A capacitive voltage transformer and its capacitance variation adjustment system

Abstract

The present invention relates to the technical field of capacitive voltage transformers, and particularly to a capacitive voltage transformer and its capacitance variation adjustment system. The adjustment system includes: a capacitance measurement module, which is provided with two groups of test electrodes. One group is connected in parallel with the high-voltage electrode of the high-voltage capacitor to obtain the high-voltage capacitance value, and the other group is connected in parallel with the low-voltage capacitor electrode to obtain the low-voltage capacitance value; a processing and control module, which receives the high-voltage capacitance value and the low-voltage capacitance value, determines whether the ratio of the high-voltage capacitance value to the low-voltage capacitance value exceeds a preset threshold. When it exceeds the preset threshold, it calculates the capacitance value that needs to be compensated and generates compensation information according to the capacitance value that needs to be compensated; a compensation intervention module, which includes a plurality of compensation capacitors with different capacitance gradients and is configured to receive the compensation information and connect the specified compensation capacitors in series according to the compensation information. The safe and stable operation of the capacitance voltage division component is ensured by the gas insulation medium, and the performance and reliability of the capacitive voltage transformer are improved by the adjustment system.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitive voltage transformers, and in particular, to a capacitive voltage transformer and its capacitance variation adjustment system. Background Art

[0002] A high-voltage capacitive voltage transformer (Capacitive Voltage Transformer, abbreviated as CVT) is a device used to measure high voltages in a power system. The high-voltage capacitive voltage transformer mainly consists of a capacitive voltage divider and an intermediate transformer.

[0003] The capacitive voltage divider is composed of a high-voltage capacitor and a medium-voltage capacitor connected in series, and is used to divide the high voltage into a medium-voltage signal in proportion. The electromagnetic unit includes an intermediate transformer, which further transforms the medium-voltage signal into a low-voltage signal for use by measuring instruments, protection devices, etc.

[0004] Existing high-voltage capacitive voltage transformers mostly use oil-paper insulation. Both the high-voltage capacitor and the medium-voltage capacitor are composed of hundreds or thousands of film capacitors wound in series. When a fault occurs in the transformer, the film element breaks down, the insulating oil cracks, and the temperature rises abnormally, and the insulation of the product cannot be restored; when the environmental temperature changes greatly, the change in the oil pressure causes fluctuations in the film capacitance, affecting the measurement accuracy of the transformer. Summary of the Invention

[0005] In order to solve the problems that when a fault occurs in the transformer, the film element breaks down, the insulating oil cracks, the temperature rises abnormally, and the insulation of the product cannot be restored; when the environmental temperature changes greatly, the change in the oil pressure causes fluctuations in the film capacitance, affecting the measurement accuracy of the transformer, the present invention provides a capacitive voltage transformer and its capacitance variation adjustment system.

[0006] In a first aspect, a capacitance variation adjustment system for a capacitive voltage transformer provided by the present invention, where both the high-voltage capacitor and the medium-voltage capacitor are composed of a plurality of ceramic capacitor elements, and the adjustment system includes:

[0007] A capacitance measurement module, provided with two groups of test electrodes, one group is connected in parallel with the high-voltage electrode of the high-voltage capacitor to obtain the high-voltage capacitance value, and the other group is connected in parallel with the low-voltage capacitor electrode to obtain the low-voltage capacitance value;

[0008] A processing and control module, which receives the high-voltage capacitance value and the low-voltage capacitance value, determines whether the ratio of the high-voltage capacitance value to the low-voltage capacitance value exceeds a preset threshold, and when it exceeds the preset threshold, calculates the capacitance value to be compensated, and generates compensation information according to the capacitance value to be compensated;

[0009] A compensation intervention module, including a plurality of compensation capacitors with different capacitance gradients, is configured to receive the compensation information and connect the specified compensation capacitors in series according to the compensation information.

[0010] Optionally, the capacitance measurement module includes a high-voltage capacitance meter, and the high-voltage meter includes a first standard capacitor, a first standard resistor, a second standard resistor, a second standard capacitor, a third standard resistor, and a fourth standard resistor. The first standard capacitor, the first standard resistor, and the second standard resistor form a high-voltage Schering bridge circuit with the high-voltage capacitor to obtain the high-voltage capacitance value, and the second standard capacitor, the third standard resistor, and the fourth standard resistor form a low-voltage Schering bridge circuit with the low-voltage capacitor to obtain the low-voltage capacitance value.

[0011] Optionally, the high-voltage Schering bridge circuit includes four arms. The first arm includes the high-voltage capacitor and an equivalent resistor connected in parallel with the high-voltage capacitor. The second arm includes the standard capacitor. The third arm includes the adjustable first standard resistor. The fourth arm includes the second standard resistor and a first adjustable capacitor connected in parallel with the second standard resistor;

[0012] The high-voltage capacitance value is calculated as:

[0013]

[0014] where is the high-voltage capacitance value, is the first standard capacitor, is the adjustable first standard resistor, is the second standard resistor;

[0015] The low-voltage Schering bridge circuit includes four arms. The first arm includes the low-voltage capacitor and an equivalent resistor connected in parallel with the low-voltage capacitor. The second arm includes the standard capacitor. The third arm includes the adjustable third standard resistor. The fourth arm includes the fourth standard resistor and a second adjustable capacitor connected in parallel with the fourth standard resistor;

[0016] The low-voltage capacitance value is calculated as:

[0017]

[0018] where is the low-voltage capacitance value, is the second standard capacitor, is the adjustable third standard resistor, is the fourth standard resistor;

[0019] Optionally, the capacitance value to be compensated is calculated as:

[0020]

[0021] where is the capacitance value to be supplemented, and k is a preset reasonable ratio;

[0022] Obtain a capacitor combination in which the sum of the capacitance values in capacitors of different gradients is equal to the capacitance value to be compensated, select one group of capacitors as the specified capacitor combination, and generate supplementary information.

[0023] Optionally, the specific steps for obtaining a compensation capacitor combination in which the sum of the capacitance values in capacitors of different gradients is equal to the capacitance value to be compensated, and selecting one group of compensation capacitors as the specified compensation capacitor combination include:

[0024] Obtain all compensation capacitor combinations for the compensation capacitors of different gradients by means of exhaustive search;

[0025] Obtain the sum of the compensation capacitance values of each compensation capacitor combination;

[0026] Obtain the compensation capacitor combinations in which the sum of all compensation capacitance values is the same as the compensation capacitance value to be supplemented;

[0027] Select the compensation capacitor combination with the fewest compensation capacitors as the specified compensation capacitor combination.

[0028] Optionally, it further includes a fault detection module, which obtains the extreme temperature difference and the temperature coefficient of the ceramic capacitor, and calculates the change limit value of the ceramic capacitance according to the extreme temperature difference and the temperature coefficient of the ceramic capacitor:

[0029] Change limit value of ceramic capacitance

[0030] is the initial ceramic capacitance, extreme temperature difference, temperature coefficient of the ceramic capacitor;

[0031] Judge whether the change limit value of the ceramic capacitance exceeds the breakdown threshold. When the change limit value of the ceramic capacitance exceeds the breakdown threshold, there is a risk of breakdown in the high-voltage capacitor and the medium-voltage capacitor.

[0032] In a second aspect, a capacitive voltage transformer includes a capacitive divider, an intermediate transformer, and the above-mentioned capacitance variation adjustment system. The capacitive divider includes a box body, a capacitive voltage division component, and a gas insulation medium. The capacitive voltage division component is arranged in the box body, and the gas insulation medium fills the space between the capacitive voltage division component and the box body; the capacitive voltage division component includes a high-voltage capacitor and a medium-voltage capacitor composed of a plurality of ceramic capacitor elements; the medium-voltage capacitor and the high-voltage capacitor are connected in series, the intermediate transformer is connected to the medium-voltage capacitor, and the capacitance variation adjustment system is arranged on the capacitive divider.

[0033] Optionally, a plurality of ceramic capacitor elements are connected in series to form a ceramic capacitor group. The high-voltage capacitor includes a plurality of parallel ceramic capacitor groups, and the medium-voltage capacitor includes a plurality of parallel ceramic capacitor groups.

[0034] Optionally, the ceramic capacitor bank includes: a plurality of ceramic capacitor elements, a fiberglass tube, a conducting electrode, and a casting material. The plurality of ceramic capacitor elements are connected in series to form a cylindrical shape and are installed in the fiberglass tube. The conducting electrode is located at the center of the cylindrical shape, and the casting material is injected between the fiberglass tube, the ceramic capacitor elements, and the conducting electrode for encapsulation.

[0035] Optionally, it further includes an inductance compensation device for compensating the capacitive reactance through the inductive reactance value, and is connected to the medium-voltage transformer.

[0036] In summary, the present invention has the following beneficial technical effects:

[0037] First, the capacitance measurement module accurately obtains the high-voltage capacitance value and the low-voltage capacitance value through two groups of test electrodes respectively, realizing real-time monitoring of capacitance changes. Secondly, the processing and control module intelligently judges whether the capacitance value ratio exceeds a preset threshold. When it exceeds, it automatically calculates the capacitance value to be compensated and generates compensation information. Finally, the compensation intervention module includes a plurality of compensation capacitors with different capacitance gradients, and can flexibly connect the specified compensation capacitors in series according to the compensation information, thereby improving the performance and reliability of the capacitive voltage transformer as a whole, and providing a strong guarantee for the stable operation of the power system;

[0038] The safe and stable operation of the capacitance voltage division component is ensured by the gas insulation medium in the capacitance voltage divider. The high-voltage and medium-voltage capacitors composed of ceramic capacitor elements ensure the accuracy of voltage division. At the same time, the capacitance variation adjustment system can monitor and flexibly compensate for the change of capacitance value in real time, greatly improving the performance and reliability of the capacitive voltage transformer, and providing a strong guarantee for the stable operation of the power system. Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of a capacitance variation adjustment system of a capacitive voltage transformer according to an embodiment of the present invention.

[0040] Figure 2 is a circuit diagram of a Schering bridge circuit according to an embodiment of the present invention.

[0041] Figure 3 is a circuit schematic diagram of adding an adjustment system to the transformer according to an embodiment of the present invention.

[0042] Figure 4 is a schematic structural diagram of a high-voltage capacitor or a low-voltage capacitor according to an embodiment of the present invention.

[0043] Among them, 1. Ceramic capacitor element; 2. Epoxy resin; 3. Fiberglass tube; 4. Conducting electrode. Detailed Embodiment

[0044] The following is a further detailed description of the present invention in conjunction with the attached Figure 1 - attached Figure 4 drawings.

[0045] Example 1

[0046] Refer to Figure 1 , in a capacitance variation adjustment system of a capacitive voltage transformer in this embodiment, both the high-voltage capacitor and the medium-voltage capacitor are composed of multiple ceramic capacitor elements 1, and the adjustment system includes:

[0047] A capacitance measurement module is provided with two groups of test electrodes. One group is connected in parallel with the high-voltage electrode of the high-voltage capacitor to obtain the high-voltage capacitance value, and the other group is connected in parallel with the low-voltage capacitor electrode to obtain the low-voltage capacitance value;

[0048] The capacitance measurement module is connected in parallel with the high-voltage electrode of the high-voltage capacitor and the low-voltage capacitor electrode respectively through two groups of test electrodes, and can accurately obtain the high-voltage capacitance value and the low-voltage capacitance value. This enables the system to monitor the change of capacitance in real time, providing an accurate data basis for subsequent processing and adjustment. By separately measuring the high-voltage capacitor and the low-voltage capacitor, the capacitance states of different parts in the capacitive voltage transformer can be understood more carefully, and the abnormal change of the capacitance value can be detected in time.

[0049] The capacitance measurement module includes a high-voltage capacitance meter. The high-voltage meter includes a first standard capacitor, a first standard resistor, a second standard resistor, a second standard capacitor, a third standard resistor and a fourth standard resistor, and forms a high-voltage Schering bridge circuit with the high-voltage capacitor to obtain the high-voltage capacitance value. The high-voltage meter forms a low-voltage Schering bridge circuit with the low-voltage capacitor to obtain the low-voltage capacitance value.

[0050] The high-voltage Schering bridge circuit includes four bridge arms. The first bridge arm includes the high-voltage capacitor and an equivalent resistor connected in parallel with the high-voltage capacitor. The second bridge arm includes a standard capacitor. The third bridge arm includes an adjustable first standard resistor. The fourth bridge arm includes a second standard resistor and a first adjustable capacitor connected in parallel with the second standard resistor;

[0051] The high-voltage capacitance value is calculated as:

[0052]

[0053] Wherein, is the high-voltage capacitance value, is the first standard capacitor, is the adjustable first standard resistor, is the second standard resistor;

[0054] The low-voltage Schering bridge circuit includes four bridge arms. The first bridge arm includes the low-voltage capacitor and an equivalent resistor connected in parallel with the low-voltage capacitor. The second bridge arm includes a standard capacitor. The third bridge arm includes an adjustable third standard resistor. The fourth bridge arm includes a fourth standard resistor and a second adjustable capacitor connected in parallel with the fourth standard resistor;

[0055] The low-voltage capacitance value is calculated as:

[0056]

[0057] Wherein, is the low-voltage capacitance value, is the second standard capacitance, is the adjustable third standard resistance, is the fourth standard resistance.

[0058] The processing control module receives the high-voltage capacitance value and the low-voltage capacitance value, determines whether the ratio of the high-voltage capacitance value to the low-voltage capacitance value exceeds a preset threshold. When it exceeds the preset threshold, it calculates the capacitance value that needs to be compensated and generates compensation information according to the capacitance value that needs to be compensated;

[0059] The processing control module can keep the ratio of the high-voltage capacitance and the low-voltage capacitance within an ideal range, thus ensuring the stability and performance of the system. Through compensation adjustment, the circuit can still operate normally under changing conditions. Prevent the deviation of the high-voltage or low-voltage capacitance from causing system failure or damage.

[0060] The capacitance value that needs to be compensated is calculated as:

[0061]

[0062] Wherein, is the capacitance value that needs to be supplemented, and k is a preset reasonable ratio;

[0063] Obtain a capacitance combination in different-gradient capacitances whose sum of capacitance values is equal to the capacitance value that needs to be compensated, select one of the capacitance combinations as the specified capacitance combination, and generate supplementary information.

[0064] A specific high-voltage Schering bridge circuit or low-voltage Schering bridge circuit is as Figure 2 shown

[0065] The specific steps for obtaining a capacitance combination in different-gradient capacitances whose sum of capacitance values is equal to the capacitance value that needs to be compensated and selecting one of the capacitance combinations as the specified capacitance combination include:

[0066] Obtain all capacitance combinations of different-gradient capacitances by the exhaustive method;

[0067] Obtain the sum of the capacitance values of each capacitance combination;

[0068] Obtain the capacitance combinations whose sum of all capacitance values is the same as the capacitance value that needs to be supplemented;

[0069] Select the capacitance combination with the fewest capacitors as the specified capacitance combination.

[0070] The compensation intervention module, including compensation capacitors with multiple different capacitance gradients, is configured to receive compensation information and serially connect specified compensation capacitors according to the compensation information.

[0071] The compensation intervention module includes compensation capacitors with multiple different capacitance gradients, and can serially connect specified compensation capacitors according to the compensation information generated by the processing control module. This design enables the system to perform flexible compensation according to actual needs and adapt to different degrees of capacitance variation. The compensation capacitors with different capacitance gradients provide more adjustment options, and can more accurately compensate for the change of capacitance value, ensuring that the performance of the capacitive voltage transformer always remains in good condition.

[0072] The fault detection module obtains the limit temperature difference and the temperature coefficient of the ceramic capacitor, and calculates the limit change value of the ceramic capacitance according to the limit temperature difference and the temperature coefficient of the ceramic capacitor:

[0073] Limit change value of ceramic capacitance

[0074] is the initial ceramic capacitance, Limit temperature difference, Temperature coefficient of ceramic capacitor;

[0075] The limit temperature difference defines the maximum temperature change range that may occur in the actual application environment. For example, the difference between the lowest operating temperature and the highest operating temperature;

[0076] The temperature coefficient of the ceramic capacitor is usually provided by the specification sheet of the ceramic capacitor, which represents the relative change rate of capacitance caused by unit temperature change, and the unit is ppm / °C (parts per million per degree Celsius).

[0077] Judge whether the limit change value of the ceramic capacitance exceeds the breakdown threshold. When the limit change value of the ceramic capacitance exceeds the breakdown threshold, there is a breakdown risk for the high-voltage capacitor and the medium-voltage capacitor;

[0078] The fault detection module can issue a warning before the capacitance of the ceramic capacitor approaches or exceeds the breakdown threshold due to temperature change, helping the system avoid damage or failure of the capacitor. By detecting the capacitance change of the ceramic capacitor, the module can help maintain the reliable operation of the circuit and prevent faults caused by capacitor breakdown. The module can monitor the health status of the capacitor, avoid operating under extreme temperature conditions, reduce potential damage, and thus extend the service life of the equipment. When a breakdown risk is detected, the system can take protective measures, such as switching to a standby circuit or reducing the operating voltage, to prevent the spread of the risk.

[0079] Embodiment 2

[0080] The difference between this embodiment and Embodiment 1 is that this embodiment provides a capacitive voltage transformer, which includes a capacitive voltage divider, an electromagnetic unit device, the above-mentioned capacitance variation adjustment system, and an inductance compensation device; the capacitive voltage divider is assembled on a high-voltage conductor. The high-voltage conductor is connected to the GIS station through a pot-type insulator;

[0081] The capacitive voltage divider includes a box body, a capacitive voltage division component, and a gas insulation medium (such as SF6, which has the function of self-healing and recovery when overvoltage breakdown occurs). The capacitive voltage division component is arranged in the box body, and the gas insulation medium fills the space between the capacitive voltage division component and the box body; the capacitive voltage division component includes a high-voltage capacitor and a medium-voltage capacitor composed of multiple ceramic capacitor elements 1; multiple ceramic capacitor elements 1 are connected in series to form a ceramic capacitor group. The high-voltage capacitor includes multiple parallel ceramic capacitor groups, and the medium-voltage capacitor includes multiple parallel ceramic capacitor groups; the capacitance variation adjustment system is arranged on the capacitive voltage divider, and the inductance compensation device is connected to the end of the medium-voltage transformer to realize the compensation of capacitive reactance by inductive reactance.

[0082] The ceramic capacitor uses a special NPO capacitor material, whose dielectric constant is between 2000 and 2100, and the dielectric loss is about 0.0011. The temperature coefficient of the dielectric of the material is ±3.0% from -40 to 70 °C. The ceramic capacitor temperature coefficients of the high-voltage capacitor and the low-voltage capacitor are the same, both being positive temperature coefficients or both being negative temperature coefficients. The high-voltage capacitor and the low-voltage capacitor use the same material, and the capacitance changes are basically the same, with a very small variation of about 0.2% to cope with the situation of large high and low temperature differences in the ambient temperature.

[0083] Refer to Figure 3 , in another embodiment, the voltage transformer specifically includes a high-voltage terminal H, a capacitive voltage divider, and a low-voltage terminal N of the capacitive voltage divider. The high-voltage terminal H, the capacitive voltage divider, and the low-voltage terminal N of the capacitive voltage divider are connected in series in sequence. The capacitive voltage divider includes a series-connected high-voltage capacitor C1 and a medium-voltage capacitor C21. A medium-voltage transformer Tr is connected between the high-voltage capacitor C1 and the medium-voltage capacitor C21. An inductance compensation device is connected to the end X0 of the medium-voltage transformer Tr to realize the compensation of capacitive reactance by inductive reactance. The low-voltage terminal N of the capacitive voltage divider and the low-voltage terminal L0 are both grounded;

[0084] The inductance compensation device includes a compensation inductor L, whose function is to generate inductive reactance to compensate the capacitive reactance in the circuit. When there is a capacitive load in the circuit, it will cause the current to lead the voltage, thus generating reactive power. The inductive reactance of the compensation inductor can cancel out the capacitive reactance, reduce the reactive power, improve the power factor of the circuit, improve the power quality, and reduce the line loss. A discharge resistor is connected in parallel with the compensation inductor L, whose function is to provide a discharge path for the capacitor after the circuit is powered off, quickly release the charge stored in the capacitor to ensure safety. In addition, the discharge resistor can also play a role in stabilizing the circuit and suppressing voltage fluctuations.

[0085] There is also a part of stray capacitance C22 in the medium-voltage capacitor. The stray capacitance C22 is connected in parallel with the medium-voltage capacitor C21 to jointly form the medium-voltage capacitor. A group of electrodes of a high-voltage measuring instrument is connected in parallel across the two ends of the high-voltage capacitor C1, and another group of electrodes of the high-voltage measuring instrument is connected in parallel between the medium-voltage capacitor and the low-voltage terminal N.

[0086] Referring to Figure 4 , the ceramic capacitor bank includes: a plurality of ceramic capacitor elements 1, a glass fiber tube 3, a conductive electrode 4, and a casting material. The plurality of ceramic capacitor elements 1 are connected in series to form a cylindrical shape and are installed in the glass fiber tube 3. The conductive electrode 4 is located at the center of the cylindrical shape. The casting material is injected between the glass fiber tube 3, the ceramic capacitor elements 1, and the conductive electrode 4 for encapsulation. In this embodiment, the casting material includes epoxy resin 2.

[0087] In summary, using a self-healing insulating gas as the insulating medium has the characteristics of self-healing and recoverability. The product has a long service life; adopting ceramic coaxial cascade distributed capacitance, it has a compact structure and a small floor area, and can realize the docking of GIS stations; it has a capacitance error adjustment system that can adjust the error caused by the large temperature span of the environment; it has the ability to detect capacitance faults. According to the number of ceramic capacitors and the capacitance of a single capacitor, the percentage of capacitance fluctuation caused by the breakdown and damage of a single capacitor can be calculated. When the detected capacitance change exceeds this value, a capacitance fault can be determined.

[0088] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the methods disclosed in the embodiments, since they correspond to the systems disclosed in the embodiments, the description is relatively simple. For the relevant parts, please refer to the description in the method part.

[0089] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0090] The above-disclosed is only the preferred embodiment of the present invention, but the present invention is not limited thereto. Any non-creative changes that can be thought of by those skilled in the art, as well as several improvements and retouches made without departing from the principle of the present invention, should fall within the protection scope of the present invention.

Claims

1. A capacitance variation adjustment system for a capacitive voltage transformer, characterized in that, Both the high-voltage capacitor and the low-voltage capacitor are composed of multiple ceramic capacitor elements. The adjustment system includes: A capacitance measurement module, which is provided with two groups of test electrodes. One group is connected in parallel with the high-voltage electrode of the high-voltage capacitor to obtain the high-voltage capacitance value, and the other group is connected in parallel with the low-voltage capacitor electrode to obtain the low-voltage capacitance value; A processing and control module, which receives the high-voltage capacitance value and the low-voltage capacitance value, judges whether the ratio of the high-voltage capacitance value to the low-voltage capacitance value exceeds a preset threshold. When it exceeds the preset threshold, it calculates the capacitance value to be compensated and generates compensation information according to the capacitance value to be compensated; A compensation intervention module, which includes multiple compensation capacitors with different capacitance gradients, and is configured to receive the compensation information and connect the specified compensation capacitors in series according to the compensation information; A fault detection module, which obtains the extreme temperature difference and the temperature coefficient of the ceramic capacitor, and calculates the change limit value of the ceramic capacitance according to the extreme temperature difference and the temperature coefficient of the ceramic capacitor: Limit of change in ceramic capacitance is the initial ceramic capacitance, extreme temperature difference, ceramic capacitance temperature coefficient; Judge whether the change limit value of the ceramic capacitance exceeds the breakdown threshold. When the change limit value of the ceramic capacitance exceeds the breakdown threshold, there is a breakdown risk for the high-voltage capacitor and the low-voltage capacitor.

2. The capacitance variation adjustment system of the capacitive voltage transformer according to claim 1, characterized in that The capacitance measurement module includes a high-voltage capacitance meter. The high-voltage capacitance meter includes a first standard capacitor, a first standard resistor, a second standard resistor, a second standard capacitor, a third standard resistor and a fourth standard resistor. The first standard capacitor, the first standard resistor and the second standard resistor form a high-voltage Schering bridge circuit with the high-voltage capacitor to obtain the high-voltage capacitance value. The second standard capacitor, the third standard resistor and the fourth standard resistor form a low-voltage Schering bridge circuit with the low-voltage capacitor to obtain the low-voltage capacitance value.

3. The capacitance variation adjustment system of the capacitive voltage transformer according to claim 2, characterized in that, The high-voltage Schering bridge circuit includes four bridge arms. The first bridge arm includes the high-voltage capacitor and an equivalent resistor connected in parallel with the high-voltage capacitor. The second bridge arm includes the first standard capacitor. The third bridge arm includes an adjustable first standard resistor. The fourth bridge arm includes the second standard resistor and a first adjustable capacitor connected in parallel with the second standard resistor; The high-voltage capacitance value is calculated as: Among them, is the high-voltage capacitance value, is the first standard capacitor, is the adjustable first standard resistor, is the second standard resistor; The low-voltage Schering bridge circuit includes four bridge arms. The first bridge arm includes the low-voltage capacitor and an equivalent resistor connected in parallel with the low-voltage capacitor. The second bridge arm includes the second standard capacitor. The third bridge arm includes an adjustable third standard resistor. The fourth bridge arm includes the fourth standard resistor and a second adjustable capacitor connected in parallel with the fourth standard resistor; The low-voltage capacitance value is calculated as: Among them, is the low-voltage capacitance value, is the second standard capacitor, is the adjustable third standard resistor, is the fourth standard resistor.

4. The capacitance variation adjustment system of the capacitive voltage transformer according to claim 3, characterized in that, The capacitance value to be compensated is calculated as: Among them, is the capacitance value to be supplemented, and k is a preset reasonable ratio; Obtain a capacitance combination in which the sum of the capacitance values in different-gradient capacitors is equal to the capacitance value to be compensated, select one group of capacitors as the specified capacitance combination, and generate supplementary information.

5. The capacitance variation adjustment system of the capacitive voltage transformer according to claim 4, characterized in that, The specific steps of obtaining a compensation capacitor combination in which the sum of the capacitance values in different-gradient capacitors is equal to the capacitance value to be compensated and selecting one group of compensation capacitors as the specified compensation capacitor combination include: Obtain all compensation capacitor combinations of different-gradient compensation capacitors by the exhaustive method; Obtain the sum of the compensation capacitor values of each compensation capacitor combination; Obtain a compensation capacitor combination in which the sum of all compensation capacitor values is the same as the compensation capacitor value to be supplemented; Select the compensation capacitor combination with the fewest compensation capacitors as the specified compensation capacitor combination.

6. A capacitive voltage transformer, characterized in that, Include: A capacitive voltage divider, an intermediate transformer, and a capacitive variation adjustment system according to any one of claims 1 to 5, the capacitive voltage divider comprising a box body, a capacitive voltage division assembly, and a gas insulation medium, the capacitive voltage division assembly being disposed within the box body, and a gas insulation medium filling the space between the capacitive voltage division assembly and the box body; the capacitive voltage division assembly comprising a high-voltage capacitor and a low-voltage capacitor composed of a plurality of ceramic capacitor elements; the low-voltage capacitor and the high-voltage capacitor being connected in series, the intermediate transformer being connected to the low-voltage capacitor, and the capacitive variation adjustment system being disposed on the capacitive voltage divider.

7. The capacitive voltage transformer according to claim 6, characterized in that, A plurality of ceramic capacitor elements are connected in series to form a ceramic capacitor bank, the high-voltage capacitor comprising a plurality of parallel-connected ceramic capacitor banks, and the low-voltage capacitor comprising a plurality of parallel-connected ceramic capacitor banks.

8. The capacitive voltage transformer according to claim 7, wherein, The ceramic capacitor bank includes: a plurality of ceramic capacitor elements, a glass fiber tube, a conducting electrode, and a casting material, the plurality of ceramic capacitor elements being connected in series into a cylindrical shape and placed into the glass fiber tube, the conducting electrode being located at the center of the cylindrical shape, and a casting material being injected between the glass fiber tube, the ceramic capacitor elements, and the conducting electrode for encapsulation.

9. The capacitive voltage transformer according to claim 6, characterized in that, It further includes an inductance compensation device for compensating the capacitive reactance through the inductive reactance value, which is connected to the intermediate transformer.

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