Ultra-high frequency sensor sensitivity checking system and method based on program control analog pulse

Abstract

The invention relates to an ultrahigh frequency sensor sensitivity checking system and method based on program control analog pulses, and belongs to the technical field of power equipment detection. The system comprises an analog pulse generation device which outputs a program-controlled pulse sequence with controlled parameters including pulse amplitude, width, rise time and oscillation frequency to a transformer; the ultrahigh-frequency sensor to be detected detects a program-controlled pulse sequence induced by the transformer and outputs a detection pulse sequence corresponding to the program-controlled pulse sequence; the sensitivity checking unit is respectively connected with the analog pulse generation device and the ultrahigh frequency sensor to be detected, and is used for receiving and analyzing the amplitude-frequency characteristics of the program-controlled pulse sequence and the detection pulse sequence; and determining the minimum detection sensitivity of the to-be-checked ultrahigh frequency sensor through amplitude response characteristic analysis, and determining the detection frequency band range of the to-be-checked ultrahigh frequency sensor through frequency response characteristic analysis. According to the invention, flexible and accurate verification of the sensitivity of the ultrahigh frequency sensor is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment detection, and particularly relates to a UHF sensor sensitivity checking system and method based on program-controlled analog pulses. BACKGROUND

[0002] In the power system, the transformer and GIS as the core equipment, the monitoring of the internal insulation state is important for preventing faults and ensuring stable operation of the system. Partial discharge is an important indicator of transformer insulation deterioration, and as the degree of partial discharge deepens, the overall insulation strength of the power equipment rapidly decreases, and eventually may cause serious faults. The UHF sensor is widely used in the detection of power equipment partial discharge detection due to its good anti-interference performance, however, in the prior art, the detection performance of the UHF sensor is not the same, and the sensitivity checking thereof depends on laboratory detection, and there is a lack of effective checking means for the performance of the UHF sensor already installed on site. The pulse form generated by the existing partial discharge calibration device is single and the amplitude is fixed, and it cannot adapt to the sensitivity checking requirements of the UHF sensor with complex on-site environment and variable installation position. SUMMARY

[0003] In view of the above analysis, the present application aims to disclose a UHF sensor sensitivity checking system and method based on program-controlled analog pulses, which solves the problem of UHF sensor sensitivity checking.

[0004] The present application discloses a UHF sensor sensitivity checking system based on program-controlled analog pulses, comprising: an analog pulse generating device, a to-be-tested UHF sensor and a sensitivity checking unit.

[0005] The analog pulse generating device and the to-be-tested UHF sensor are connected with the transformer respectively.

[0006] The analog pulse generating device is used for outputting a program-controlled pulse sequence with controlled parameters including pulse amplitude, width, rise time and oscillation frequency to the transformer.

[0007] The to-be-tested UHF sensor is used for detecting the program-controlled pulse sequence induced by the transformer and outputting a detection pulse sequence corresponding to the program-controlled pulse sequence.

[0008] The sensitivity checking unit is connected with the analog pulse generating device and the to-be-tested UHF sensor respectively, and is used for receiving and analyzing the amplitude-frequency characteristics of the program-controlled pulse sequence and the detection pulse sequence; through amplitude response characteristic analysis, the minimum detection sensitivity of the to-be-checked UHF sensor is determined, and through frequency response characteristic analysis, the detection frequency band range of the to-be-checked UHF sensor is determined.

[0009] The present application also discloses a sensitivity checking method using the UHF sensor sensitivity checking system based on program-controlled analog pulses, comprising:

[0010] Step S1, a sensitivity checking environment is constructed, an analog pulse generating device and a to-be-tested ultrahigh frequency sensor are connected with a transformer respectively; a sensitivity checking unit is connected with the analog pulse generating device and the to-be-tested ultrahigh frequency sensor respectively;

[0011] Step S2, the analog pulse generating device outputs a program-controlled pulse sequence including parameters such as pulse amplitude, width, rise time and oscillation frequency to the transformer;

[0012] Step S3, the to-be-tested ultrahigh frequency sensor detects the program-controlled pulse sequence induced by the transformer and outputs a detection pulse sequence corresponding to the program-controlled pulse sequence;

[0013] Step S4, the sensitivity checking unit receives and analyzes the amplitude-frequency characteristics of the program-controlled pulse sequence and the detection pulse sequence; the minimum detection sensitivity of the to-be-tested ultrahigh frequency sensor is determined through amplitude response characteristic analysis, and the detection frequency band range of the to-be-tested ultrahigh frequency sensor is determined through frequency response characteristic analysis.

[0014] The present application can achieve the following beneficial effects:

[0015] The ultrahigh frequency sensor sensitivity checking system and method based on program-controlled analog pulses disclosed in the present application realize flexible and accurate checking of the sensitivity of ultrahigh frequency sensors, and the beneficial effects thereof include:

[0016] 1. Strong parameter adjustability: by independently or combinedly adjusting parameters such as the amplitude, width, rise time and oscillation frequency of the pulse signal, a variety of partial discharge signal characteristics can be simulated, complex scenarios in actual detection of ultrahigh frequency sensors are covered, and the problem of single pulse form and fixed parameters of traditional devices is solved.

[0017] 2. Close to real fault simulation: analog signals highly consistent with the actual partial discharge characteristics inside power equipment can be generated, providing a more realistic test benchmark for sensor sensitivity checking.

[0018] 3. Detection efficiency and accuracy are improved: automatic parameter setting and signal analysis are realized through program control, the effective detection threshold and frequency band range of the sensor are quickly determined, the checking time is significantly shortened, and the result reliability is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not considered as limiting the present application, and in the entire drawings, the same reference signs represent the same components;

[0020] Figure 1 A connection schematic block diagram of the ultrahigh frequency sensor sensitivity checking system based on program-controlled analog pulses in the embodiments of the present application is shown;

[0021] Figure 2 A schematic block diagram of the connection of the analog pulse generation device in the embodiment of the present application is shown in the figure;

[0022] Figure 3 A circuit schematic diagram of the pulse signal generation module in the embodiment of the present application is shown in the figure;

[0023] Figure 4 A circuit schematic diagram of the direct current voltage control module in the embodiment of the present application is shown in the figure;

[0024] Figure 5 A circuit schematic diagram of the waveform modulation module in the embodiment of the present application is shown in the figure;

[0025] Figure 6 A structure schematic diagram of the to-be-tested ultra-high frequency sensor in the embodiment of the present application is shown in the figure;

[0026] Figure 7 A structure schematic diagram of the flat plate capacitor including a shielding cover in the to-be-tested ultra-high frequency sensor in the embodiment of the present application is shown in the figure;

[0027] Figure 8 A flow chart of the sensitivity checking method of the ultra-high frequency sensor based on the program-controlled analog pulse in the embodiment of the present application is shown in the figure.

[0028] The figure shows the structure of the to-be-tested ultra-high frequency sensor, wherein 1 represents a pole plate, 2 represents a coupling medium, 3 represents a shielding cover, 4 represents a signal adapter, 5 represents a signal processing unit, 6 represents a signal transmission unit, 7 represents a grounding copper bar, 8 represents a transformer, 9 represents a winding, 10 represents an iron core, 11 represents an iron core grounding sleeve, 12 represents a signal extraction device, 13 represents a signal acquisition and analysis system, 14 represents a display and storage device, 31 represents an upper shell, 32 represents a lower shell, 33 represents an insulating column, 34 represents an insulating hollow nut, and 35 represents a rotating shaft. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings form a part of the present application and are used to explain the principles of the embodiments of the present application.

[0030] Embodiment one

[0031] One embodiment of the present application discloses a sensitivity checking system of an ultra-high frequency sensor based on a program-controlled analog pulse, as shown in the figure, which comprises an analog pulse generation device, a to-be-tested ultra-high frequency sensor and a sensitivity checking unit. Figure 1

[0032] The analog pulse generation device and the to-be-tested ultra-high frequency sensor are respectively connected with the transformer.

[0033] The analog pulse generation device is used to output a program-controlled pulse sequence including parameters such as pulse amplitude, width, rise time and oscillation frequency to the transformer. ​

[0034] The to-be-tested ultra-high frequency sensor is used for detecting a program-controlled pulse sequence induced by the transformer and outputting a detection pulse sequence corresponding to the program-controlled pulse sequence.

[0035] The sensitivity checking unit is connected with the analog pulse generating device and the to-be-tested ultra-high frequency sensor respectively, and is used for receiving and analyzing the amplitude-frequency characteristics of the program-controlled pulse sequence and the detection pulse sequence; the minimum detection sensitivity of the to-be-tested ultra-high frequency sensor is determined through the amplitude response characteristic analysis, and the detection frequency band range of the to-be-tested ultra-high frequency sensor is determined through the frequency response characteristic analysis.

[0036] As shown in Figure 2 The analog pulse generating device comprises a direct current voltage control module, a pulse signal generating module, a waveform modulation module, a power amplification module and a signal transmitting module.

[0037] The direct current voltage control module is used for generating a direct current voltage with a controlled amplitude under program control and outputting the direct current voltage to the pulse signal generating module.

[0038] The pulse signal generating module is used for generating a program-controlled pulse sequence with a nanosecond-level front under the triggering of a program-controlled trigger pulse; and the amplitude of each pulse of the program-controlled pulse sequence is controlled by the direct current voltage output by the direct current voltage control module.

[0039] The waveform modulation module is used for program-controlled adjustment of parameters of each pulse of the program-controlled pulse sequence output by the pulse signal generating module, including pulse width, rise time and oscillation frequency, so as to simulate partial discharge signals covering various signal parameter ranges actually detected by the ultra-high frequency sensor.

[0040] The power amplification module is used for power amplification of each pulse of the pulse sequence after waveform adjustment, so as to ensure that the output pulse signal has sufficient energy and can effectively excite the ultra-high frequency sensor, so that the signal strength received by the ultra-high frequency sensor during sensitivity checking is close to the actual working signal strength.

[0041] Preferably, a wideband radio frequency power amplifier (working frequency band 300MHz-3GHz, gain≥30dB) is adopted to ensure that the output signal power can reach more than 10W.

[0042] The signal transmitting module is connected with the power amplification module and is equipped with a 50Ω impedance matched UHF transmitting antenna (working frequency 300MHz-3000MHz) connected through a coaxial cable, and is used for outputting the pulse signal after power amplification to the ultra-high frequency transmitting antenna; the output port of the ultra-high frequency transmitting antenna is matched with the input impedance (usually 50Ω) of the ultra-high frequency sensor, so as to ensure efficient transmission and coupling of the signal and reduce the loss and distortion of the signal in the transmission process.

[0043] Specifically, the pulse signal generating module is composed of multiple-stage series avalanche transistor groups, and the nanosecond front pulse signal is generated by controlling the avalanche breakdown of the crystal triode through the square wave trigger signal, and the amplitude of the nanosecond front pulse signal is controlled by controlling the direct current charging voltage.

[0044] More specifically, the pulse signal generating module comprises a first-stage avalanche transistor group, a first-stage base differential circuit, a first-stage discharge buffer circuit, a second-stage base differential circuit, a second-stage avalanche transistor group, a main discharge capacitor and a second-stage discharge buffer circuit; wherein,

[0045] The first-stage avalanche transistor group comprises M avalanche transistor groups in parallel; the collector of each avalanche transistor of the first stage is connected with a resistor R3, the resistor R3 is connected with a direct current voltage UCC, the emitter of each avalanche transistor is grounded, and the base of each avalanche transistor is connected together and connected with the output end of the first-stage base differential circuit;

[0046] The first-stage base differential circuit comprises resistors R1 and R2 and a capacitor C1; the resistor R1 is connected between one end of the capacitor C1 and the ground, and the resistor R2 is connected between the other end of the capacitor C1 and the ground; an externally input trigger pulse is input from one end of the resistor R1 and the capacitor C1; and the differential signal is output from one end of the resistor R2 and the capacitor C1 to the base of the first-stage avalanche transistor group;

[0047] The first-stage discharge buffer circuit comprises a resistor R10 and a fast recovery diode D2; the resistor R10 and the fast recovery diode D2 are connected in series between the base of the first-stage avalanche transistor and the ground;

[0048] The second-stage base differential circuit comprises a capacitor C2 and a resistor R8, the capacitor C2 and the resistor R8 are connected in series, the connection end of the capacitor C2 and the resistor R8 is the output end of the second-stage base differential circuit, the other end of the capacitor C2 is connected with the collector of each avalanche transistor of the first stage, and the other end of the resistor R8 is grounded;

[0049] The second-stage avalanche transistor group comprises N avalanche transistor groups in parallel; the collector of each avalanche transistor of the second stage is connected with a resistor R4, the resistor R4 is connected with a direct current voltage UCC, the base of each avalanche transistor of the second stage is connected to the output end of the second-stage base differential circuit through a respective base resistor, and the emitter of each avalanche transistor of the second stage is connected to the output end of the second-stage base differential circuit;

[0050] One end of the main discharge capacitor is connected with the collector of each avalanche transistor of the second stage, and the other end of the main discharge capacitor is used as the output end of the pulse signal generating module;

[0051] The second-stage discharge buffer circuit comprises a resistor R9 and a fast recovery diode D1; the resistor R9 and the fast recovery diode D1 are connected in series between the output end of the first-stage pulse signal generating module and the ground.

[0052] The number of transistors in the first-stage avalanche transistor group and the second-stage avalanche transistor group is determined according to the requirement of the pulse current. Figure 3 As shown in the figure, a specific circuit example is given, in which the first-stage avalanche transistor group and the second-stage avalanche transistor group each has three transistors.

[0053] In the example, the trigger pulse is first connected to the base of the transistors Q1-Q3 in the first-stage avalanche transistor group which are in a critical avalanche state after being differentiated; at least one of the transistors Q1-Q3 undergoes avalanche; the output signal of the transistors in the first-stage avalanche transistor group after undergoing avalanche is differentiated by the second-stage base differentiation circuit and then output as a pulse signal to the emitter of the transistors Q4-Q6 in the second-stage avalanche transistor group, which increases the voltage drop between the collector and the emitter of the transistors Q4-Q6, so that at least one of the transistors Q4-Q6 undergoes avalanche; the voltage drop of the newly turned-on transistor causes the voltage drop on the other two non-conducting transistors to be redistributed, so that eventually each of the avalanche transistors undergoes avalanche. In the first-stage discharge buffer circuit and the second-stage discharge buffer circuit, the fast recovery diodes are used to reduce the back-bounce during discharge and to play a temperature compensation role.

[0054] The direct current voltage UCC charges the capacitor C2 through the resistors R3 and R5; after the trigger pulse is connected to cause the transistors to undergo avalanche, the conduction of the first-stage and second-stage avalanche transistors causes the capacitor C2 to discharge through the second-stage avalanche transistors and the resistors connected to the base of the second-stage avalanche transistors, so as to output a step signal to the capacitor C3 to obtain an output pulse after being differentiated. By changing C2 and UCC, the peak-to-peak value of the output pulse can be changed. Increasing C2 not only increases the peak-to-peak value, but also increases the output pulse width.

[0055] Specifically, the direct current voltage control module includes a digital potentiometer and an operational amplifier.

[0056] The SCL and SDA connection terminals of the digital potentiometer are input with program-controlled configuration, and the output terminal is connected to the operational amplifier. The operational amplifier is connected to form a proportional amplifier circuit, which outputs the voltage output by the digital potentiometer to the UCC terminal of the pulse signal generation module after proportional amplification, so as to control the amplitude of the output pulse of the pulse signal generation module.

[0057] The value of the program-controlled configuration word input through the SDA connection terminal corresponds to the amplitude of the output pulse of the pulse signal generation module, and the time sequence of the program-controlled control command of the SCL connection terminal corresponds to the time sequence of the output pulse of the pulse signal generation module.

[0058] More specifically, the circuit connection of the direct current voltage control module is as shown in the figure. Figure 4As shown, the VDD pin and the H pin of the digital potentiometer are connected to the power supply VCC, the SCL terminal is connected to the program control command, the SDA terminal is connected to the program control configuration word, and the W pin outputs the voltage value of the power supply VCC to the non-inverting input terminal of the operational amplifier; the division ratio is set by the program control configuration word; the inverting input terminal of the operational amplifier is connected to the ground through the resistor R1, and the output terminal is fed back to the inverting input terminal through the resistor R2; the voltage is amplified through the proportional relationship of R1 and R2 to obtain a controllable direct current voltage.

[0059] Specifically, the waveform modulation module comprises a pulse width adjusting submodule, a rise time adjusting submodule and an oscillation frequency adjusting submodule; wherein,

[0060] In the pulse width adjusting submodule, a plurality of parallel RC damping circuits are included; each RC damping circuit comprises a resistor and a capacitor connected in series between the output terminal of the pulse signal generating module and the ground, and the connection terminal of the resistor and the capacitor is taken as the output terminal of the RC damping circuit; the output terminals of the plurality of RC damping circuits are connected together as the output terminal of the pulse width adjusting submodule; each RC damping circuit further comprises a switch connected in series, which is used for controlling whether the RC damping circuit participates in the pulse width adjustment; by controlling the number of closed switches, the pulse width is adjusted.

[0061] In the rise time adjusting submodule, a plurality of parallel resistors and capacitors are included; the parallel resistors and capacitors are connected in series with respective control switches and then connected between the output terminal of the pulse width adjusting submodule and the ground, thereby forming an RC differential circuit with the pulse rise time controlled by the switches; by controlling the number of closed switches, the number of resistors and capacitors changing the differential parameters accessed to the circuit is selected, thereby adjusting the pulse rise time.

[0062] In the oscillation frequency adjusting submodule, a plurality of parallel LC resonance circuits are included; in each LC resonance circuit, the input signal is output after passing through the series-connected inductor and capacitor, and the output terminals of the plurality of LC resonance circuits are connected together as the output terminal of the waveform modulation module; each LC resonance circuit further comprises a switch connected in series, which is used for controlling whether the LC resonance circuit participates in the oscillation frequency adjustment; by controlling the number of closed switches, the pulse oscillation frequency is adjusted.

[0063] Specifically, the circuit connection of the waveform modulation module can be referred to Figure 5 .

[0064] Preferably, the plurality of switches in the waveform modulation module are multi-tap switches composed of a relay array or a switch tube array.

[0065] The control end of the switch is connected to the corresponding control signal decoded by a decoder, the input of the decoder is the encoded signal set by the program-controlled device according to the pulse width, the rise time and the oscillation frequency parameters, the encoded signal is decoded by the decoder into the corresponding control signal, and the control signal is output to the corresponding switch in the pulse width adjusting sub-module, the rise time adjusting sub-module and the oscillation frequency adjusting sub-module, so as to control the closing or opening of the switch and realize the adjustment of the pulse signal pulse width, the rise time and the oscillation frequency.

[0066] Specifically, the to-be-tested ultra-high frequency sensor is coupled in a capacitive manner and is connected to the transformer core grounding copper bar; when the program-controlled pulse sequence output by the analog pulse generating device to the transformer is induced by the transformer and flows out from the transformer core grounding copper bar, the to-be-tested ultra-high frequency sensor coupled to the transformer core grounding copper bar extracts the ultra-high frequency signal of the core grounding current and detects the program-controlled pulse sequence induced by the transformer.

[0067] As shown in Figure 6 the to-be-tested ultra-high frequency sensor includes a polar plate, a signal adapter, a signal processing unit and a signal transmission unit; wherein,

[0068] The polar plate is a metal plate and is arranged outside the transformer core grounding copper bar, a coupling medium is arranged between the polar plate and the grounding copper bar, a flat plate capacitor is formed between the polar plate and the grounding copper bar through the coupling medium, and the flat plate capacitor is used for coupling the ultra-high frequency signal in the grounding copper bar;

[0069] The signal adapter is connected to the polar plate and is used for leading out the ultra-high frequency signal coupled to the polar plate;

[0070] The signal processing unit is connected to the adapter and is used for amplifying, filtering and detecting the ultra-high frequency signal led out by the adapter;

[0071] The signal transmission unit is connected to the signal processing unit and is used for transmitting the processed ultra-high frequency signal to the sensitivity checking unit.

[0072] In the embodiment, the capacity of the flat plate capacitor is satisfied through three aspects of design; the effective output voltage formed on the polar plate due to coupling is equal to the voltage value of the local potential fluctuation generated by the local discharge signal flowing through the surface of the copper bar.

[0073] The first is to increase the effective area of the metal plate; the second is to increase the relative dielectric constant of the insulating layer; and the third is to reduce the distance between the metal plate and the grounding copper bar.

[0074] Specifically, to increase the effective area of the metal plate, in the embodiment,

[0075] The width of the polar plate is slightly wider than the width of the grounding copper bar with a set width allowance; the width allowance can be set according to the actual construction situation.

[0076] The length of the plate is in the range of

[0077] The minimum length value meets the requirement of effectively coupling to the complete propagation electric field region of the ground copper bar.

[0078] The maximum length value is determined according to the volume of the plate, the process cost, and the marginal effect of the capacitance.

[0079] For example, generally, the width of the ground copper bar is usually 4-6 mm, and the length can reach more than 1 m.

[0080] Therefore, the width of the plate can be set to 7-9 mm, preferably 8 mm. In this way, the width of the metal plate is slightly wider than the width of the ground copper bar, which can not only ensure complete envelope of the electric field distribution, but also avoid the influence of the edge effect.

[0081] Moreover, considering the weight of the metal plate itself, if the length of the metal plate is too short (such as 10 mm), it can only cover a distance of the copper bar, and only capture the local electric field, which is low in signal coupling efficiency.

[0082] If the length of the metal plate is too long (such as 70 mm), the capacitance gain brought by increasing the length of the metal plate tends to be flat (marginal effect decreases), but the volume and process cost increase, which brings low benefits.

[0083] The preferred range is 30-50 mm, which can effectively couple to a more complete propagation electric field region and obtain higher signal energy, and will not bring a large increase in volume and process cost, which is a more appropriate length range for the metal plate.

[0084] In order to obtain the maximum capacitance in the preferred length range, the final size is preferably 50 mm.

[0085] Increasing the relative dielectric constant can significantly increase the capacitance value, but high dielectric materials are difficult to process and are brittle and fragile, which is not suitable for on-site use.

[0086] Specifically, in order to increase the relative dielectric constant of the insulating layer, in the embodiment,

[0087] A ceramic sheet / coating with a relative dielectric constant of 6-10 is selected, such as a barium titanate thin layer, to further improve the signal coupling effect.

[0088] Specifically, in order to reduce the distance between the plate and the ground copper bar, in the embodiment,

[0089] Considering that it is difficult to make block-shaped materials, a ceramic coating is directly applied to the opposite surfaces of the plate and the ground copper bar, and then the plate is crimped on the ground copper bar to form a flat plate capacitor, thereby minimizing the distance.

[0090] Specifically, in this embodiment, the UHF sensor under test also includes a shielding cover;

[0091] The shielding cover is made of metal and is wrapped around the outside of the electrode plate to reduce external electromagnetic interference.

[0092] Preferably, in order to lead the signal out of the shielding cover, a vertical guide rod is set at the center of the metal plate of the electrode plate. One end of the vertical guide rod is connected to the metal plate, and the other end extends out of the shielding cover. A signal adapter is connected to the end of the vertical guide rod that extends out of the shielding cover.

[0093] The ultra-high frequency signal in the grounded copper busbar coupled to the plate capacitor is transmitted to the signal converter through the vertical guide rod at the center of the plate, and then led out to the signal processing unit through the signal converter.

[0094] The shielding cover serves two purposes: firstly, it provides shielding, and secondly, it applies pressure to the electrode plate and the grounding copper busbar, pressing the grounding copper busbar tightly against the electrode plate.

[0095] like Figure 7 As shown, the shielding cover includes an upper shell, a lower shell, an insulating column, an insulating hollow nut, and a rotating shaft;

[0096] The upper and lower shells are both made of the same metal material. The upper and lower shells are connected at one end by a pivot, and the upper and lower shells open and close around the pivot.

[0097] The inner wall of the lower housing is fixedly connected to one end of the insulating column;

[0098] The upper housing has a threaded hole, the thread of which matches the external thread of the insulating hollow nut. The insulating hollow nut is fixed to the upper housing by the matching thread. The electrode plate is located inside the upper housing, and the vertical guide rod on the electrode plate passes through the upper housing from the center hole of the insulating hollow nut.

[0099] Preferably, the central hole of the insulating hollow nut is provided with an internal thread, and the outer surface of the vertical guide rod is provided with an external thread that matches the internal thread of the central hole. By providing matching threads, on the one hand, the electrode plate can be connected to the upper shell of the shielding cover by the insulating hollow nut; on the other hand, when the insulating hollow nut is rotated, the electrode plate can be moved along the axial direction of the insulating hollow nut, changing the position of the electrode plate in the upper shell.

[0100] Within the cylindrical shielding space formed by the upper and lower housings surrounding the grounding copper busbar, the other end of the insulating post vertically abuts against the inner side of the grounding copper busbar; the electrode plate extending from the upper housing through the vertical guide rod is opposite to the outer side of the grounding copper busbar; the vertical guide rod and the insulating post are in a straight line, and rotating the insulating hollow nut causes the electrode plate to move inward relative to the upper housing, bringing the insulating post and the vertical guide rod closer together, pressing the grounding copper busbar and the electrode plate together, so that the grounding copper busbar, the electrode plate and the coupling medium between them constitute a plate capacitor with a set capacitance;

[0101] After the upper shell and the lower shell are opened, the insulating column and the polar plate and the grounding copper bar are separated, and the polar plate is taken out from the grounding copper bar;

[0102] Preferably, the signal adapter is an SMA radio frequency connector with external threads for the inner conductor in the middle;

[0103] The threaded hole is provided at one end of the vertical guide rod connected with the SMA radio frequency connector; the threads of the threaded hole match the external threads of the inner conductor of the SMA radio frequency connector; and the SMA radio frequency connector is fixed to one end of the vertical guide rod through the matching threads.

[0104] Specifically, the signal processing unit includes an amplifier and a filter;

[0105] The amplifier is used to amplify the weak ultra-high frequency signal coupled thereto;

[0106] The filter is used to remove noise and interference components in the signal and improve the signal-to-noise ratio of the signal.

[0107] Specifically, the signal transmission unit is a coaxial cable or other transmission medium suitable for transmitting ultra-high frequency signals, which can stably transmit the processed ultra-high frequency signals to an external monitoring device.

[0108] Specifically, the sensitivity checking unit includes an amplitude response characteristic analysis module and a frequency response characteristic analysis module;

[0109] The amplitude response characteristic analysis module is used to determine the minimum detection sensitivity and the sensitivity curve of the ultra-high frequency sensor to be checked;

[0110] When the amplitude response characteristic analysis is performed, the amplitude response characteristic analysis module receives the pulses U in with gradually increasing amplitudes output by the analog pulse generating device in , and the pulses U out output by the ultra-high frequency sensor to be measured when the input pulses U in ; and calculates the sensitivity Z of the sensor draws the U in -Z curve as the sensitivity curve; finds the first pulse U out greater than the noise level U0 in the pulses U in with gradually increasing amplitudes, and takes the sensitivity Z corresponding to the sensitivity curve as the minimum sensitivity of the sensor to be measured;

[0111] The noise level U0 is measured by the amplitude response characteristic analysis module before the amplitude response characteristic analysis, and when the noise level is measured, the analog pulse generating device is turned off, and the amplitude of the output signal U0 of the to-be-tested ultrahigh frequency sensor accessed at this time is recorded by the amplitude response characteristic analysis module as the noise level under the current test condition.

[0112] The frequency response characteristic analysis module is used to determine the detection frequency band range of the to-be-checked ultrahigh frequency sensor.

[0113] When the frequency response characteristic analysis is performed, the amplitude response characteristic analysis module receives the pulse U in with gradually increased frequency output by the analog pulse generating device in , and the pulse U out output by the to-be-tested ultrahigh frequency sensor when the input pulse U in is received; the two signals are subjected to FFT transformation respectively, and corresponding frequency signals G in and G out are obtained respectively; the frequency response value of the sensor is calculated ; and the frequency response curve is drawn; the upper and lower limit cutoff frequencies of the frequency response value at the average frequency response ± 3dB are determined on the frequency response curve, and are used as the measured frequency band range of the to-be-tested sensor.

[0114] In summary, the ultrahigh frequency sensor sensitivity checking system based on the program-controlled analog pulse of the embodiment of the application realizes flexible and accurate checking of the sensitivity of the ultrahigh frequency sensor, and the beneficial effects include:

[0115] 1. Strong parameter adjustability: by independently or combinedly adjusting the parameters such as the amplitude, width, rise time and oscillation frequency of the pulse signal, various partial discharge signal characteristics can be simulated, complex scenes in actual detection of the ultrahigh frequency sensor are covered, and the problem of single pulse form and fixed parameters of the traditional device is solved.

[0116] 2. Close to real fault simulation: the analog signal highly consistent with the actual partial discharge characteristics inside the power equipment can be generated, and a more real test benchmark is provided for the sensor sensitivity checking.

[0117] 3. Detection efficiency and accuracy are improved: the effective detection threshold and the frequency band range of the sensor are quickly determined through automatic parameter setting and signal analysis realized by programming control, the checking time is significantly shortened, and the result reliability is improved.

[0118] Embodiment two

[0119] An embodiment of the application discloses a sensitivity checking method using the ultrahigh frequency sensor sensitivity checking system based on the program-controlled analog pulse in the embodiment one, as shown in FIG. 2, which comprises the following steps: Figure 8

[0120] Step S1: Construct a sensitivity verification environment by connecting the analog pulse generator and the UHF sensor under test to the transformer respectively; connect the sensitivity verification unit to the analog pulse generator and the UHF sensor under test respectively.

[0121] Step S2: The analog pulse generator outputs a programmable pulse sequence to the transformer, including parameters such as pulse amplitude, width, rise time and oscillation frequency.

[0122] For example, gradually increase the pulse amplitude starting from 20mV, with each pulse increasing by 20mV in turn;

[0123] Step S3: The UHF sensor under test detects the programmable pulse sequence induced by the transformer and outputs the detection pulse sequence corresponding to the programmable pulse sequence.

[0124] Step S4: The sensitivity verification unit receives and analyzes the amplitude-frequency characteristics of the programmable pulse sequence and the detection pulse sequence; through amplitude response characteristic analysis, it determines the minimum detection sensitivity of the UHF sensor to be verified; and through frequency response characteristic analysis, it determines the detection frequency band range of the UHF sensor to be verified.

[0125] Specifically, including:

[0126] Step S1: Determine the noise level under the current test conditions;

[0127] The analog pulse generator is turned off, and the amplitude response characteristic analysis module records the amplitude of the output signal U0 of the ultra-high frequency sensor under test connected to the sensitivity verification unit at this time, which is used as the noise level under the current test conditions.

[0128] Step S2: Perform amplitude response characteristic analysis to determine the minimum detection sensitivity and sensitivity curve of the UHF sensor to be checked;

[0129] Specifically, including:

[0130] 1) Receive pulses U with progressively increasing amplitude output from the analog pulse generator. in ;

[0131] 2) Receive the input pulse U from the UHF sensor under test. in The pulse U output at time out ;

[0132] 3) Calculate the sensor sensitivity. Drawing U in The -Z curve is the sensitivity curve;

[0133] 4) In pulses U with progressively increasing amplitude in Find the first corresponding pulse U out Pulse U greater than noise level U0 inThe sensitivity Z corresponding to the sensitivity curve is taken as the minimum sensitivity of the measured sensor in the measurement;

[0134] Step S3, frequency response characteristic analysis is performed to determine the detection frequency band range of the high-frequency sensor to be checked;

[0135] Specifically, it includes:

[0136] 1) receiving the pulses U with gradually increasing frequencies output by the analog pulse generating device in ;

[0137] 2) receiving the pulses U output by the high-frequency sensor to be measured when the input pulses U in ; out ;

[0138] 3) performing FFT transformation on the two signals respectively, and obtaining the corresponding frequency signals G in and G out respectively; calculating the frequency response value of the sensor ;

[0139] 4) determining the upper and lower limit cutoff frequencies of the frequency response value within ±3dB of the average frequency response on the frequency response curve, as the measured sensor frequency band range.

[0140] More technical details in this embodiment are the same as the technical details disclosed in Embodiment 1 and have the same technical effects. Please refer to the specific description, and here it is not repeated.

[0141] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A sensitivity verification system for ultra-high frequency sensors based on programmable analog pulses, characterized in that, include: Simulated pulse generation device, ultra-high frequency sensor under test, and sensitivity verification unit; The analog pulse generator and the ultra-high frequency sensor under test are respectively connected to the transformer; A simulated pulse generator is used to output a programmable pulse sequence to a transformer, including parameters such as pulse amplitude, width, rise time, and oscillation frequency. The ultra-high frequency sensor under test is used to detect the programmable pulse sequence induced by the transformer and outputs a detection pulse sequence corresponding to the programmable pulse sequence. The sensitivity verification unit is connected to the analog pulse generation device and the ultra-high frequency sensor under test, respectively, and is used to receive and analyze the amplitude-frequency characteristics of the programmable pulse sequence and the detection pulse sequence. By analyzing the amplitude response characteristics, the minimum detection sensitivity of the UHF sensor to be verified was determined, and by analyzing the frequency response characteristics, the detection frequency band range of the UHF sensor to be verified was determined.

2. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 1, characterized in that, The analog pulse generating device includes a DC voltage control module, a pulse signal generation module, and a waveform modulation module; The DC voltage control module is used to generate a DC voltage with controlled amplitude under program control and output it to the pulse signal generation module; The pulse signal generation module is used to generate a programmable pulse sequence with nanosecond-level leading edges when triggered by a trigger pulse. The amplitude of each pulse in the DC voltage control programmable pulse sequence output by the DC voltage control module; The waveform modulation module is used to programmatically adjust the parameters of each pulse in the programmable pulse sequence output by the pulse signal generation module, including pulse width, rise time, and oscillation frequency, to simulate partial discharge signals covering the range of various signal parameters encountered by the UHF sensor in actual detection.

3. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 2, characterized in that, The pulse signal generation module includes a first-stage avalanche transistor group, a first-stage base differentiating circuit, a first-stage discharge buffer circuit, a second-stage base differentiating circuit, a second-stage avalanche transistor group, a main discharge capacitor, and a second-stage discharge buffer circuit; among which, The first-stage avalanche transistor group consists of M avalanche transistor groups connected in parallel; the collector of each avalanche transistor in the first stage is connected to resistor R3, and DC voltage UCC is connected through resistor R3. The emitters of all transistors are grounded, and the bases are connected together and connected to the output terminal of the first-stage base differentiating circuit. The first-stage base differentiating circuit includes resistors R1 and R2 and capacitor C1; resistor R1 is connected between one end of capacitor C1 and ground, and resistor R2 is connected between the other end of capacitor C1 and ground; the externally input trigger pulse is input from the end where resistor R1 and capacitor C1 are connected; the differentiated signal is output from the end where resistor R2 and capacitor C1 are connected to the base of the first-stage avalanche transistor group. The first-stage discharge buffer circuit includes a resistor R10 and a fast recovery diode D2; the resistor R10 and the fast recovery diode D2 are connected in series between the base of the first-stage avalanche transistor and ground; The second-stage base differentiator circuit includes capacitor C2 and resistor R8, which are connected in series. The connection point of capacitor C2 and resistor R8 is the output terminal of the second-stage base differentiator circuit. The other end of capacitor C2 is connected to the collector of each avalanche transistor in the first stage, and the other end of resistor R8 is grounded. The second-stage avalanche transistor group consists of N avalanche transistors connected in parallel; the collector of each avalanche transistor in the second stage is connected to resistor R4, and DC voltage UCC is connected through resistor R4; the base of each avalanche transistor in the second stage is connected to the output terminal of the second-stage base differentiating circuit through its respective base resistor; the emitter of each avalanche transistor in the second stage is connected to the output terminal of the second-stage base differentiating circuit. One end of the main discharge capacitor is connected to the collector of each avalanche transistor in the second stage, and the other end serves as the output terminal of the pulse signal generation module. The second-stage discharge buffer circuit includes resistor R9 and fast recovery diode D1; resistor R9 and fast recovery diode D1 are connected in series between the output terminal of the first-stage pulse signal generation module and ground.

4. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 2, characterized in that, The DC voltage control module includes a digital potentiometer and an operational amplifier; The SCL and SDA terminals of the digital potentiometer are configured by a programmable input, and the output terminal is connected to an operational amplifier. The operational amplifier is connected to a proportional amplifier circuit to proportionally amplify the voltage output by the digital potentiometer and then output it to the pulse signal generation module to control the amplitude of the pulse output by the pulse signal generation module. The value of the programmable configuration word input at the SDA terminal corresponds to the amplitude of the pulse output by the pulse signal generation module, and the timing of the programmable control command at the SCL terminal corresponds to the timing of the pulse output by the pulse signal generation module.

5. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 2, characterized in that, The waveform modulation module includes a pulse width adjustment submodule, a rise time adjustment submodule, and an oscillation frequency adjustment submodule; wherein, The pulse width modulation (PWM) submodule includes multiple parallel RC damping circuits. Each RC damping circuit includes a resistor and capacitor connected in series between the output of the pulse signal generation module and ground, with the connection point of the resistor and capacitor serving as the output of the RC damping circuit. The outputs of multiple RC damping circuits are connected together to form the output of the PWM submodule. Each RC damping circuit also has a switch connected in series to control whether that circuit participates in pulse width modulation. By controlling the closing of different numbers of switches, the pulse width can be adjusted. The rise time adjustment submodule includes multiple resistors and capacitors arranged in parallel. These parallel resistors and capacitors are connected in series with their respective control switches and then connected between the output terminal of the pulse width adjustment submodule and ground, forming an RC differential circuit whose pulse rise time is controlled by the switches. By controlling the number of switches closed, the number of resistors and capacitors connected to the circuit to change the differential parameters is selected for adjusting the pulse rise time. The oscillation frequency adjustment submodule includes multiple parallel LC resonant circuits. The input signal in each LC resonant circuit is output after passing through a series inductor and capacitor. The output terminals of the multiple LC resonant circuits are connected together as the output terminal of the waveform modulation module. Each LC resonant circuit also has a switch connected in series to control whether the LC resonant circuit participates in the oscillation frequency adjustment. By controlling the closing of different numbers of switches, the pulse oscillation frequency can be adjusted.

6. The ultra-high frequency sensor sensitivity verification system based on programmable analog pulses according to any one of claims 1-5, characterized in that, The UHF sensor under test is connected to the transformer core grounding copper busbar via capacitive coupling. When the programmable pulse sequence output by the analog pulse generator to the transformer is induced by the transformer and flows out from the transformer core grounding copper busbar, the UHF sensor under test coupled to the transformer core grounding copper busbar extracts the UHF signal of the core grounding current and detects the programmable pulse sequence induced by the transformer.

7. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 6, characterized in that, The ultra-high frequency sensor under test includes: an electrode plate, a signal converter, a signal processing unit, and a signal transmission unit; among which, The electrode plate is a metal plate, which is set on the outside of the grounding copper busbar of the transformer core. A coupling medium is provided between the electrode plate and the grounding copper busbar. The coupling medium and the grounding copper busbar form a parallel plate capacitor for coupling the ultra-high frequency signal in the grounding copper busbar. The signal converter is connected to the electrode plate and is used to extract the ultra-high frequency signal coupled to the electrode plate; The signal processing unit is connected to the adapter and is used to amplify, filter, and detect the UHF signal output from the adapter. The signal transmission unit is connected to the signal processing unit and is used to transmit the processed UHF signal to the sensitivity verification unit.

8. The UHF sensor sensitivity verification system based on programmable analog pulses according to claim 7, characterized in that, The ultra-high frequency sensor under test also includes a shielding cover; the shielding cover is made of metal and is wrapped around the outside of the parallel plate capacitor to reduce external electromagnetic interference. A vertical guide rod is provided at the center of the metal plate of the electrode plate. The vertical guide rod extends out of the shielding cover and a signal adapter is connected to the end of the vertical guide rod. The ultra-high frequency signal in the grounded copper busbar coupled to the plate capacitor is transmitted to the signal converter through the vertical guide rod at the center of the plate, and then led out to the signal processing unit through the signal converter.

9. The ultra-high frequency sensor sensitivity verification system based on programmable analog pulses according to any one of claims 1-5, characterized in that, The sensitivity verification unit includes an amplitude response characteristic analysis module and a frequency response characteristic analysis module; The amplitude response characteristic analysis module is used to determine the minimum detection sensitivity and sensitivity curve of the UHF sensor to be verified; During amplitude response characteristic analysis, the amplitude response characteristic analysis module receives pulses U with progressively increasing amplitudes output from the analog pulse generator. in And the ultra-high frequency sensor under test in the input pulse U in The pulse U output at time out ; Calculate the sensitivity of the sensor Drawing U in The -Z curve is the sensitivity curve; in pulses with progressively increasing amplitude U... in Find the first corresponding pulse U out Pulse U greater than noise level U0 in The sensitivity Z corresponding to the sensitivity curve is taken as the minimum sensitivity of the sensor under test; the noise level U0 is measured by the amplitude response characteristic analysis module before the amplitude response characteristic analysis; The frequency response characteristic analysis module is used to determine the detection frequency band range of the ultra-high frequency sensor to be verified; During frequency response characteristic analysis, the amplitude response characteristic analysis module receives pulses U with progressively increasing frequency output from the analog pulse generator. in ; And the ultra-high frequency sensor under test at the input pulse U in The pulse U output at time out Perform FFT transformations on the two signals respectively to obtain the corresponding frequency signals G. in and G out ; Calculate the frequency response value of the sensor Plot the frequency response curve; determine the upper and lower cutoff frequencies of the average frequency response value ±3dB from the frequency response curve, which will be used as the frequency band range of the sensor under test.

10. A sensitivity verification method using the ultra-high frequency sensor sensitivity verification system based on programmable analog pulses as described in any one of claims 1-9, characterized in that, include: Step S1: Construct a sensitivity verification environment by connecting the analog pulse generator and the UHF sensor under test to the transformer respectively; connect the sensitivity verification unit to the analog pulse generator and the UHF sensor under test respectively. Step S2: The analog pulse generator outputs a programmable pulse sequence to the transformer, including parameters such as pulse amplitude, width, rise time and oscillation frequency. Step S3: The UHF sensor under test detects the programmable pulse sequence induced by the transformer and outputs the detection pulse sequence corresponding to the programmable pulse sequence. Step S4: The sensitivity verification unit receives and analyzes the amplitude-frequency characteristics of the programmable pulse sequence and the detection pulse sequence; By analyzing the amplitude response characteristics, the minimum detection sensitivity of the UHF sensor to be verified was determined, and by analyzing the frequency response characteristics, the detection frequency band range of the UHF sensor to be verified was determined.

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