also save the data to the auxiliary storage device via the volatile storage device.

[0043] The present application describes various exemplary embodiments, but various features, forms, and functions described in one or more embodiments are not limited to application in specific embodiments and can be applied to the embodiments alone or in various combinations. Therefore, it can be considered that numerous modifications not shown in the examples are also included in the technical scope disclosed in the present application, for example, including the case where at least one component is modified, added or omitted, and the case where at least one component is extracted and combined with components of other embodiments. Description of symbols

[0044] 1 gas insulated switchgear, 2 metal container, 3 bushing, 4 insulation adapter, 5 insulation bus, 6 insulation tube, 7 voltage detector, 8 partial discharge analyzer, 10 partial discharge monitoring device, 31 central conductor, 32 insulation member, 41 insulation container, 42 contactor, 43 insulation adapter housing ground layer, 44 conductive cover, 45 insulation member, 46 insulation adapter ground terminal, 47 electric field relaxation electrode, 51 central conductor, 52 insulation member, 53 insulation bus housing ground layer, 54 insulation bus ground terminal, 81 overvoltage protection circuit unit, 82 amplifier unit, 83 filter unit, 84 AD conversion unit, 85 partial discharge occurrence determination unit, 86 partial discharge occurrence position determination unit, 87 partial discharge occurrence cause determination unit, 100 processor, 101 storage device.

Claims

1. A partial discharge monitoring device for a gas-insulated switchgear, the gas-insulated switchgear being connected to an external device via an insulating adapter and an insulating busbar, the partial discharge monitoring device for the gas-insulated switchgear being characterized by comprising: a voltage detector connected between a shell grounding layer of the insulating adapter and a shell grounding layer of the insulating busbar and detecting a voltage pulse caused by partial discharge and a phase of a system voltage of the gas insulated switchgear; as well as a partial discharge analyzer that analyzes partial discharge based on the voltage pulse detected by the voltage detector, The partial discharge analyzer includes: a partial discharge occurrence position determination unit, the partial discharge occurrence position determination unit determining the occurrence position of the partial discharge based on the polarity of the voltage pulse; and a partial discharge occurrence cause determination unit, which determines the cause of the partial discharge based on the φ-qn mode shape of the partial discharge and the occurrence position of the partial discharge determined by the partial discharge occurrence position determination unit, when the phase of the system voltage at the timing of the voltage pulse generation is set to φ, the intensity of the voltage pulse is set to q, and the occurrence frequency of the voltage pulse is set to n.

2. The partial discharge monitoring device for a gas insulated switchgear according to claim 1, characterized in that: The voltage detector is also connected to an electric field relaxation electrode provided in the insulating adapter, and the voltage detector detects a phase of the system voltage via the electric field relaxation electrode.

3. The partial discharge monitoring device for a gas insulated switchgear according to claim 1 or 2, characterized in that: The partial discharge analyzer stores in advance shapes of a plurality of φ-qn patterns of the partial discharge corresponding to a plurality of causes of occurrence of the partial discharge.

4. The partial discharge monitoring device for a gas insulated switchgear according to claim 3, characterized in that: The partial discharge occurrence cause determination unit recognizes the shape of the partial discharge φ-qn pattern as an image shape, and determines whether the recognized image shape of the partial discharge φ-qn pattern is consistent with a plurality of pre-stored image shapes of the partial discharge φ-qn patterns using AI technology.

5. The partial discharge monitoring device for a gas insulated switchgear according to any one of claims 1 to 4, characterized in that: The voltage detector is composed of an instrument current transformer.

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