Capacitive equipment insulation state monitoring terminal and system

Abstract

The utility model provides a capacitive equipment insulation state monitoring terminal and system, and belongs to the technical field of electric power. The monitoring terminal comprises a current acquisition circuit and a data processing circuit; the current acquisition circuit comprises a current transformer, a surge protection sub-circuit, an IV conversion sub-circuit, a program control amplification sub-circuit, a band-pass filtering sub-circuit and an analog-to-digital conversion sub-circuit. The two input ends of the surge protection sub-circuit are electrically connected with the two output ends of the current transformer, the two output ends of the surge protection sub-circuit are electrically connected with the two input ends of the IV conversion sub-circuit, and the output end of the IV conversion sub-circuit is electrically connected with the input end of the program control amplification sub-circuit. The output end of the program control amplification sub-circuit is electrically connected with the input end of the band-pass filtering sub-circuit, the output end of the band-pass filtering sub-circuit is electrically connected with the input end of the analog-to-digital conversion sub-circuit, and the output end of the analog-to-digital conversion sub-circuit is electrically connected with the input end of the data processing circuit.

Description

Capacitive Equipment Insulation Condition Monitoring Terminal and System Technical Field

[0001] This disclosure relates to the field of power technology, and in particular to a terminal and system for monitoring the insulation status of capacitor-type equipment. Background Technology

[0002] Capacitive equipment accounts for over 40% of the total number of devices in substations, with surge arresters and dry-type current transformers being the two main types. The insulation performance of capacitive equipment directly affects the effectiveness of lightning protection and the safety of equipment operation.

[0003] In related technologies, insulation condition testing methods for capacitive equipment are mainly divided into non-energized testing and energized testing. Among them, non-energized testing relies on periodic power outages for maintenance, requiring personnel to be on-site. This method has problems such as power outage testing, long testing intervals, high safety risks, and difficulty in detecting sudden insulation breakdowns, which can lead to problematic equipment operating energized and even causing more serious accidents. Summary of the Invention

[0004] This disclosure provides a terminal and system for monitoring the insulation status of capacitive equipment, enabling online monitoring of the insulation status of capacitive equipment and avoiding the problems associated with non-energized detection in related technologies. The technical solution is as follows:

[0005] On one hand, at least one embodiment of this disclosure provides a capacitor-type equipment insulation status monitoring terminal, which includes: a current acquisition circuit and a data processing circuit;

[0006] The current acquisition circuit includes a current transformer, a surge protection sub-circuit, an IV conversion sub-circuit, a programmable amplifier sub-circuit, a bandpass filter sub-circuit, and an analog-to-digital converter sub-circuit.

[0007] The two input terminals of the surge protection sub-circuit are electrically connected to the two output terminals of the current transformer. The two output terminals of the surge protection sub-circuit are electrically connected to the two input terminals of the IV conversion sub-circuit. The output terminal of the IV conversion sub-circuit is electrically connected to the input terminal of the programmable amplifier sub-circuit. The output terminal of the programmable amplifier sub-circuit is electrically connected to the input terminal of the bandpass filter sub-circuit. The output terminal of the bandpass filter sub-circuit is electrically connected to the input terminal of the analog-to-digital converter sub-circuit. The output terminal of the analog-to-digital converter sub-circuit is electrically connected to the input terminal of the data processing circuit.

[0008] Optionally, the surge protection sub-circuit includes a first resistor R1, a second resistor R2, a first diode D1, and a second diode D2;

[0009] One end of the first resistor R1 is electrically connected to one output terminal of the current transformer, and one end of the second resistor R2 is electrically connected to the other output terminal of the current transformer.

[0010] The other end of the first resistor R1 is electrically connected to the input terminal of the first diode D1, the output terminal of the second diode D2, and one input terminal of the IV converter sub-circuit, respectively.

[0011] The other end of the second resistor R2 is electrically connected to the output terminal of the first diode D1, the input terminal of the second diode D2, and the other input terminal of the IV converter circuit.

[0012] Optionally, the IV converter sub-circuit includes a first operational amplifier U1 and a third resistor R3;

[0013] The non-inverting input and inverting input of the first operational amplifier U1 are electrically connected to the two outputs of the surge protection sub-circuit, respectively.

[0014] The two ends of the third resistor R3 are electrically connected to the inverting input terminal and the output terminal of the first operational amplifier U1, respectively.

[0015] Optionally, the programmable amplifier sub-circuit includes a fourth resistor R4, a fifth resistor R5, a second operational amplifier U2, a sixth resistor R6, a seventh resistor R7, a third operational amplifier U3, an eighth resistor R8, a ninth resistor R9, a fourth operational amplifier U4, and a multiplexer switch K.

[0016] The multiple-choice switch K includes four input pins Y0 to Y3 and one common pin; the common pin of the multiple-choice switch K is electrically connected to the input terminal of the bandpass filter sub-circuit.

[0017] The input pin Y0 of the multiple-choice switch K, the non-inverting input of the second operational amplifier U2, the non-inverting input of the third operational amplifier U3, and the non-inverting input of the fourth operational amplifier U4 are all electrically connected to the output of the IV converter sub-circuit.

[0018] The output terminal of the second operational amplifier U2 is electrically connected to the input pin Y1 of the multiple-choice switch K, the output terminal of the third operational amplifier U3 is electrically connected to the input pin Y2 of the multiple-choice switch K, and the output terminal of the fourth operational amplifier U4 is electrically connected to the input pin Y3 of the multiple-choice switch K.

[0019] One end of the fourth resistor R4 is grounded, and the other end of the fourth resistor R4 is electrically connected to the inverting input terminal of the second operational amplifier U2 and one end of the fifth resistor R5, respectively. The other end of the fifth resistor R5 is electrically connected to the output terminal of the second operational amplifier U2.

[0020] One end of the sixth resistor R6 is grounded, and the other end of the sixth resistor R6 is electrically connected to the inverting input terminal of the third operational amplifier U3 and one end of the seventh resistor R7, respectively. The other end of the seventh resistor R7 is electrically connected to the output terminal of the third operational amplifier U3.

[0021] One end of the eighth resistor R8 is grounded, and the other end of the eighth resistor R8 is electrically connected to the inverting input terminal of the fourth operational amplifier U4 and one end of the ninth resistor R9, respectively. The other end of the ninth resistor R9 is electrically connected to the output terminal of the fourth operational amplifier U4.

[0022] Optionally, the bandpass filter sub-circuit includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first capacitor C1, a second capacitor C2, and a fifth operational amplifier U5;

[0023] One end of the tenth resistor R10 is electrically connected to the output terminal of the programmable amplifier sub-circuit, and the other end of the tenth resistor R10 is electrically connected to one end of the eleventh resistor R11, one end of the first capacitor C1, and one end of the second capacitor C2, respectively.

[0024] The other end of the eleventh resistor R11 is grounded, the other end of the first capacitor C1 is electrically connected to one end of the twelfth resistor R12 and the output terminal of the fifth operational amplifier U5, and the other end of the second capacitor C2 is electrically connected to the other end of the twelfth resistor R12 and the inverting input terminal of the fifth operational amplifier U5.

[0025] The non-inverting input terminal of the fifth operational amplifier U5 is grounded, and the output terminal of the fifth operational amplifier U5 is electrically connected to the input terminal of the analog-to-digital converter sub-circuit.

[0026] Optionally, the analog-to-digital conversion sub-circuit includes an analog-to-digital converter.

[0027] Optionally, the data processing circuit includes an STM32 microcontroller.

[0028] Optionally, the capacitor-type equipment insulation status monitoring terminal further includes:

[0029] Photovoltaic panels, power management units, and batteries;

[0030] The power management unit is electrically connected to the photovoltaic panel, the battery, and the data processing circuit, respectively.

[0031] Optionally, the capacitor-type equipment insulation status monitoring terminal further includes:

[0032] Synchronization unit and communication unit;

[0033] Both the synchronization unit and the communication unit are electrically connected to the data processing circuit.

[0034] On the other hand, at least one embodiment of this disclosure provides a capacitive device insulation condition monitoring system, which includes a plurality of capacitive device insulation condition monitoring terminals and a smart gateway as described in any of the preceding aspects;

[0035] Multiple capacitor-type equipment insulation status monitoring terminals are connected to the power grid backend server through the smart gateway.

[0036] The beneficial effects of the technical solutions provided in this disclosure are:

[0037] The monitoring terminal provided in this embodiment includes a current acquisition circuit and a data processing circuit. The current acquisition circuit includes a current transformer, a surge protection sub-circuit, an IV converter sub-circuit, a programmable amplifier sub-circuit, a bandpass filter sub-circuit, and an analog-to-digital converter sub-circuit. The current transformer detects the leakage current of capacitive devices through non-contact measurement. The surge protection sub-circuit protects the IV converter sub-circuit. The IV converter sub-circuit converts the current signal output by the capacitive device into a voltage signal, which is amplified by the programmable amplifier sub-circuit. The bandpass filter sub-circuit performs bandpass filtering to filter the amplified signal. The filtered signal is converted into a digital signal by the analog-to-digital converter sub-circuit, and the magnitude of the leakage current is obtained through the data processing circuit. This monitoring terminal can save a lot of manpower, improve work efficiency and safety, and achieve early fault identification. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 is a structural schematic diagram of a capacitive device insulation status monitoring terminal provided in some embodiments of this disclosure;

[0040] Figure 2 is a circuit diagram of a capacitor-type device insulation status monitoring terminal provided in some embodiments of this disclosure;

[0041] Figure 3 is a schematic diagram of the structure of a capacitive device insulation condition monitoring system provided in some embodiments of this disclosure. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0043] Figure 1 is a schematic diagram of the structure of a capacitive device insulation condition monitoring terminal provided in some embodiments of this disclosure. Referring to Figure 1, the capacitive device insulation condition monitoring terminal includes: a current acquisition circuit 101 and a data processing circuit 102.

[0044] Figure 2 is a circuit diagram of a capacitor-type device insulation status monitoring terminal provided in some embodiments of this disclosure. Referring to Figure 2, the current acquisition circuit 101 includes a current transformer 100, a surge protection sub-circuit 111, an IV conversion sub-circuit 112, a programmable amplifier sub-circuit 113, a bandpass filter sub-circuit 114, and an analog-to-digital converter sub-circuit 115.

[0045] The two input terminals of the surge protection subcircuit 111 are electrically connected to the two output terminals of the current transformer 100. The two output terminals of the surge protection subcircuit 111 are electrically connected to the two input terminals of the IV conversion subcircuit 112. The output terminal of the IV conversion subcircuit 112 is electrically connected to the input terminal of the programmable amplifier subcircuit 113. The output terminal of the programmable amplifier subcircuit 113 is electrically connected to the input terminal of the bandpass filter subcircuit 114. The output terminal of the bandpass filter subcircuit 114 is electrically connected to the input terminal of the analog-to-digital converter subcircuit 115. The output terminal of the analog-to-digital converter subcircuit 115 is electrically connected to the input terminal of the data processing circuit 102.

[0046] The monitoring terminal provided in this embodiment includes a current acquisition circuit and a data processing circuit. The current acquisition circuit includes a current transformer, a surge protection sub-circuit, an IV converter sub-circuit, a programmable amplifier sub-circuit, a bandpass filter sub-circuit, and an analog-to-digital converter sub-circuit. The current transformer detects the leakage current of capacitive devices through non-contact measurement. The surge protection sub-circuit protects the IV converter sub-circuit. The IV converter sub-circuit converts the current signal output by the capacitive device into a voltage signal, which is amplified by the programmable amplifier sub-circuit. The bandpass filter sub-circuit performs bandpass filtering to filter the amplified signal. The filtered signal is converted into a digital signal by the analog-to-digital converter sub-circuit, and the magnitude of the leakage current is obtained through the data processing circuit. This monitoring terminal can save a lot of manpower, improve work efficiency and safety, and achieve early fault identification.

[0047] The magnitude of leakage current can indicate the insulation status of capacitive devices.

[0048] In this embodiment of the disclosure, the current transformer 100 is used for coupling connection to measure the leakage current of the capacitive device to be monitored.

[0049] Here, the capacitive device to be monitored can be a surge arrester or a dry-type current transformer (to distinguish it from the 100 in the monitoring terminal, it will be referred to as a dry-type CT device below).

[0050] For surge arresters, a monitoring terminal is installed in parallel on a mechanical discharge counter. The monitoring terminal includes a lead wire, which is connected in parallel with the mechanical discharge counter. The lead wire passes through a current transformer 100, which measures the leakage current of the surge arrester through induction.

[0051] For dry CT equipment, the bottom lead wire of the end screen grounding terminal box of the dry CT equipment is led out and passes through the current transformer 100 inside the monitoring terminal. The current transformer 100 measures the leakage current of the dry CT equipment by sensing.

[0052] In this embodiment of the disclosure, the data processing circuit 102 performs the above-mentioned data processing function as a conventional algorithm function, which will not be described in detail in this embodiment of the disclosure.

[0053] As shown in Figure 2, the surge protection sub-circuit 111 may include a first resistor R1, a second resistor R2, a first diode D1, and a second diode D2.

[0054] One end of the first resistor R1 is electrically connected to one output terminal of the current transformer 100, and one end of the second resistor R2 is electrically connected to the other output terminal of the current transformer 100.

[0055] The other end of the first resistor R1 is electrically connected to the input terminal of the first diode D1, the output terminal of the second diode D2, and one input terminal of the IV converter circuit 112, respectively.

[0056] The other end of the second resistor R2 is electrically connected to the output terminal of the first diode D1, the input terminal of the second diode D2, and the other input terminal of the IV converter circuit 112.

[0057] As shown in Figure 2, the IV converter sub-circuit 112 may include a first operational amplifier U1 and a third resistor R3.

[0058] The non-inverting input and inverting input of the first operational amplifier U1 are electrically connected to the two outputs of the surge protection sub-circuit 111, respectively.

[0059] The two ends of the third resistor R3 are electrically connected to the inverting input terminal and the output terminal of the first operational amplifier U1, respectively.

[0060] The current transformer has a turns ratio of N, and its secondary output current is 1 / N of the primary output current. The surge protection sub-circuit protects the first operational amplifier U1 in the IV converter sub-circuit. Since the maximum output current of the first operational amplifier U1 is generally around 10mA, when the transformer lead of the dry-type CT equipment under test generates a surge current of several thousand amperes due to power grid fluctuations or lightning strikes, the secondary output current of the current transformer reaches the ampere level. If there is no surge protection sub-circuit, the ampere-level current directly input to the first operational amplifier U1 will cause the first operational amplifier U1 to burn out.

[0061] When the surge protection sub-circuit is connected, the first resistor R1 and the second resistor R2 constitute the secondary circuit load resistor of the current transformer. When a surge current is generated, the first resistor R1 and the second resistor R2 can limit the current.

[0062] At the same time, the input voltage of the first operational amplifier U1 is clamped to a safe value by the first diode D1 and the second diode D2, thus protecting the input terminal of the first operational amplifier U1 from both current limiting and voltage clamping aspects.

[0063] The resistance values ​​of the first resistor R1 and the second resistor R2 are relatively large. When the current transformer is working normally, its secondary output current is small, and the influence of the first resistor R1 and the second resistor R2 on the secondary output current of the current transformer is negligible. The IV converter circuit can convert the secondary output current of the current transformer into a voltage signal, as shown in the following formula:

[0064] V=I*R3 (1)

[0065] Where I is the secondary current value of the current transformer, and R3 is the resistance value of the third resistor R3.

[0066] As shown in Figure 2, the programmable amplifier sub-circuit 113 may include a fourth resistor R4, a fifth resistor R5, a second operational amplifier U2, a sixth resistor R6, a seventh resistor R7, a third operational amplifier U3, an eighth resistor R8, a ninth resistor R9, a fourth operational amplifier U4, and a multiplexer switch K.

[0067] The multiple-choice switch K includes four input pins Y0 to Y3 and one common pin; the common pin of the multiple-choice switch K is electrically connected to the input terminal of the bandpass filter sub-circuit 114.

[0068] The input pin Y0 of the multiple-choice switch K, the non-inverting input of the second operational amplifier U2, the non-inverting input of the third operational amplifier U3, and the non-inverting input of the fourth operational amplifier U4 are all electrically connected to the output of the IV converter circuit 112.

[0069] The output terminal of the second operational amplifier U2 is electrically connected to the input pin Y1 of the multiple-choice switch K, the output terminal of the third operational amplifier U3 is electrically connected to the input pin Y2 of the multiple-choice switch K, and the output terminal of the fourth operational amplifier U4 is electrically connected to the input pin Y3 of the multiple-choice switch K.

[0070] One end of the fourth resistor R4 is grounded, and the other end of the fourth resistor R4 is electrically connected to the inverting input terminal of the second operational amplifier U2 and one end of the fifth resistor R5, respectively. The other end of the fifth resistor R5 is electrically connected to the output terminal of the second operational amplifier U2.

[0071] One end of the sixth resistor R6 is grounded, and the other end of the sixth resistor R6 is electrically connected to the inverting input terminal of the third operational amplifier U3 and one end of the seventh resistor R7, respectively. The other end of the seventh resistor R7 is electrically connected to the output terminal of the third operational amplifier U3.

[0072] One end of the eighth resistor R8 is grounded, and the other end of the eighth resistor R8 is electrically connected to the inverting input terminal of the fourth operational amplifier U4 and one end of the ninth resistor R9, respectively. The other end of the ninth resistor R9 is electrically connected to the output terminal of the fourth operational amplifier U4.

[0073] Among them, the amplification factors of the branches containing the second operational amplifier U2, the third operational amplifier U3, and the fourth operational amplifier U4 are different, for example, 10 times, 100 times, and 1000 times respectively.

[0074] When the common pin of the multi-selector switch is connected to the input pin Y0 of the multi-selector switch, the voltage signal of the IV converter circuit 112 is not amplified. When the common output Z of the multi-selector switch is connected to the input pin Y1 of the multi-selector switch, the voltage signal is amplified tenfold. When the common output Z of the multi-selector switch is connected to the input pin Y2 of the multi-selector switch, the voltage signal is amplified one hundredfold. When the common output Z of the multi-selector switch is connected to the input pin Y3 of the multi-selector switch, the voltage signal is amplified one thousandfold.

[0075] The programmable amplifier sub-circuit 113 can be used to switch between different amplifier circuits to achieve programmable gain control.

[0076] In this embodiment, the programmable amplifier sub-circuit 113 performs the above-mentioned program control function as a conventional control function, which will not be described in detail in this embodiment.

[0077] As shown in Figure 2, the bandpass filter sub-circuit 114 may include a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first capacitor C1, a second capacitor C2, and a fifth operational amplifier U5.

[0078] One end of the tenth resistor R10 is electrically connected to the output terminal of the programmable amplifier sub-circuit 113, and the other end of the tenth resistor R10 is electrically connected to one end of the eleventh resistor R11, one end of the first capacitor C1 and one end of the second capacitor C2, respectively.

[0079] The other end of the eleventh resistor R11 is grounded, the other end of the first capacitor C1 is electrically connected to one end of the twelfth resistor R12 and the output terminal of the fifth operational amplifier U5, and the other end of the second capacitor C2 is electrically connected to the other end of the twelfth resistor R12 and the inverting input terminal of the fifth operational amplifier U5.

[0080] The non-inverting input terminal of the fifth operational amplifier U5 is grounded, and the output terminal of the fifth operational amplifier U5 is electrically connected to the input terminal of the analog-to-digital converter sub-circuit 115.

[0081] The bandpass filter circuit is implemented by the above-mentioned bandpass filter sub-circuit 114, which retains only the target frequency signal of the test, and the signals higher or lower than the target frequency will be filtered out.

[0082] As shown in Figure 2, the analog-to-digital conversion sub-circuit 115 may include an analog-to-digital converter. The analog-to-digital converter converts the filtered voltage signal into a digital signal for subsequent calculation by the data calculation module.

[0083] In this embodiment of the disclosure, the data processing circuit 102 may include an STM32 microcontroller.

[0084] It should be noted that the circuit structure shown in Figure 2 is only an example. In other embodiments, each sub-circuit may include more or fewer electrical components.

[0085] Referring again to Figure 1, the capacitor-type equipment insulation status monitoring terminal further includes:

[0086] Photovoltaic panel 103, power management unit 104 and battery 105.

[0087] The power management unit 104 is electrically connected to the photovoltaic panel 103, the battery 105 and the data processing circuit 102 respectively.

[0088] Photovoltaic panels convert light energy into electrical energy, use a power management unit to charge the battery, and then use the battery to power the data processing circuit.

[0089] Battery 105 can be a lithium battery.

[0090] Referring again to Figure 1, the capacitor-type equipment insulation status monitoring terminal further includes:

[0091] Synchronization unit 106 and communication unit 107.

[0092] Both the synchronization unit 106 and the communication unit 107 are electrically connected to the data processing circuit 102.

[0093] By receiving a unified trigger acquisition command through the synchronization unit, data synchronous acquisition of different capacitor-type devices on the same busbar can be realized, such as synchronous acquisition of leakage current of surge arresters and dry-type current transformers. The communication unit connects to the smart gateway and reports the data to the smart gateway.

[0094] Among them, the communication unit 107 can be a long-range (LoRa) communication unit.

[0095] Figure 3 is a schematic diagram of the structure of a capacitive device insulation condition monitoring system provided in some embodiments of this disclosure. Referring to Figure 3, the capacitive device insulation condition monitoring system includes multiple capacitive device insulation condition monitoring terminals 10 and intelligent gateways 20 as shown in Figures 1 and 2.

[0096] Multiple capacitor-type equipment insulation status monitoring terminals 10 are connected to the power grid backend server through the smart gateway 20.

[0097] The aforementioned monitoring terminals can monitor different capacitive devices on the same busbar separately, such as surge arresters and dry-type current transformers, with monitoring terminals deployed separately.

[0098] As shown in Figure 3, the intelligent gateway 20 includes a security gateway and an encryption module. The intelligent gateway encrypts the data reported by the capacitor-type equipment insulation status monitoring terminal and then securely transmits the data to the power grid backend server.

[0099] This system can also automatically upload and centrally manage leakage current data of capacitive equipment, achieving the goal of digital transformation in the monitoring of insulation status of capacitive equipment.

[0100] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A capacitor-type equipment insulation condition monitoring terminal, characterized in that, The capacitor-type equipment insulation status monitoring terminal includes: a current acquisition circuit (101) and a data processing circuit (102); the current acquisition circuit (101) includes a current transformer (100), a surge protection sub-circuit (111), an IV conversion sub-circuit (112), a programmable amplifier sub-circuit (113), a bandpass filter sub-circuit (114), and an analog-to-digital converter sub-circuit (115); the two input terminals of the surge protection sub-circuit (111) are electrically connected to the two output terminals of the current transformer (100), and the two output terminals of the surge protection sub-circuit (111) are... One output terminal is electrically connected to the two input terminals of the IV conversion sub-circuit (112). The output terminal of the IV conversion sub-circuit (112) is electrically connected to the input terminal of the programmable amplifier sub-circuit (113). The output terminal of the programmable amplifier sub-circuit (113) is electrically connected to the input terminal of the bandpass filter sub-circuit (114). The output terminal of the bandpass filter sub-circuit (114) is electrically connected to the input terminal of the analog-to-digital converter sub-circuit (115). The output terminal of the analog-to-digital converter sub-circuit (115) is electrically connected to the input terminal of the data processing circuit (102).

2. The capacitor-type equipment insulation status monitoring terminal according to claim 1, characterized in that, The surge protection sub-circuit (111) includes a first resistor R1, a second resistor R2, a first diode D1, and a second diode D2; one end of the first resistor R1 is electrically connected to one output terminal of the current transformer (100), and one end of the second resistor R2 is electrically connected to the other output terminal of the current transformer (100); the other end of the first resistor R1 is electrically connected to the input terminal of the first diode D1, the output terminal of the second diode D2, and one input terminal of the IV conversion sub-circuit (112); the other end of the second resistor R2 is electrically connected to the output terminal of the first diode D1, the input terminal of the second diode D2, and the other input terminal of the IV conversion sub-circuit (112).

3. The capacitor-type equipment insulation status monitoring terminal according to claim 1, characterized in that, The IV conversion sub-circuit (112) includes a first operational amplifier U1 and a third resistor R3; the non-inverting input terminal and the inverting input terminal of the first operational amplifier U1 are electrically connected to the two output terminals of the surge protection sub-circuit (111), respectively; the two ends of the third resistor R3 are electrically connected to the inverting input terminal and the output terminal of the first operational amplifier U1, respectively.

4. The capacitor-type equipment insulation status monitoring terminal according to claim 1, characterized in that, The programmable amplifier subcircuit (113) includes a fourth resistor R4, a fifth resistor R5, a second operational amplifier U2, a sixth resistor R6, a seventh resistor R7, a third operational amplifier U3, an eighth resistor R8, a ninth resistor R9, a fourth operational amplifier U4, and a multiplexer switch K. The multiplexer switch K includes four input pins Y0 to Y3 and a common pin. The common pin of the multiplexer switch K is electrically connected to the input terminal of the bandpass filter subcircuit (114). The input pin Y0 of the multiplexer switch K, the non-inverting input terminal of the second operational amplifier U2, the non-inverting input terminal of the third operational amplifier U3, and the non-inverting input terminal of the fourth operational amplifier U4 are all electrically connected to the output terminal of the IV conversion subcircuit (112). The output terminal of the second operational amplifier U2 is electrically connected to the input pin Y1 of the multiplexer switch K, and the output terminal of the third operational amplifier U3 is electrically connected to the input pin Y2 of the multiplexer switch K. The output terminal of the fourth operational amplifier U4 is electrically connected to the input pin Y3 of the multiplexer K; one end of the fourth resistor R4 is grounded, and the other end of the fourth resistor R4 is electrically connected to the inverting input terminal of the second operational amplifier U2 and one end of the fifth resistor R5, and the other end of the fifth resistor R5 is electrically connected to the output terminal of the second operational amplifier U2; one end of the sixth resistor R6 is grounded, and the other end of the sixth resistor R6 is electrically connected to the inverting input terminal of the third operational amplifier U3 and one end of the seventh resistor R7, and the other end of the seventh resistor R7 is electrically connected to the output terminal of the third operational amplifier U3; one end of the eighth resistor R8 is grounded, and the other end of the eighth resistor R8 is electrically connected to the inverting input terminal of the fourth operational amplifier U4 and one end of the ninth resistor R9, and the other end of the ninth resistor R9 is electrically connected to the output terminal of the fourth operational amplifier U4.

5. The capacitor-type equipment insulation status monitoring terminal according to claim 1, characterized in that, The bandpass filter sub-circuit (114) includes a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first capacitor C1, a second capacitor C2, and a fifth operational amplifier U5. One end of the tenth resistor R10 is electrically connected to the output terminal of the programmable amplifier sub-circuit (113), and the other end of the tenth resistor R10 is electrically connected to one end of the eleventh resistor R11, one end of the first capacitor C1, and one end of the second capacitor C2. The other end of the eleventh resistor R11 is grounded. The other end of the first capacitor C1 is electrically connected to one end of the twelfth resistor R12 and the output terminal of the fifth operational amplifier U5. The other end of the second capacitor C2 is electrically connected to the other end of the twelfth resistor R12 and the inverting input terminal of the fifth operational amplifier U5. The non-inverting input terminal of the fifth operational amplifier U5 is grounded, and the output terminal of the fifth operational amplifier U5 is electrically connected to the input terminal of the analog-to-digital converter sub-circuit (115).

6. The capacitor-type equipment insulation status monitoring terminal according to any one of claims 1 to 5, characterized in that, The analog-to-digital converter sub-circuit (115) includes an analog-to-digital converter.

7. The capacitor-type equipment insulation status monitoring terminal according to any one of claims 1 to 5, characterized in that, The data processing circuit (102) includes an STM32 microcontroller.

8. The capacitor-type equipment insulation status monitoring terminal according to any one of claims 1 to 5, characterized in that, The capacitor-type equipment insulation status monitoring terminal also includes: a photovoltaic panel (103), a power management unit (104), and a battery (105); the power management unit (104) is electrically connected to the photovoltaic panel (103), the battery (105), and the data processing circuit (102), respectively.

9. The capacitor-type equipment insulation status monitoring terminal according to any one of claims 1 to 5, characterized in that, The capacitor-type equipment insulation status monitoring terminal further includes a synchronization unit (106) and a communication unit (107); both the synchronization unit (106) and the communication unit (107) are electrically connected to the data processing circuit (102).

10. A capacitor-type equipment insulation condition monitoring system, characterized in that, The capacitor-type equipment insulation status monitoring system includes multiple capacitor-type equipment insulation status monitoring terminals (10) as described in any one of claims 1 to 9 and an intelligent gateway (20); the multiple capacitor-type equipment insulation status monitoring terminals (10) are connected to the power grid backend server through the intelligent gateway (20).

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