Direct current wall bushing grounding body corona discharge test device and processing method

Abstract

The invention provides a direct current wall bushing grounding body corona discharge test device and a processing method. The device comprises a supporting device, a grounding body corona simulation device and a partial discharge detection device, wherein the supporting device is used for supporting the direct-current wall bushing, the supporting device is arranged on one side of a flange plate on the direct-current wall bushing, and the direct-current wall bushing is used for being electrically connected with a direct-current generator; the grounding body corona simulation device is arranged on the side, away from the supporting device, of the flange plate on the direct-current wall bushing. The partial discharge detection device is electrically connected with the grounding body corona simulation device and used for detecting the discharge capacity of the grounding body corona simulation device, and the partial discharge detection device is electrically connected with the data analysis device so as to send the discharge capacity to the data analysis device. According to the invention, the influence of the length of the grounding body on corona discharge of the grounding body can be accurately obtained, so that the length of the grounding body to be tested is designed and adjusted, and safe and stable operation of the direct-current wall bushing under rated voltage is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of grounding body corona discharge testing, and in particular to a DC wall bushing grounding body corona discharge testing device and a processing method. Background Art

[0002] DC transmission, with its significant technical advantages such as large capacity, long distances, low losses, and space savings, is widely used in cross-regional grid interconnection and renewable energy transmission. DC wall bushings are installed on the walls of converter station valve halls to connect equipment inside and outside the valve halls. They ensure good insulation and mechanical strength for high-voltage conductors passing through walls or ground shields. Due to the structural characteristics of DC wall bushings, the central flange of the bushing must be connected to a ground wire for reliable grounding.

[0003] Currently, there are no clear wiring standards for bushing mid-flange grounding wires in engineering applications. This lack of unified standards leads to a high degree of arbitrariness in grounding wire placement. When the longitudinal length of the grounding conductor near the DC wall bushing is excessive, localized electric field concentration can easily occur on the grounding conductor, triggering corona discharge. Corona discharge generates a large amount of charge, with oppositely polarized charges easily accumulating on the surface of the DC wall bushing's composite jacket. If the bushing's insulation contains minor defects or weak points, the accumulation of surface charge can distort the local electric field. When the field strength exceeds the design value, a discharge breakdown failure can occur, seriously threatening the bushing's long-term reliability and safety. However, the impact of the DC wall bushing grounding conductor length on corona discharge is currently unknown, hindering the stable operation of the DC wall bushing. Summary of the Invention

[0004] In light of this, the present invention proposes a DC wall bushing grounding corona discharge test device, aiming to address the prior art issue of not being able to determine the effect of the DC wall bushing grounding body length on grounding body corona discharge. The present invention also proposes a grounding body treatment method using the DC wall bushing grounding body corona discharge test device.

[0005] In one aspect, the present invention proposes a DC wall bushing grounding body corona discharge test device, which includes: a supporting device, a grounding body corona simulation device and a partial discharge detection device; wherein the supporting device is used to support the DC wall bushing, and the supporting device is placed on one side of the flange on the DC wall bushing, and the DC wall bushing is used to be electrically connected to a DC generator; the grounding body corona simulation device is arranged on the side of the flange on the DC wall bushing away from the supporting device; the partial discharge detection device is electrically connected to the grounding body corona simulation device, and is used to detect the discharge amount of the grounding body corona simulation device, and the partial discharge detection device is used to be electrically connected to a data analysis device to send the discharge amount to the data analysis device.

[0006] Furthermore, in the above-mentioned DC wall bushing grounding body corona discharge test device, the grounding body corona simulation device includes: a base and a needle-shaped connector; wherein the base is arranged on the side of the flange on the DC wall bushing away from the supporting device and is electrically connected to the partial discharge detection device; the first end of the connector is connected to the base, and the second end of the connector is needle-shaped and is a free end.

[0007] Furthermore, in the above-mentioned DC wall bushing grounding body corona discharge test device, a DC generator is used to be electrically connected to a control device to apply a DC voltage to the DC wall bushing under the control of the control device so that the voltage of the DC wall bushing increases from zero to the rated operating voltage, and the DC generator is used to record the corona starting partial discharge voltage of the grounding body corona simulation device and send the corona starting partial discharge voltage to the control device; the data analysis device is electrically connected to the control device and is used to establish a mathematical model based on the corona starting partial discharge voltage and the discharge amount under the rated operating voltage, and determine the maximum length of the grounding body installed on the DC wall bushing based on the mathematical model.

[0008] In the present invention, a supporting device supports the DC wall bushing, thereby simulating the working state of the DC wall bushing. The grounding body corona simulation device is arranged on the side of the flange on the DC wall bushing away from the supporting device to simulate the grounding body of the DC wall bushing in the actual operating state. The DC generator applies a DC voltage to the DC wall bushing. The partial discharge detection device detects the discharge amount of the grounding body corona simulation device and sends it to the data analysis device, so that the data analysis device can determine the maximum length of the grounding body installed on the DC wall bushing, and compare the length of the grounding body to be tested with the maximum length of the grounding body to determine whether the length of the grounding body to be tested is qualified. In this way, the device can effectively simulate the corona discharge of the grounding body of the DC wall bushing, and then can accurately know the influence of the length of the grounding body on the corona discharge of the grounding body, so as to design and adjust the length of the grounding body to be tested, ensuring the safe and stable operation of the DC wall bushing under the rated voltage, and solving the problem in the prior art that it is impossible to know the influence of the length of the DC wall bushing grounding body on the corona discharge of the grounding body.

[0009] On the other hand, the present invention also proposes a grounding body treatment method using any of the above-mentioned DC wall bushing grounding body corona discharge test devices, the method comprising the following steps: arbitrarily selecting a DC wall bushing of a voltage level, and sequentially selecting grounding body corona simulation devices of different lengths l to be installed on the DC wall bushing; sequentially performing a grounding body corona discharge test on the grounding body corona simulation device under each length l, and sequentially measuring the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding body corona simulation device under each length l. m Discharge capacity Ql ; According to the corona starting partial discharge voltage Uc and rated operating voltage U of the grounding body corona simulation device under various lengths l m Discharge capacity Q l , forming a data set {l,Uc,Q l}; According to the data set {l,Uc,Q l} and discharge capacity Q l The maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is determined based on the relationship between the voltage and the electric field strength E; the length of the grounding body to be tested is compared with the maximum length lmax of the grounding body. When the length of the grounding body to be tested is less than the maximum length lmax of the grounding body, the length of the grounding body to be tested is determined to be qualified.

[0010] Furthermore, in the above-mentioned grounding body treatment method, the grounding body corona discharge test is carried out on the grounding body corona simulation device under each length l, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding body corona simulation device under each length l are measured in turn. m Discharge capacity Q l In the step, a DC voltage is applied to the DC wall bushing through a DC generator, and the voltage of the DC wall bushing is increased from zero to the rated operating voltage U m .

[0011] Furthermore, in the above-mentioned grounding body treatment method, the grounding body corona discharge test is carried out on the grounding body corona simulation device under each length l, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding body corona simulation device under each length l are measured in turn. m Discharge capacity Q l In the steps, at least two ground body corona discharge tests are carried out on the ground body corona simulation device under each length l, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device measured each time are compared. m Discharge capacity Q l Calculate the average values respectively and record them as the corona starting partial discharge voltage Uc and rated operating voltage Uc of the grounding body corona simulation device under the length l. m Discharge capacity Q l .

[0012] Furthermore, in the above grounding body processing method, according to the data set {l, Uc, Q l} and discharge capacity Q l The relationship between the rated operating voltage U and the electric field strength E is further determined by determining the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level. mThe electric field strength Em of the corona discharge of the lower grounding body; according to the rated operating voltage U m The electric field strength Em of the corona discharge of the lower grounding body determines the discharge quantity Q l The relationship between the electric field strength E; According to the data set {l, Uc, Q l} and discharge capacity Q l Based on the relationship between the grounding body corona discharge and the electric field strength E, a mathematical model of grounding body corona discharge is established; according to the mathematical model of grounding body corona discharge, the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is determined.

[0013] Furthermore, in the above grounding body processing method, the rated operating voltage U m The electric field strength Em of the lower grounding body corona discharge is in the step of the rated operating voltage U m The formula for the electric field intensity Em of the lower grounding body corona discharge is: Where, L is the length of the DC wall bushing on the side of the flange away from the support device, l is the distance between the free end of the grounding corona simulator and the flange, and k is the reverse thrust coefficient. m The electric field strength Em of the corona discharge of the lower grounding body determines the discharge quantity Q l The relationship between the electric field strength E and the discharge amount Q l The relationship between the electric field strength E is: Where α is the temperature correction coefficient, K and n are constants related to the test, and E max It is the maximum value of the electric field strength of the grounded corona discharge.

[0014] Furthermore, in the above grounding body processing method, according to the data set {l, Uc, Q l} and discharge capacity Q l The relationship between the electric field strength E and the grounding corona discharge is established according to the data set {l, Uc, Q l}, use the least squares method to determine E max , K, k and n values, combined discharge capacity Q l The relationship formula between the electric field strength E is used to establish the mathematical model of grounding corona discharge, and the goodness of fit R 2 ≥0.98.

[0015] Furthermore, in the above-mentioned grounding body processing method, in the step of determining the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level according to the mathematical model of grounding body corona discharge, when E max =E mWhen , the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is:

[0016] In the present invention, a DC wall bushing of a voltage level and a grounding corona simulation device of different lengths l are selected, and a grounding corona discharge test is performed on the grounding corona simulation device of each length l in turn, and then the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding corona simulation device of various lengths l are calculated. m Discharge capacity Q l Form a data set, and then according to the discharge amount Q l The relationship between the length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is determined, and then the length of the grounding body to be tested is judged according to the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level, so as to determine whether the length of the grounding body to be tested is qualified. In this way, the quantitative relationship of the test is used to directly guide the design and adjustment of the length of the DC wall bushing grounding body on site, and the influence of the length of the DC wall bushing grounding body on the corona discharge of the grounding body can be accurately known, so as to ensure the safe and stable operation of the DC wall bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0018] Figure 1 A schematic structural diagram of a DC wall bushing grounding corona discharge test device provided in an embodiment of the present invention;

[0019] Figure 2 A flow chart of a grounding body processing method provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of linear fitting of the corona initiation partial discharge voltage Uc of a grounding body corona simulation device at various lengths l in the grounding body treatment method provided by an embodiment of the present invention;

[0021] Figure 4 In the grounding body processing method provided by the embodiment of the present invention, the grounding body corona simulation device under various lengths l is operated at a rated operating voltage U m Discharge capacity Q l Schematic diagram of polynomial fitting. DETAILED DESCRIPTION

[0022] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] Device Example:

[0024] See also Figure 1 , Figure 1 A schematic diagram of the structure of a DC wall bushing grounding corona discharge test device provided in an embodiment of the present invention. As shown in the figure, the DC wall bushing grounding corona discharge test device includes: a support device 1, a grounding corona simulation device 2, and a partial discharge detection device 3. The support device 1 is used to support the DC wall bushing 4, and the support device 1 is placed on the first side ( Figure 1 Specifically, a flange 41 is provided at the middle of the DC wall bushing 4, and the connection position between the DC wall bushing 4 and the supporting device 1 is located on one side of the first side of the flange 41, that is, the first end ( Figure 1 The right end shown in FIG4 is located outside the first side of the flange 41, and the second end of the DC wall bushing 4 ( Figure 1 The left end shown) is located on the second side of the flange 41 ( Figure 1 The first and second sides of the flange 41 are opposite to each other, and the support device 1 is positioned between the first side of the flange 41 and the first end of the DC wall bushing 4. In this embodiment, the support device 1 and the first side of the flange 41 are adjacent to each other. The structure of the support device 1 can be determined based on actual conditions, as long as it can support the DC wall bushing 4. This embodiment does not impose any restrictions on this.

[0025] The DC wall bushing 4 is electrically connected to a DC generator 5. Specifically, a first end of the DC wall bushing 4 is electrically connected to the DC generator 5, which applies a DC voltage to the DC wall bushing 4. More specifically, the DC generator 5 is electrically connected to a control device 7, which controls the DC generator 5 to apply the DC voltage to the DC wall bushing 4. The control device 7 can be a computer or other device, and this embodiment does not impose any limitations thereto.

[0026] The grounding body corona simulation device 2 is arranged on the side of the flange 41 on the DC wall bushing 4 that is away from the supporting device 1, that is, the second side of the flange 41. Specifically, the first end of the grounding body corona simulation device 2 is vertically connected to the second side of the flange 41, and the second end of the grounding body corona simulation device 2 is a free end.

[0027] Preferably, the grounding body corona simulation device 2 includes a base 21 and a needle-shaped connector 22. The base 21 is disposed on the side of the flange 41 on the DC wall bushing 4 facing away from the support device 1, that is, the base 21 is disposed on the second side of the flange 41. The first end of the connector 22 is perpendicularly connected to the base 21, and the second end of the connector 22 is needle-shaped and free.

[0028] The partial discharge detection device 3 is electrically connected to the grounded body corona simulator 2. Specifically, the partial discharge detection device 3 is electrically connected to the base 21. The partial discharge detection device 3 is used to detect the discharge amount of the corona discharge in the grounded body corona simulator 2. The partial discharge detection device 3 is also electrically connected to the data analysis device 6 to transmit the discharge amount to the data analysis device 6.

[0029] The control device 7 controls the DC generator 5 to apply a DC voltage to the DC wall bushing 4 so that its polarization voltage is within the allowable range of the DC test, and increases the voltage of the DC wall bushing 4 from zero to the rated operating voltage U m In addition, the DC generator 5 records the corona initiation partial discharge voltage Uc of the grounded body corona simulation device 2, that is, the corona inception voltage Uc, that is, the critical voltage at which the partial discharge amount Q>0 appears for the first time, and the DC generator 5 sends the corona initiation partial discharge voltage Uc to the control device 7.

[0030] The data analysis device 6 is electrically connected to the control device 7. The data analysis device 6 is used to receive the corona initiation partial discharge voltage Uc sent by the control device 7 and the discharge amount sent by the partial discharge detection device 3, and to calculate the discharge amount according to the corona initiation partial discharge voltage Uc and the rated operating voltage U m Discharge capacity Q l , and the discharge capacity Q l The relationship between the grounding body corona discharge and the electric field strength E is established, and the maximum length of the grounding body installed on the DC wall bushing 4 is determined according to the mathematical model of the grounding body corona discharge.

[0031] During the specific implementation, a DC wall bushing with a voltage level was selected from the bushings used in engineering applications, and grounding body corona simulation devices 2 with different lengths l were selected, where the length l is the distance between the free end of the grounding body corona simulation device 2 and the second side of the flange 41, that is, the distance between the needle-shaped free end of the connecting body 22 and the second side of the flange 41.

[0032] Then, the grounding body corona simulation device 2 of each length l is sequentially set on the second side of the flange 41, and the grounding body corona discharge test is performed on the grounding body corona simulation device of each length l. When the grounding body corona discharge test is performed on the grounding body corona simulation device 2 of each length l, the control device 7 applies a high-voltage DC voltage to the DC wall bushing 4 through the DC generator 5, and adopts a step-by-step boost method to increase the voltage of the DC wall bushing 4 from zero to the rated operating voltage U m In addition, the DC generator 5 records the corona starting partial discharge voltage Uc of the ground body corona simulation device under each length l. The corona discharge induced by the ground body corona simulation device 2 is monitored by the partial discharge detection device 3. The high-frequency current signal is converted into discharge amount data through the signal processing circuit and transmitted to the data analysis device 6 for recording and analysis. The data analysis device 6 records the discharge amount data at the rated operating voltage U m Discharge capacity Q l The grounding corona simulation device under each length l is subjected to at least two grounding corona discharge tests, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding corona simulation device measured each time are compared. m Discharge capacity Q l Calculate the average value respectively, and then record the average value as the corona starting partial discharge voltage Uc and rated operating voltage U of the grounding body corona simulation device under the length l. m Discharge capacity Q l In this way, according to the corona starting partial discharge voltage Uc and rated operating voltage U of the grounding body corona simulation device under various lengths l, m Discharge capacity Q l , forming a data set {l,Uc,Q l Then, according to the dataset {l,Uc,Q l} and discharge capacity Q l The relationship between the voltage and the electric field strength E is used to establish a mathematical model of corona discharge of the grounding body. According to the mathematical model of corona discharge of the grounding body, the maximum value lmax of the length of the grounding body installed on the DC wall bushing 4 is determined, that is, the maximum value lmax of the length of the grounding body installed on the DC wall bushing under the selected voltage level is determined. The length of the grounding body to be tested is compared with the maximum value lmax of the length of the grounding body. When the length of the grounding body to be tested is less than the maximum value lmax of the length of the grounding body, the length of the grounding body to be tested is determined to be qualified. When the length of the grounding body to be tested is greater than or equal to the maximum value lmax of the length of the grounding body, the length of the grounding body to be tested is rearranged or the grounding body to be tested is trimmed so that the length of the grounding body to be tested in three directions is less than lmax.

[0033] During specific implementation, the DC wall bushing grounding body corona discharge test device may also include: two electrostatic potential measuring instruments 8. The two electrostatic potential measuring instruments 8 are respectively placed on opposite sides of the DC wall bushing 4, and the two electrostatic potential measuring instruments 8 are located between the second end of the DC wall bushing 4 and the flange 41. The positions of the two electrostatic potential measuring instruments 8 correspond to each other, and the heights of the two electrostatic potential measuring instruments 8 are parallel to the middle position of the large shed of the DC wall bushing 4. The data analysis device 6 is electrically connected to the two electrostatic potential measuring instruments 8, and each electrostatic potential measuring instrument 8 is used to detect the surface potential data of the DC wall bushing 4 when the grounding body corona simulation device 2 discharges, and send the surface potential data to the data analysis device 6. In this way, the data analysis device 6 receives the surface potential data of the DC wall bushing 4 detected by the two electrostatic potential measuring instruments 8 and the discharge amount of the grounding body corona simulation device 2 detected by the partial discharge detection device 3, wherein the multi-source signal synchronization acquisition error is less than 10μs.

[0034] In a specific implementation, the DC wall bushing 4 is a DC wall bushing used in actual engineering applications, and its electrical performance meets the requirements of standards IEC 60137 and GB / T 4109.

[0035] The grounding body corona simulation device 2 simulates the grounding body near the DC wall bushing. The grounding body corona simulation device 2 is made of a material with good conductive properties (such as copper or aluminum), can achieve three-degree-of-freedom adjustment, and its main function is to generate corona discharge.

[0036] The DC generator 5 provides a DC voltage without partial discharge for the DC wall bushing 4 , with a ripple factor of less than 1% and a voltage stability of ±0.5, and is used for polarizing the DC wall bushing 4 .

[0037] During specific implementation, the DC wall bushing grounding body corona discharge test device is arranged in an anechoic chamber to ensure that the local discharge amount in the test device environment is ≤5pC.

[0038] It can be seen that in this embodiment, the support device 1 supports the DC wall bushing 4, thereby simulating the working state of the DC wall bushing 4, and the grounding body corona simulation device 2 is arranged on the side of the flange 41 on the DC wall bushing 4 away from the support device 1 to simulate the grounding body of the DC wall bushing 4 in the actual operating state. The DC generator 5 applies a DC voltage to the DC wall bushing 4, and the partial discharge detection device 3 detects the discharge amount of the grounding body corona simulation device 2 and sends it to the data analysis device 6, so that the data analysis device 6 can determine the maximum length of the grounding body installed on the DC wall bushing, and compare the length of the grounding body to be tested with the maximum length of the grounding body to determine whether the length of the grounding body to be tested is qualified. In this way, the device can effectively simulate the corona discharge of the DC wall bushing grounding body, and then can accurately know the influence of the length of the grounding body on the corona discharge of the grounding body, so as to design and adjust the length of the grounding body to be tested, ensuring the safe and stable operation of the DC wall bushing 4 under the rated voltage, and solving the problem in the prior art that it is impossible to know the influence of the length of the DC wall bushing grounding body on the corona discharge of the grounding body.

[0039] Method system embodiment:

[0040] This embodiment also proposes a grounding body treatment method using the DC wall bushing grounding body corona discharge test device. Figure 2 , the grounding body processing method includes the following steps:

[0041] Step S1: randomly select a DC wall bushing of a voltage level, and sequentially select grounding body corona simulation devices of different lengths l to be installed on the DC wall bushing.

[0042] Specifically, a DC wall bushing with a specific voltage level was selected from engineering applications, and several grounding corona simulators with different lengths were selected. For example, a ±100kV DC wall bushing was selected, and the grounding corona simulators had different lengths: 15cm, 20cm, 30cm, 40cm, and 80cm. The positive polarity corona inception voltage was then measured.

[0043] In this embodiment, see Figure 1 The length L of the DC wall bushing 4 placed on the second side of the flange 41, that is, the distance between the second end of the DC wall bushing 4 and the second side of the flange 41, is 1820 mm.

[0044] See also Figure 1The selected DC wall bushing 4 is installed on the support device 1 of the DC wall bushing grounding corona discharge test apparatus. The DC wall bushing grounding corona discharge test apparatus is the same as that described in the aforementioned apparatus embodiment. The specific implementation process of the DC wall bushing grounding corona discharge test apparatus is described above and will not be further described here. Furthermore, a grounding corona simulator 2 of each length l is sequentially installed on the side of the flange 41 of the DC wall bushing 4 facing away from the support device 1.

[0045] Step S2, sequentially performing a ground body corona discharge test on the ground body corona simulation device under each length l, and sequentially measuring the corona initiation partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device under each length l. m Discharge capacity Q l .

[0046] Specifically, the ground body corona discharge test is carried out on the ground body corona simulation device under each length l, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device under each length l are measured in turn. m Discharge capacity Q l The length l is the distance from the free end of the grounding body corona simulator 2 to the side of the flange 41 of the DC wall bushing 4 facing away from the support device 1 (ie, the second side of the flange 41 ).

[0047] When the ground corona discharge test is performed on the ground corona simulation device at each length l, a DC voltage is applied to the DC wall bushing 4 through the DC generator 5, and the voltage of the DC wall bushing 4 is increased from zero to the rated operating voltage U m Specifically, the control device 7 controls the DC generator 5 to apply a DC voltage to the DC wall bushing 4 , and the DC generator 5 records the corona initiation partial discharge voltage Uc at each length l and sends it to the control device 7 .

[0048] For each length l of the ground body corona simulation device, at least two ground body corona discharge tests are carried out, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device measured in each test are compared. m Discharge capacity Q l Calculate the average value respectively, and then record the average value as the corona starting partial discharge voltage Uc and rated operating voltage U of the grounding body corona simulation device under the length l. m Discharge capacity Q l .

[0049] For example, when the length of the grounding corona simulator 2 is 15 cm, the 15 cm long grounding corona simulator 2 is set on the second side of the flange 41, and the grounding corona discharge test is performed on the grounding corona simulator 2 three times. Each test increases the voltage of the DC wall bushing 4 from zero to the rated operating voltage U m , record the corona initiation partial discharge voltage Uc and rated operating voltage U of each test m Discharge capacity Q l , and then take the average value of the corona initiation partial discharge voltage Uc recorded in the three tests, and record the average value as the corona initiation partial discharge voltage Uc of the 15cm long grounding body corona simulation device 2. m Discharge capacity Q l Take the average value, and record it as the rated operating voltage U of the 15cm long grounded corona simulator 2 m Discharge capacity Q l .

[0050] The test process for other lengths of grounded body corona simulation devices is the same as the test process for the above-mentioned 15 cm long grounded body corona simulation device, and will not be repeated here.

[0051] Step S3, according to the corona starting partial discharge voltage Uc and the rated operating voltage U of the grounding body corona simulation device under various lengths l m Discharge capacity Q l , forming a data set {l,Uc,Q l}.

[0052] Specifically, the corona onset partial discharge voltage Uc of the grounding body corona simulation device under various lengths l is linearly fitted to obtain the relationship between l and Uc. Figure 3 The needle tip length on the horizontal axis is the length l of the grounding body corona simulation device, and the positive polarity voltage on the vertical axis is the corona starting partial discharge voltage Uc of the grounding body corona simulation device. Then, the rated operating voltage U m Discharge capacity Q l Perform polynomial fitting to obtain l and Q l For details, see Figure 4 The partial discharge amount on the vertical axis is the rated operating voltage U m Discharge capacity Q l According to the relationship between l and Uc and l and Q l The relationship between the dataset {l,Uc,Q l}.

[0053] Step S4, according to the data set {l, Uc, Q l} and discharge capacity Ql The relationship between the voltage level and the electric field strength E is used to determine the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level, that is, to determine the maximum length lmax of the grounding body installed on the DC wall bushing of the voltage level selected in the selection step S1.

[0054] Specifically, step S4 further includes:

[0055] Sub-step S41, determining the rated operating voltage U m The electric field strength Em of the corona discharge of the lower grounding body.

[0056] Specifically, based on the Kaptzov hypothesis, the corona onset electric field intensity Ec of the DC wall bushing grounding corona discharge is expressed as:

[0057] Therefore, the rated operating voltage U m The formula for the electric field intensity Em of the corona discharge of the DC wall bushing grounding body is: Denote this as Formula 1.

[0058] In the above formula, L is the length of the DC wall bushing on the side of the flange away from the support device (i.e., see Figure 1 , the distance between the second end of the DC wall bushing and the second side of the flange), l is the distance between the free end of the grounding body corona simulator and the flange (i.e., see Figure 1 , the distance between the needle-shaped free end of the connecting body 22 and the second end of the flange 41), k is the thrust coefficient.

[0059] Sub-step S42, according to the rated operating voltage U m The electric field strength Em of the corona discharge of the lower grounding body determines the discharge quantity Q l The relationship between the electric field strength E.

[0060] Specifically, when the DC wall bushing operates at the rated operating voltage Um, the corona discharge Q l It has a power exponential relationship with the electric field strength E, so the discharge amount Q l The relationship between the electric field strength E is: Denote this as Formula 2.

[0061] In the above formula, α is the temperature correction coefficient, K and n are constants related to the test, and E max It is the maximum value of the electric field strength of the grounded corona discharge.

[0062] Sub-step S43, according to the data set {l, Uc, Q l} and discharge capacity Ql The relationship between the electric field strength E is established to establish a mathematical model of corona discharge of grounding body.

[0063] Specifically, according to the dataset {l,Uc,Q l}, use the least squares method to determine E max , K, k and n values, combined discharge capacity Q l The relationship formula between the electric field strength E and the grounding body corona discharge is established (Formula 2), and the goodness of fit R 2 ≥0.98.

[0064] Sub-step S44 , determining the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level according to a mathematical model of corona discharge of the grounding body.

[0065] Specifically, to ensure that there is no corona on the grounding body near the DC wall bushing under rated operating conditions, E max =E m Corresponding to lmax.

[0066] When E max =E m When , the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is:

[0067] This is expressed as Formula 3.

[0068] In step S5 , the length of the grounding body to be tested is compared with the maximum length lmax of the grounding body. When the length of the grounding body to be tested is less than the maximum length lmax of the grounding body, the length of the grounding body to be tested is determined to be qualified.

[0069] Specifically, the grounding body to be tested is set on the second side of the flange, and then the grounding body corona discharge test is performed on the grounding body to be tested to determine the corona starting partial discharge voltage Uc of the grounding body to be tested, and the corona starting partial discharge voltage Uc of the grounding body to be tested is compared with the E determined in the above-mentioned establishment sub-step S43. max Substitute the length of the grounding element under test (L) and k into Formula 3 to calculate the specific value of lmax. Then, compare the length of the grounding element under test with the specific value of lmax. If the grounding element under test is less than lmax, the length of the grounding element under test is considered qualified. If the grounding element under test is greater than or equal to lmax, it needs to be rearranged. It is recommended to rearrange the length of the grounding element under test or trim it so that its dimensions in all three directions are less than lmax.

[0070] The data analysis device 6 receives the corona initiation partial discharge voltage Uc of the ground body corona simulation device under each length l and the rated operating voltage U m Discharge capacity Q l , and calculate the average value respectively, and form the data set {l,Uc,Q l}, establish a mathematical model of corona discharge of the grounding body and determine the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level.

[0071] It can be seen that in this embodiment, a DC wall bushing of a certain voltage level and a grounding corona simulation device of different lengths l are selected, and the grounding corona discharge test is carried out on the grounding corona simulation device of each length l in turn, and then the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding corona simulation device of various lengths l are calculated. m Discharge capacity Q l Form a data set, and then according to the discharge amount Q l The relationship between the length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is determined, and then the length of the grounding body to be tested is judged according to the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level, so as to determine whether the length of the grounding body to be tested is qualified. In this way, the quantitative relationship of the test is used to directly guide the design and adjustment of the length of the DC wall bushing grounding body on site, and the influence of the length of the DC wall bushing grounding body on the corona discharge of the grounding body can be accurately known, so as to ensure the safe and stable operation of the DC wall bushing.

[0072] This method uses a grounding body corona discharge test device and establishes a mathematical model of grounding body corona discharge. It can quantify the relationship between the length of the grounding body and corona discharge, provide a quantitative basis for the corona discharge of the grounding body near the DC wall bushing, and then determine whether the length of the DC wall bushing grounding body on site is qualified. It guides the design and adjustment of the length of the DC wall bushing grounding body on site, and can effectively prevent the corona discharge of the grounding body near the DC wall bushing, avoid the accumulation of surface charge on the surface of the DC wall bushing due to the corona discharge of the grounding body, and extend the service life of the DC wall bushing.

[0073] It should be noted that the principles of the DC wall bushing grounding body corona discharge test device and the grounding body treatment method in the present invention are the same, and relevant parts can be referenced to each other.

[0074] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0075] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A DC wall bushing grounding corona discharge test device, characterized in that: include: Support device (1), grounding body corona simulation device (2) and partial discharge detection device (3); wherein, The supporting device (1) is used to support a DC wall bushing (4), and the supporting device (1) is placed on one side of a flange (41) on the DC wall bushing (4), and the DC wall bushing (4) is used to be electrically connected to a DC generator (5); The grounding body corona simulation device (2) is arranged on a side of the flange (41) on the DC wall bushing (4) facing away from the supporting device (1); The partial discharge detection device (3) is electrically connected to the grounded body corona simulation device (2) and is used to detect the discharge amount of the grounded body corona simulation device (2). Furthermore, the partial discharge detection device (3) is electrically connected to a data analysis device (6) to send the discharge amount to the data analysis device (6).

2. The DC wall bushing grounding body corona discharge test device according to claim 1, characterized in that: The grounded body corona simulation device (2) comprises: a base (21) and a needle-shaped connector (22); wherein, The base (21) is arranged on a side of the flange (41) on the DC wall bushing (4) facing away from the support device (1) and is electrically connected to the partial discharge detection device (3); The first end of the connector (22) is connected to the base (21), and the second end of the connector (22) is needle-point-shaped and is a free end.

3. The DC wall bushing grounding body corona discharge test device according to claim 1, characterized in that: The DC generator (5) is used to be electrically connected to a control device (7) to apply a DC voltage to the DC wall bushing (4) under the control of the control device (7), so that the voltage of the DC wall bushing (4) increases from zero to a rated operating voltage, and the DC generator (5) is used to record the corona initiation partial discharge voltage of the grounding body corona simulation device (2) and send the corona initiation partial discharge voltage to the control device (7); The data analysis device (6) is electrically connected to the control device (7) and is used to establish a mathematical model based on the corona initiation partial discharge voltage and the discharge amount under the rated operating voltage, and to determine the maximum length of the grounding body installed on the DC wall bushing (4) based on the mathematical model.

4. A method for treating a grounding body using the DC wall bushing grounding body corona discharge test device according to any one of claims 1 to 3, characterized in that: The steps include: A DC wall bushing of any voltage level is randomly selected, and grounding body corona simulation devices of different lengths l are sequentially selected and installed on the DC wall bushing; The grounding corona discharge test is carried out on the grounding corona simulation device under each length l, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding corona simulation device under each length l are measured in turn. m Discharge capacity Q l ; According to the corona starting partial discharge voltage Uc and rated operating voltage U of the grounding body corona simulation device under various lengths l m Discharge capacity Q l , forming a data set {l,Uc,Q l }; According to the dataset {l,Uc,Q l } and discharge capacity Q l The relationship between the grounding length lmax and the electric field strength E is used to determine the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level; The length of the grounding body to be tested is compared with the maximum length lmax of the grounding body. When the length of the grounding body to be tested is less than the maximum length lmax of the grounding body, it is determined that the length of the grounding body to be tested is qualified.

5. The grounding body processing method according to claim 4, characterized in that: The grounding body corona discharge test is carried out on the grounding body corona simulation device under each length l in turn, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the grounding body corona simulation device under each length l are measured in turn. m Discharge capacity Q l In the steps, A DC voltage is applied to the DC wall bushing through a DC generator, and the voltage of the DC wall bushing is increased from zero to the rated operating voltage U m .

6. The grounding body processing method according to claim 5, characterized in that: The ground body corona discharge test is carried out on the ground body corona simulation device under each length l in turn, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device under each length l are measured in turn. m Discharge capacity Q l In the steps, For each length l of the ground body corona simulation device, at least two ground body corona discharge tests are carried out, and the corona starting partial discharge voltage Uc and the rated operating voltage Uc of the ground body corona simulation device measured in each test are compared. m Discharge capacity Q l Calculate the average values respectively and record them as the corona starting partial discharge voltage Uc and rated operating voltage Uc of the grounding body corona simulation device under the length l. m Discharge capacity Q l .

7. The grounding body processing method according to claim 4, characterized in that: The data set {l, Uc, Q l } and discharge capacity Q l The step of determining the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level further includes: Determine the rated operating voltage U m The electric field intensity Em of the corona discharge of the lower grounding body; According to the rated operating voltage U m The electric field strength Em of the corona discharge of the lower grounding body determines the discharge quantity Q l The relationship between the electric field strength E; According to the dataset {l,Uc,Q l } and the discharge amount Q l The relationship between the electric field strength E and the grounding body corona discharge mathematical model is established; The maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is determined according to the mathematical model of corona discharge of the grounding body.

8. The grounding body processing method according to claim 7, characterized in that: Determining the rated operating voltage U m In the step of the electric field strength Em of the lower grounding body corona discharge, the rated operating voltage U m The formula for the electric field intensity Em of the lower grounding body corona discharge is: Where L is the length of the DC wall bushing on the side of the flange away from the support device, l is the distance between the free end of the grounding corona simulator and the flange, and k is the back-calculation coefficient. According to the rated operating voltage U m The electric field strength Em of the corona discharge of the lower grounding body determines the discharge quantity Q l The relationship between the electric field strength E and the discharge amount Q is l The relationship between the electric field strength E is: Where α is the temperature correction coefficient, K and n are constants related to the test, and E max It is the maximum value of the electric field strength of the grounded corona discharge.

9. The grounding body processing method according to claim 8, characterized in that: The data set {l, Uc, Q l } and the discharge amount Q l The relationship between the electric field strength E and the steps to establish the mathematical model of grounding corona discharge is as follows: According to the dataset {l,Uc,Q l }, use the least squares method to determine E max , K, k and n values, combined with the discharge amount Q l The relationship formula between the electric field strength E is used to establish the mathematical model of grounding corona discharge, and the goodness of fit R 2 ≥0.

98.

10. The grounding body processing method according to claim 9, characterized in that: In the step of determining the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level according to the mathematical model of corona discharge of the grounding body, When E max =E m When , the maximum length lmax of the grounding body installed on the DC wall bushing of the selected voltage level is:

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