Partial discharge source positioning system, positioning method and partial discharge detection equipment

Abstract

The present invention relates to the field of high-voltage electrical appliances, and in particular to a partial discharge source positioning system, comprising a partial discharge detection device, a first capacitive device 2 connected to a power transformer 1, including a capacitor C1 and a capacitor C2 arranged therein and connected in series between a bus and a ground GND in sequence; and also including a capacitor C3 and a capacitor C4 connected in series between the bus and the ground GND in sequence; a sensor T1 is coupled to a conductor connecting the power transformer 1 and the bus, and the sensor T1, both ends of the capacitor C2, and both ends of the capacitor C4 are respectively connected to the partial discharge detection device; the partial discharge detection device identifies external interference or locates the position of the partial discharge source according to the polarities of the voltage signals U1, U2, and U3 outputted by the three, respectively; the system of the present invention is conducive to efficiently locating the occurrence of unknown partial discharge faults, thereby improving the efficiency of inspection and maintenance operations. The present invention also relates to a partial discharge source positioning method and a partial discharge detection device using the method.

Description

Technical Field

[0001] The invention belongs to the field of high-voltage electrical appliances and relates to a partial discharge source positioning system, a positioning method and partial discharge detection equipment. Background Art

[0002] Transformer partial discharge is a common fault type of power transformer. It refers to the non-penetrating discharge that occurs at the edge of the transformer gap, conductor, and oil film under high voltage conditions. Since transformer partial discharge will produce an accumulation effect and cause aging of transformer components, it is an important fault type that affects the stable operation and normal state of the transformer.

[0003] The methods for measuring partial discharge of transformers are divided into two categories: electrical measurement and non-electrical measurement. The electrical measurement method is highly sensitive and widely used. The principle of the electrical measurement method is that each partial discharge of the transformer is accompanied by a certain amount of charge passing through the dielectric, causing a voltage change on the external electrode of the sample. The time of each discharge is very short, on the order of 10ns in the air gap and only 1ms in the oil gap. Such a short pulse will generate high-frequency electromagnetic signals to radiate outward. The electrical measurement method is based on these principles for detection. Electrical measurement methods include pulse current method, radio interference voltage method, dielectric loss analysis method, etc.

[0004] The pulse current method is widely used to measure the voltage (instantaneous) change or pulse current change caused by partial discharge at both ends of the sample. The detection is performed by connecting the detection impedance to the measurement loop. The principle is that when an internal partial discharge occurs inside the transformer, a discharge pulse current will be generated. When the pulse current passes through a grounding loop composed of a coupling capacitor and a detection impedance, a voltage will be generated at both ends of the detection impedance. The voltage is proportional to the amount of partial discharge of the transformer. After a specific calculation of the pulse voltage, the corresponding partial discharge amount inside the transformer can be obtained.

[0005] However, when conducting partial discharge detection of the transformer under operating conditions, it will inevitably be affected by the partial discharge of other power equipment in the substation and external interference noise (such as external interference current). In addition, the existing technology conducts partial discharge detection of the transformer through capacitive equipment connected to the transformer, such as through bushings, cable terminals, etc., and identifies the partial discharge detected by the bushings or cable terminals as partial discharge of the transformer. This detection method has certain practicality, but there is also a situation where the partial discharge comes from the bushing or cable terminal itself, not from the transformer, and there is a problem of being unable to accurately determine whether there is partial discharge in the power transformer. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the prior art and provide a partial discharge source positioning system which can identify external interference current and locate the position of the partial discharge source.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A partial discharge source locating system, comprising a partial discharge detection device, a first capacitive device 2 connected to a power transformer 1, the first capacitive device 2 comprising a capacitor C1 and a capacitor C2 arranged therein and sequentially connected in series between a bus and a ground GND, the partial discharge source locating system further comprising a capacitor C3 and a capacitor C4 sequentially connected in series between the bus and the ground GND;

[0009] The sensor T1 is coupled to the conductor connecting the power transformer 1 and the busbar, the output end of the sensor T1 is connected to the partial discharge detection device to output the voltage signal U1, the two ends of the capacitor C2 are respectively connected to the partial discharge detection device to output the voltage signal U2, and the two ends of the capacitor C4 are respectively connected to the partial discharge detection device to output the voltage signal U3; the partial discharge detection device identifies external interference or locates the position of the partial discharge source according to the polarities of the voltage signal U1, the voltage signal U2 and the voltage signal U3.

[0010] Preferably, the partial discharge source locating system further comprises a signal coupling device SCU1, a signal coupling device SCU2 and a signal coupling device SCU3, the output end of the sensor T1 is connected to the signal coupling device SCU1, both ends of the capacitor C2 are respectively connected to the signal coupling device SCU2, both ends of the capacitor C4 are respectively connected to the signal coupling device SCU3, the signal coupling device SCU1, the signal coupling device SCU2 and the signal coupling device SCU3 are respectively connected to the partial discharge detection equipment for collecting the voltage signal U1, the voltage signal U2 and the voltage signal U3;

[0011] The signal coupling device SCU1, signal coupling device SCU2, signal coupling device SCU3 and partial discharge detection equipment are independent devices; or, the signal coupling device SCU1, signal coupling device SCU2, signal coupling device SC3 and partial discharge source detection equipment are an integrated device.

[0012] Preferably, the capacitor C3 and the capacitor C4 are also arranged in the first capacitive device 2 .

[0013] Preferably, the capacitor C3 and the capacitor C4 are arranged in the second capacitive device 3 .

[0014] Preferably, the first capacitive device 2 includes an insulating core having a capacitive voltage-divider insulating structure, and a plurality of capacitive screens alternately arranged with the insulating layer are embedded in the insulating core. The capacitor C1, capacitor C2, capacitor C3 and capacitor C4 are all embedded in the insulating core and are composed of a plurality of capacitive screens embedded in the insulating core.

[0015] Preferably, the first capacitive device 2 is a bushing, a lightning arrester, a current transformer, a voltage transformer or a cable terminal.

[0016] Preferably, the first capacitive device 2 is a bushing, which also includes a primary conductor 20 and an insulating core wrapped around the outside of the primary conductor 20, the primary conductor 20 is connected to the power transformer 1, and the sensor T1 is coupled to the primary conductor 20; the capacitors C1, C2, C3 and C4 are all embedded in the insulating core, and the two ends of the insulating core are respectively provided with an upper flange 22 and a lower flange 23, and the middle is provided with a mounting flange 15; the capacitor C1 is composed of a plurality of coaxial capacitor screens alternately arranged with insulating layers with gradually increasing diameters and gradually shortening lengths, the capacitor C2 is a tap capacitor of the capacitor C1, or the capacitor C2 is composed of a group of capacitor screens arranged outside the outermost capacitor screen of the capacitor C1 in parallel; the capacitor C3 is composed of a group of mutually insulated and mutually overlapping capacitor screens arranged outside the capacitor screen of the corresponding capacitor C1 along the axial direction from one end of the upper flange 12 to the ground end of the mounting flange 15, the capacitor C4 is a tap capacitor of the capacitor C3, or the capacitor C4 is composed of a group of capacitor screens arranged outside the outermost capacitor screen of the capacitor C3 in parallel.

[0017] Preferably, the first capacitive device 2 and the second capacitive device 3 are any two of a bushing, a lightning arrester, a current transformer, a voltage transformer, a cable terminal or a cable intermediate head.

[0018] Preferably, the first capacitive device 2 is a bushing, and the second capacitive device 3 is a lightning arrester.

[0019] Preferably, the bushing also includes a primary conductor 20 and an insulating core wrapped around the outside of the primary conductor 20, the primary conductor 20 is connected to the power transformer 1, and the sensor T1 is coupled to the primary conductor 20; the capacitor C1 and the capacitor C2 are both embedded in the insulating core, the capacitor C1 is a main insulating capacitor, and is composed of a plurality of coaxial capacitor screens that are alternately arranged with the insulating layer and have gradually increasing diameters and gradually shortening lengths; the capacitor C2 is a tap capacitor of the capacitor C1, or the capacitor C2 is composed of a group of capacitor screens arranged in parallel outside the outermost capacitor screen of the capacitor C1.

[0020] Preferably, the second capacitive device 3 is a lightning arrester, which includes a valve plate core formed by stacking multiple valve plates and an insulating core sleeved outside the valve plate core. The capacitor C3 and capacitor C4 are composed of valve plates of the lightning arrester. The capacitor C3 is composed of multiple valve plates stacked in sequence, and the capacitor C4 is composed of at least one valve plate stacked under the multiple valve plates stacked under the capacitor C3.

[0021] Preferably, the second capacitive device 3 is a lightning arrester, which includes a valve core formed by stacking multiple valve plates and an insulating core sleeved outside the valve core, capacitor C3 and capacitor C4 are both embedded in the insulating core, capacitor C3 is composed of a series of mutually insulated and stacked capacitor screens arranged from one end to the other end of the insulating core; capacitor C4 is a tap capacitor of capacitor C3, or capacitor C4 is composed of a group of capacitor screens arranged in parallel outside the outermost capacitor screen of capacitor C3.

[0022] Preferably, if the polarity of the voltage signal U1 is opposite to the polarity of the voltage signal U2 and the voltage signal U3, it is judged that a partial discharge source appears in the power transformer 1; if the polarity of the voltage signal U2 is opposite to the polarity of the voltage signal U1 and the voltage signal U3, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U1, the voltage signal U2 and the voltage signal U3 are the same, it is judged that an external interference current appears.

[0023] Preferably, the capacitor C3 and the capacitor C4 are also arranged in the first capacitive device 2 ; if the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2 , it is determined that a partial discharge source exists in the first capacitive device 2 .

[0024] Preferably, the capacitor C3 and the capacitor C4 are arranged in the second capacitive device 3 ; if the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2 , it is determined that a partial discharge source exists in the second capacitive device 3 .

[0025] A method for locating partial discharge sources.

[0026] Receive a collected voltage signal U1 of a power transformer, and receive a voltage signal U2 and a voltage signal U3 collected by a capacitive device connected to the power transformer;

[0027] When a partial discharge source is detected, if the polarity of the voltage signal U1 is opposite to the polarity of the voltage signal U2 and the voltage signal U3, it is determined that a partial discharge source exists in the power transformer;

[0028] If the polarity of the voltage signal U2 is opposite to the polarities of the voltage signal U1 and the voltage signal U3, it is determined that a partial discharge source occurs in the capacitive device that outputs the voltage signal U2;

[0029] If the polarity of the voltage signal U3 is opposite to the polarities of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source occurs in the capacitive device that outputs the voltage signal U3;

[0030] If the polarities of the voltage signal U1 , the voltage signal U2 and the voltage signal U3 are the same, it is determined to be external interference.

[0031] A partial discharge detection device comprises a processor, and the processor executes the partial discharge source locating method.

[0032] The partial discharge source locating system of the present invention can detect partial discharge sources under the operating conditions of the power transformer, can distinguish and exclude external interference currents and partial discharge sources, and realize the positioning of partial discharge sources, thereby ensuring the reliable and stable operation of the power transformer, and is conducive to efficiently locating the location where partial discharge faults occur, thereby improving the efficiency of inspection and maintenance operations.

[0033] In addition, the partial discharge source locating system of the present invention uses existing capacitive equipment connected to the power transformer for detection, such as bushings, lightning arresters, current transformers, voltage transformers, cable terminals or cable intermediate heads, without adding additional equipment, and has a simple structure and is easy to install and use.

[0034] The present invention also provides a partial discharge detection device with a partial discharge source locating function and a partial discharge source locating method. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a first embodiment of a partial discharge source positioning system of the present invention;

[0036] Figure 2 is a structural schematic diagram of a second embodiment of the partial discharge source locating system of the present invention;

[0037] Figure 3 It is a circuit principle diagram of the partial discharge source positioning system of the present invention;

[0038] Figure 4 It is a structural schematic diagram of the sleeve of the present invention;

[0039] Figure 5 It is a structural schematic diagram of the lightning arrester of the present invention;

[0040] Figure 6 It is a structural schematic diagram of another embodiment of the lightning arrester of the present invention;

[0041] Figure 7 It is a schematic diagram of the module structure of the first embodiment of the partial discharge detection device of the present invention;

[0042] Figure 8 It is a schematic diagram of the module structure of the second embodiment of the local detection equipment of the present invention. DETAILED DESCRIPTION

[0043] The following is combined with Figure 1-3 The given examples further illustrate the specific implementation of the partial discharge source locating system of the present invention. The partial discharge source locating system of the present invention is not limited to the description of the following examples.

[0044] The partial discharge source positioning system of the present invention can be used for partial discharge detection of power transformers. The power transformer 1 is equivalent to an equivalent capacitor C0 connected in series between a bus and a ground GND, comprising a partial discharge detection device, a first capacitive device 2 connected to the power transformer 1, the first capacitive device 2 comprising a capacitor C1 and a capacitor C2 arranged therein and connected in series between the bus and the ground GND in sequence, the partial discharge source positioning system further comprising a capacitor C3 and a capacitor C4 connected in series between the bus and the ground GND in sequence; a sensor T1 is coupled to a conductor connecting the power transformer 1 and the bus, an output end of the sensor T1 is connected to the partial discharge detection device to output a voltage signal U1, two ends of the capacitor C2 are respectively connected to the partial discharge detection device to output a voltage signal U2, and two ends of the capacitor C4 are respectively connected to the partial discharge detection device to output a voltage signal U3; the partial discharge detection device identifies external interference or locates the position of the partial discharge source according to the polarities of the voltage signals U1, U2 and U3. Under normal circumstances, the voltage signals U1, U2 and U3 are all power frequency voltage signals. When external interference current I1 or partial discharge occurs, the voltage signals U1, U2 and U3 will generate pulse voltage signals different from the power frequency voltage signals. The partial discharge detection device only needs to collect the voltage signal U2 at both ends of the capacitor C2 or the voltage signal U3 or the voltage signal U1 at both ends of the capacitor C4 to detect the partial discharge source. This belongs to the prior art and will not be described here. However, the partial discharge detection device of the prior art cannot determine whether the detected partial discharge source is from the power transformer or from the first capacitive device.

[0045] The partial discharge source locating system of the present invention can detect partial discharge of a power transformer and a capacitive device under operating conditions, and can detect the partial discharge source under the operating conditions of the power transformer. By collecting the voltage signal U1 of the power transformer and the voltage signals U2 and U3 of two capacitive devices connected to the power transformer, the external interference current I1 and the partial discharge source can be distinguished and excluded through polarity judgment, and the partial discharge source can be located whether it comes from the transformer or the capacitive device, thereby ensuring reliable and stable operation of the power transformer, facilitating efficient positioning of the location of partial discharge faults, and thus improving the efficiency of inspection and maintenance operations.

[0046] The partial discharge source positioning system also includes a signal coupling device SCU1, a signal coupling device SCU2 and a signal coupling device SCU3, the output end of the sensor T1 is connected to the signal coupling device SCU1, the two ends of the capacitor C2 are respectively connected to the signal coupling device SCU2, the two ends of the capacitor C4 are respectively connected to the signal coupling device SCU3, the signal coupling device SCU1, the signal coupling device SCU2 and the signal coupling device SCU3 are respectively connected to the partial discharge detection device for collecting voltage signals U1, voltage signals U2 and voltage signals U3. It should be pointed out that the signal coupling device SCU1, the signal coupling device SCU2, the signal coupling device SCU3 and the partial discharge detection device are independent devices. Alternatively, the signal coupling device SCU1, the signal coupling device SCU2, the signal coupling device SCU3 and the partial discharge source detection device are an integrated device as a whole, the signal coupling device SCU1, the signal coupling device SCU2, the signal coupling device SCU3 are located in the partial discharge source detection device, and are connected to the capacitive device through a wire, which is conducive to reducing the number of components of the partial discharge source positioning system of the present invention, simplifying the wiring structure, and improving assembly efficiency. The signal coupling device SCU1, the signal coupling device SCU2, and the signal coupling device SCU3 are used to collect the industrial frequency voltage signal across the capacitor, and their implementation belongs to the prior art in this field and will not be described in detail here.

[0047] Preferably, the capacitor C3 and the capacitor C4 are also arranged in the first capacitive device 2, that is, the capacitors C1, C2, C3 and C4 are located in the same capacitive device. Further, the first capacitive device 2 can be a bushing, a lightning arrester, a current transformer (CT), a voltage transformer (PT), a cable terminal, etc., a device having an insulating core with a capacitive voltage-dividing insulating structure. A plurality of capacitive screens alternately arranged with the insulating layer are embedded in the insulating core, and the capacitors C1, C2, C3 and C4 are all embedded in the insulating core, and are all composed of a plurality of capacitive screens embedded in the insulating core.

[0048] Preferably, the capacitor C3 and the capacitor C4 are arranged in the second capacitive device 3, that is, the capacitor C1 and the capacitor C2 are located in an independent capacitive device, and the capacitor C3 and the capacitor C4 are located in another independent capacitive device. For example, the first capacitive device 2 and the second capacitive device 3 are any two of a bushing, a lightning arrester, a current transformer, a voltage transformer, a cable terminal or a cable intermediate head.

[0049] It should be noted that the capacitor C3 and the capacitor C4 may be arranged neither in the first capacitive device 2 nor in the second capacitive device 3, but may be independent of the first capacitive device 2, the second capacitive device 3 and the capacitance of the power transformer 1. Of course, this requires the arrangement of additional capacitive devices, which increases the difficulty of installation and maintenance.

[0050] Preferably, if the polarity of the voltage signal U1 output by the signal coupling device SCU1 is opposite to the polarity of the voltage signal U2 output by the signal coupling device SCU2 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears inside the power transformer 1; if the polarity of the voltage signal U2 output by the signal coupling device SCU2 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device SCU2, and the voltage signal U3 output by the signal coupling device SCU3 are the same, it is judged that an external interference current I1 appears.

[0051] Preferably, the capacitor C3 and the capacitor C4 are also arranged in the first capacitive device 2; if the polarity of the voltage signal U3 output by the signal coupling device SCU3 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U2 output by the signal coupling device SCU2, it is determined that a partial discharge source appears in the first capacitive device 2.

[0052] Preferably, the capacitor C3 and the capacitor C4 are arranged in the second capacitive device 3, and the second capacitive device 3 is connected to the power transformer 1; if the polarity of the voltage signal U3 output by the signal coupling device SCU3 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U2 output by the signal coupling device SCU2, it is determined that a partial discharge source appears in the second capacitive device 3.

[0053] The signal coupling devices SCU1, SCU2 and SCU3 are used to collect voltage signals, which belong to the prior art and will not be described in detail here.

[0054] like Figure 2 , 4 FIG. 1 shows a first embodiment of the partial discharge source positioning system of the present invention.

[0055] The power transformer 1 can be regarded as a capacitor in terms of electrical performance, that is, an equivalent capacitor C0 connected in series between the busbar and the ground GND. The power transformer 1 is provided with a first capacitive device 2, which is a bushing. The capacitor C1, the capacitor C2, the capacitor C3 and the capacitor C4 are all arranged in the first capacitive device 2, that is, arranged in the bushing. The bushing also includes a primary conductor 20; the capacitor C1 and the capacitor C2 are connected in series between the busbar and the ground GND in sequence, the constant capacitance C3 and the capacitor C4 are connected in series between the busbar and the ground GND in sequence, and the primary conductor 20 is connected to the power transformer 1, that is, the primary conductor 20 and the equivalent capacitor C0 are connected in series in sequence. connected between the busbar and the ground GND; the partial discharge source positioning system includes a sensor T1, a signal coupling device SCU1, a signal coupling device SCU2, a signal coupling device SCU3 and a partial discharge detection device, the sensor T1 is a Rogowski coil LS, the Rogowski coil LS is coupled to the primary conductor 20, the output end of the Rogowski coil LS is connected to the signal coupling device SCU1, the two ends of the capacitor C2 are respectively connected to the signal coupling device SCU2, the two ends of the capacitor C4 are respectively connected to the signal coupling device SCU3, the signal coupling device SCU1, the signal coupling device SCU2, and the signal coupling device SCU3 are respectively connected to the partial discharge detection device.

[0056] When the partial discharge source locating system of the present invention performs detection, if the polarity of the voltage signal U1 output by the signal coupling device SCU1 is opposite to the polarity of the voltage signal U2 output by the signal coupling device SCU2 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the power transformer 1; if the polarity of the voltage signal U2 output by the signal coupling device SCU2 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U3 output by the signal coupling device SCU3 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U2 output by the signal coupling device SCU2, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device SCU2, and the voltage signal U3 output by the signal coupling device SCU3 are the same, it is judged that an external interference current I1 appears.

[0057] Preferably, Figure 4 FIG. 2 shows an embodiment in which the first capacitive device 2 is a sleeve.

[0058] The bushing includes a primary conductor 20 and an insulating core wrapped outside the primary conductor 20, and capacitors C1, C2, C3 and C4 are all embedded in the insulating core; the bushing also includes an inlet terminal 26, an outlet terminal 21, an upper flange 22, a lower flange 23, and a mounting flange 25, wherein the upper flange 22 and the lower flange 23 are respectively arranged at both ends of the insulating core, the mounting flange 25 is arranged in the middle of the insulating core, and the insulating core is located on the upper side of the mounting flange 25 and is also sleeved with a tightly crimped insulating outer sheath, the inlet terminal 26 is connected to the primary conductor 20 and is arranged at one end of the upper flange 22, and the outlet terminal 21 is connected to the wire 1 and is arranged at one end of the lower flange 13. Preferably, the insulating outer sheath is a silicone rubber umbrella skirt 14, the upper flange 12 is a Jiang Jun seat, and the lower flange 13 is a pressure equalizing ball.

[0059] The capacitor C1 is composed of a plurality of coaxial capacitor screens which are alternately arranged with insulating layers and have gradually increasing diameters and gradually decreasing lengths. The capacitor C1 plays a core role in voltage division and insulation.

[0060] Preferably, the capacitor C2 is a tap capacitor of the capacitor C1, that is, a capacitor tap connected to the penultimate screen (or penultimate screens) at the end of the capacitor C1, and the capacitor C2 is composed of a plurality of capacitor screens at the end of the capacitor C1, and the number of capacitor screens of the capacitor C2 is ≥ 1. Alternatively, the capacitor C2 is a capacitor independent of the capacitor C1, and the capacitor C2 is composed of a group of capacitor screens wound outside the outermost capacitor screen of the capacitor C1 in parallel.

[0061] The capacitor C3 is a shielding capacitor, which is composed of a series of mutually insulated and mutually overlapping capacitor screens wound or laid along the axial direction from one end of the upper flange 22 to the ground end of the mounting flange 25 when the capacitor C1 is manufactured. The capacitor screen of the capacitor C3 is wound or laid outside the capacitor screen of the corresponding capacitor C1, and is continuously offset from the high-voltage terminal along the axial direction and mutually overlapped. Specifically, as Figure 4 In the direction shown, the capacitor screens of the capacitor C3 are alternately wound or laid on the outside of the main insulating capacitor C1 with the insulating layer from the upper end to the lower end of the insulating core, and the adjacent capacitor screens are insulated from each other and overlap each other, and the multiple capacitor screens of the capacitor C3 are successively offset downward from top to bottom along the axial direction of the primary conductor 20, that is, of the two adjacent capacitor screens, the lower end of the upper capacitor screen is located inside the lower capacitor screen, and the lower end of the upper capacitor screen is overlapped with the upper end of the lower capacitor screen.

[0062] Preferably, the capacitor C4 is a tap capacitor of the capacitor C3, which is composed of a plurality of capacitor screens at the end of the capacitor C3, and the number of capacitor screens of the capacitor C4 is ≥ 1. Alternatively, the capacitor C4 is a capacitor independent of the capacitor C3, and the capacitor C4 is composed of a group of capacitor screens wound outside the outermost capacitor screen of the capacitor C3 in parallel.

[0063] It should be noted that the innermost capacitor screens of the capacitors C1 and C3 are respectively electrically connected to the primary conductor 1 and have the same potential, and the outermost capacitor screens of the capacitors C2 and C4 are grounded.

[0064] The first capacitive device 2 can also be a current transformer (CT), a voltage transformer (PT), a cable terminal, a cable intermediate head, a lightning arrester, etc., a device with an insulating core with a capacitive voltage-dividing insulation structure, and capacitors C1, C2, C3, and C4 can be arranged in the insulating core.

[0065] like Figure 1 , 4 , 5 are the second embodiment of the partial discharge source locating system of the present invention.

[0066] The power transformer 1 can be regarded as a capacitor in terms of electrical performance, that is, an equivalent capacitor C0 connected in series between the busbar and the ground GND. The power transformer 1 is provided with a first capacitive device 2, which is a bushing. The capacitor C1 and the capacitor C2 are arranged in the bushing and the capacitor C1 and the capacitor C2 are connected in series between the busbar and the ground GND in sequence. The capacitor C3 and the capacitor C4 are arranged in the second capacitive device 3. The second capacitive device 3 is a lightning arrester. The capacitor C3 and the capacitor C4 are connected in series between the busbar and the ground GND in sequence. The bushing includes a primary conductor 20 and an insulating core wrapped outside the primary conductor 20. The primary conductor 20 and the equivalent capacitor CO is connected in series between the busbar and the ground GND in sequence; the partial discharge source positioning system includes a sensor T1, a signal coupling device SCU1, a signal coupling device SCU2, a signal coupling device SCU3 and a partial discharge detection device, the sensor T1 is a Rogowski coil LS, the Rogowski coil LS is coupled to the primary conductor 20, the output end of the Rogowski coil LS is connected to the signal coupling device SCU1, the two ends of the capacitor C2 are respectively connected to the signal coupling device SCU2, the two ends of the capacitor C4 are respectively connected to the signal coupling device SCU3, the signal coupling device SCU1, the signal coupling device SCU2, and the signal coupling device SCU3 are respectively connected to the partial discharge detection device.

[0067] When the partial discharge source locating system of the present invention performs detection, if the polarity of the voltage signal U1 output by the signal coupling device SCU1 is opposite to the polarity of the voltage signal U2 output by the signal coupling device SCU2 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the power transformer 1; if the polarity of the voltage signal U2 output by the signal coupling device SCU2 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U3 output by the signal coupling device SCU3 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U2 output by the signal coupling device SCU2, it is judged that a partial discharge source appears in the second capacitive device 3; if the polarity of the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device SCU2, and the voltage signal U3 output by the signal coupling device SCU3 are the same, it is judged that an external interference current I1 appears.

[0068] Preferably, Figure 4 As shown, the capacitor C1 and the capacitor C2 are both embedded in the insulating core of the bushing. The capacitor C1 is a main insulating capacitor, which is composed of a plurality of coaxial capacitor screens which are alternately arranged with the insulating layer and have gradually increasing diameters and gradually decreasing lengths. The innermost capacitor screen of the capacitor C1 is electrically connected to the primary conductor 20 and has the same potential, and the outermost capacitor screen of the capacitor C2 is grounded.

[0069] Preferably, the capacitor C2 is a tap capacitor of the capacitor C1, or the capacitor C2 is a capacitor independent of the capacitor C1. The capacitor C3 and the capacitor C4 may not be provided in the casing, or the capacitor C3 may be provided as a shielding capacitor as required, or the capacitor C3 and the capacitor C4 may be provided as required.

[0070] Preferably, Figure 5 As shown, the lightning arrester includes a valve core formed by stacking multiple valve plates and an insulating core sleeved outside the valve core. Capacitor C3 and capacitor C4 are both embedded in the insulating core. Capacitor C3 is composed of a string of mutually insulated and stacked capacitor screens wound or laid from one end of the insulating core to the other end.

[0071] Preferably, the capacitor C4 is a tap capacitor of the capacitor C3, and is composed of a plurality of capacitor screens at the end of the capacitor C3, and the number of capacitor screens of the capacitor C4 is ≥ 1. Alternatively, the capacitor C4 is a capacitor independent of the capacitor C3, and is composed of a group of capacitor sheets arranged outside the outermost capacitor screen of the capacitor C3.

[0072] Specifically, Figure 5As shown, both ends of the insulating core of the arrester are provided with an arrester inlet terminal 30 and an arrester base 31, the arrester inlet terminal 30 is a high-voltage end, the arrester base 11a is grounded as a grounding end, the insulating core is provided with a silicone rubber umbrella skirt sheath 34, the capacitor C3 is composed of a series of mutually insulated and mutually overlapping capacitor screens wound or laid from one end of the arrester inlet terminal 30 close to the high-voltage end of the insulating core to the grounding end of the other end, the capacitor screen of the capacitor C3 is continuously offset and mutually overlapped from the arrester inlet terminal 30 to the arrester base 31 along the axial direction of the arrester, the capacitor C3 is a voltage divider valve plate capacitor, the innermost capacitor screen of the capacitor C3 is electrically connected to the arrester inlet terminal 30 and has the same potential, which plays a role in improving the performance of the arrester, and the outermost capacitor screen of the capacitor C4 is grounded.

[0073] Preferably, Figure 5 As shown, the arrester also includes a pressure equalizing cover 32 and a compression spring 36. The pressure equalizing cover 32 is arranged between the arrester incoming terminal 30 and the insulating core body. A silicone rubber umbrella skirt sheath 34 is tightly sleeved on the insulating core body. One end of the pressure equalizing cover 32 is connected to the arrester incoming terminal 30, and the other end is connected to the silicone rubber umbrella skirt sheath 34. The compression spring 36 is arranged between the pressure equalizing cover 32 and the valve plate to press the valve plate onto the arrester base 31.

[0074] Obviously, the first capacitive device 2 may also be a lightning arrester with capacitors C1 and C2 inside, and the second capacitive device 3 may be a bushing with capacitors C3 and C4 inside, which may also implement the technical solution of the present invention and belong to the protection scope of the present invention.

[0075] like Figure 1 , 4 , 6 are the third embodiment of the local discharge source locating system of the present invention.

[0076] The difference between this embodiment and the second embodiment mainly lies in the structure of the second capacitive device 3. The second capacitive device 3 is still a lightning arrester, and the capacitor C3 and the capacitor C4 are arranged in the lightning arrester.

[0077] like Figure 6 As shown, the arrester includes a valve core formed by stacking multiple valve plates and an insulating core sleeved outside the valve core. The capacitors C3 and C4 are composed of valve plates of the arrester. The capacitor C3 is composed of multiple valve plates stacked in sequence. The capacitor C3 is a valve capacitor. The capacitor C4 is composed of at least one valve plate under the multiple valve plates stacked on the capacitor C3. The capacitors C3 and C4 are connected in series. Figure 6 In the figure, the capacitor C4 is composed of a valve plate arranged between the capacitor C3 and the arrester base 31. The valve plate of the capacitor C4 outputs a monitoring signal through a signal line. The multiple valve plates can prevent the hazards of high transient overvoltage and also play a role in sampling and monitoring.

[0078] Of course, the arrester can be provided with capacitors formed by valve plates and capacitors in the insulating core at the same time as needed. For example, the first capacitive device 2 of the local discharge source positioning system of the present invention is a lightning arrester, and capacitors C1, C2, C3 and C4 are provided in the lightning arrester. The capacitors C1 and C2 are formed by valve plates (such as capacitors C3 and C4 in Example 3), and the capacitors C3 and C4 are formed by capacitor screens in the insulating core of the lightning arrester (such as capacitors C3 and C4 in Example 2). It should be pointed out that the insulating core of the bushing and the arrester of the present invention is preferably made of glass fibers impregnated with epoxy resin as an insulating layer, and a semi-conductive tape or a metal tape as a capacitor screen, and the insulating layer and the capacitor screen are alternately wound.

[0079] The following is a third embodiment of the partial discharge source locating system of the present invention.

[0080] The power transformer 1 can be regarded as a capacitor in terms of electrical performance, that is, an equivalent capacitor C0 connected in series between the busbar and the ground GND. The power transformer 1 is provided with a first capacitive device 2, which is any one of a bushing, a lightning arrester, a current transformer, a voltage transformer or a cable terminal. Capacitors C3 and C4 are external capacitors independent of the power transformer 1 and the first capacitive device 2, and the two are connected in series between the busbar and the ground GND in sequence. The first capacitive device 2 includes capacitors C1 and C2 connected in series between the busbar and the ground GND in sequence. The partial discharge source positioning system The invention comprises a sensor T1, a signal coupling device SCU1, a signal coupling device SCU2, a signal coupling device SCU3 and a partial discharge detection device. The sensor T1 is a Rogowski coil LS, which is coupled to a conductor connecting a busbar and an equivalent capacitor CO, and an output end of the Rogowski coil LS is connected to the signal coupling device SCU1, two ends of a capacitor C2 are respectively connected to the signal coupling device SCU2, two ends of a capacitor C4 are respectively connected to the signal coupling device SCU3, and the signal coupling device SCU1, the signal coupling device SCU2 and the signal coupling device SCU3 are respectively connected to the partial discharge detection device.

[0081] When the partial discharge source locating system of the present invention performs detection, if the polarity of the voltage signal U1 output by the signal coupling device SCU1 is opposite to the polarity of the voltage signal U2 output by the signal coupling device SCU2 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the power transformer 1; if the polarity of the voltage signal U2 output by the signal coupling device SCU2 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U3 output by the signal coupling device SCU3, it is judged that a partial discharge source appears in the first capacitive device 2; if the polarity of the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device SCU2, and the voltage signal U3 output by the signal coupling device SCU3 are the same, it is judged that an external interference current I1 appears.

[0082] like Figure 7 FIG. 1 shows a first embodiment of a partial discharge detection device according to the present invention.

[0083] The partial discharge source detection device includes a signal conditioning unit connected to a signal coupling device SCU1, a signal coupling device SCU2, and a signal coupling device SCU3 respectively, a partial discharge signal identification unit connected to the signal conditioning unit, a signal sampling and processing unit connected to the partial discharge signal identification unit, and a display system and a communication unit connected to the signal sampling and processing units respectively.

[0084] Among them, the signal conditioning unit can amplify, filter and other processes the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device, and the voltage signal U3 output by the signal coupling device SCU3; the partial discharge signal identification unit realizes the positioning of the partial discharge source and the detection of the partial discharge source of different equipment through the hardware circuit; the signal sampling and processing unit is used to display the processing result of the partial discharge signal identification unit through the display system, and send it to the host computer and / or the user end (such as a smart phone, a tablet computer, etc.) through the communication unit, so as to facilitate the user to monitor the operating status of the transformer in real time, and to deal with the partial discharge source in time when it occurs, so as to ensure the reliable and stable operation of the power transformer.

[0085] like Figure 8 FIG. 2 shows a second embodiment of the partial discharge detection device of the present invention.

[0086] The difference between this embodiment and the above-mentioned embodiments is that the partial discharge source detection device of this embodiment is not provided with a partial discharge signal identification unit.

[0087] Among them, the function of the signal conditioning unit of this embodiment is the same as that of the above embodiment; the signal sampling and processing unit of this embodiment realizes the positioning of the partial discharge source and the detection of the partial discharge source of different devices through an algorithm, and displays the processing result through a display system, and sends it to a host computer and / or a user terminal (such as a smart phone, a tablet computer, etc.) through a communication unit, so that the user can monitor the operating status of the transformer in real time, and when a partial discharge source occurs, timely deal with it to ensure the reliable and stable operation of the power transformer. The signal sampling and processing unit includes a processor, which can be a single-chip microcomputer or other processors that can meet the application requirements.

[0088] It should be pointed out that if Figure 7 and 8 As shown, ports 1-N (wherein N is an integer greater than or equal to 3) of the signal conditioning unit are used to connect to the signal coupling device. The signal coupling device SU1 / SU2 / SU3 of the present invention is respectively connected to the three ports. Of course, the partial discharge source locating system of the present invention is not limited to locating the partial discharge source of the three devices of the power transformer, bushing and lightning arrester, but can also be used for locating the partial discharge source of more devices.

[0089] like Figure 3 As shown, it is the circuit principle diagram of the partial discharge source positioning system of the present invention.

[0090] The power transformer 1 is connected in series between the bus and the ground GND as an equivalent capacitor C0, the capacitors C1 and C2 are connected in series between the bus and the ground GND, the capacitors C3 and C4 are connected in series between the bus and the ground GND, the sensor T1 is coupled to the conductor connecting the bus and the equivalent capacitor CO, the output end of the sensor T1 is connected to the signal coupling device SCU1, the two ends of the capacitor C2 are connected to the signal coupling device SCU2, the two ends of the capacitor C4 are connected to the signal coupling device SCU3, the signal coupling devices SCU1, SCU2 and SCU3 are connected to the partial discharge positioning device ( Figure 3 The partial discharge source positioning system of the present invention has the following four situations:

[0091] In case one, when an external interference current I1 appears, the external interference current I1 flows from the bus into each branch respectively, so that the polarities of the voltage signal U1 output by the signal coupling device SCU1, the voltage signal U2 output by the signal coupling device SCU2, and the voltage signal U3 output by the signal coupling device SCU3 are the same.

[0092] In the second situation, when partial discharge occurs inside the transformer, that is, when a partial discharge source appears in the equivalent capacitor C0, a pulse current I0 will be generated from the equivalent capacitor C0 to the busbar. For example, the current direction of I0 is from the ground to the busbar. Assuming that the current direction is negative, the sensor T1 senses the pulse current I0 and converts it into a voltage signal U1 through the signal coupling device SCU1. The polarity of the voltage signal U1 is the same as that of the pulse current I0, which is negative. The pulse current I1 causes the signal coupling device SCU2 to output a voltage signal U2, and causes the signal coupling device SCU3 to output a voltage signal U3. The polarities of the voltage signal U2 and the voltage signal U3 are opposite to the polarity of the voltage signal U1, which is positive.

[0093] In case three, similarly, when a partial discharge source appears inside the capacitor C1, the polarity of the voltage signal U2 output by the signal coupling device SCU2 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U3 output by the signal coupling device SCU3.

[0094] In case 4, similarly, when a partial discharge source appears inside the capacitor C3, the polarity of the voltage signal U3 output by the signal coupling device SCU3 is opposite to the polarity of the voltage signal U1 output by the signal coupling device SCU1 and the polarity of the voltage signal U2 output by the signal coupling device SCU2.

[0095] In other words, when the partial discharge source locating system of the present invention is in situation one, it means that there is no partial discharge source inside the power transformer 1, the bushing and / or the lightning arrester, but an external interference current I1 appears; when the partial discharge source locating system of the present invention is in situation two, it means that there is a partial discharge source in the power transformer 1; the capacitors C1, C2, C3, and C4 are all arranged in the bushing and the partial discharge source locating system is in situation three or situation four, which means that there is a partial discharge source in the bushing; the capacitor C1 and the capacitor C2 are arranged in the bushing, the capacitor C3 and the capacitor C4 are arranged in the lightning arrester, and when the partial discharge source locating system is in situation three, it means that there is a partial discharge source in the bushing, and when the partial discharge source locating system is in situation four, it means that there is a partial discharge source in the lightning arrester.

[0096] The partial discharge locating device includes a processor, which receives a collected voltage signal U1 of the power transformer, and a voltage signal U2 and a voltage signal U3 collected by a capacitive device connected to the power transformer, wherein the voltage signal U2 and the voltage signal U3 come from the same first capacitive device 2, or the voltage signal U2 and the voltage signal U3 come from the first capacitive device 2 and the second capacitive device 3, respectively.

[0097] The partial discharge locating device can determine whether there is a partial discharge source through the collected voltage signal U2, and further distinguish whether the partial discharge source comes from the power transformer, the first capacitive device 2, the second capacitive device 3, or the external interference (external interference current I1) through the polarity judgment of the voltage signal U1, the voltage signal U2 and the voltage signal U3, thereby realizing the positioning of the partial discharge source.

[0098] The processor of the partial discharge locating device executes the following method:

[0099] Receive a collected voltage signal U1 of a power transformer, and receive a voltage signal U2 and a voltage signal U3 collected by a capacitive device connected to the power transformer;

[0100] When a partial discharge source is detected, if the polarity of the voltage signal U1 is opposite to the polarity of the voltage signal U2 and the voltage signal U3, it is determined that a partial discharge source exists inside the power transformer 1; if the polarity of the voltage signal U2 is opposite to the polarity of the voltage signal U1 and the voltage signal U3, it is determined that a partial discharge source exists inside the capacitive device that outputs the voltage signal U2, i.e., the first capacitive device 2; if the polarities of the voltage signal U1, the voltage signal U2, and the voltage signal U3 are the same, it is determined that external interference (external interference current I1) exists, and no partial discharge source exists in the power transformer and the capacitive device.

[0101] If the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source exists in the capacitive device that outputs the voltage signal U3. When the voltage signal U2 and the voltage signal U3 are both from the same first capacitive device 2, the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source exists in the first capacitive device 2; when the voltage signal U2 and the voltage signal U3 are respectively from the first capacitive device 2 and the second capacitive device 3, if the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source exists in the second capacitive device 3.

[0102] The processor of the partial discharge positioning device can adopt an ARM chip (or other processors that can meet the application requirements), and the partial discharge positioning device also includes a storage unit, a communication unit, and a power supply unit. The partial discharge positioning device can also integrate a signal coupling device SCU1, a signal coupling device SCU2, and a signal coupling device SCU3, wherein the input end of the signal coupling device SCU1 is used to connect to the signal acquisition unit (Rogowski coil) of the power transformer, the input end of the signal coupling device SCU2 is used to connect to the first capacitive device connected to the power transformer, the input end of the signal coupling device SCU3 is used to connect to the first capacitive device connected to the power transformer, or the input end of the signal coupling device SCU3 is used to connect to the second capacitive device connected to the power transformer.

[0103] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A partial discharge source positioning system, characterized in that: The invention comprises a partial discharge detection device, a first capacitive device (2) connected to a power transformer (1), the first capacitive device (2) comprising a capacitor C1 and a capacitor C2 arranged therein and connected in series between a bus and a ground GND in sequence, and the partial discharge source positioning system further comprising a capacitor C3 and a capacitor C4 connected in series between the bus and the ground GND in sequence; The partial discharge source locating system also includes a signal coupling device SCU1, a signal coupling device SCU2 and a signal coupling device SCU3, the output end of the sensor T1 is connected to the signal coupling device SCU1, the two ends of the capacitor C2 are respectively connected to the signal coupling device SCU2, the two ends of the capacitor C4 are respectively connected to the signal coupling device SCU3, the signal coupling device SCU1, the signal coupling device SCU2 and the signal coupling device SCU3 are respectively connected to the partial discharge detection equipment for collecting the voltage signal U1, the voltage signal U2 and the voltage signal U3 respectively; the signal coupling device SCU1, the signal coupling device SCU2, the signal coupling device SCU3 and the partial discharge detection equipment are independent devices; or, the signal coupling device SCU1, the signal coupling device SCU2, the signal coupling device SC3 and the partial discharge source detection equipment are an integrated device as a whole; The sensor T1 is coupled to a conductor connecting the power transformer (1) and the busbar, the output end of the sensor T1 is connected to a partial discharge detection device to output a voltage signal U1, the two ends of the capacitor C2 are respectively connected to the partial discharge detection device to output a voltage signal U2, and the two ends of the capacitor C4 are respectively connected to the partial discharge detection device to output a voltage signal U3; the partial discharge detection device identifies external interference or locates the position of the partial discharge source according to the polarities of the voltage signal U1, the voltage signal U2 and the voltage signal U3; If the polarity of the voltage signal U1 is opposite to the polarity of the voltage signal U2 and the voltage signal U3, it is determined that a partial discharge source exists in the power transformer (1); if the polarity of the voltage signal U2 is opposite to the polarity of the voltage signal U1 and the voltage signal U3, it is determined that a partial discharge source exists in the first capacitive device (2); if the polarity of the voltage signal U1, the voltage signal U2 and the voltage signal U3 are the same, it is determined that an external interference current exists.

2. The partial discharge source locating system according to claim 1, characterized in that: The capacitor C3 and the capacitor C4 are also arranged in the first capacitive device (2).

3. The partial discharge source positioning system according to claim 1, characterized in that: The capacitor C3 and the capacitor C4 are arranged in the second capacitive device (3).

4. The partial discharge source locating system according to claim 2, characterized in that: The first capacitive device (2) comprises an insulating core having a capacitive voltage-dividing insulating structure, wherein a plurality of capacitive screens alternately arranged with insulating layers are embedded in the insulating core, and the capacitors C1, C2, C3 and C4 are all embedded in the insulating core and are composed of a plurality of capacitive screens embedded in the insulating core.

5. The partial discharge source locating system according to claim 4, characterized in that: The first capacitive device (2) is a bushing, a lightning arrester, a current transformer, a voltage transformer or a cable terminal.

6. The partial discharge source locating system according to claim 2, characterized in that: The first capacitive device (2) is a bushing, which also includes a primary conductor (20) and an insulating core wrapped around the primary conductor (20), the primary conductor (20) is connected to the power transformer (1), and the sensor T1 is coupled to the primary conductor (20); the capacitor C1, the capacitor C2, the capacitor C3 and the capacitor C4 are all embedded in the insulating core, the two ends of the insulating core are respectively provided with an upper flange (22) and a lower flange (23), and the middle is provided with a mounting flange (15); the capacitor C1 is composed of a plurality of insulating layers, with the diameter gradually increasing and the length gradually decreasing, alternating with the insulating layer. The invention is composed of a plurality of coaxial capacitor screens, wherein the capacitor C2 is a tap capacitor of the capacitor C1, or the capacitor C2 is composed of a group of capacitor screens arranged outside the outermost capacitor screen of the capacitor C1 in parallel; the capacitor C3 is composed of a group of mutually insulated and mutually overlapping capacitor screens arranged outside the corresponding capacitor screen of the capacitor C1 along the axial direction from one end of the upper flange (12) to the grounding end of the mounting flange (15); the capacitor C4 is a tap capacitor of the capacitor C3, or the capacitor C4 is composed of a group of capacitor screens arranged outside the outermost capacitor screen of the capacitor C3 in parallel.

7. The partial discharge source locating system according to claim 3, characterized in that: The first capacitive device (2) and the second capacitive device (3) are any two of a bushing, a lightning arrester, a current transformer, a voltage transformer, a cable terminal or a cable intermediate head.

8. The partial discharge source locating system according to claim 3, characterized in that: The first capacitive device (2) is a bushing, and the second capacitive device (3) is a lightning arrester.

9. The partial discharge source locating system according to claim 8, characterized in that: The bushing also includes a primary conductor (20) and an insulating core wrapped around the primary conductor (20), the primary conductor (20) being connected to the power transformer (1), and the sensor T1 being coupled to the primary conductor (20); the capacitor C1 and the capacitor C2 being both embedded in the insulating core, the capacitor C1 being a main insulating capacitor, and being composed of a plurality of coaxial capacitor screens, which are arranged alternately with the insulating layer and have gradually increasing diameters and gradually decreasing lengths; the capacitor C2 being a tap capacitor of the capacitor C1, or the capacitor C2 being composed of a group of capacitor screens arranged in parallel outside the outermost capacitor screen of the capacitor C1.

10. The partial discharge source locating system according to claim 3, characterized in that: The second capacitive device (3) is a lightning arrester, which includes a valve core formed by stacking multiple valve plates and an insulating core sleeved outside the valve core. The capacitors C3 and C4 are composed of valve plates of the lightning arrester. The capacitor C3 is composed of multiple valve plates stacked in sequence, and the capacitor C4 is composed of at least one valve plate stacked below the multiple valve plates stacked on the capacitor C3.

11. The partial discharge source locating system according to claim 3, characterized in that: The second capacitive device (3) is a lightning arrester, which includes a valve core formed by stacking multiple valve plates and an insulating core sleeved outside the valve core. Capacitors C3 and C4 are both embedded in the insulating core. Capacitor C3 is composed of a series of mutually insulated and mutually stacked capacitor screens arranged from one end to the other end of the insulating core; capacitor C4 is a tap capacitor of capacitor C3, or capacitor C4 is composed of a group of capacitor screens arranged in parallel outside the outermost capacitor screen of capacitor C3.

12. The partial discharge source locating system according to claim 1, characterized in that: The capacitor C3 and the capacitor C4 are also arranged in the first capacitive device (2); if the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source exists in the first capacitive device (2).

13. The partial discharge source locating system according to claim 1, characterized in that: The capacitor C3 and the capacitor C4 are arranged in the second capacitive device (3); if the polarity of the voltage signal U3 is opposite to the polarity of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source exists in the second capacitive device (3).

14. A method for locating a partial discharge source, characterized in that: Receive a collected voltage signal U1 of a power transformer, and receive a voltage signal U2 and a voltage signal U3 collected by a capacitive device connected to the power transformer; When a partial discharge source is detected, if the polarity of the voltage signal U1 is opposite to the polarity of the voltage signal U2 and the voltage signal U3, it is determined that a partial discharge source exists in the power transformer; If the polarity of the voltage signal U2 is opposite to the polarities of the voltage signal U1 and the voltage signal U3, it is determined that a partial discharge source occurs in the capacitive device that outputs the voltage signal U2; If the polarity of the voltage signal U3 is opposite to the polarities of the voltage signal U1 and the voltage signal U2, it is determined that a partial discharge source occurs in the capacitive device that outputs the voltage signal U3; If the polarities of the voltage signal U1 , the voltage signal U2 and the voltage signal U3 are the same, it is determined to be external interference.

15. A partial discharge detection device, comprising a processor, characterized in that: The processor executes the partial discharge source locating method described in claim 14.

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