A device, system, method and use for measuring capacitance

Abstract

This invention discloses a device, system, method, and application for measuring capacitance, relating to the field of electrical variable measurement technology. The device includes a housing, a first electrode, a second electrode, and insulating legs. The electrodes are used to connect to a testing instrument, and the housing has ventilation holes. The method includes obtaining the stray capacitance of the second flange of a capacitive voltage transformer to ground before commissioning, measuring the capacitance of the capacitance measuring device before commissioning using the positive connection method, and obtaining the capacitance of the capacitance measuring device during initial inspection. Using the capacitance of the capacitance measuring device as a reference, the stray capacitance during initial inspection is calculated by comparison. The system includes a testing instrument, the above-mentioned device, and a measurement module. The application includes eliminating interference from stray capacitance. Through the capacitance measuring device, the stray capacitance during initial inspection can be obtained, thereby obtaining a more accurate capacitance of the upper section capacitor of the capacitive voltage transformer during initial inspection.

Description

Technical Field

[0001] This invention relates to the field of electrical variable measurement technology, and in particular to a device, system, method, and application for measuring capacitance. Background Technology

[0002] The author conducted a search using the query TACD_ALL:(CVT AND upper section AND capacity), and obtained the following relatively similar existing technical solutions.

[0003] The application, CN111239671A, is entitled "A Method for Measuring the Capacitance and Dielectric Loss Value of the Upper-Section Coupling Capacitor of a CVT." Considering that both the upper and middle section coupling capacitors are pure capacitors, they can be connected in parallel for measurement. Therefore, the total capacitance and total dielectric loss of the parallel capacitor structure are first measured using a frequency converter dielectric loss tester and a reverse connection method. Then, the capacitance and dielectric loss value of the middle section coupling capacitor are measured separately using a forward connection method. Finally, given the capacitance and dielectric loss values ​​of the middle section coupling capacitor, the capacitance and dielectric loss values ​​of the upper section coupling capacitor are calculated using theoretical formulas based on electrical relationships. This method ensures scientific accuracy and rigor, and significantly reduces equipment maintenance and power production costs compared to existing disassembly methods. It is particularly suitable for multi-section capacitor voltage transformers of 500kV and above.

[0004] The application, published under CN109901096A, is titled "An Online Monitoring System and Method for Metering Accuracy of Capacitive Voltage Transformers." It includes a synchronous acquisition card, a voltage converter, a capacitive voltage transformer, and an electromagnetic voltage transformer. The primary sides of both the capacitive and electromagnetic voltage transformers are connected to a high-voltage bus, and their secondary sides are connected to the voltage converter via secondary cables. Both voltage converters are connected to the synchronous acquisition card, which also includes modules for measuring ambient temperature, ambient humidity, and leakage current. The electromagnetic voltage transformer is used as a standard PT, and the capacitive voltage transformer simultaneously acquires voltage signals. Using the standard PT's signal as a benchmark, the operating status of the CVT is determined by calculating the ratio (amplitude and phase) between the signal acquired by the CVT and the standard signal. If the error exceeds the set allowable range, it indicates a problem with the CVT, requiring timely repair or replacement.

[0005] The authorization announcement number is CN103063931B, and the name is "500kV CVT Multiple Dielectric Loss Testing System and Test Method Thereof". It includes an on-board dielectric loss tester and a capacitive voltage transformer. The on-board dielectric loss tester includes a transformer with two output windings. One end of output winding one is connected in series with a relay, and the other end is grounded. One end of output winding two is grounded, and the other end is connected to the capacitive voltage transformer through a high-voltage vacuum relay. The testing system is automated, requiring only one connection and one-button operation to complete all test items for a 500kV CVT, effectively reducing testing time. Through effective functional integration, it reduces size, reduces wiring attempts, improves work efficiency, reduces labor intensity, and shortens testing time by 2 / 3. The instrument has two output channels and simultaneously completes two capacitance measurements.

[0006] Based on the above three patent documents and existing technical solutions, the inventors analyze the existing technical solutions as follows.

[0007] Capacitance type voltage transformers (CVTs) are used in power systems to measure voltage for meters and protection devices. They can also couple carrier frequencies to transmission lines for long-distance communication, remote measurement, and selective high-frequency line protection.

[0008] After a CVT is put into operation, the dielectric loss and capacitance of the upper section of the CVT are usually measured using a reverse connection method. The reverse connection collects signals from the high-voltage output line, but the stray capacitance of the large metal flange to other grounded parts usually causes inaccurate measurements of the dielectric loss and capacitance of the upper section of the CVT.

[0009] Existing technical issues and considerations:

[0010] How to solve the technical problem of not being able to obtain the capacitance of stray capacitors. Summary of the Invention

[0011] This invention provides an apparatus, system, method, and application for measuring capacitance, solving the technical problem of not being able to obtain the capacitance of stray capacitance during initial inspection.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0013] A device for measuring capacitance includes a housing, a first electrode, a second electrode, and an insulating leg. The housing is used for insulation, and the insulating leg is connected to the housing and used to support the housing. The first electrode is located on one side of the housing and is used to connect to the high-voltage output line of the tester. The second electrode is located on the other side of the housing and is used to connect to the signal acquisition line of the tester. The first electrode and the second electrode form the capacitance C5 of the capacitance measuring device. A ventilation hole is provided on the housing.

[0014] A further technical solution is that the shell is a cube.

[0015] A method for measuring capacitance, based on the aforementioned apparatus, includes a measurement step, which comprises obtaining the capacitance C of stray capacitance C3 of the second flange of a capacitive voltage transformer (CVT) to ground before commissioning. 3初始 The capacitance C of the capacitance measuring device C5 before commissioning was obtained by measuring using the positive connection method. 5初始 The capacitance C of the capacitance measuring device C5 during the initial inspection was obtained by measuring using the positive connection method. 5首检 Using the capacitance C5 of the capacitance measuring device as a reference, the capacitance C of the stray capacitance C3 during the initial inspection was calculated by comparison. 3首检 .

[0016] A further technical solution involves eliminating the interference of stray capacitance C3 during the measurement process to obtain the upper section capacitance C of the capacitive voltage transformer (CVT) during the initial inspection. 11 Capacitance C 11首检 .

[0017] A further technical solution involves: in the measurement step, measuring the capacitance C before the capacitance measuring device is put into operation. 5初始 And the capacitance C during the first inspection 5首检 And the capacitance C of stray capacitor C3 before commissioning 3初始 Substituting into equation (11), the capacitance C of stray capacitor C3 during the first inspection is calculated. 3首检 ;

[0018] C 3首检 =C 3初始 ÷(C 5初始 ÷C 5首检 )=(C 3初始 ×C 5首检 )÷C 5初始 Equation (11)

[0019] In equation (11), C 3首检 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection is C. 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 5初始 The capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, C 5首检 The capacitance of capacitor C5 in the stray capacitance measuring device is used for initial inspection.

[0020] A further technical solution involves: in the measurement step, measuring the upper section capacitance C of the capacitive voltage transformer (CVT) before commissioning using the positive connection method. 11 initial capacitance C 11初始The initial capacitance C of the upper section of the capacitive voltage transformer (CVT) before commissioning was obtained by measuring the reverse wiring shielding method. 4初始 Substituting into equation (1), the initial capacitance C3 of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground before commissioning is calculated. 3初始 ;

[0021] C 3初始 =C 4初始 -C 11初始 Equation (1)

[0022] In equation (1), C 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 4初始 The capacitance of the upper section of the capacitive voltage transformer (CVT) before commissioning is C4. 11初始 The upper capacitor C of the capacitive voltage transformer (CVT) before commissioning 11 The electrical capacity.

[0023] A further technical solution involves: in the measurement step, measuring the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection using the reverse wiring shielding method. 4首检 Substituting into equation (2), the upper section capacitance C of the capacitive voltage transformer (CVT) during the first inspection is calculated. 11 Capacitance C 11首检 ;

[0024] C 11首检 =C 4首检 -C 3首检 Equation (2)

[0025] In equation (2), C 11首检 For the initial inspection of the capacitive voltage transformer (CVT), the upper capacitor C is... 11 The capacitance, C 4首检 This refers to the capacitance of the upper section of the capacitive voltage transformer (CVT) C4 during the initial inspection. 3首检 This refers to the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection.

[0026] A system for measuring capacitance includes a tester, the aforementioned apparatus, and a measurement module. The tester measures capacitance, and the measurement module obtains the capacitance C3 of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground before commissioning. 3初始 Obtain the capacitance C of the capacitance measuring device C5 before commissioning. 5初始 The capacitance C of the capacitance measuring device C5 during the initial inspection is obtained. 5首检 The capacitance C of stray capacitor C3 during the first inspection is calculated according to equation (11).3首检 ;

[0027] C 3首检 =C 3初始 ÷(C 5初始 ÷C 5首检 )=(C 3初始 ×C 5首检 )÷C 5初始 Equation (11)

[0028] In equation (11), C 3首检 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection is C. 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 5初始 The capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, C 5首检 This refers to the capacitance of capacitor C5 in the stray capacitance measuring device during the initial inspection.

[0029] A further technical solution involves a measurement module that is also used to obtain the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection. 4首检 The upper section capacitance C of the capacitive voltage transformer (CVT) during the first inspection is calculated according to equation (2). 11 Capacitance C 11首检 ;

[0030] C 11首检 =C 4首检 -C 3首检 Equation (2)

[0031] In equation (2), C 11首检 For the initial inspection of the capacitive voltage transformer (CVT), the upper capacitor C is... 11 The capacitance, C 4首检 This refers to the capacitance of the upper section of the capacitive voltage transformer (CVT) C4 during the initial inspection. 3首检 This refers to the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection.

[0032] An apparatus for measuring capacitance includes a computer-readable storage medium storing a computer program that, when executed by a processor, performs the corresponding steps described above.

[0033] One application, based on the above-described device, and the known stray capacitance C3 of the second flange of a pre-commissioning capacitive voltage transformer (CVT) to ground, is... 3初始 The capacitance C5 of the capacitance measuring device is used as a reference to calculate the capacitance C of the stray capacitance C3 during the initial inspection. 3首检To eliminate interference from stray capacitor C3 and obtain a more accurate value for the upper capacitor C of the capacitive voltage transformer (CVT) during the initial inspection. 11 Capacitance C 11首检 .

[0034] The beneficial effects of adopting the above technical solution are as follows:

[0035] First, a device for measuring capacitance includes a housing, a first electrode, a second electrode, and insulating legs. The housing provides insulation, and the insulating legs are connected to and support the housing. The first electrode is located on one side of the housing and is connected to the high-voltage output line of a tester. The second electrode is located on the other side of the housing and is connected to the signal acquisition line of the tester. The first and second electrodes form the capacitance C5 of the capacitance measuring device. A ventilation hole is provided on the housing. This technical solution, through the capacitance measuring device, can obtain the capacitance of stray capacitance.

[0036] Taking the first inspection as an example, this technical solution can obtain the capacitance of stray capacitors during the first inspection by using a capacitance measuring device.

[0037] Second, a method for measuring capacitance, based on the aforementioned apparatus, includes a measurement step, which comprises obtaining the capacitance C of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground before commissioning. 3初始 The capacitance C of the capacitance measuring device C5 before commissioning was obtained by measuring using the positive connection method. 5初始 The capacitance C of the capacitance measuring device C5 during the initial inspection was obtained by measuring using the positive connection method. 5首检 Using the capacitance C5 of the capacitance measuring device as a reference, the capacitance C of the stray capacitance C3 during the initial inspection was calculated by comparison. 3首检 This technical solution, based on a capacitance measuring device, uses the capacitance C5 of the device as a reference to calculate the capacitance C of the stray capacitance C3 during the initial inspection. 3首检 .

[0038] Third, a system for measuring capacitance includes a tester, the aforementioned device, and a measurement module. The tester measures capacitance, and the measurement module obtains the capacitance C3 of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground before commissioning. 3初始 Obtain the capacitance C of the capacitance measuring device C5 before commissioning. 5初始 The capacitance C of the capacitance measuring device C5 during the initial inspection is obtained. 5首检 The capacitance C of stray capacitor C3 during the first inspection is calculated according to equation (11). 3首检 This technical solution, based on a capacitance measuring device, uses the capacitance C5 of the device as a reference to calculate the capacitance C of the stray capacitance C3 during the initial inspection.3首检 .

[0039] Fourth, an apparatus for measuring capacitance includes a computer-readable storage medium storing a computer program that, when executed by a processor, performs the aforementioned corresponding steps. This technical solution, based on a capacitance measuring device, uses the capacitance C5 of the capacitance measuring device as a reference and calculates the capacitance C of the stray capacitance C3 during the initial inspection. 3首检 .

[0040] Fifth, one application, based on the above-mentioned device, and the known stray capacitance C3 of the second flange of a pre-commissioning capacitive voltage transformer (CVT) to ground. 3初始 The capacitance C5 of the capacitance measuring device is used as a reference to calculate the capacitance C of the stray capacitance C3 during the initial inspection. 3首检 To eliminate interference from stray capacitor C3 and obtain a more accurate value for the upper capacitor C of the capacitive voltage transformer (CVT) during the initial inspection. 11 Capacitance C 11首检 .

[0041] See the detailed implementation section for further description. Attached Figure Description

[0042] Figure 1 This is a structural diagram of the capacitance measuring device of the present invention;

[0043] Figure 2 This is a flowchart of Embodiment 3 of the present invention;

[0044] Figure 3 C is obtained by measuring the positive connection method in this invention. 11初始 Wiring diagram;

[0045] Figure 4 C is obtained by the reverse wiring shielding method in this invention. 4初始 Wiring diagram.

[0046] in:

[0047] 1. First stainless steel electrode;

[0048] 2. Second stainless steel electrode;

[0049] 3. Insulation board;

[0050] 4 insulated outriggers;

[0051] 5 ventilation holes;

[0052] 21. High-voltage output line;

[0053] 22 signal acquisition lines;

[0054] 23 Tester;

[0055] 31 First flange;

[0056] 32 Second flange;

[0057] 33 Third flange;

[0058] 41. Primary conductor. Detailed Implementation

[0059] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0060] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0061] Example 1:

[0062] like Figure 1 As shown, the present invention discloses a device for measuring capacitance, comprising a housing, a first electrode, a second electrode, and an insulating leg. The housing is used for insulation, and the insulating leg is fixedly connected to the housing and used to support the housing. The first electrode is fixedly connected to one side of the housing and is used to connect to the high voltage output line of the tester. The second electrode is fixedly connected to the other side of the housing and is used to connect to the signal acquisition line of the tester. The first electrode and the second electrode form the capacitance C5 of the capacitance measuring device. A ventilation hole is provided on the housing.

[0063] like Figure 1 As shown, the first electrode is a first stainless steel electrode 1 made of stainless steel plate;

[0064] The second electrode is a second stainless steel electrode 2 made of a stainless steel plate;

[0065] The housing is a cube, and the other four sides of the housing, except for the stainless steel plate, are insulating plates 3 made of fiberglass epoxy resin. Each side has four ventilation holes 5 to ensure good ventilation of the device.

[0066] Insulating support leg 4 is fixedly connected to the bottom of the housing.

[0067] Instructions for use of Example 1:

[0068] like Figure 1 As shown, the high voltage output line 21 of the tester 23 used to measure dielectric loss and capacitance is connected to the first stainless steel electrode 1, and the signal acquisition line 22 is connected to the second stainless steel electrode 2. The capacitance between the two stainless steel plates can be measured by using the positive connection method.

[0069] Example 2:

[0070] like Figures 2-4 As shown, the present invention discloses a method for measuring capacitance, and the apparatus based on Embodiment 1 includes a measurement step.

[0071] like Figure 2 As shown, the measurement steps are specifically divided into the following steps:

[0072] Before S1 is put into operation, the initial capacitance of the upper section capacitor and the initial capacitance of the upper section total capacitor of the capacitive voltage transformer (CVT) are measured and the capacitance of the capacitance measuring device is obtained. The initial capacitance of the stray capacitance of the second flange of the capacitive voltage transformer (CVT) to ground is calculated.

[0073] like Figure 3 As shown, based on the positive connection method, the upper section capacitance C of the capacitive voltage transformer (CVT) before commissioning was measured. 11 initial capacitance C 11初始 .

[0074] like Figure 3 As shown, there is a first flange 31, a second flange 32, and a third flange 33. The CVT consists of a first flange 31, an upper section, a second flange 32, a middle section, a third flange 33, and a lower section connected sequentially from top to bottom.

[0075] Based on the direct connection method, the capacitance C of the capacitance measuring device C5 before commissioning was measured. 5初始 .

[0076] like Figure 4 As shown, based on the reverse wiring shielding method, the initial capacitance C of the upper section of the capacitive voltage transformer (CVT) before commissioning was measured. 4初始 .

[0077] like Figure 4 As shown, the primary conductor 41. The first flange 31 of the CVT is grounded via the primary conductor 41.

[0078] Substituting the obtained data into equation (1), the initial capacitance C3 of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground before commissioning is calculated. 3初始 .

[0079] C 3初始 =C 4初始 -C11初始 Equation (1)

[0080] In equation (1), C 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 4初始 The capacitance of the upper section of the capacitive voltage transformer (CVT) before commissioning is C4. 11初始 The upper capacitor C of the capacitive voltage transformer (CVT) before commissioning 11 The electrical capacity.

[0081] During the initial S2 inspection, the capacitance of the capacitance measuring device is measured, and the capacitance of stray capacitance is calculated.

[0082] According to Example 1, the capacitance C of the capacitance measuring device C5 during the first inspection is measured. 5首检 .

[0083] Using the capacitance C5 of the capacitance measuring device as a reference, the capacitance C of the stray capacitance C3 during the initial inspection was calculated by comparison. 3首检 ,Right now:

[0084] The capacitance C obtained before the capacitance measuring device was put into operation 5初始 And the capacitance C obtained during the first inspection 5首检 And the capacitance C of the stray capacitor C3 obtained before commissioning 3初始 Substituting into equation (11), the capacitance C of stray capacitor C3 during the first inspection is calculated. 3首检 .

[0085] C 3首检 =C 3初始 ÷(C 5初始 ÷C 5首检 )=(C 3初始 ×C 5首检 )÷C 5初始 Equation (11)

[0086] In equation (11), C 3首检 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection is C. 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 5初始 The capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, C 5首检 The capacitance of capacitor C5 in the stray capacitance measuring device is used for initial inspection.

[0087] During the initial inspection of S3, the capacitance of the upper capacitor of the capacitive voltage transformer (CVT) is calculated.

[0088] Eliminate interference from stray capacitor C3 to obtain the upper section capacitance C of the capacitive voltage transformer (CVT) during the initial inspection. 11 Capacitance C 11首检 ,Right now:

[0089] Based on the reverse wiring shielding method, the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection was measured. 4首检 Substituting into equation (2), the upper section capacitance C of the capacitive voltage transformer (CVT) during the first inspection is calculated. 11 Capacitance C 11首检 .

[0090] C 11首检 =C 4首检 -C 3首检 Equation (2)

[0091] In equation (2), C 11首检 For the initial inspection of the capacitive voltage transformer (CVT), the upper capacitor C is... 11 The capacitance, C 4首检 This refers to the capacitance of the upper section of the capacitive voltage transformer (CVT) C4 during the initial inspection. 3首检 This refers to the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection.

[0092] Example 3:

[0093] The present invention discloses a system for measuring capacitance, including a tester, the apparatus of Embodiment 1, and a measurement module. The tester is used to measure capacitance.

[0094] The measurement module is used to obtain the capacitance C3 of the stray capacitance C3 between the second flange of the capacitive voltage transformer (CVT) and ground before commissioning. 3初始 Obtain the capacitance C of the capacitance measuring device C5 before commissioning. 5初始 The capacitance C of the capacitance measuring device C5 during the initial inspection is obtained. 5首检 The capacitance C of stray capacitor C3 during the first inspection is calculated according to equation (11). 3首检 .

[0095] C 3首检 =C 3初始 ÷(C 5初始 ÷C 5首检 )=(C 3初始 ×C 5首检 )÷C 5初始 Equation (11)

[0096] In equation (11), C 3首检 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection is C. 3初始The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 5初始 The capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, C 5首检 The capacitance of capacitor C5 in the stray capacitance measuring device is used for initial inspection.

[0097] The tester is used to measure dielectric loss and capacitance. The tester itself is existing technology and will not be described in detail here.

[0098] Example 4:

[0099] Example 4 differs from Example 3 in that the measurement module is also used to obtain the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the first inspection. 4首检 The upper section capacitance C of the capacitive voltage transformer (CVT) during the first inspection is calculated according to equation (2). 11 Capacitance C 11首检 .

[0100] The present invention discloses a system for measuring capacitance, including a tester, the apparatus of Embodiment 1, and a measurement module. The tester is used to measure capacitance.

[0101] The measurement module is also used to obtain the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection. 4首检 The upper section capacitance C of the capacitive voltage transformer (CVT) during the first inspection is calculated according to equation (2). 11 Capacitance C 11首检 .

[0102] C 11首检 =C 4首检 -C 3首检 Equation (2)

[0103] In equation (2), C 11首检 For the initial inspection of the capacitive voltage transformer (CVT), the upper capacitor C is... 11 The capacitance, C 4首检 This refers to the capacitance of the upper section of the capacitive voltage transformer (CVT) C4 during the initial inspection. 3首检 This refers to the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection.

[0104] Example 5:

[0105] The present invention discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in Embodiment 2.

[0106] Example 6:

[0107] This invention discloses a device based on Embodiment 1, and the capacitance C of the stray capacitance C3 of the second flange of a known pre-commissioning capacitive voltage transformer (CVT) to ground. 3初始 The capacitance C5 of the capacitance measuring device is used as a reference to calculate the capacitance C of the stray capacitance C3 during the initial inspection. 3首检 To eliminate interference from stray capacitor C3 and obtain a more accurate value for the upper capacitor C of the capacitive voltage transformer (CVT) during the initial inspection. 11 Capacitance C 11首检 .

[0108] Compared to the above embodiment, the shell is a cuboid, and the cross-sectional shape of the shell is rectangular.

[0109] Compared to the above embodiments, the present invention can be used for three-section CVTs or two-section CVTs. The corresponding wiring method is prior art, and the similarities in the wiring method will not be repeated here.

[0110] In contrast to the above embodiment, the electrode is made of copper sheet.

[0111] Compared to the above embodiments, the ventilation holes are multiple and evenly distributed on the surface of the housing. This ensures that the capacitance measuring device of the present invention operates in the same environment as the CVT, including temperature and humidity.

[0112] Compared to the above embodiments, the program module can also be a hardware module made using existing logic operation technology to implement the corresponding logic operation steps, communication steps and control steps, thereby realizing the above-mentioned corresponding steps. The logic operation unit is existing technology and will not be described in detail here.

[0113] Research and development process:

[0114] 1. Technical problems to be solved

[0115] After the CVT is put into operation, when measuring the dielectric loss and capacitance of the upper section of the CVT during a power outage, because the primary conductor at the top of the CVT is grounded, the reverse connection method can only be used to test the capacitance. 11 The capacitance. Reverse wiring acquires signals from the high-voltage output line, but the stray capacitance of the large metal flange to other grounded parts usually causes C... 11 The problem of inaccurate capacitance testing.

[0116] 2 Technical Solution

[0117] I want to get C 11首检 The derivation process is as follows:

[0118] The first analytical step involves measuring the upper capacitor C of the capacitive voltage transformer (CVT) before commissioning, based on the positive connection method. 11 initial capacitance C 11初始.

[0119] like Figure 3 As shown, before the equipment is put into operation, the top of the CVT is in an ungrounded state. The accurate capacitance C of the upper section of the CVT can be accurately tested by applying pressure at the first flange 31 and reading the current at the second flange 32 using the positive connection method. 11初始 .

[0120] The second analysis step, based on the reverse wiring shielding method, measures the initial capacitance C of the upper section of the capacitive voltage transformer (CVT) before commissioning. 4初始 .

[0121] like Figure 4 As shown, the total upper section capacitance C4 of the capacitive voltage transformer (CVT) before commissioning is the upper section capacitance C of the capacitive voltage transformer (CVT) before commissioning. 11 The capacitance formed by connecting in parallel with the stray capacitance C3 of the second flange 32 to ground.

[0122] like Figure 4 As shown, to further explain, if a reverse wiring shielding method is used to apply pressure at the second flange 32 before the equipment is put into operation, and the current is measured by forming a loop through the grounding grid, while simultaneously shielding the current influence of the lower section capacitor through the signal acquisition line, the upper section capacitor C of the CVT can be measured. 11初始 And other stray capacitances to ground C connected in parallel 3初始 Total capacitance C 4初始 .

[0123] The third analysis step involves calculating the initial capacitance C3 of the stray capacitance C3 between the second flange 32 and ground of the capacitive voltage transformer (CVT) before commissioning. 3初始 .

[0124] We can calculate the stray capacitance C using these two test methods. 3初始 .

[0125] C 3初始 =C 4初始 -C 11初始 Equation (1)

[0126] In equation (1), C 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 4初始 The capacitance of the upper section of the capacitive voltage transformer (CVT) before commissioning is C4. 11初始 The upper capacitor C of the capacitive voltage transformer (CVT) before commissioning 11 The electrical capacity.

[0127] Before commissioning, the equipment is in one state. The first and second measurement steps require the same environment, either both measurements are taken in the factory or both measurements are taken at the construction site.

[0128] The fourth analysis step involves measuring the total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection, based on the reverse wiring shielding method. 4首检 .

[0129] In the later testing after the equipment is put into operation, taking the first power-off test after the CVT is energized (hereinafter referred to as the first test) as an example, since the top of the CVT is not grounded, only the reverse wiring shielding method can be used during the test.

[0130] like Figure 4 As shown, the total capacitance C4 of the upper section of the capacitive voltage transformer (CVT) during the initial inspection is the same as the capacitance C of the upper section of the CVT during the initial inspection. 11 The capacitance formed by connecting in parallel with the stray capacitance C3 of the second flange 32 to ground.

[0131] like Figure 4 As shown, to further explain, the capacitance C of the upper section of the CVT during the initial inspection can be measured using a testing instrument. 11首检 With stray capacitance C 3首检 Parallel total capacitance C 4首检 The total capacitance C of the upper section of the capacitive voltage transformer (CVT) during the initial inspection is obtained directly from the readings on the testing instrument. 4首检 .

[0132] The fifth analysis step aims to determine the total capacitance C4 of the upper section of the capacitive voltage transformer (CVT) during the initial inspection. 4首检 Subtract the capacitance C of stray capacitor C3 3首检 Obtain the capacitor C from the previous section 11 Capacitance C 11首检 .

[0133] To explain further, use C 4首检 Subtract C 3首检 That is, the accurate upper capacitor C 11首检 The capacitance, i.e.

[0134] C 11首检 =C 4首检 -C 3首检 Equation (2)

[0135] In equation (2), C 11首检 For the initial inspection of the capacitive voltage transformer (CVT), the upper capacitor C is... 11 The capacitance, C 4首检 This refers to the capacitance of the upper section of the capacitive voltage transformer (CVT) C4 during the initial inspection. 3首检This refers to the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection.

[0136] However, the stray capacitance C3 will change to some extent depending on the test time, i.e., C 3首检 ≠C 3初始 Existing testing methods cannot directly yield C. 3首检 The value of .

[0137] According to the capacitance calculation formula:

[0138] C=ε×S / 4×π×K×D Equation (3)

[0139] In formula (3):

[0140] C – Capacitance, unit: farad;

[0141] ε—dielectric constant;

[0142] S – Area, unit: square meters;

[0143] π — Pi (the mathematical constant of a circle).

[0144] K – electrostatic constant;

[0145] D – Distance between electrodes, in meters;

[0146] It is known that the size and distance of surrounding equipment will not change after the CVT is put into operation, therefore S and D are constant values; π and K are also constant values. Therefore, only the change in dielectric constant ε will cause a change in stray capacitance C3, and the change is directly proportional to the change in dielectric constant ε.

[0147] The sixth analysis step involves finding a way to obtain the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the initial inspection. This allows us to calculate the upper section capacitance C using equation (2) from the fifth step. 11 Capacitance C 11首检 .

[0148] Indirect connection method to find C 3首检 :

[0149] The seventh analysis step involves measuring the capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, based on the positive connection method. 5初始 ; and the capacitance C of the stray capacitance measuring device C5 obtained during the first inspection. 5首检 .

[0150] like Figure 1As shown, an auxiliary device for stray capacitance testing is invented. The device is a cube with stainless steel plates on the left and right sides and fiberglass epoxy resin insulating plates on the other four sides. Each side has four holes to ensure good ventilation. The high-voltage output line 21 of the dielectric loss and capacitance tester 23 is connected to the first stainless steel electrode 1, and the signal acquisition line 22 is connected to the second stainless steel electrode 2. The capacitance between the two stainless steel plates can be measured using the positive connection method.

[0151] Before the equipment is put into operation, the auxiliary device and the CVT are measured simultaneously, and the measured capacitance of the stray capacitance test auxiliary device is recorded as C. 5初始 During the initial CVT dielectric loss and capacitance tests, the capacitance of the stray capacitance test auxiliary device was measured and recorded as C. 5首检 .but

[0152] C 5初始 =ε 初始 ×S / 4×π×K×D Equation (4)

[0153] C 5首检 =ε 首检 ×S / 4×π×K×D Equation (5)

[0154] C 3初始 =ε 初始 ×S / 4×π×K×D Equation (6)

[0155] C 3首检 =ε 首检 ×S / 4×π×K×D Equation (7)

[0156] Therefore, dividing equation (4) by equation (5) yields:

[0157] C 5初始 ÷C 5首检 =ε 初始 ÷ε 首检 Equation (8)

[0158] Dividing equation (6) by equation (7) yields:

[0159] C 3初始 ÷C 3首检 =ε 初始 ÷ε 首检 Equation (9)

[0160] so,

[0161] C 5初始 ÷C 5首检 =ε 初始 ÷ε 首检 =C 3初始 ÷C 3首检 Equation (10)

[0162] but:

[0163] C 3首检 =C 3初始 ÷(C 5初始 ÷C 5首检 )=(C 3初始 ×C 5首检 )÷C 5初始 Equation (11)

[0164] In equation (11), C 3首检 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection is C. 3初始 The capacitance of stray capacitance C3 to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is C. 5初始 The capacitance C5 of the stray capacitance measuring device of the present invention before commissioning, C 5首检 The capacitance of capacitor C5 in the stray capacitance measuring device is used for initial inspection.

[0165] The eighth analysis step, based on equation (11), calculates the capacitance C of the stray capacitance C3 of the second flange of the capacitive voltage transformer (CVT) to ground during the first inspection. 3首检 .

[0166] To explain further, C 3初始 C 5初始 C represents the stray capacitance calculated and measured using the positive connection before equipment commissioning, as well as the capacitance of the stray capacitance testing auxiliary device. 5首检 To measure the capacitance of the stray capacitance testing auxiliary device simultaneously with the CVT dielectric loss and capacitance tests during the initial inspection, since both are known quantities, the stray capacitance C during the initial inspection can be indirectly obtained through testing and calculation. 3首检 The accurate value.

[0167] 3. Beneficial effects

[0168] A more accurate stray capacitance value can be obtained through indirect measurement and calculation, thereby eliminating its interference and making the measured capacitance of the previous power supply more accurate and convenient to compare with the initial value.

[0169] 4 Inventive Concept

[0170] Invent a stray capacitance testing auxiliary device to test C 3初始 C 5初始 C 5首检 The accurate stray capacitance C is calculated. 3首检 Therefore, when using the reverse wiring shielding method for measurement, it can be done through equation (2)C. 11首检 =C 4首检 -C 3首检 The accurate calculation of the upper section capacitance C 11首检 The value of .

[0171] Technical contributions of this application:

[0172] After communicating with the authors and inventors, the project team believes that the technical contribution of this project lies in:

[0173] like Figure 1 As shown, the structural invention, such as the capacitance measuring device of Embodiment 1, is used to measure stray capacitance, i.e., a stray capacitance testing auxiliary device.

[0174] like Figure 2 As shown, in the invention, step S1 introduces the measurement of the capacitance of the capacitance measuring device before commissioning, and step S2 introduces the measurement of the capacitance of the capacitance measuring device during the first inspection, and calculates the capacitance of stray capacitors. The capacitance of stray capacitors obtained by this method is more accurate.

[0175] A further method invention involves calculating the capacitance of the upper section capacitor of the capacitive voltage transformer (CVT) during the initial inspection in step S3. This method eliminates interference from stray capacitor C3 and obtains the upper section capacitor C of the CVT during the initial inspection. 11 Capacitance C 11首检 More accurate.

[0176] After this application had been running internally for a period of time, the beneficial aspects reported by on-site technicians were:

[0177] This project relates to an apparatus, method, and system for improving the accuracy of CVT section dielectric loss and capacitance testing, thus contributing to the field of improving the accuracy of CVT section dielectric loss and capacitance testing.

[0178] The device includes a housing, a first electrode, a second electrode, and insulating legs. The electrodes are used to connect to a testing instrument, and the housing has ventilation holes. The method includes obtaining the stray capacitance of the second flange of the capacitive voltage transformer to ground before commissioning, measuring the capacitance of the capacitance measuring device before commissioning using the positive connection method, measuring the capacitance of the capacitance measuring device during the first inspection using the positive connection method, and using the capacitance of the capacitance measuring device as a reference to calculate the stray capacitance during the first inspection. The system includes a testing instrument, the above-mentioned device, and a measurement module. Its purpose includes eliminating interference from stray capacitance and obtaining a more accurate capacitance of the upper section capacitor of the capacitive voltage transformer during the first inspection. Through the capacitance measuring device, etc., it is possible to obtain the capacitance of stray capacitance during the first inspection.

[0179] Currently, the technical solution of this invention has undergone pilot testing, which is a small-scale trial of the product before large-scale mass production. After the pilot testing was completed, a user survey was conducted on a small scale, and the survey results showed that user satisfaction was high. Now, preparations have begun for the formal production and industrialization of the product (including intellectual property risk warning surveys).

Claims

1. A method for measuring capacitance, characterized in that: Based on a device for measuring capacitance, the device includes a housing, a first electrode, a second electrode, and insulating legs. The housing provides insulation, and the insulating legs are connected to and support the housing. The first electrode is located on one side of the housing and is connected to the high-voltage output line of the tester. The second electrode is located on the other side of the housing and is connected to the signal acquisition line of the tester. The first electrode and the second electrode form the capacitance of the capacitance measuring device. Ventilation holes are provided on the casing; the measurement steps include obtaining the stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning. capacitance The capacitance of the capacitance measuring device before commissioning was obtained by measuring using the positive connection method. capacitance The capacitance of the capacitance measuring device during the initial inspection was obtained by measuring the capacitance using the positive connection method. capacitance The capacitance of the capacitance measuring device For reference, the stray capacitance obtained during the initial inspection was compared and calculated. capacitance Eliminate stray capacitance Interference, to obtain the upper section capacitor of the capacitive voltage transformer (CVT) during the first inspection. capacitance In the later stages of equipment commissioning testing, the first inspection is the initial power-off test after the CVT is energized; in the measurement steps, the capacitance of the capacitance measuring device before commissioning is measured. and the capacity during the first inspection and stray capacitors before commissioning capacitance Substituting into equation (11), the stray capacitance during the first inspection is calculated. capacitance ; In equation (11), The stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, Stray capacitance to ground of the second flange of the pre-commissioning capacitive voltage transformer (CVT) The capacitance, Capacitance of the stray capacitance measuring device before commissioning The capacitance, Capacitance of the first-inspection stray capacitance measuring device The electrical capacity.

2. The method for measuring capacitance according to claim 1, characterized in that: The shell is a cube.

3. The method for measuring capacitance according to claim 1, characterized in that: In the measurement procedure, the upper section capacitance of the capacitive voltage transformer (CVT) before commissioning is measured using the positive connection method. initial capacitance The total upper section capacitance of the capacitive voltage transformer (CVT) before commissioning was obtained based on the reverse wiring shielding method. initial capacitance Substituting into equation (1), the stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) before commissioning is calculated. initial capacitance ; In equation (1), Stray capacitance to ground of the second flange of the pre-commissioning capacitive voltage transformer (CVT) The capacitance, The upper capacitor of the capacitor-type voltage transformer (CVT) before commissioning Stray capacitance to ground of the second flange Total capacitance in parallel The capacitance, The upper capacitor of the capacitor-type voltage transformer (CVT) before commissioning The electrical capacity.

4. The method for measuring capacitance according to claim 1, characterized in that: In the measurement procedure, the total upper section capacitance of the capacitive voltage transformer (CVT) during the initial inspection is obtained based on the reverse wiring shielding method. Total capacity Substituting into equation (2), the upper section capacitance of the capacitive voltage transformer (CVT) during the first inspection is calculated. capacitance ; In equation (2), The upper capacitor of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, The total capacitance of the upper section of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, The stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection. The electrical capacity.

5. A system for measuring capacitance, characterized in that: The method for measuring capacitance as described in claim 1 includes a tester, a device for measuring capacitance, and a measurement module. The tester is used to measure capacitance, and the measurement module is used to obtain the stray capacitance between the second flange of the capacitive voltage transformer (CVT) and ground before commissioning. capacitance Obtain the capacitance of the capacitance measuring device before commissioning. capacitance Obtain the capacitance of the capacitance measuring device during the initial inspection. capacitance In the later testing after the equipment is put into operation, the first power outage test after the CVT is energized is taken as the first test; the stray capacitance at the time of the first test is calculated according to formula (11). capacitance ; In equation (11), The stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, Stray capacitance to ground of the second flange of the pre-commissioning capacitive voltage transformer (CVT) The capacitance, Capacitance of the stray capacitance measuring device before commissioning The capacitance, Capacitance of the first-inspection stray capacitance measuring device The electrical capacity.

6. A system for measuring capacitance according to claim 5, characterized in that: The measurement module is also used to obtain the total upper section capacitance of the capacitive voltage transformer (CVT) during the initial inspection. Total capacity The upper section capacitance of the capacitive voltage transformer (CVT) during the first inspection is calculated according to equation (2). capacitance ; In equation (2), The upper capacitor of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, The total capacitance of the upper section of the capacitive voltage transformer (CVT) during the initial inspection. The capacitance, The stray capacitance to ground of the second flange of the capacitive voltage transformer (CVT) during the initial inspection. The electrical capacity.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it implements the steps in a method for measuring capacitance as described in claim 1, 3, or 4.

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