Capacitive voltage transformer with transient overvoltage measurement function

Abstract

The application relates to a capacitive voltage transformer with a transient overvoltage measurement function, comprising a capacitive voltage divider, an electromagnetic unit and a secondary terminal block; the capacitive voltage divider comprises a high-voltage capacitor, a medium-voltage capacitor and a transient overvoltage measurement module, the high-voltage capacitor, the medium-voltage capacitor and the transient overvoltage measurement module are connected in series from top to bottom, and the high-voltage capacitor, the medium-voltage capacitor and the transient overvoltage measurement module all adopt the same insulating medium; one end of the transient overvoltage measurement module away from the medium-voltage capacitor is connected with the secondary terminal block to form a transient measurement loop; the intermediate voltage of the medium-voltage capacitor is led out and connected with the first end of an intermediate transformer in the electromagnetic unit, and a plurality of groups of secondary windings of the intermediate transformer are connected with the secondary terminal block to form a power frequency measurement loop; by adopting the same insulating medium for the high-voltage capacitor, the medium-voltage capacitor and the transient overvoltage measurement module, it is ensured that the three have the same temperature coefficient, and thus the voltage measurement precision is improved.

Description

Technical Field

[0001] This invention relates to the field of capacitive voltage transformer technology, and in particular to a capacitive voltage transformer with transient overvoltage measurement function. Background Technology

[0002] Currently, capacitive voltage transformers (CVTs) are widely used in 110kV and above high-voltage power grid systems due to their excellent insulation performance, low manufacturing cost, and strong anti-ferromagnetic resonance capability. A conventional CVT mainly consists of two parts: a capacitive voltage divider and an electromagnetic unit. Its working principle involves a high-voltage voltage divider composed of a high-voltage capacitor and a medium-voltage capacitor, followed by electromagnetic transformation via an intermediate transformer, compensating reactor, damper, and other components within the electromagnetic unit. The final output is a standard secondary power frequency voltage signal to meet the metering, measurement, and protection requirements under normal power grid operating conditions.

[0003] With the advancement of new power system construction, the requirements for refined and safe management of power grid operation are continuously increasing, placing a strong demand on the ability to accurately, frequently, and rapidly monitor transient overvoltages in the power grid. However, traditional CVT structures, limited by their own hardware architecture and transmission characteristics, generally suffer from poor transient transmission performance, limited functionality, and significant signal measurement interference. They are unable to accurately capture high-frequency, rapid transient voltage signals and are ill-suited to the current operational requirements for accurate monitoring of transient overvoltages in the power grid, exhibiting significant technical shortcomings.

[0004] To address the insufficient transient signal measurement capability of traditional CVTs, an improved CVT technology solution has been proposed in the existing technology. This solution adds a low-voltage ceramic capacitor C3 inside the electromagnetic unit of the traditional CVT. The acquisition and measurement of transient overvoltage signals are achieved by relying on the newly added low-voltage capacitor, thereby making up for the deficiency of traditional equipment in being unable to monitor transient overvoltages.

[0005] However, this improved technical solution still has many substantial defects in practical applications: First, the equipment's measurement stability and anti-interference performance are poor. The high and low voltage capacitors in the improved solution use different dielectric materials, and the temperature coefficients of these dielectrics differ significantly. During equipment operation, changes in ambient temperature can easily cause the overall voltage division ratio to shift, drastically reducing the accuracy of transient overvoltage and conventional voltage tests, making it difficult to guarantee measurement precision. Second, the equipment is difficult to modify and has poor adaptability. The low-voltage capacitor is built into the electromagnetic unit, requiring an additional dedicated protection module. Simultaneously, the overall sealing of the equipment and the adaptability of the assembly process must be considered. Compared to traditional CVTs, the overall structural modifications are significant, resulting in high equipment modification costs and complex assembly processes, which is not conducive to the upgrading and mass application of existing power grid equipment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a capacitive voltage transformer with transient overvoltage measurement function. Its advantages include the ability to achieve homogeneous dielectric capacitance, ensuring consistent temperature coefficients, improving measurement anti-interference capabilities, and guaranteeing the accuracy of transient waveform measurement.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: a capacitive voltage transformer with transient overvoltage measurement function, comprising a capacitive voltage divider, an electromagnetic unit, and a secondary terminal block; the capacitive voltage divider includes a high-voltage capacitor, a medium-voltage capacitor, and a transient overvoltage measurement module, wherein the high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module are connected in series from top to bottom, and all three use the same insulating medium; the end of the transient overvoltage measurement module away from the medium-voltage capacitor is connected to the secondary terminal block to form a transient measurement circuit; the intermediate voltage of the medium-voltage capacitor is led out and connected to the first end of the intermediate transformer in the electromagnetic unit, and multiple sets of secondary windings of the intermediate transformer are all connected to the secondary terminal block to form a power frequency metering circuit, wherein the transient measurement circuit and the power frequency metering circuit do not interfere with each other; wherein the multiple sets of secondary windings include a #1 secondary winding, a #2 secondary winding, a #3 secondary winding, and a #4 residual voltage winding.

[0008] Preferably, the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention includes a high-voltage capacitor comprising multiple capacitor segments, each of which is encapsulated in multiple bushings, and each bushing is filled with insulating oil. Each bushing includes a porcelain bushing, a top flange, and a bottom flange. The top flange is sealed to the top of the porcelain bushing, and the bottom flange is sealed to the bottom of the porcelain bushing. The top flange is connected to the top of the capacitor segment encapsulated in the bushing via a first cable, and the bottom of the capacitor segment is connected to the bottom flange via a second cable. Multiple bushings are connected sequentially from top to bottom to connect the multiple capacitor segments in series. The medium-voltage capacitor and the transient overvoltage measurement module are both disposed in the bottommost bushing, and the electromagnetic unit is disposed at the bottom of the bottommost bushing.

[0009] Preferably, the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention includes an electromagnetic unit comprising a housing, an intermediate transformer, and a compensating reactor. The housing is configured to form a cavity, and a connecting flange is provided at the top of the housing. The bottom end of the bushing located at the bottom is bolted to the connecting flange. A first epoxy lead-out pipe and a second epoxy lead-out pipe are provided on the connecting flange. The top ends of the first epoxy lead-out pipe and the second epoxy lead-out pipe are inserted into the bottom bushing, and the bottom ends of the first epoxy lead-out pipe and the second epoxy lead-out pipe are both inserted into the cavity. Inside the cavity; the intermediate transformer and the compensating reactor are both disposed within the cavity. A shell is provided on the outer side wall of the outer casing, and the chamber enclosed by the shell communicates with the cavity. The secondary terminal block is disposed within the chamber. The transient overvoltage measurement module is led out through the first epoxy lead-out pipe and connected to the secondary terminal block. The intermediate voltage of the medium-voltage capacitor is led out through the second epoxy casting sleeve and connected to the first end of the intermediate transformer. The tail end of the intermediate transformer is connected to the compensating reactor. Multiple sets of secondary windings of the intermediate transformer are all connected to the secondary terminal block.

[0010] Preferably, in the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention, the high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module all use the same membrane-paper composite dielectric.

[0011] Preferably, in the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention, the absolute value of the temperature coefficient of the high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module is ≤3×10⁻⁶. -4 K -1 .

[0012] Preferably, the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention further includes a damper in the electromagnetic unit, and the damper is connected in parallel across the remaining voltage winding da-dn.

[0013] Preferably, the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention further includes a surge arrester in the electromagnetic unit. The surge arrester is disposed in the accommodating cavity, one end of the surge arrester is connected to the compensating reactor, and the other end of the surge arrester is grounded.

[0014] Preferably, in the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention, each bushing is provided with a breathing metal expander, and the top of the breathing metal expander is connected to the bottom surface of the top flange.

[0015] Preferably, in the capacitive voltage transformer with transient overvoltage measurement function provided by the present invention, both the first epoxy lead-out tube and the second epoxy lead-out tube are integrally cast from epoxy resin.

[0016] In summary, the beneficial technical effects of this invention are as follows: The capacitive voltage transformer with transient overvoltage measurement function provided in this application includes a capacitive voltage divider, an electromagnetic unit, and a secondary terminal block; the capacitive voltage divider includes a high-voltage capacitor, a medium-voltage capacitor, and a transient overvoltage measurement module, which are connected in series from top to bottom, and all three components use the same insulating medium; the end of the transient overvoltage measurement module furthest from the medium-voltage capacitor is connected to the secondary terminal block to form a transient measurement circuit; the intermediate voltage of the medium-voltage capacitor is led out and connected to the electromagnetic unit... The intermediate transformer is connected to the first end, and multiple sets of secondary windings of the intermediate transformer are connected to the secondary terminal block to form a power frequency metering circuit. The transient measurement circuit and the power frequency metering circuit do not interfere with each other. By setting the high-voltage capacitor, medium-voltage capacitor and transient overvoltage measurement module to use the same insulating medium, it is ensured that the three have the same temperature coefficient. When the ambient temperature changes, the capacitance change trend of the high-voltage capacitor, medium-voltage capacitor and transient overvoltage measurement module is consistent, thereby ensuring that the voltage division ratio from the primary high-voltage end to the low-voltage end of the transient overvoltage measurement module is highly stable throughout the entire operating temperature range, thereby improving the voltage measurement accuracy. Attached Figure Description

[0017] Figure 1 This is an electrical schematic diagram of a capacitive voltage transformer with transient overvoltage measurement function provided in an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the overall structure of a capacitive voltage transformer with transient overvoltage measurement function provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of the first epoxy lead-out tube and the second epoxy lead-out tube in the capacitive voltage transformer with transient overvoltage measurement function provided in the embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the secondary terminal block in a capacitive voltage transformer with transient overvoltage measurement function provided in an embodiment of the present invention.

[0021] In the diagram, 1 is a capacitive voltage transformer; 10 is a capacitive voltage divider; C1 is a high-voltage capacitor; 111 is a bushing; 1111 is a porcelain bushing; 1112 is a top flange; 1113 is a bottom flange; 1114 is a breathing metal expander; 1115 is insulating oil; C2 is a medium-voltage capacitor; 13 is a transient overvoltage measurement module; 20 is an electromagnetic unit; 21 is a housing; 22 is a connecting flange; 221 is the first epoxy lead-out pipe; 222 is the second epoxy lead-out pipe; Tr is an intermediate transformer; 1a-1n is the #1 secondary winding; 2a-2n is the #2 secondary winding; 3a-3n is the #3 secondary winding; da-dn is the #4 residual voltage winding; L is a compensating reactor; D is a damper; BL is a surge arrester; 30 is a secondary terminal block; 31 is a housing. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Reference Figure 1 This invention discloses a capacitive voltage transformer 1 with transient overvoltage measurement function, comprising a capacitive voltage divider 10, an electromagnetic unit 20, and a secondary terminal block 30. The capacitive voltage divider 10 includes a high-voltage capacitor, a medium-voltage capacitor, and a transient overvoltage measurement module 13. The high-voltage capacitor C1, the medium-voltage capacitor C2, and the transient overvoltage measurement module 13 are connected in series from top to bottom. The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module 13 all use the same insulating medium. By setting C1, C2, and the transient overvoltage measurement module 13 to use the same insulating medium, it is ensured that the three have the same temperature coefficient. When the ambient temperature changes, the capacitance change trends of C1, C2, and the transient overvoltage measurement module 13 are consistent, thereby ensuring that the voltage division ratio from the primary high-voltage end to the low-voltage end of the transient overvoltage measurement module 13 is highly stable throughout the entire operating temperature range, thus improving the voltage measurement accuracy.

[0024] The high-voltage capacitor C1, medium-voltage capacitor C2, and transient overvoltage measurement module 13 all use the same membrane-paper composite dielectric. The absolute value of the temperature coefficient of the high-voltage capacitor, medium-voltage capacitor, and transient overvoltage measurement module 13 is ≤3×10⁻⁶. -4 K -1 This configuration ensures a stable partial pressure ratio across the entire temperature range with an error of less than 3%, achieving homogeneous media, guaranteeing the temperature coefficient, and preventing partial pressure ratio drift.

[0025] Specifically, the transient overvoltage measurement module 13 is composed of multiple sets of capacitors connected in parallel. Under the rated primary voltage, the output power frequency voltage across the transient overvoltage measurement module 13 is 100 / √3 V, forming a pure capacitive voltage divider path with C1 and C2 without inductive components. The transient overvoltage measurement module 13 is a sealed capacitor structure, resulting in a short signal output path, no cable transmission interference, and no electrical connection safety hazards.

[0026] In this implementation, the end of the transient overvoltage measurement module 13 furthest from the medium-voltage capacitor C2 is connected to the secondary terminal block 30 to form a transient measurement circuit. The intermediate voltage of the medium-voltage capacitor C2 is led out and connected to the first end of the intermediate transformer Tr in the electromagnetic unit 20. The multiple secondary windings of the intermediate transformer are all connected to the secondary terminal block 30 to form a power frequency metering circuit. The transient measurement circuit and the power frequency metering circuit do not interfere with each other. With this setting, the transient measurement and power frequency metering dual circuits are led out to avoid interference and ensure the accuracy of transient waveform measurement.

[0027] The multiple secondary windings include secondary winding 1a-1n, secondary winding 2a-2n, secondary winding 3a-3n, and residual voltage winding 4da-dn. Secondary winding 1a-1n, secondary winding 2a-2n, secondary winding 3a-3n, and residual voltage winding 4da-dn output metering, measurement, protection, and residual voltage signals, respectively.

[0028] Specifically, the intermediate voltage of the medium-voltage capacitor C2 is led out and connected to the primary side of the intermediate transformer Tr in the electromagnetic unit 20. The multiple secondary windings of the intermediate transformer are all connected to the secondary terminal block 30 to form a power frequency metering circuit.

[0029] Continue to refer to Figure 1 and Figure 2 In this embodiment, the high-voltage capacitor C1 includes multiple capacitor segments, which are encapsulated in multiple bushings 111. Each bushing 111 is filled with insulating oil 1115. Each bushing 111 includes a porcelain bushing 1111, a top flange 1112, and a bottom flange 1113. The top flange 1112 is sealed to the top of the porcelain bushing 1111, and the bottom flange 1113 is sealed to the bottom of the porcelain bushing 1111. The top flange 1112 is connected to the top of the capacitor segment encapsulated in the bushing 111 via a first cable, and the bottom of the capacitor segment is connected to the bottom flange 1113 via a second cable. Multiple bushings 111 are connected sequentially from top to bottom to connect the multiple capacitor segments in series. The medium-voltage capacitor and the transient overvoltage measurement module 13 are both located in the bottommost bushing 111, and the electromagnetic unit 20 is located at the bottom of the bottommost bushing 111.

[0030] by Figure 1As shown, in this embodiment, the high-voltage capacitor C1 includes three segments: C11, C12, and C13. The C11, C12, and C13 segments are connected in series from top to bottom to form the high-voltage capacitor C1. The C11, C12, and C13 segments are encapsulated in three sleeves 111. The medium-voltage capacitor and the transient overvoltage measurement module 13 are both disposed in the sleeve 111 encapsulating the C13 segment. The C13 segment, the medium-voltage capacitor, and the transient overvoltage measurement module 13 are arranged in sequence from top to bottom. The bottom end of the sleeve 111 encapsulating the C13 segment is connected to the top end of the electromagnetic unit 20.

[0031] Each bushing 111 is equipped with a breathable metal expander 1114, the top of which is connected to the bottom of the top flange 1112. By setting the breathable metal expander 1114, it is connected to the outside atmosphere, which can stably maintain a slight positive pressure inside the porcelain bushing 1111, and prevent negative pressure and air cavities from forming inside the porcelain bushing 1111. The insulating oil 1115 does not come into contact with air or moisture throughout the process, which greatly slows down oil oxidation and moisture deterioration, extends the insulation life of the capacitor element, and prevents moisture intrusion from reducing the insulation strength.

[0032] During use, the insulating oil 1115 will expand and contract due to changes in ambient temperature and equipment operating temperature. The breathing metal expander 1114 has a corrugated elastic metal structure and can expand and contract synchronously with the internal oil pressure: when the temperature rises and the oil volume expands, the breathing metal expander 1114 extends outward to expand its capacity; when the temperature drops and the oil contracts, the breathing metal expander 1114 retracts to replenish its capacity, matching the volume change of the insulating oil 1115 throughout the process and balancing the inner cavity volume of the bushing 111.

[0033] Continue to refer to Figures 1 to 4In this embodiment, the electromagnetic unit 20 includes a housing 21, an intermediate transformer Tr, and a compensating reactor L. The housing 21 is configured to form an accommodating cavity. A connecting flange 22 is provided at the top of the housing 21. The bottom end of the sleeve 111 at the bottom is bolted to the connecting flange 22. A first epoxy lead-out pipe 221 and a second epoxy lead-out pipe 222 are provided on the connecting flange 22. The top ends of the first epoxy lead-out pipe 221 and the second epoxy lead-out pipe 222 are inserted into the sleeve 111 at the bottom, and the bottom ends of the first epoxy lead-out pipe 221 and the second epoxy lead-out pipe 222 are both inserted into the accommodating cavity. The intermediate transformer Tr and the compensating reactor L are both housed in the accommodating cavity. A housing 31 is provided on the outer wall of the outer casing 21. The cavity enclosed by the housing 31 is connected to the accommodating cavity. The secondary terminal block 30 is housed in the cavity. The transient overvoltage measurement module 13 is led out through the first epoxy lead-out pipe 221 and connected to the secondary terminal block 30. The intermediate voltage of the medium voltage capacitor C2 is led out through the second epoxy casting sleeve 111 and connected to the first end of the intermediate transformer Tr. The tail end of the intermediate transformer Tr is connected to the compensating reactor L. The multiple sets of secondary windings of the intermediate transformer Tr are all connected to the secondary terminal block 30.

[0034] Both the first epoxy lead-out pipe 221 and the second epoxy lead-out pipe 222 are integrally cast from epoxy resin.

[0035] Specifically, the bottom flange 1113 in the bottommost bushing 111 is bolted to the connecting flange 22. The intermediate voltage of the medium-voltage capacitor C2 is led out through the second epoxy-cast bushing 111 and connected to the first end of the primary side of the intermediate transformer Tr. The tail end of the primary side of the intermediate transformer Tr is connected to the compensating reactor L.

[0036] The electromagnetic unit 20 also includes a damper D, which is connected in parallel across the remaining voltage winding da-dn.

[0037] Specifically, the electromagnetic unit 20 also includes a surge arrester BL, which is installed in the accommodating cavity. One end of the surge arrester BL is connected to the compensating reactor L, and the other end of the surge arrester BL is grounded.

[0038] The working principle of the capacitive voltage transformer 1 with transient overvoltage measurement function provided in this embodiment is as follows: The working principle of power frequency metering and protection measurement is as follows: Under the normal power frequency operation condition of the power grid, the primary power frequency high voltage is divided by the high voltage capacitor C1 and the medium voltage capacitor C2. The intermediate power frequency voltage is drawn from the low voltage side of the medium voltage capacitor C2. This intermediate voltage is introduced into the bottom electromagnetic unit 20 through the second epoxy lead tube 222 and connected to the primary side of the intermediate transformer Tr. After electromagnetic transformation by the intermediate transformer Tr, the standard power frequency secondary voltage is output by its multiple sets of secondary windings, which respectively supply the power metering, bus voltage measurement, relay protection and residual voltage monitoring equipment. It fully retains all the power frequency functions of the traditional CVT. The transient measurement circuit does not participate in the power frequency transformation process and will not cause any load interference to the power frequency metering and protection circuit.

[0039] Working principle of broadband transient overvoltage measurement: When the power grid experiences high-frequency rapid transient disturbances such as lightning overvoltage or switching overvoltage, the high-frequency transient voltage signal can be transmitted without attenuation through a pure capacitive path composed of C1, C2, and the transient overvoltage measurement module 13. The capacitance value of the transient overvoltage measurement module 13 is precisely matched, and under rated primary voltage conditions, the transient overvoltage measurement module 13 stably outputs a 100 / √3 V power frequency reference voltage across its terminals, while simultaneously measuring the kHz... The high-frequency transient signal has a flat and wide-band transmission characteristic; the acquisition lead of the transient overvoltage measurement module 13 passes through the outer shell 21 separately through the first epoxy lead tube 221 and is directly connected to the secondary terminal block 30 to output the transient signal; while the intermediate voltage of the power frequency supplied by the medium voltage capacitor C2 to the electromagnetic unit 20 is led out by the second epoxy lead tube 222. The two circuits adopt separate epoxy lead tube wiring to achieve physical isolation between the transient measurement circuit and the power frequency metering circuit, and prevent power frequency excitation and harmonic interference from coupling to the transient measurement channel, so as to completely restore the real transient overvoltage waveform; the steady-state harmonic and instantaneous transient overvoltage signals output by the transient overvoltage measurement module 13 are connected to the external waveform recording device and wide-band voltage monitoring equipment through the secondary terminal block 30 to achieve accurate capture and recording of transient overvoltage amplitude, waveform and occurrence frequency.

[0040] The capacitive voltage transformer 1 with transient overvoltage measurement function provided in this application includes a capacitive voltage divider 10, an electromagnetic unit 20, and a secondary terminal block 30. The capacitive voltage divider 10 includes a high-voltage capacitor, a medium-voltage capacitor, and a transient overvoltage measurement module 13. The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module 13 are connected in series from top to bottom. The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module 13 all use the same insulating medium. The end of the transient overvoltage measurement module 13 away from the medium-voltage capacitor is connected to the secondary terminal block 30 to form a transient measurement circuit. The intermediate voltage of the medium-voltage capacitor is led out and connected to the intermediate voltage of the electromagnetic unit 20. The first end of the intermediate transformer is connected, and multiple sets of secondary windings of the intermediate transformer are all connected to the secondary terminal block 30 to form a power frequency metering circuit. The transient measurement circuit and the power frequency metering circuit do not interfere with each other. By setting the high-voltage capacitor, medium-voltage capacitor and transient overvoltage measurement module 13 to use the same insulating medium, it is ensured that the three have the same temperature coefficient. When the ambient temperature changes, the capacitance change trends of the high-voltage capacitor, medium-voltage capacitor and transient overvoltage measurement module 13 are consistent, thereby ensuring that the voltage division ratio from the primary high-voltage end to the low-voltage end of the transient overvoltage measurement module 13 is highly stable throughout the entire operating temperature range, thereby improving the voltage measurement accuracy.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A capacitive voltage transformer with transient overvoltage measurement function, characterized in that: Includes a capacitor voltage divider, an electromagnetic unit, and a secondary terminal block; The capacitive voltage divider includes a high-voltage capacitor, a medium-voltage capacitor, and a transient overvoltage measurement module. The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module are connected in series from top to bottom. The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module all use the same insulating medium. The end of the transient overvoltage measurement module furthest from the medium-voltage capacitor is connected to the secondary terminal block to form a transient measurement circuit; The intermediate voltage of the medium-voltage capacitor is led out and connected to the first end of the intermediate transformer in the electromagnetic unit. The multiple sets of secondary windings of the intermediate transformer are all connected to the secondary terminal block to form a power frequency metering circuit. The transient measurement circuit and the power frequency metering circuit do not interfere with each other. The multiple sets of secondary windings include secondary winding #1, secondary winding #2, secondary winding #3 and residual voltage winding #4.

2. The capacitive voltage transformer with transient overvoltage measurement function according to claim 1, characterized in that: The high-voltage capacitor includes multiple capacitor segments, which are encapsulated in multiple bushings, and each bushing is filled with insulating oil. Each of the bushings includes a porcelain bushing, a top flange, and a bottom flange. The top flange is sealed to the top of the porcelain bushing, and the bottom flange is sealed to the bottom of the porcelain bushing. The top flange is connected to the top of the capacitor segment encapsulated within the bushing via a first cable, and the bottom of the capacitor segment is connected to the bottom flange via a second cable. Multiple bushings are connected sequentially from top to bottom to connect multiple capacitor segments in series. The medium-voltage capacitor and the transient overvoltage measurement module are both located inside the bottommost bushing, and the electromagnetic unit is located at the bottom end of the bottommost bushing.

3. The capacitive voltage transformer with transient overvoltage measurement function according to claim 2, characterized in that: The electromagnetic unit includes a housing, the intermediate transformer, and a compensating reactor. The housing is configured to form a cavity. A connecting flange is provided at the top of the housing. The bottom end of the sleeve located at the bottom is bolted to the connecting flange. A first epoxy lead-out pipe and a second epoxy lead-out pipe are provided on the connecting flange. The top ends of the first epoxy lead-out pipe and the second epoxy lead-out pipe are inserted into the sleeve located at the bottom, and the bottom ends of the first epoxy lead-out pipe and the second epoxy lead-out pipe are both inserted into the cavity. The intermediate transformer and the compensating reactor are both housed within the accommodating cavity. A shell is provided on the outer wall of the outer casing, and the cavity enclosed by the shell communicates with the accommodating cavity. The secondary terminal block is located within the cavity. The transient overvoltage measurement module is led out through a first epoxy lead-out pipe and connected to the secondary terminal block. The intermediate voltage of the medium-voltage capacitor is led out through a second epoxy casting sleeve and connected to the first end of the intermediate transformer. The tail end of the intermediate transformer is connected to the compensating reactor. Multiple sets of secondary windings of the intermediate transformer are all connected to the secondary terminal block.

4. The capacitive voltage transformer with transient overvoltage measurement function according to claim 1, characterized in that: The high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module all use the same film-paper composite dielectric.

5. The capacitive voltage transformer with transient overvoltage measurement function according to claim 1, characterized in that: The absolute value of the temperature coefficient of the high-voltage capacitor, the medium-voltage capacitor, and the transient overvoltage measurement module is ≤3×10⁻⁶. -4 K -1 .

6. The capacitive voltage transformer with transient overvoltage measurement function according to claim 1, characterized in that: The electromagnetic unit also includes a damper, which is connected in parallel across the remaining voltage winding da-dn.

7. The capacitive voltage transformer with transient overvoltage measurement function according to claim 3, characterized in that: The electromagnetic unit also includes a surge arrester, which is disposed within the accommodating cavity. One end of the surge arrester is connected to the compensating reactor, and the other end of the surge arrester is grounded.

8. The capacitive voltage transformer with transient overvoltage measurement function according to claim 2, characterized in that: Each of the sleeves is equipped with a breathable metal expander, the top of which is connected to the bottom surface of the top flange.

9. The capacitive voltage transformer with transient overvoltage measurement function according to claim 3, characterized in that: Both the first epoxy lead-out pipe and the second epoxy lead-out pipe are integrally cast from epoxy resin.

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