Space charge measuring device and method of composite oil paper insulation structure

Abstract

The invention relates to a space charge measuring device and method of a composite oil paper insulation structure, and belongs to the technical field of electromagnetic measurement, the space charge measuring device of the composite oil paper insulation structure comprises an upper electrode, a lower electrode and a lower electrode, the conductor electrode and the semiconductor electrode are laminated at the central position of the upper electrode, and the bottom surface enveloped by the insulator and the bottom surface of the semiconductor electrode are positioned on the same plane; and the lower electrode is internally provided with a groove matched with the upper electrode in size, and the groove is used for placing a composite oil paper insulation structure. According to the invention, while space charge measurement of the composite oil paper insulation structure is realized, the error of space charge measurement is reduced, and the accuracy of space charge measurement is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic measurement, and in particular to a device and method for measuring space charge of a composite oil-paper insulation structure. Background Art

[0002] With the continuous improvement of voltage and capacity requirements of power systems, ultra-high and ultra-high voltage direct current transmission has been widely used and developed, becoming an important means to optimize energy distribution. In the process of ultra-high voltage direct current transmission, the converter transformer is the core equipment, but due to factors such as high voltage level and uneven electric field distribution, the converter transformer has a high failure rate. Data shows that the failure rate of converter transformers is about twice that of ordinary power transformers, of which about 50% are caused by insulation problems.

[0003] Oil-paper insulation is one of the important insulation structures of oil-immersed transformers. Due to the strong electric field and oil-paper interface in its working environment, space charge accumulation is easy to occur inside the oil-paper insulation, which causes local electric field distortion, accelerates insulation aging, increases the risk of insulation failure, and seriously affects the operation safety of the transformer. Therefore, it is of great significance to study the distribution of space charge inside the insulation paper and propose targeted transformer oil-paper insulation charge transport characteristics to evaluate and predict the transformer oil-paper aging state, which is of great significance to ensure the safe and stable operation of power equipment.

[0004] The existing devices for measuring the space charge of insulating paper can measure the oil-paper insulation structure and control the temperature and electric field. However, there are certain defects in the electrode structure design of the composite oil-paper bonded structure space charge measurement device. When the paper-oil-paper composite oil-paper insulation sample is squeezed by the upper electrode, the upper insulating paper will inevitably produce a downward pressure and concave deformation, which will lead to space charge measurement errors. Summary of the invention

[0005] In view of this, it is necessary to provide a space charge measurement device and method for a composite oil-paper insulation structure to solve the problem that the current composite oil-paper insulation structure space charge measurement device generates measurement errors due to the deformation of the insulation paper during measurement.

[0006] In order to solve the above problems, the present invention provides a space charge measuring device for a composite oil-paper insulation structure, comprising: An upper electrode, comprising a conductor electrode, a semiconductor electrode and an insulator envelope, wherein the conductor electrode and the semiconductor electrode are stacked at the center of the upper electrode, and the bottom surface of the insulator envelope is in the same plane as the bottom surface of the semiconductor electrode; A lower electrode is provided with a groove matching the size of the upper electrode for accommodating a composite oil-paper insulation structure.

[0007] In a possible implementation manner, the device further includes: Power supply module, including DC power supply and pulse power supply; The upper electrode connection cavity includes an electric transmission port, a DC protection resistor, a DC blocking capacitor, a coupling resistor, an electrode connection rod, an insulator filling, a retractable spring, and a shielding metal shell; The DC power supply is connected to the electrode connecting rod through the power transmission port and the DC protection resistor; The pulse power source is connected to the electrode connecting rod through the power transmission port and the DC blocking capacitor; The coupling resistor is connected to the shielding metal shell; A hole matching the size of the conductor electrode is provided at the center of the bottom of the electrode connecting rod, so that when the upper electrode connecting cavity is connected to the upper electrode, the electrode connecting rod is in good contact with the conductor electrode; The retractable spring is fixed to the bottom filled with the insulator, and is in a stretched state when the upper electrode connection cavity is separated from the upper electrode, and is in a compressed state when the upper electrode connection cavity is connected to the upper electrode.

[0008] In a possible implementation manner, the device further includes: Signal acquisition and shielding module, including metal shielding box, piezoelectric sensor, sound absorption module, signal amplifier, and signal output port; The metal shielding box is fixed to the bottom of the lower electrode by magnetic shielding fixing screws; The piezoelectric sensor is arranged at the center of the bottom of the lower electrode; The sound absorption module is arranged at the bottom of the piezoelectric sensor; The signal output port is arranged on the side wall of the metal shielding box; The piezoelectric sensor is connected to the signal output port via the signal amplifier.

[0009] In a possible implementation manner, the device further includes: A top end cover, the top end cover is arranged above the upper electrode connection cavity and connected to the lower electrode by fixing screws; The top end cover is used to control the connection and separation between the upper electrode connection cavity and the upper electrode.

[0010] In a possible implementation, an oil heating pipeline is further provided in the lower electrode, and the oil heating pipeline is used to control the temperature of the lower electrode and the composite oil-paper insulation structure.

[0011] The present invention also provides a method for measuring the space charge of a composite oil-paper insulation structure implemented based on the space charge measuring device of the composite oil-paper insulation structure as described above, comprising: When the upper electrode connection cavity is connected to the upper electrode, a DC voltage polarization is performed on the composite oil-paper insulation structure based on a DC power supply; Applying a pulse signal to the composite oil-paper insulation structure after DC voltage polarization based on a pulse power supply, and obtaining an output pulse signal from a signal output port; Based on the output pulse signal, the spatial charge distribution of the composite oil-paper insulation structure is determined.

[0012] In a possible implementation, the upper electrode connection cavity is connected to the upper electrode, including: The retractable spring in the upper electrode connection cavity is in a squeezed state, the electrode connection rod is in good contact with the conductor electrode in the upper electrode, and the bottom surface of the semiconductor electrode in the upper electrode is in close contact with the top surface of the composite oil-paper insulation structure.

[0013] In a possible implementation, the DC voltage polarization of the composite oil-paper insulation structure based on a DC power supply includes: Based on the DC power supply, the composite oil-paper insulation structure is polarized by a DC voltage through the electrode connecting rod and the upper electrode; The step of applying a pulse signal to the composite oil-paper insulation structure polarized by a DC voltage based on a pulse power supply comprises: Based on the pulse power supply, a pulse signal is applied to the composite oil-paper insulation structure through the electrode connecting rod and the upper electrode.

[0014] In a possible implementation, the output pulse signal is obtained by amplifying the signal collected by the piezoelectric sensor through a signal amplifier and transmitting the amplified signal to the signal output port.

[0015] In a possible implementation, determining the spatial charge distribution of the composite oil-paper insulation structure based on the output pulse signal includes: The output pulse signal is subjected to signal averaging processing, deconvolution processing and data recovery processing in sequence to obtain the spatial charge distribution of the composite oil-paper insulation structure.

[0016] The beneficial effects of the present invention are as follows: the space charge measurement device and method of the composite oil-paper insulation structure provided by the present invention, by enveloping a conductor electrode, a semiconductor electrode and an insulator to form an upper electrode of an integral structure, and arranging a groove structure matching the size of the upper electrode on the lower electrode, when the upper electrode is in close contact with the composite oil-paper insulation structure and is squeezed, due to the supporting effect of the three layers of insulation paper at the edge of the composite oil-paper insulation structure, deformation of the insulation sample at the corresponding position of the conductor electrode is avoided, thereby improving the accuracy of the space charge measurement of the composite oil-paper insulation structure. While realizing the space charge measurement of the composite oil-paper insulation structure, the present invention reduces the error of the space charge measurement and improves the accuracy of the space charge measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of an embodiment of a space charge measurement device for a composite oil-paper insulation structure provided by the present invention; Figure 2 A schematic flow chart of an embodiment of a method for measuring space charge of a composite oil-paper insulation structure provided by the present invention; Figure 3 A schematic structural diagram of another embodiment of a space charge measuring device for a composite oil-paper insulation structure provided by the present invention; Figure 4 A schematic structural diagram of an electrode structure of an embodiment of a space charge measurement device for a composite oil-paper insulation structure provided by the present invention; Figure 5 A top view of the structure of an electrode structure of an embodiment of a space charge measurement device for a composite oil-paper insulation structure provided by the present invention. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0019] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0020] In the description of the present invention, reference to an "embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive of other embodiments. It is explicitly and implicitly understood by those skilled in the art that the described embodiments may be combined with other embodiments.

[0021] With the continuous improvement of voltage and capacity requirements of power systems, ultra-high and ultra-high voltage direct current transmission has been widely used and developed, becoming an important means to optimize energy distribution. In the process of ultra-high voltage direct current transmission, the converter transformer is the core equipment, but due to factors such as high voltage level and uneven electric field distribution, the converter transformer has a high failure rate. Data shows that the failure rate of converter transformers is about twice that of ordinary power transformers, of which about 50% are caused by insulation problems.

[0022] Oil-paper insulation is one of the important insulation structures of oil-immersed transformers. Due to the strong electric field and oil-paper interface in its working environment, space charge accumulation is easy to occur inside the oil-paper insulation, which causes local electric field distortion, accelerates insulation aging, increases the risk of insulation failure, and seriously affects the operation safety of the transformer. Therefore, it is of great significance to study the distribution of space charge inside the insulation paper and propose targeted transformer oil-paper insulation charge transport characteristics to evaluate and predict the transformer oil-paper aging state, which is of great significance to ensure the safe and stable operation of power equipment.

[0023] The Pulsed Electro-Acoustic (PEA) space charge measurement technology is based on the Coulomb force law. By applying a nanosecond pulse voltage to the insulating sample, the space charge inside the insulating sample generates a Coulomb force under the action of the pulse electric field, forming a pressure pulse wave, which is then received by the piezoelectric sensor attached to the electrode on the other side, and the pressure signal is converted into an electrical signal, thereby inferring the space charge distribution inside the sample based on the test and the structural parameters of the plate. Compared with other measurement methods, the PEA method has the characteristics of simple structure, convenient testing, and low cost. Therefore, it has gradually become one of the most important test methods in the field of space charge and has broad prospects.

[0024] The existing devices for measuring the space charge of insulating paper can measure the oil-paper insulation structure and control the temperature and electric field, but there are certain defects in the design of the electrode structure for the space charge measurement device of the composite oil-paper bonded structure. Taking the paper-oil-paper composite structure as an example, a hollow disc is placed in the middle layer and filled with oil. In order to apply a stable electric field to the paper-oil-paper composite structure, the diameter of the upper electrode should be smaller than the diameter of the oil gap in the middle layer. At the same time, the upper electrode needs to apply a certain pressure to the sample to ensure close contact between the two. Since the oil gap structure does not have a strong supporting force, in the traditional device, after the paper-oil-paper composite oil-paper insulation sample is squeezed by the upper electrode, the upper insulating paper will inevitably produce a downward pressure and concave deformation, resulting in space charge measurement errors. Therefore, when measuring the space charge of the composite oil-paper insulation structure, it is very necessary to optimize the electrode structure.

[0025] In order to solve the above problems, the present invention provides a space charge measuring device for a composite oil-paper insulation structure.

[0026] The specific embodiments are described in detail below: A specific embodiment of the present invention discloses a space charge measurement device for a composite oil-paper insulation structure, combined with Figure 1 Come and see, Figure 1 This is a schematic structural diagram of an embodiment of a space charge measuring device for a composite oil-paper insulation structure provided by the present invention. The space charge measuring device 100 for a composite oil-paper insulation structure includes: The upper electrode 110 includes a conductor electrode 111, a semiconductor electrode 112 and an insulator envelope 113. The conductor electrode 111 and the semiconductor electrode 112 are stacked and arranged at the center of the upper electrode 110. The bottom surface of the insulator envelope 113 is on the same plane as the bottom surface of the semiconductor electrode 112. The lower electrode 120 is provided with a groove matching the size of the upper electrode 110 for placing the composite oil-paper insulation structure.

[0027] During implementation, the composite oil-paper insulation structure can be first placed in the groove of the lower electrode, and then the bottom surface of the upper electrode can be made in close contact with the composite oil-paper insulation structure, that is, the bottom surface of the semiconductor electrode can be made in close contact with the composite oil-paper insulation structure. Then, the composite oil-paper insulation structure can be polarized by applying an electric signal to the upper electrode, and a pulse signal can be applied to the polarized composite oil-paper insulation structure to obtain the spatial charge distribution of the composite oil-paper insulation structure.

[0028] At the same time, when the bottom surface of the semiconductor electrode is in close contact with the composite oil-paper insulation structure, the support of the three layers of insulation paper at the edge of the composite oil-paper insulation structure avoids deformation of the insulation sample at the corresponding position of the conductor electrode in the existing measurement structure.

[0029] Compared with the prior art, the space charge measurement device of the composite oil-paper insulation structure provided in this embodiment forms an upper electrode with an integral structure by enveloping a conductor electrode, a semiconductor electrode and an insulator, and sets a groove structure matching the size of the upper electrode on the lower electrode. When the upper electrode is in close contact with the composite oil-paper insulation structure and is squeezed, the support of the three layers of insulation paper at the edge of the composite oil-paper insulation structure avoids deformation of the insulation sample at the corresponding position of the conductor electrode, thereby improving the accuracy of the space charge measurement of the composite oil-paper insulation structure. While realizing the space charge measurement of the composite oil-paper insulation structure, the present invention reduces the error of the space charge measurement and improves the accuracy of the space charge measurement.

[0030] Exemplarily, the device further includes: Power supply module, including DC power supply and pulse power supply; The upper electrode connection cavity includes an electric transmission port, a DC protection resistor, a DC blocking capacitor, a coupling resistor, an electrode connection rod, an insulator filling, a retractable spring, and a shielding metal shell; The DC power supply is connected to the electrode connecting rod through the power transmission port and the DC protection resistor; The pulse power source is connected to the electrode connecting rod through the power transmission port and the DC blocking capacitor; The coupling resistor is connected to the shielding metal shell; A hole matching the size of the conductor electrode is provided at the center of the bottom of the electrode connecting rod, so that when the upper electrode connecting cavity is connected to the upper electrode, the electrode connecting rod is in good contact with the conductor electrode; The retractable spring is fixed to the bottom filled with the insulator, and is in a stretched state when the upper electrode connection cavity is separated from the upper electrode, and is in a compressed state when the upper electrode connection cavity is connected to the upper electrode.

[0031] Specifically, the space charge measurement device of the composite oil-paper insulation structure may also include a power module and an upper electrode connection cavity. The power module may be used to provide polarization current and pulse signals, and the upper electrode connection cavity is used for circuit protection and signal shielding, and can also transmit the electrical signal provided by the power module to the upper electrode.

[0032] The DC protection resistor, DC blocking capacitor and coupling resistor in the upper electrode connection cavity constitute a protection circuit. The DC power supply is connected to the electrode connection rod through the DC protection resistor via the power transmission port; the pulse power supply is connected to the electrode connection rod through the power transmission port via the DC blocking capacitor. In addition, the pulse power supply is also connected to the shielded metal shell through the coupling resistor to achieve grounding.

[0033] At the same time, a hole matching the size of the conductor electrode is provided at the center of the bottom of the electrode connecting rod. When the upper electrode connecting cavity is connected to the upper electrode, the electrode connecting rod is in good contact with the conductor electrode to realize the transmission of electrical signals.

[0034] A retractable spring is also fixed to the bottom of the insulator filling. The retractable spring is in a stretched state when the upper electrode connection cavity is separated from the upper electrode, and is in a squeezed state when the upper electrode connection cavity is connected to the upper electrode, so as to ensure that the upper electrode connection cavity and the upper electrode are in close contact.

[0035] Exemplarily, the device further includes: Signal acquisition and shielding module, including metal shielding box, piezoelectric sensor, sound absorption module, signal amplifier, and signal output port; The metal shielding box is fixed to the bottom of the lower electrode by magnetic shielding fixing screws; The piezoelectric sensor is arranged at the center of the bottom of the lower electrode; The sound absorption module is arranged at the bottom of the piezoelectric sensor; The signal output port is arranged on the side wall of the metal shielding box; The piezoelectric sensor is connected to the signal output port via the signal amplifier.

[0036] Specifically, the space charge measurement device of the composite oil-paper insulation structure may also include a signal acquisition and shielding module, which is used for signal acquisition of the composite oil-paper insulation structure and realizes signal shielding during the signal acquisition process to avoid external interference.

[0037] The metal shielding box can be fixed to the bottom of the lower electrode by means of magnetic shielding fixing screws. The piezoelectric sensor can be arranged at the center of the bottom of the lower electrode to collect the signal generated by the composite oil-paper insulation structure. At the same time, a sound absorption module can be arranged at the bottom of the piezoelectric sensor to further avoid the interference of noise signals on the piezoelectric sensor.

[0038] The side wall of the metal shielding box is provided with a signal output port, and the signal collected by the piezoelectric sensor can first pass through the signal amplifier and then be transmitted to the signal output port.

[0039] Exemplarily, the device further includes: A top end cover, the top end cover is arranged above the upper electrode connection cavity and connected to the lower electrode by fixing screws; The top end cover is used to control the connection and separation between the upper electrode connection cavity and the upper electrode.

[0040] Specifically, the space charge measurement device of the composite oil-paper insulation structure may also include a top end cover, which is connected to the lower electrode via a fixing screw. By adjusting the screw-in length of the fixing screw, the connection and separation of the upper electrode connecting cavity and the upper electrode can be controlled.

[0041] Exemplarily, an oil heating pipeline is further provided in the lower electrode, and the oil heating pipeline is used to control the temperature of the lower electrode and the composite oil-paper insulation structure.

[0042] Specifically, an oil heating pipeline is also provided in the lower electrode. The oil heating pipeline forms a ring structure with the groove of the lower plate as the center. Insulating oil with a set temperature circulates in the pipeline to control the temperature of the lower electrode and the composite oil-paper insulation structure.

[0043] The present invention also discloses a method for measuring the space charge of a composite oil-paper insulation structure based on the space charge measuring device of the composite oil-paper insulation structure as described above, and Figure 2 Come and see, Figure 2 A schematic flow chart of an embodiment of a method for measuring space charge of a composite oil-paper insulation structure provided by the present invention includes steps S201 to S203, wherein: In step S201, when the upper electrode connection cavity is connected to the upper electrode, a DC voltage polarization is performed on the composite oil-paper insulation structure based on a DC power supply; In step S202, a pulse signal is applied to the composite oil-paper insulation structure after DC voltage polarization based on a pulse power supply, and an output pulse signal is obtained from a signal output port; In step S203, the spatial charge distribution of the composite oil-paper insulation structure is determined based on the output pulse signal.

[0044] During implementation, the composite oil-paper insulation structure is first placed in the groove of the lower electrode, and then the upper electrode connection cavity can be connected to the upper electrode, so that the power module can transmit the electrical signal to the composite oil-paper insulation structure. Then, the composite oil-paper insulation structure can be polarized by a DC voltage through a DC power supply.

[0045] After the DC voltage polarization of the composite oil-paper insulation structure is completed, a pulse signal can be applied to the polarized composite oil-paper insulation structure through a pulse power supply, and then an output pulse signal can be obtained from the signal output port. In addition, after the output pulse signal is obtained, the output pulse signal can be observed and processed by means of an oscilloscope and a computer.

[0046] Finally, the spatial charge distribution of the composite oil-paper insulation structure can be obtained by analyzing and processing the output pulse signal.

[0047] Compared with the prior art, the space charge measurement method of the composite oil-paper insulation structure provided in this embodiment is achieved by enveloping a conductor electrode, a semiconductor electrode and an insulator to form an upper electrode with an integral structure, and arranging a groove structure matching the size of the upper electrode on the lower electrode. When the upper electrode is in close contact with the composite oil-paper insulation structure and is squeezed, the support of the three layers of insulation paper at the edge of the composite oil-paper insulation structure avoids deformation of the insulation sample at the corresponding position of the conductor electrode, thereby improving the accuracy of the space charge measurement of the composite oil-paper insulation structure. While realizing the space charge measurement of the composite oil-paper insulation structure, the present invention reduces the error of the space charge measurement and improves the accuracy of the space charge measurement.

[0048] Exemplarily, the upper electrode connection cavity is connected to the upper electrode, including: The retractable spring in the upper electrode connection cavity is in a squeezed state, the electrode connection rod is in good contact with the conductor electrode in the upper electrode, and the bottom surface of the semiconductor electrode in the upper electrode is in close contact with the top surface of the composite oil-paper insulation structure.

[0049] Specifically, the upper electrode connecting cavity is connected to the upper electrode, that is, the retractable spring in the upper electrode connecting cavity is in an extruded state, the electrode connecting rod is in good contact with the conductor electrode in the upper electrode, and the bottom surface of the semiconductor electrode in the upper electrode is in close contact with the top surface of the composite oil-paper insulation structure, so that the electrical signal output by the power module can be transmitted to the composite oil-paper insulation structure.

[0050] Exemplarily, the DC voltage polarization of the composite oil-paper insulation structure based on a DC power supply includes: Based on the DC power supply, the composite oil-paper insulation structure is polarized by a DC voltage through the electrode connecting rod and the upper electrode; The step of applying a pulse signal to the composite oil-paper insulation structure polarized by a DC voltage based on a pulse power supply comprises: Based on the pulse power supply, a pulse signal is applied to the composite oil-paper insulation structure through the electrode connecting rod and the upper electrode.

[0051] Specifically, when the composite oil-paper insulation structure is subjected to DC voltage polarization through a DC power supply, that is, a DC voltage is applied to the electrode connecting rod through the DC power supply, and then the electrode connecting rod transmits the DC voltage to the composite oil-paper insulation structure through the upper electrode, thereby realizing DC voltage polarization of the composite oil-paper insulation structure.

[0052] Similarly, when a pulse signal is applied to the composite oil-paper insulation structure after DC voltage polarization through a pulse power supply, a pulse signal is also applied to the electrode connecting rod through the pulse power supply, and then the electrode connecting rod transmits the pulse signal to the composite oil-paper insulation structure through the upper electrode.

[0053] Exemplarily, the output pulse signal is obtained by amplifying the signal collected by the piezoelectric sensor through a signal amplifier and transmitting it to the signal output port.

[0054] Specifically, in order to further improve the accuracy of space charge measurement of the composite oil-paper insulation structure, the signal collected by the piezoelectric sensor can be amplified by a signal amplifier and then transmitted to the signal output port to obtain an output pulse signal.

[0055] Exemplarily, determining the spatial charge distribution of the composite oil-paper insulation structure based on the output pulse signal includes: The output pulse signal is subjected to signal averaging processing, deconvolution processing and data recovery processing in sequence to obtain the spatial charge distribution of the composite oil-paper insulation structure.

[0056] Specifically, when determining the spatial charge distribution of the composite oil-paper insulation structure according to the output pulse signal, the output pulse signal can be sequentially subjected to signal averaging, deconvolution and data recovery processing, thereby obtaining the spatial charge distribution of the composite oil-paper insulation structure. The signal averaging, deconvolution and data recovery processing can adopt the processing methods in the prior art, which will not be described in detail here.

[0057] The following is a specific application scenario to better illustrate the technical solution of the present invention: Combination Figure 3 Come and see, Figure 3 A schematic structural diagram of another embodiment of a space charge measuring device for a composite oil-paper insulation structure provided by the present invention, the device comprising: 1: High-voltage DC power supply; 2: High-voltage nanosecond pulse power supply; 3: Aluminum electrode; 4: Semiconductor electrode; 5: Epoxy resin envelope; 6: Grooved flat electrode; 7: Heating oil pipeline; 8: Top end cover; 9: Power transmission port; 10: DC protection resistor R1; 11: DC blocking capacitor C; 12: Coupling resistor R2; 13: Electrode connecting rod; 14: Epoxy resin filling; 15: Retractable spring; 16: Shielded metal shell; 17: Upper electrode fixing screw; 18: Metal shielding box; 19: PVDF piezoelectric sensor; 20: Polymethyl methacrylate PMMA sound absorbing material; 21: Low-noise signal amplifier; 22: Oscilloscope; 23: Computer; 24: Signal output port; 25: Magnetic shielding fixing screw; 26: Composite oil-paper insulation structure.

[0058] The space charge measuring device of the composite oil-paper insulation structure comprises a power supply device, a composite upper electrode, a lower electrode, an upper electrode connecting cavity, and a signal acquisition and shielding device.

[0059] The power supply device includes a high-voltage DC power supply 1 and a high-voltage nanosecond pulse power supply 2. The high-voltage DC power supply 1 is connected to the electrode connecting rod 4 through a DC protection resistor R1, and the high-voltage nanosecond pulse power supply 2 is also connected to the electrode connecting rod 4 after passing through a DC isolation capacitor C. In addition, the pulse power supply side is connected to a coupling resistor R2 and grounded.

[0060] Combination Figure 4 Come and see, Figure 4 The schematic diagram of the structure of an embodiment of the electrode structure of the space charge measurement device of the composite oil-paper insulation structure provided by the present invention is that the composite upper electrode is an integral structure composed of an aluminum electrode 3, a semiconductor electrode 4, and an epoxy resin envelope 5. The aluminum electrode 3 and the semiconductor electrode 4 have the same diameter, and the diameter of the epoxy resin envelope 5 is three times the diameter of the aluminum electrode. The aluminum electrode 3 and the semiconductor electrode 4 are stacked and placed at the center of the composite upper electrode, and the bottom surface of the external epoxy resin envelope 5 is coplanar with the bottom surface of the semiconductor electrode 1.

[0061] The grooved flat plate electrode 6 is fixedly connected to the metal shielding box 18 via magnetic shielding fixing screws 25 - 1 , 25 - 2 .

[0062] The PVDF piezoelectric sensor 19 is closely attached to the center of the bottom surface of the grooved flat electrode 6, the PMMA sound absorbing material 20 is closely attached to the bottom surface of the PVDF piezoelectric sensor 19, and the piezoelectric sensor output line is connected to the low noise amplifier 21. The PVDF piezoelectric sensor 19, the PMMA sound absorbing material 20, and the low noise signal amplifier 21 are all placed inside the metal shielding box 18. The output line of the low noise amplifier 21 is connected to the oscilloscope 22 through the signal output port 24.

[0063] A hole is provided at the center of the bottom of the epoxy resin filling 14 , and the size of the hole is consistent with the size of the aluminum electrode 3 , so that when the upper electrode connection cavity is lowered, the electrode connection rod 13 and the aluminum electrode 3 are well connected.

[0064] A retractable spring 15 is fixed at the bottom of the epoxy resin filling 14, and the spring is in a stretched state when the upper electrode connecting cavity is separated from the upper electrode; when the upper electrode connecting cavity is lowered, the spring 15 contacts and is squeezed with the composite upper electrode, and uniformly applies pressure to the composite upper electrode, so that the composite upper electrode is in close contact with the composite oil-paper insulation structure.

[0065] The top end cover 8 and the upper electrode connection cavity are connected to the lower electrode plate and fixed via the upper electrode fixing screws 17 - 1 , 17 - 2 .

[0066] Combination Figure 5 Come and see, Figure 5A top view of the structure of an electrode structure of an embodiment of a space charge measuring device of a composite oil-paper insulation structure provided by the present invention, wherein a grooved flat plate electrode 6 is provided with an oil heating pipe 7, forming a ring structure with the groove of the lower electrode plate as the center, and insulating oil of a set temperature circulates in the pipe, flowing in from the oil heating pipe inlet 7-1 and out from the oil heating pipe inlet 7-2, for temperature control of the lower electrode plate and the sample.

[0067] After the above equipment components are connected, the specific process of measuring the space charge of the composite oil-paper insulation structure is as follows: 1. The PVDF piezoelectric sensor 19 and the PMMA sound-absorbing material 20 are fixedly connected to the bottom surface of the grooved flat electrode 6, the PVDF piezoelectric sensor 19 is connected to the low-noise signal amplifier 21, and its lead wire is connected to the oscilloscope 22 and the computer 23 in sequence through the signal output port 24, and the lower electrode plate is fixedly connected to the metal shielding box 18 through the magnetic shielding fixing screws 25.

[0068] 2. Place the composite oil-paper insulation structure 26 in the lower electrode groove, and place the composite upper electrode consisting of the aluminum electrode 3, the semiconductor electrode 4, and the epoxy resin envelope 5 in the lower electrode groove.

[0069] 3. Place the upper electrode connection cavity (9-16) on the upper part of the composite upper electrode so that the electrode connection rod 13 is in close contact with the aluminum electrode 3. Place the top end cover 8 above the upper electrode connection cavity and fix it to the lower electrode plate through the upper electrode fixing screw 17. At this time, the retractable spring 15 and the composite upper electrode (3-5) are squeezed so that the bottom surface of the composite upper electrode (3-5) is in close contact with the top surface of the composite oil-paper insulation structure 26.

[0070] 4. Ground the shielded metal shell 16 and the metal shielding box 18, connect the high-voltage DC power supply 1 and the high-voltage nanosecond pulse power supply 2 to the power transmission port 9 respectively, and debug the high-voltage DC power supply 1 and the high-voltage nanosecond pulse power supply 2 to the output state.

[0071] 5. Turn on the high-voltage DC power supply 1 and apply DC polarization treatment to the composite oil-paper insulation structure 26 .

[0072] 6. After the high-voltage DC power supply 1 is applied for a set time, the low-noise signal amplifier 21, the oscilloscope 22 and the computer 23 are turned on, and the high-voltage pulse power supply 2 is turned on to perform synchronous acquisition of pulse signals.

[0073] 7. The collected pulse electrical signals are averaged, deconvolved and data recovered to obtain the spatial charge distribution data of the sample.

[0074] The present invention encapsulates an aluminum electrode, a semiconductor electrode and an external epoxy resin to form a composite upper electrode with an integral structure, and sets a groove structure matching the size of the composite upper electrode on the lower electrode. The space charge measurement device after optimizing the electrode structure, when the composite upper electrode is in close contact with the composite oil-paper insulation structure and is squeezed, the support of the three layers of insulation paper at the edge avoids deformation of the insulation sample at the corresponding position of the aluminum electrode in the traditional structure, thereby making the space charge measurement under the composite oil-paper insulation structure more accurate.

[0075] The present invention discloses a space charge measurement device and method for a composite oil-paper insulation structure. The device and method are provided by enveloping a conductor electrode, a semiconductor electrode and an insulator to form an upper electrode with an integral structure, and arranging a groove structure matching the size of the upper electrode on a lower electrode. When the upper electrode is in close contact with the composite oil-paper insulation structure and is squeezed, the support effect of three layers of insulation paper at the edge of the composite oil-paper insulation structure prevents deformation of the insulation sample at the corresponding position of the conductor electrode, thereby improving the accuracy of the space charge measurement of the composite oil-paper insulation structure. The present invention reduces the error of the space charge measurement and improves the accuracy of the space charge measurement while realizing the space charge measurement of the composite oil-paper insulation structure.

[0076] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A space charge measurement device for a composite oil-paper insulation structure, characterized in that: include: An upper electrode, comprising a conductor electrode, a semiconductor electrode and an insulator envelope, wherein the conductor electrode and the semiconductor electrode are stacked at the center of the upper electrode, and the bottom surface of the insulator envelope is in the same plane as the bottom surface of the semiconductor electrode; A lower electrode is provided with a groove matching the size of the upper electrode for accommodating a composite oil-paper insulation structure.

2. The space charge measuring device of the composite oil-paper insulation structure according to claim 1 is characterized in that: The device also includes: Power supply module, including DC power supply and pulse power supply; The upper electrode connection cavity includes an electric transmission port, a DC protection resistor, a DC blocking capacitor, a coupling resistor, an electrode connection rod, an insulator filling, a retractable spring, and a shielding metal shell; The DC power supply is connected to the electrode connecting rod through the power transmission port and the DC protection resistor; The pulse power source is connected to the electrode connecting rod through the power transmission port and the DC blocking capacitor; The coupling resistor is connected to the shielding metal shell; A hole matching the size of the conductor electrode is provided at the center of the bottom of the electrode connecting rod, so that when the upper electrode connecting cavity is connected to the upper electrode, the electrode connecting rod is in good contact with the conductor electrode; The retractable spring is fixed to the bottom filled with the insulator, and is in a stretched state when the upper electrode connection cavity is separated from the upper electrode, and is in a compressed state when the upper electrode connection cavity is connected to the upper electrode.

3. The space charge measuring device of the composite oil-paper insulation structure according to claim 2 is characterized in that: The device also includes: Signal acquisition and shielding module, including metal shielding box, piezoelectric sensor, sound absorption module, signal amplifier, and signal output port; The metal shielding box is fixed to the bottom of the lower electrode by magnetic shielding fixing screws; The piezoelectric sensor is arranged at the center of the bottom of the lower electrode; The sound absorption module is arranged at the bottom of the piezoelectric sensor; The signal output port is arranged on the side wall of the metal shielding box; The piezoelectric sensor is connected to the signal output port via the signal amplifier.

4. The space charge measuring device of the composite oil-paper insulation structure according to claim 3 is characterized in that: The device also includes: A top end cover, the top end cover is arranged above the upper electrode connection cavity and connected to the lower electrode by fixing screws; The top end cover is used to control the connection and separation between the upper electrode connection cavity and the upper electrode.

5. The space charge measuring device of the composite oil-paper insulation structure according to claim 4 is characterized in that: An oil heating pipeline is also provided in the lower electrode, and the oil heating pipeline is used to control the temperature of the lower electrode and the composite oil-paper insulation structure.

6. A method for measuring space charge of a composite oil-paper insulation structure implemented based on the space charge measuring device of the composite oil-paper insulation structure according to any one of claims 1 to 5, characterized in that: include: When the upper electrode connection cavity is connected to the upper electrode, a DC voltage polarization is performed on the composite oil-paper insulation structure based on a DC power supply; Applying a pulse signal to the composite oil-paper insulation structure after DC voltage polarization based on a pulse power supply, and obtaining an output pulse signal from a signal output port; Based on the output pulse signal, the spatial charge distribution of the composite oil-paper insulation structure is determined.

7. The method for measuring space charge of a composite oil-paper insulation structure according to claim 6, characterized in that: The upper electrode connection cavity is connected to the upper electrode, comprising: The retractable spring in the upper electrode connection cavity is in a squeezed state, the electrode connection rod is in good contact with the conductor electrode in the upper electrode, and the bottom surface of the semiconductor electrode in the upper electrode is in close contact with the top surface of the composite oil-paper insulation structure.

8. The method for measuring space charge of a composite oil-paper insulation structure according to claim 7, characterized in that: The method of performing DC voltage polarization on the composite oil-paper insulation structure based on a DC power supply includes: Based on the DC power supply, the composite oil-paper insulation structure is polarized by a DC voltage through the electrode connecting rod and the upper electrode; The step of applying a pulse signal to the composite oil-paper insulation structure polarized by a DC voltage based on a pulse power supply comprises: Based on the pulse power supply, a pulse signal is applied to the composite oil-paper insulation structure through the electrode connecting rod and the upper electrode.

9. The method for measuring space charge of a composite oil-paper insulation structure according to claim 8, characterized in that: The output pulse signal is obtained by amplifying the signal collected by the piezoelectric sensor through a signal amplifier and transmitting it to the signal output port.

10. The method for measuring space charge of a composite oil-paper insulation structure according to claim 9, characterized in that: The step of determining the spatial charge distribution of the composite oil-paper insulation structure based on the output pulse signal comprises: The output pulse signal is subjected to signal averaging processing, deconvolution processing and data recovery processing in sequence to obtain the spatial charge distribution of the composite oil-paper insulation structure.

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