Partial discharge monitor supporting frequency sweeping and frequency selecting functions

Abstract

The utility model discloses a partial discharge monitor which is used for monitoring partial discharge in a power system and supports a frequency sweeping and selecting function, the partial discharge monitor comprises a shell, a mainboard and a UHF antenna, and the mainboard is provided with a processor, a frequency sweeping and selecting device and a UHF antenna interface. The UHF antenna is connected to the UHF antenna interface, and transmits a received UHF high-frequency electromagnetic wave signal to the sweep frequency selector through the UHF antenna interface and the mainboard circuit. The frequency sweep frequency selector performs frequency sweep on the received UHF high-frequency electromagnetic wave signal under the control of the processor and transmits a frequency sweep signal to the processor; and the processor determines a specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by the partial discharge monitor, and controls the sweep frequency selector to select the specific frequency band for receiving the UHF high-frequency electromagnetic wave signal so as to monitor the UHF high-frequency electromagnetic wave signal caused by partial discharge in the specific frequency band. According to the utility model, frequency sweeping and frequency selection can be carried out on monitoring signals, so that UHF high-frequency electromagnetic wave signals are prevented from being influenced by environmental noise and interference signals to a great extent, and the false alarm rate is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of fault detection in power systems, and particularly relates to a partial discharge monitor supporting a frequency sweeping and frequency selection function. Background Art

[0002] In scenarios such as industrial production and civil life, the power system is an essential and important component; ensuring the safe and stable operation of the power system is an important way to ensure the sound development of various industrial productions and livelihood projects. China's power system and power Internet of Things system are in a stage of rapid development, and the scale of the power system and the commissioning of related facilities are both increasing rapidly. The power system and power Internet of Things system have put forward higher requirements for the safety, stability, reliability, and economy of power equipment; among them, the insulation performance of power equipment is related to the stable operation of the entire power system. Partial discharge is one of the important manifestations of the lack of insulation performance of power equipment. Among various fault manifestations in the power system, the proportion of partial discharge in fault manifestations exceeds 80%. Partial discharge is also the main factor affecting the insulation performance of power equipment. Each partial discharge will cause the insulation performance of power equipment to decline to varying degrees. Monitoring partial discharge is the main method to test the insulation performance of power equipment.

[0003] During the process of partial discharge in electrical equipment, an ultra-wideband high-frequency electromagnetic wave signal will be generated. By monitoring and analyzing this high-frequency electromagnetic wave signal, the partial discharge state of the electrical equipment can be reflected. Existing UHF detection devices mainly detect electromagnetic wave signals in the range of 300 - 1500Mhz. Since the monitoring environment contains environmental noise and electromagnetic wave interference signals in various frequency bands (such as various communication frequency bands), the UHF detection device will collect environmental noise and interference signals together. When the interference signal increases, the detection processing will obtain a relatively high output of power value. Thus, even if there is no partial discharge in the power system, the UHF detection device still feeds back partial discharge alarm information, resulting in false alarm phenomena.

[0004] The utility model patent with the authorization announcement number of CN219641854U proposes a superheterodyne receiver for partial discharge detection based on UHF frequency sweeping, including a band selection filter for suppressing time-domain frequency interference during frequency conversion. The band selection filter is electrically connected to a low-noise amplifier for small-energy electromagnetic signals. The low-noise amplifier is electrically connected to a first frequency conversion unit. The first frequency conversion unit is electrically connected to a bandwidth and gain control unit one. The bandwidth and gain control unit one is electrically connected to a second frequency conversion unit. The second frequency conversion unit is electrically connected to a bandwidth and gain control unit two. However, this patent only extracts the phase and amplitude of the partial discharge signal to reduce the requirements and data volume of the data acquisition system, achieving the purpose of both detecting signals and reducing the technical requirements and costs of the detection system, and cannot suppress environmental noise and interference signals through frequency selection. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] The main technical problem to be solved by the present utility model is that the existing partial discharge monitor cannot perform frequency sweeping and frequency selection, so that when detecting the UHF high-frequency electromagnetic wave signal generated by partial discharge, it is greatly affected by environmental noise and interference signals, and the probability of false alarm is relatively high.

[0007] (2) Technical solution

[0008] To solve the above technical problems, the present utility model provides a partial discharge monitor supporting frequency sweeping and frequency selection functions for monitoring partial discharge in a power system, which includes a housing, a main board and a UHF antenna. A processor, a frequency sweeping and frequency selection device and a UHF antenna interface are provided on the main board. The UHF antenna is connected to the UHF antenna interface, and the received UHF high-frequency electromagnetic wave signal is transmitted to the frequency sweeping and frequency selection device through the UHF antenna interface and the main board circuit; the frequency sweeping and frequency selection device is connected to the processor through the main board circuit, and under the control of the processor, performs frequency sweeping on the received UHF high-frequency electromagnetic wave signal, and transmits a frequency sweeping signal to the processor; the processor is used to determine a specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by the partial discharge monitor, and control the frequency sweeping and frequency selection device to select a specific frequency band for receiving the UHF high-frequency electromagnetic wave signal, so as to monitor the UHF high-frequency electromagnetic wave signal caused by partial discharge in the specific frequency band.

[0009] According to a preferred embodiment of the present utility model, the processor determines the specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by the partial discharge monitor in the absence of partial discharge. This process is used as a passive calibration process and is performed before monitoring the UHF high-frequency electromagnetic wave signal caused by partial discharge in the specific frequency band.

[0010] According to a preferred embodiment of the present utility model, an electromagnetic wave transmitting and frequency selection device and an electromagnetic wave transmitting antenna interface are further provided on the main board; the partial discharge monitor further includes an electromagnetic wave transmitting antenna; the electromagnetic wave transmitting and frequency selection device is connected to the processor through the main board circuit, and under the control of the processor, generates a transmission signal with a specific frequency and transmits it to the electromagnetic wave transmitting antenna interface through the main board circuit;

[0011] The electromagnetic wave transmitting antenna is connected to the electromagnetic wave transmitting antenna interface, and converts the transmission signal with the specific frequency into a simulated UHF high-frequency electromagnetic wave signal for transmission.

[0012] According to a preferred embodiment of the present utility model, while the processor controls the electromagnetic wave emission frequency selector and the electromagnetic wave emission antenna to work, it enables the UHF antenna and the sweep frequency selector to perform frequency selection for receiving UHF high-frequency electromagnetic wave signals, so as to receive the UHF high-frequency electromagnetic wave signals of the specific frequency band for active calibration.

[0013] According to a preferred embodiment of the present utility model, the processor processes the UHF high-frequency electromagnetic wave signals of the specific frequency band for active calibration. This process serves as the active calibration process, which is carried out after the passive calibration process and before monitoring the UHF high-frequency electromagnetic wave signals caused by partial discharge in this specific frequency band.

[0014] According to a preferred embodiment of the present utility model, a first AD converter is further provided on the main board, which is respectively connected to the sweep frequency selector and the processor through the main board circuit; after receiving the UHF high-frequency electromagnetic wave signals of the specific frequency band selected by the sweep frequency selector, the first AD converter performs AD conversion and transmits it to the processor.

[0015] According to a preferred embodiment of the present utility model, the ADC is a multi-channel ADC, and the specific frequency band is multiple frequency bands.

[0016] According to a preferred embodiment of the present utility model, a detector is further provided on the main board, which is respectively connected to the sweep frequency selector and the processor through the main board circuit; after receiving the UHF high-frequency electromagnetic wave signals of the specific frequency band selected by the sweep frequency selector, the detector performs detection processing to obtain the relative power value of the UHF high-frequency electromagnetic wave signals of the specific frequency band and transmits it to the processor.

[0017] According to a preferred embodiment of the present utility model, the detector is a multi-channel detector, and the specific frequency band is multiple frequency bands.

[0018] According to a preferred embodiment of the present utility model, a first filter and a first automatic gain control circuit are further provided on the main board; the first filter is connected to the UHF antenna interface through the main board circuit and is used for filtering the UHF high-frequency electromagnetic wave signals received by the UHF antenna interface; the first automatic gain control circuit is connected to the first filter and the sweep frequency selector through the main board circuit and is used for automatically controlling the gain of the filtered UHF high-frequency electromagnetic wave signals and then transmitting them to the sweep frequency selector.

[0019] (III) Beneficial effects

[0020] The partial discharge monitor proposed by the present utility model can perform frequency sweeping and frequency selection, thereby enabling passive calibration and / or active calibration, so as to greatly avoid the influence of the UHF high-frequency electromagnetic wave signal received by the partial discharge monitor from environmental noise and interference signals, improve the accuracy of detecting the UHF high-frequency signal caused by partial discharge, and reduce the false alarm rate. Description of the Drawings

[0021] Figure 1 is an exploded view of the structure of a partial discharge monitor supporting the frequency sweeping and frequency selection functions according to an embodiment of the present utility model;

[0022] Figure 2 is Figure 1 the component circuit diagram of the partial discharge monitor supporting the frequency sweeping and frequency selection functions of the embodiment of Detailed Embodiment

[0023] To solve the above technical problems, the present utility model proposes a partial discharge monitor supporting the frequency sweeping and frequency selection functions for monitoring partial discharge in a power system. In addition to having a housing and a main board, the partial discharge monitor is also configured with a UHF antenna, and a processor, a frequency sweeping and frequency selection device, and a UHF antenna interface are provided on the main board, and the UHF antenna is connected to the UHF antenna interface.

[0024] The frequency sweeping and frequency selection device sweeps the received UHF high-frequency electromagnetic wave signal under the control of the processor and transmits the frequency sweeping signal to the processor. Thus, the processor can determine the specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by this partial discharge monitor, and control the frequency sweeping and frequency selection device to select the specific frequency band for receiving the UHF high-frequency electromagnetic wave signal, so as to monitor the UHF high-frequency electromagnetic wave signal caused by partial discharge in this specific frequency band.

[0025] The processor determines the specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by this partial discharge monitor in the absence of partial discharge. This process is used as the process of passive calibration and is carried out before monitoring the UHF high-frequency electromagnetic wave signal caused by partial discharge in this specific frequency band.

[0026] As a preferred embodiment, the partial discharge monitor further includes an electromagnetic wave transmitting antenna. The electromagnetic wave transmitting frequency selector is connected to the processor through the main board circuit, generates a transmission signal of a specific frequency under the control of the processor, and transmits it to the electromagnetic wave transmitting antenna interface through the main board circuit. The electromagnetic wave transmitting antenna is connected to the electromagnetic wave transmitting antenna interface and converts the transmission signal of the specific frequency into a simulated UHF high-frequency electromagnetic wave signal for transmission. While the processor controls the electromagnetic wave transmitting frequency selector and the electromagnetic wave transmitting antenna to work, it enables the UHF antenna and the frequency sweeping and frequency selecting device to select frequencies for receiving UHF high-frequency electromagnetic wave signals, so as to receive the UHF high-frequency electromagnetic wave signals of the specific frequency band for active calibration. The processor then processes the UHF high-frequency electromagnetic wave signals of the specific frequency band for active calibration. Therefore, this process is used as the active calibration process, which is carried out after the passive calibration process and before monitoring the UHF high-frequency electromagnetic wave signals caused by partial discharge in this specific frequency band.

[0027] It can be seen that the partial discharge monitor of the present invention can perform frequency sweeping and frequency selection, thereby enabling passive calibration and / or active calibration of the UHF high-frequency electromagnetic wave detection device, greatly avoiding the influence of UHF high-frequency electromagnetic wave signals by environmental noise and interference signals, thus greatly improving the accuracy of detecting UHF high-frequency signals caused by partial discharge and reducing the false alarm rate.

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the following further elaborates on the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0029] Figure 1 is a structural decomposition diagram of a partial discharge monitor supporting the frequency sweeping and frequency selection functions according to an embodiment of the present invention. As Figure 1 shown, the partial discharge monitor of this embodiment includes a main board 1 and a housing for accommodating the main board. The housing includes a top cover 2 and a bottom cover 3. The main board 1 is fixed by support members and fixing members inside the top cover 2 and the bottom cover 3. Since the support and fixing methods are all conventional means in the art and can be designed according to the actual shape of the device, the details will not be elaborated here.

[0030] The overall shape of the partial discharge monitor is a cuboid. The top cover 2 and the bottom cover 3 are buckled relative to each other, and the main board 1 is also square as a whole, with a size slightly smaller than the top cover 2 and the bottom cover 3. Various components or component interfaces are arranged on one side of the main board 1. It should be understood that the overall shapes of the partial discharge monitor, the housing, and the main board can all be changed and can be adjusted to various required shapes according to actual needs.

[0031] In addition to the main board 1 and the housing, the partial discharge monitor of this embodiment further includes a UHF antenna 14. UHF refers to "ultra-high frequency". The UHF antenna is used to receive UHF high-frequency electromagnetic wave signals. It should be noted that the UHF high-frequency electromagnetic wave signals referred to in the present utility model refer to electromagnetic wave signals with a frequency range between 300 MHz and 3 GHz. The high-frequency electromagnetic wave signals generated by partial discharge in the range of 300 MHz to 3 GHz are transient signals in the time domain and ultra-wideband signals in the frequency domain.

[0032] See again Figure 1 , on the main board 1, there are provided a processor 11, a frequency-sweeping and frequency-selecting device 12, a UHF antenna interface 13, a first analog-to-digital converter (ADC) 18, a detector 19, a first filter 20, and a first automatic gain control circuit 21. The UHF antenna 14 is connected to the UHF antenna interface 13. Thus, the UHF high-frequency electromagnetic wave signals received by the UHF antenna are transmitted to the first filter 20 through the UHF antenna interface 13 and the main board circuit.

[0033] The first filter 20 is a band-pass filter, which only allows electromagnetic wave signals within this range to pass through. For example, if a frequency band range of 300 - 2200 MHz is configured, and if other frequency band ranges are required, the band-pass filter can be adjusted. The first filter 20 is connected to the first automatic gain control circuit 21 through the main board circuit, and transmits the filtered signal to the first automatic gain control circuit 21.

[0034] The first automatic gain control circuit 21 performs gain or attenuation processing on the signals output by the first filter 20. Specifically, the first automatic gain control circuit 21 automatically detects whether the intensity of the collected electromagnetic wave signals is too high or too low. For electromagnetic waves with too high signal energy, automatic attenuation processing is performed to prevent damage to the subsequent circuits; for electromagnetic waves with relatively low signal intensity, automatic gain processing is performed to facilitate the analysis and processing of subsequent circuits. The first automatic gain control circuit 21 is connected to the frequency-sweeping and frequency-selecting device 12 through the main board circuit, and transmits the signals after automatic gain control to the frequency-sweeping and frequency-selecting device 12.

[0035] The frequency-sweeping and frequency-selecting device 12 is connected to the processor through the main board circuit, and starts the "frequency-sweeping function" or "frequency-band selection function" under the control of the processor 11. The processor 11 can be an MCU or a CPU. When the processor 11 controls the frequency-sweeping and frequency-selecting device 12 to perform the frequency-sweeping working mode, the frequency-sweeping and frequency-selecting device 12 outputs broadband range electromagnetic wave signals (such as broadband signals in the range of 300 - 2200 MHz) adjusted by the first automatic gain control circuit 21. On the one hand, the electromagnetic wave signals in the range of 300 - 2200 MHz output by the frequency-sweeper enter the detector 19 for the average power output of the signals, and on the other hand, they are subjected to time-domain digital acquisition through the first analog-to-digital converter 18 for subsequent digital signal analysis and processing.

[0036] The processor 11 performs frequency sweeping on the UHF high-frequency electromagnetic wave signals in the range of 300 - 2200 MHz and then conducts time-domain and frequency-domain analysis to obtain the characteristic parameters of the 300 - 2200 MHz signals. After multiple measurements, the data characteristics of such frequency-swept signals are used as the calibration parameters for environmental noise and interference signals. This calibration process is simply referred to as "passive calibration" in the present utility model. The specific calibration method is a conventional means in the art and will not be elaborated here.

[0037] According to the frequency band distribution of the calibrated environmental noise and interference signals, the processor 11 actively configures the operating parameters of the frequency-sweeping and frequency-selecting device 12, so that the frequency-sweeping and frequency-selecting device 12 avoids a large amount of output of environmental noise and interference signals, and selects a frequency band that can not only detect the partial discharge UHF signals but also maximize the avoidance of background noise and environmental interference signals. For example, the selection of 4 frequency bands of ch1: 330 - 350 MHz, ch2: 660 - 700 MHz, ch3: 1400 - 1460 MHz, and ch4: 1790 - 1850 MHz. The actual number of frequency bands and the frequency band width are adjusted according to the environmental noise and interference signals at the application site. The multi-band UHF high-frequency electromagnetic wave signals output after being selected by the frequency-sweeping and frequency-selecting device 12 have a high signal-to-noise ratio. On the one hand, these signals enter the detector 19 to output the relative power values of the multi-band UHF signals. On the other hand, they enter the first AD converter 18 for time-domain waveform acquisition. At this time, the detected power values and time-domain waveform data of the UHF signals obtained by the processor 11 can maximize the avoidance of the influence of the interference machine background noise, thereby improving the signal-to-noise ratio and monitoring accuracy of the entire partial discharge monitor and reducing false alarms.

[0038] Since the specific frequency bands determined by the present utility model may be multiple frequency bands, therefore, the first AD converter 18 in this embodiment is a multi-channel high-speed AD converter, and the detector 19 is a multi-channel detector.

[0039] In this embodiment, the partial discharge monitor further includes an electromagnetic wave transmitting antenna 17. At the same time, an electromagnetic wave transmitting frequency selector 15 and an electromagnetic wave transmitting antenna interface 16 are also provided on the main board 1. The electromagnetic wave transmitting frequency selector 15 is connected to the processor 11 through the main board circuit, generates a transmission signal with a specific frequency under the control of the processor, and transmits it to the electromagnetic wave transmitting antenna interface 16 through the main board circuit.

[0040] The electromagnetic wave transmitting antenna 17 is connected to the electromagnetic wave transmitting antenna interface 16, and converts the transmitting signal of a specific frequency into an analog UHF high-frequency electromagnetic wave signal for transmission. The electromagnetic wave transmitting frequency selector 15 can, under the control of the processor 11, select electromagnetic wave signals in a specific frequency band and transmit them externally through the electromagnetic wave transmitting antenna 17. The transmitted frequency band range and the number of frequency bands can be configured and adjusted. For example, the electromagnetic wave transmitting frequency selector 15 selects electromagnetic wave signals of 4 channels under the control of the processor 11: ch1: 330~350 MHz, ch2: 660~700 MHz, ch3: 1400~1460 MHz, ch4: 1790~1850 MHz; after the signals of these 4 frequency bands are transmitted externally through the electromagnetic wave transmitting antenna 17, the processor 11 controls the sweep frequency selector 12 of the control system to work, and the working mode is the same as the two monitoring modes of "sweeping frequency" and "selecting frequency" monitoring mentioned above.

[0041] In this embodiment, electromagnetic wave signals of a specific frequency band and the number of frequency bands are actively selected and transmitted into the monitoring environment, and the UHF signal characteristics collected by the device are collected when the transmitted electromagnetic wave signals coexist with environmental noise and interference signals, and the signal characteristics are recorded. The process of calibrating the UHF high-frequency electromagnetic wave signal characteristics is called "active calibration". By actively transmitting high-frequency electromagnetic wave signals in the frequency band where partial discharge exists, the monitoring state of partial discharge signals under environmental noise and interference conditions is simulated. The specific calibration method belongs to the conventional technology in this field and will not be elaborated here.

[0042] Figure 2 is Figure 1 The component circuit diagram of the partial discharge monitor supporting the sweep frequency and frequency selection functions in the embodiment. Also refer to Figure 1 and Figure 2 It can be seen that the partial discharge monitor in this embodiment further includes a TEV antenna 31, a voiceprint MIC 41, a UWB communication module 51, a memory 61, as well as a second filter 32, a second automatic gain control circuit 33 and a second AD converter 34.

[0043] The TEV antenna 31, the second filter 32, the second automatic gain control circuit 33 and the second AD converter 34 are used for monitoring TEV (local wave) caused by partial discharge. The TEV antenna 31 is used to collect the TEV signal generated along with the partial discharge. The functions of the second filter 32 and the second automatic gain control circuit 33 are similar to those of the first filter 20 and the first automatic gain control circuit 21, mainly for frequency selection and power adjustment of the signal. The processor 11 performs time-domain and frequency-domain analysis on the collected TEV signal. In the state where no partial discharge occurs, after multiple measurements, the TEV signal is used as the background noise and the included interference signals in the environment to achieve the "passive calibration" of TEV. During the subsequent monitoring process of partial discharge by the partial discharge monitor, the monitored TEV signal is analyzed and compared with the background noise and interference signals in the initial state to avoid false alarms of partial discharge for the background noise and interference signals by the partial discharge monitor. Thus, the situation of false alarms of partial discharge by the partial discharge monitor is reduced.

[0044] The acoustic fingerprint MIC 41 is used for monitoring partial discharge AE (ultrasonic wave). In the state where no partial discharge occurs, the acoustic fingerprint information in the monitoring environment is collected in an array. After the processor 11 performs time-domain and frequency-domain analysis on the acoustic fingerprint data, it is used as the background noise and interference signals in the monitoring environment to achieve the "passive calibration" of AE. During the subsequent monitoring process of partial discharge by the acoustic fingerprint MIC 41, the characteristics of the calibrated environmental background noise and interference signals are compared in real time, so as to avoid false alarms caused by simply monitoring partial discharge based on the presence or absence and intensity of the AE (ultrasonic) signal.

[0045] The UWB communication module 51 realizes the UWB communication function. UWB is a kind of ultra-wideband wireless communication technology, whose characteristic is to use a very large bandwidth to transmit data, and uses extremely short pulse signals or broadband continuous wave signals to achieve high-speed data transmission. Because the UWB signal is very wide in the frequency spectrum, it has relatively little influence on narrowband interference and has strong anti-interference ability. In the present utility model, since digital sampling, storage and transmission are performed on UHF, TEV and AE signals, using UWB communication can quickly realize the function of a large amount of data transmission while not interfering with the acquisition of UHF signals of partial discharge. Using UWB communication can achieve time synchronization at the level of microseconds or even nanoseconds, and can realize the time synchronization function between multiple sensors, which has a good promoting effect on the need for multi-sensor joint monitoring and data fusion analysis.

[0046] The memory 61 is connected to the processor 11 through the main board circuit, and is used for storing UHF, TEV and AE signals. At the same time, it is also used for storing the data that the processor 11 needs to store temporarily or long-term when processing data, such as the signal parameters for calibrating environmental noise and interference signals and the frequency band range that needs to be set.

[0047] In addition, the partial discharge monitor of this embodiment further includes a built-in battery 71 and an external power supply interface 81 to supply power to each component of the monitor. The built-in battery 71 is placed inside the housing, and the external power supply interface 81 is connected to an external power supply through an opening on the housing.

[0048] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A partial discharge monitor supporting frequency sweeping and frequency selection function, used for monitoring partial discharge of power system, comprising a housing, a main board and a UHF antenna, characterized in that: The mainboard is provided with a processor, a frequency sweep selector and a UHF antenna interface; The UHF antenna is connected to the UHF antenna interface, and transmits the received UHF high-frequency electromagnetic wave signal to the sweep frequency selector through the UHF antenna interface and the mainboard circuit; The frequency sweeping selector is connected to the processor via a mainboard circuit, and under the control of the processor, sweeps the received UHF high-frequency electromagnetic wave signal and transmits the frequency sweeping signal to the processor; The processor is used to determine the specific frequency band of the UHF high-frequency electromagnetic wave signal to be monitored by the partial discharge monitor, and control the sweep frequency selector to select the specific frequency band for receiving the UHF high-frequency electromagnetic wave signal to monitor the UHF high-frequency electromagnetic wave signal caused by partial discharge in the specific frequency band.

2. The partial discharge monitor supporting frequency sweeping and frequency selection function as claimed in claim 1, characterized in that: The mainboard is also provided with an electromagnetic wave transmission frequency selector and an electromagnetic wave transmission antenna interface; The partial discharge monitor also includes an electromagnetic wave transmitting antenna; The electromagnetic wave transmission frequency selector is connected to the processor via the mainboard circuit, and generates a transmission signal of a specific frequency under the control of the processor, and transmits the signal to the electromagnetic wave transmission antenna interface via the mainboard circuit; The electromagnetic wave transmitting antenna is connected to the electromagnetic wave transmitting antenna interface, and converts the transmitting signal of the specific frequency into a simulated UHF high-frequency electromagnetic wave signal for transmission.

3. The partial discharge monitor supporting frequency sweeping and frequency selection function as claimed in claim 2, characterized in that: The processor controls the electromagnetic wave transmitting frequency selector and the electromagnetic wave transmitting antenna to work, while enabling the UHF antenna and the sweeping frequency selector to perform frequency selection for receiving UHF high-frequency electromagnetic wave signals, so as to receive UHF high-frequency electromagnetic wave signals in the specific frequency band used for active calibration.

4. The partial discharge monitor supporting frequency sweeping and frequency selection function according to any one of claims 1 to 3, characterized in that: The mainboard is also provided with a first AD converter, which is connected to the frequency sweep selector and the processor respectively through the mainboard circuit; The first AD converter receives the UHF high-frequency electromagnetic wave signal of the specific frequency band selected by the sweep frequency selector, performs AD conversion, and transmits it to the processor.

5. The partial discharge monitor supporting frequency sweeping and frequency selection function as claimed in claim 4, characterized in that: The first AD converter is a multi-channel AD converter, and the specific frequency band is a plurality of frequency bands.

6. The partial discharge monitor supporting frequency sweeping and frequency selection function according to any one of claims 1 to 3, characterized in that: The mainboard is also provided with a detector, which is connected to the sweep frequency selector and the processor respectively through the mainboard circuit; The detector receives the UHF high-frequency electromagnetic wave signal of the specific frequency band selected by the sweep frequency selector and performs detection processing to obtain the relative power value of the UHF high-frequency electromagnetic wave signal of the specific frequency band and transmits it to the processor.

7. The partial discharge monitor supporting frequency sweeping and frequency selection function as claimed in claim 6, characterized in that: The detector is a multi-channel detector, and the specific frequency band is a plurality of frequency bands.

8. The partial discharge monitor supporting frequency sweeping and frequency selection function according to any one of claims 1 to 3, characterized in that: The main board is also provided with a first filter and a first automatic gain control circuit; The first filter is connected to the UHF antenna interface through a mainboard circuit, and is used to filter the UHF high-frequency electromagnetic wave signal received by the UHF antenna interface; The first automatic gain control circuit is connected to the first filter and the sweep frequency selector through a mainboard circuit, and is used for performing automatic gain control on the filtered UHF high-frequency electromagnetic wave signal and then transmitting it to the sweep frequency selector.

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