CN203965572U - Based on the system of flexible piezoelectric membraneous material monitoring GIS partial discharge position - Google Patents

Abstract

The utility model discloses a kind of system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position, comprise the calibrate AE sensor, signal deteching circuit, signal processing circuit, electric power management circuit and the warning circuit that are close on GIS outer wall, described calibrate AE sensor signal passes to signal processing circuit through signal deteching circuit, described electric power management circuit provides direct supply, and described warning circuit is electrically connected with signal processing circuit.Realize the object that finds fast and accurately discharge position.

Description

System for Monitoring Partial Discharge Location in GIS Based on Flexible Piezoelectric Film Material

technical field

The utility model relates to the field of electric power monitoring, in particular to a system for monitoring the partial discharge position of a GIS based on a flexible piezoelectric film material.

Background technique

With the extensive application of GIS in the power system, almost all of the company's new substations in recent years are GIS equipment.

When partial discharge occurs inside the GIS, the high temperature generated during the discharge process causes the gas molecules to undergo violent thermal motion, and propagates through the adjacent gas medium to form sound waves. Since the discharge time is very short, the sound wave spectrum generated Very wide, from tens of hertz to several megahertz. This shows that shock vibration and sound will be generated when the internal discharge of GIS, so the partial discharge signal can be measured by installing an ultrasonic sensor on the outer wall of the cavity.

As shown in Figure 1, when the internal discharge occurs, the sound wave and the structure are bidirectionally coupled, and the sound pressure signal acts vertically on the GIS shell, the inner surface of the pot insulator and the outer surface of the conductive metal rod as an excitation source to cause the structure to vibrate, and the vibration at the same time It will also have a reaction to the internal sound field, and the interaction effect will cause the aluminum alloy metal cylindrical barrel to vibrate in the gas. Therefore, by measuring the vibration of the aluminum alloy metal cylinder, the discharge occurring inside the GIS can be monitored.

As an important step of the GIS handover test, the withstand voltage test is of great significance to ensure the normal operation of the equipment. However, during the handover test withstand voltage process, GIS breakdown or flashover often occurs, and now the method of listening with human ears is generally used to determine which interval has breakdown. Due to the short withstand voltage time and the sound propagation in the metal cylinder wall after GIS breakdown, it is difficult to accurately determine where the discharge occurs.

The research on GIS flashover breakdown positioning technology has done a lot of basic research work at home and abroad. Most of them are monitored by multi-channel ultrasonic sensors, or by ultra-high frequency partial discharge instruments.

For monitoring with multi-channel ultrasonic sensors, the number of monitoring points used is limited by the number of instrument channels, with a maximum of 12-16 channels. Moreover, the signal is attenuated, and the maximum distance is only 20 meters. For GIS with many intervals and long bus distance, it is far from meeting the requirements of the site. However, the decomposition product test is not suitable for on-site requirements because it takes a period of time for the decomposition product of SF6 to be produced after breakdown, and it cannot be tested immediately, and it is measured one by one.

In recent years, some electric power scientific research institutions at home and abroad are developing and researching more effective and convenient technologies and equipment suitable for GIS defect location. The main research methods are as follows: ultrasonic detection method, ultra-high frequency detection method, and decomposition gas detection method. The characteristics of various detection technologies are shown in Table 1.

Table 1. Research methods of GIS partial discharge fault location technology:

Utility model content

The purpose of this utility model is to solve the above problems and propose a system for monitoring the partial discharge position of GIS based on the flexible piezoelectric film material, so as to realize the advantage of quickly and accurately finding the discharge position.

For realizing above-mentioned object, the technical scheme that the utility model adopts is:

A system for monitoring the partial discharge position of a GIS based on a flexible piezoelectric film material, comprising an acoustic emission sensor, a signal detection circuit, a signal processing circuit, a power management circuit and an alarm circuit that are closely attached to the outer wall of the GIS, and the signal of the acoustic emission sensor is passed through The signal detection circuit transmits to the signal processing circuit, the power management circuit provides a DC power supply, and the alarm circuit is electrically connected to the signal processing circuit;

The signal detection circuit includes a charge conversion unit, a pre-amplification unit, a filter unit, a post-amplification unit and an effective value conversion unit; the charge conversion unit, the pre-amplification unit, the filter unit, the post-amplification unit and the effective value conversion unit in turn in series.

Further, the acoustic emission sensor uses PVDF piezoelectric film material.

Further, the charge conversion unit includes an operational amplifier U8, a resistor R8, a capacitor C8, a resistor R18, a capacitor C7 and a resistor R6, and the resistor R8, capacitor C8 and resistor R18 are connected in series to the inverting input of the operational amplifier U8 One end of the resistor R6 is connected to the a node, the other end of the resistor R6 is connected to the output terminal of the operational amplifier U8, one end of the capacitor C7 is connected to the b node, and the other end of the capacitor C7 is connected to the operational amplifier U8 output connection.

Further, the pre-amplification unit includes an op amp U7, a resistor R26, a resistor R7 and an adjustable resistor R29, the resistor R26 is connected in series with the inverting input terminal of the op amp U7, and one end of the resistor R7 is connected to the op amp The inverting input terminal of U7 is connected, and the other end of this resistor R7 is connected with the output terminal of operational amplifier U7, and described adjustable resistor R29 is offset voltage compensation rheostat, and the two fixed ends of this adjustable resistor R29 are connected with operational amplifier The two potential adjustment terminals of U7 are connected, and the adjustable terminal of the adjustable resistor R29 is connected with the positive-phase voltage terminal of the operational amplifier U7.

Further, the filter unit adopts a superimposed circuit of a high-pass filter circuit and a low-pass filter circuit, and the high-pass filter circuit includes an operational amplifier U6B, a capacitor C41, a capacitor C42 and a resistor R21, and the capacitor C41 and the capacitor C42 are connected in series in the operational The non-inverting input terminal of the amplifier U6B, the resistor R21 is connected in series between the inverting input terminal of the operational amplifier U6B and the output terminal of the operational amplifier U6B;

The low-pass filter circuit includes an operational amplifier U6A, a capacitor C39, a capacitor C37, a capacitor C40 and a resistor R5, and the capacitor C39 and the capacitor C37 are connected in series between the non-inverting input terminal of the operational amplifier U6A and the output terminal of the operational amplifier U6A Between, the capacitor C40 is connected in series with the output terminal of the operational amplifier U6A, and the resistor R5 is connected in series between the inverting input terminal of the operational amplifier U6A and the output terminal of the operational amplifier U6A.

Further, the post-amplification unit includes an operational amplifier U10, a resistor R62 and a resistor R61, the resistor R62 is connected in series between the inverting input terminal of the operational amplifier U10 and the output terminal of the operational amplifier U10, and the resistor R61 Connect in series with the inverting input of op amp U10.

Further, the effective value conversion unit adopts AD637 effective value conversion chip.

Further, the signal processing circuit adopts a single-chip microcomputer.

The technical solution of the utility model has the following beneficial effects:

The technical scheme of the utility model adopts acoustic emission sensor, signal detection circuit, signal processing circuit, power management circuit, alarm circuit, and signal processing circuit to detect the partial discharge position of GIS, so as to realize the purpose of quickly and accurately finding the discharge position.

The ultrasonic probe made of PVDF piezoelectric film material has the advantages of high sensitivity, anti-overload, good anti-interference, easy operation, small size and light weight.

The technical solutions of the present utility model will be further described in detail through the drawings and embodiments below.

Description of drawings

Figure 1 is a schematic diagram of the structure principle of the existing GIS air separation unit;

Fig. 2 is a schematic diagram of the placement position of the probe in the GIS cylinder structural analysis model;

Fig. 3 a to Fig. 3 g are the sound pressure and the frequency change diagram of the middle probe A point to G point in the figure;

Fig. 4 is the functional block diagram of the system based on flexible piezoelectric film material monitoring GIS partial discharge position described in the embodiment of the present invention;

Fig. 5 is a schematic diagram of GIS partial discharge position detection;

6 is an electronic circuit diagram of the charge conversion unit described in the embodiment of the present invention;

7 is an electronic circuit diagram of the pre-amplification unit described in the embodiment of the present invention;

8 is an electronic circuit diagram of the high-pass filter circuit described in the embodiment of the present invention;

9 is an electronic circuit diagram of the low-pass filter circuit described in the embodiment of the present invention;

Fig. 10 is an electronic circuit diagram of the rear amplification unit described in the embodiment of the present invention;

Fig. 11 is the electronic circuit diagram of the effective value conversion unit described in the embodiment of the present invention;

Fig. 12 is the electronic circuit diagram of the 5v power conversion circuit described in the embodiment of the present invention;

Fig. 13 is the electronic circuit diagram of the 3.3v power conversion circuit described in the embodiment of the present invention;

Fig. 14 is the electronic circuit diagram of the -5v power conversion circuit described in the embodiment of the present invention;

Fig. 15 is an electronic circuit diagram of the alarm circuit described in the embodiment of the present invention.

In conjunction with the accompanying drawings, reference signs are as follows in the utility model embodiment:

1-conductive rod; 2-basin insulator; 3-GIS shell; 4-fault chamber; 5-epoxy disc insulator; 6-aluminum alloy cylindrical barrel; 7-metal conductive rod; 8-sulfur hexafluoride gas ; 9 - sound source.

Detailed ways

The preferred embodiments of the present utility model are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present utility model, and are not intended to limit the present utility model.

In order to study the sound field distribution characteristics inside and outside the GIS cylinder structure in detail, a probe is placed in the analysis model to calculate the sound pressure at this point, and the sound pressure distribution at different measurement positions is calculated within the frequency range. The location of the probe is shown in Figure 2. Among them, A, C, and G are located on the outer surface of the aluminum alloy drum, and A, G are located above and below the point sound source, and C is located on the upper left far away from the sound source. E and F are respectively located on the inner and outer surfaces of the insulator, and B is located on the inner surface of the airtight aluminum alloy drum. D is located close to the sound source and the conductive rod.

From Figure 3a and Figure 3g above, it can be seen that the distribution of internal and external acoustic signals in GIS is as follows:

1) Sound pressure distribution inside and outside the GIS shell

Comparing the sound pressure values of points A and B, the sound pressure of point A is smaller than that of point B, and there is a large difference (80-100dB) in the low frequency range (10-30kHz), while in the high frequency (40-200kHz) A The difference between the sound pressure at point B and the sound pressure at point B is reduced to 20-40dB, which indicates that the sound intensity on the inner surface of the aluminum alloy shell is greater than that on the outer surface of the aluminum alloy shell. Measuring the discharge in the enclosure requires a sensor with higher sensitivity, or the signal on the surface of the enclosure needs to be amplified to obtain the same order of magnitude as the sound intensity measured inside.

2) Sound pressure distribution on the surface of the GIS shell

Comparing the sound pressure values at points A, C, and G, it can be seen that the sound pressure at point A is higher than that at point C (about 2-10dB), which means that the sound wave is attenuated when propagating in the solid aluminum alloy shell. The signal size of the ultrasonic sensor can be used to qualitatively confirm the distance between the sensor and the discharge sound source along the wall of the GIS barrel. Secondly, the sound pressure at point A is basically similar to that at point G, which means that in the radial direction of the same position on the GIS aluminum alloy shell, the signals acquired by the sensor are basically equal, and the position of the discharge sound source cannot be distinguished.

3) Sound pressure distribution on both sides of the insulating basin

Comparing the sound pressure values of points E and F, in the range of low frequency (1-20kHz), it can be seen that the sound pressure of point F is much smaller than that of point E (the attenuation is close to 120dB), but in the range of ultrasonic (20-200kHz) , although the sound pressure at point F is smaller than that at point E, it only attenuates by about 50dB, which shows that the audio sound waves emitted by the discharge are attenuated very seriously after passing through the epoxy insulator.

4) GIS internal sound pressure distribution

Comparing the sound pressure values of points D and E, which are also located in the closed sound field, it can be seen that the sound pressure of point D is much higher than that of point E (about 3-5dB), which shows that the sound waves emitted by the discharge are in the sulfur hexafluoride gas. propagation with some attenuation.

As shown in Fig. 4, a system based on flexible piezoelectric film material to monitor the partial discharge position of GIS, including acoustic emission sensor, signal detection circuit, signal processing circuit, power management circuit and alarm circuit, which is closely attached to the outer wall of GIS, The transmitting sensor signal is transmitted to the signal processing circuit through the signal detection circuit, the power management circuit provides DC power, and the alarm circuit is electrically connected to the signal processing circuit;

The signal detection circuit includes a charge conversion unit, a pre-amplification unit, a filter unit, a post-amplification unit and an effective value conversion unit; the charge conversion unit, the pre-amplification unit, the filter unit, the post-amplification unit and the effective value conversion unit are connected in series in sequence.

The acoustic emission sensor uses PVDF piezoelectric film material. Distributed in multiple gas chambers of the GIS. The PVDF piezoelectric film is a three-layer film. The upper and lower surfaces of the PVDF sensing core have been covered with very thin aluminum electrodes, with a thickness of 230 microns. In practical applications, the shape of the PVDF piezoelectric film can be tailored according to needs. , which will inevitably cause flaws on the edge of the film, and it is also susceptible to external electronic interference, which will cause inaccurate measurement and affect the detection effect. Therefore, in order to improve the durability and stability of the piezoelectric film, the PVDF piezoelectric film must be encapsulated.

The main technological process of making sensors with PVDF piezoelectric film is mainly divided into: determining the required shape, cutting, edge treatment, non-metallized edge, extracting electrodes and adding a protective layer.

(1) Edge processing

Cut the PVDF piezoelectric film into a rectangular shape of 3cm*1cm, and during the cutting process, many metal burrs are easily left on the edge of the aluminum electrode, which will cause a short circuit in the thickness direction of the PVDF piezoelectric film, and then affect the the working effect of the sensor. Therefore, when cutting the PVDF piezoelectric film, the flatness of the edge is very important. In order to prevent the burrs from affecting the detection effect, acetone and alcohol are used as corrosive agents to corrode the electrode burrs that may be connected to the edge of the film. This completes the non-metallization of the edge of the PVDF piezoelectric film. Finally, a multimeter is used to detect the thickness of the film. Whether there is a short circuit on the circuit to ensure the effect of corrosion.

(2) lead wire

Because the thickness of the PVDF piezoelectric film is very small, and it is very flexible, and the electrodes on the surface are very thin, so conventional methods such as welding are not suitable for PVDF piezoelectric films. In this technical solution, in order to prevent the sensor from having problems due to the influence of the lead wire contact, the upper and lower poles of the sensor are drawn out in the same direction, so that the connection of the lead wire and the shielding wire can be facilitated, and then the charge signal can be guaranteed. Maximum uninterrupted access to conditioning circuits. The method adopted is the penetrating type that is easy to do in the laboratory, that is, two methods of crimping with crimping terminals and riveting with small hollow rivets.

(3) Add protective layer

In order to prevent the electrodes from being damaged and to prevent the sensor from being disturbed by external noise, it is very necessary to add a protective layer to the sensor. Since the PVDF piezoelectric film is a film material with excellent elasticity, and the piezoelectric material will generate a strong signal when it is subjected to a large strain, which is easy to receive, so the packaging material must have sufficient elasticity so as not to affect the sensor. performance, to ensure that the sensor can transmit the sensing information to the maximum; moreover, PVDF piezoelectric film is a sensor with high internal resistance and weak signal, because of its high sensitivity, it responds very obviously to external interference, such as people talking sound signals, power frequency signals, etc. Therefore, this also requires good insulation performance of the packaging material; finally, since the thickness of the PVDF piezoelectric film is very small, the material for the film packaging should not be thick, so as to ensure the superior performance of the sensor. Through the above analysis, this technical solution selects UV resin as the packaging material of the sensor, pastes a layer of polyethylene film with a thickness of 8 microns on the top and bottom of the film material, and then irradiates with ultraviolet light, and the effect is very good after curing. On the other hand, in order to prevent the wires drawn from the surface from being damaged and cause poor sensor contact and to ensure that the PVDF piezoelectric film sensor can output a stable signal when it is bent, the connection between the electrodes and the leads is covered with silicone. For the effective area of the film and the lead-out electrode part, choose to package separately, because the thickness of the two is different, in order to minimize external interference and ensure the stability of the output signal, the effect of separate packaging is better.

(4) Electromagnetic shielding problem

Since the nature of the piezoelectric film is capacitive, the ability to resist electromagnetic interference is not strong, and it can be ignored when the output signal is very high or the data accuracy is not high. However, in this technical solution, it is known through experiments that the magnitude of the measured ultrasonic signal is at the millivolt level, so measures need to be taken to shield electromagnetic interference. The measures taken are to add shielding devices and use coaxial cables. The main thing is that the connection between the lead wire and the coaxial cable must be reinforced to prevent the sensor from causing acoustic interference due to vibration.

The basic performance indicators of the fabricated sensors are shown in Table 2.

Table 2. The main performance indicators of the sensor:

As shown in Figure 6, the charge conversion unit includes an operational amplifier U8, a resistor R8, a capacitor C8, a resistor R18, a capacitor C7 and a resistor R6, and the resistor R8, capacitor C8 and resistor R18 are connected in series at the inverting input terminal of the operational amplifier U8 , one end of the resistor R6 is connected to node a, the other end of the resistor R6 is connected to the output end of the operational amplifier U8, one end of the capacitor C7 is connected to the node b, and the other end of the capacitor C7 is connected to the output end of the operational amplifier U8.

The PVDF piezoelectric film sensor is a capacitive sensor, and its output signal is a charge proportional to the input ultrasonic vibration signal. In the actual circuit, the charge cannot be directly detected because the impedance is too high. Only by converting the amount of charge into the corresponding voltage can it be further detected, and this charge conversion circuit is designed for this purpose. This charge conversion circuit is composed of operational amplifier LF356N, precision resistors, polystyrene capacitors, etc. Among them, the LF356N operational amplifier has high input impedance, low offset and bias voltage, high common mode rejection ratio, high gain bandwidth product and large DC Advantages such as voltage gain. Ideal for use in charge conversion circuits.

In order to ensure the conversion accuracy of the charge conversion circuit, high-precision capacitance and resistance must be selected when selecting the corresponding feedback capacitance and resistance. Here we use metal film resistors and precision polystyrene capacitors with an accuracy of 0.5%.

Among them, the value of resistor R18 determines the response of the circuit to high-frequency signals; the value of resistor R6 determines the response characteristics of the circuit to low-frequency signals. Capacitor C7 is a feedback capacitor.

As shown in Figure 7, the pre-amplification unit includes operational amplifier U7, resistor R26, resistor R7 and adjustable resistor R29. The resistor R26 is connected in series with the inverting input terminal of the operational amplifier U7, and one end of the resistor R7 is connected to the negative input terminal of the operational amplifier U7. The other end of the resistor R7 is connected to the output terminal of the op amp U7, the adjustable resistor R29 is an offset voltage compensation rheostat, the two fixed ends of the adjustable resistor R29 are connected to the two potentials of the op amp U7 The adjustable end of the adjustable resistor R29 is connected to the positive phase voltage end of the operational amplifier U7.

After the charge transformation, the impedance transformation and signal transformation of the signal are completed, and the charge signal is converted into a corresponding voltage signal. However, since the converted signal is weak, in order to obtain a higher signal-to-noise ratio, the signal needs to be pre-amplified to a certain extent. Amplify useful signals to lay the foundation for subsequent filtering.

The design of the pre-amplification circuit should mainly consider the characteristics of the operational amplifier. The operational amplifier chip selected in this technical solution design is LF356N, which has the advantages of gain bandwidth product 5MHZ, high input impedance, low bias and offset voltage, etc. In particular, the gain-bandwidth product meets the actual requirements of the pre-amplification circuit. Therefore, this operational amplifier is selected as the pre-amplification circuit chip. In the circuit design, a standard inverse proportional amplification circuit is adopted, and the amplification factor is 2 times. Among them, the resistor R7 is the feedback resistor, and the adjustable resistor R29 is the offset voltage compensation rheostat to adjust the zero output. Capacitor C36 and capacitor C38 are power filter capacitors.

When signal acquisition circuit, we should not only consider how to acquire useful signals, but also how to filter out the clutter interference from the scene and the circuit itself. The on-site working environment of GIS equipment is complex, and various noises such as mechanical vibration, impact, sound of personnel activities, and power frequency interference from circuits all affect the normal and accurate operation of the equipment. In order to eliminate high-frequency and low-frequency interference from the scene, a signal filter circuit is specially designed.

When designing the filter circuit, the main considerations are as follows:

First of all, the filter circuit effectively filters out low-frequency interference. Since GIS equipment is installed both indoors and outdoors, the ambient noise cannot be shielded when GIS is working. If these environmental interference signals are not effectively filtered out in the detection circuit, it will affect the work of the GIS flashover fault location detector. , And then cause the GIS flashover fault locator to malfunction.

Secondly, the filter circuit effectively filters out the electromagnetic wave signal. When a GIS flashover fault occurs, not only a large number of low-frequency signal components, but also a large number of high-frequency electromagnetic wave components are generated. During the actual experiment and exploration process, it was found that the cable leading out of the detection sensor is like an antenna, which introduces the electromagnetic wave signal into the detection circuit, and the interference signal must be effectively filtered to avoid the distortion of signal acquisition.

To sum up, in the filter circuit design, a high-pass filter circuit and a low-pass filter circuit are superimposed to form a band-pass filter circuit. The order of each filter circuit is designed as a second-order circuit, so that the attenuation factor of the filter circuit is 40dB, and the signal interference is effectively filtered out. The filter circuit design is as follows:

The filter unit adopts a superimposed circuit of a high-pass filter circuit and a low-pass filter circuit, as shown in Figure 8, the high-pass filter circuit includes an operational amplifier U6B, a capacitor C41, a capacitor C42 and a resistor R21, and the capacitor C41 and capacitor C42 are connected in series in the operational amplifier U6B The non-inverting input terminal, the resistor R21 is connected in series with the op amp.

The op amp is TL062C, which is a high-speed op amp with a slew rate of 3.5V/us, suitable for use as a filter circuit op amp.

As shown in Figure 9, the low-pass filter circuit includes an operational amplifier U6A, a capacitor C39, a capacitor C37, a capacitor C40 and a resistor R5, and the capacitor C39 and capacitor C37 are connected in series at the non-inverting input terminal of the operational amplifier U6A and the output of the operational amplifier U6A Between terminals, the capacitor C40 is connected in series with the output terminal of the operational amplifier U6A, and the resistor R5 is connected in series between the inverting input terminal of the operational amplifier U6A and the output terminal of the operational amplifier U6A.

Among them, C2 and C3 are network labels of different resistance values in the low-pass filter circuit. Representative values are 30K, 20K, 10K, 6.2K, 3K. The corresponding signal cut-off frequencies are: 995.2Hz, 4.9KHz, 9.6KHz, 19.6KHz, 30KHz.

Signal magnification at the reverse input terminal:

C35 and C37 are power filter circuits. Filter out power clutter interference.

The amplitude of the signal after filtering is relatively small. In order to increase the range of the detection signal, the signal needs to be further amplified. The determination of the amplification factor needs to consider the gain-bandwidth product of the op amp. The LF356N operational amplifier gain-bandwidth product is 5MHZ, and there is no problem with the 10-fold amplification of the signal, so the magnification of the post-amplification circuit is determined to be 10 times here.

As shown in Figure 10, the post-amplification unit includes an operational amplifier U10, a resistor R62 and a resistor R61, and the resistor R62 is connected in series between the inverting input terminal of the operational amplifier U10 and the output terminal of the operational amplifier U10, and the resistor R61 and the operational amplifier The inverting input of device U10 is connected in series.

Resistor R62 is a feedback resistor, resistor R63 is a zero output adjustment potentiometer, capacitor C44, and capacitor C43 are power filter capacitors.

As shown in Figure 11, the signal after the post-amplification circuit is still a bipolar signal. In order to facilitate the acquisition and processing of the single-chip microcomputer, and at the same time perform effective value conversion processing on the signal, the AD637 effective value conversion chip is selected to form the effective value conversion circuit.

Capacitor C17 is an external capacitor, which is used to set the average time of the signal. This technical solution selects a small capacitor of 1nF, which is convenient for capturing instantaneously changing signals. The capacitor C14 is a DC blocking capacitor, which blocks the DC bias signal generated after the post-amplification.

The resistor R16 and the capacitor C16 are passive low-pass filter units. Perform low-pass filtering on the AD637 output signal. Make the output signal smoother.

The signal processing circuit is mainly composed of a single-chip computer. The main functions are: signal A/D conversion, processing of collected data, etc. And connect the display unit.

power management circuit

The signal processing circuit is powered by a rechargeable battery, and the power supply voltage is 7.2V. Since the working voltage of the internal integrated chip is +5V, +3.3V, etc., it is necessary to perform voltage conversion on the input power supply. As shown in Figure 12, the LM2940 has the function of power conversion, which can convert the input voltage range from 6.25V to 26V to +5V voltage output. At the same time, the output current exceeds 1A, which is sufficient to meet the requirements of this circuit. And its working temperature and storage temperature are -40oC ~ 85oC, meet the industrial requirements. It should be noted that the analog ground and the digital ground are separated by resistors R14 and R15 to avoid mutual interference. The capacitor acts as a filter here.

As shown in Figure 13, the ASM1117 chip and the LM2940 chip have similar functions and play the role of power conversion. Since the operating voltage range of C8051 is 2.7V to 3.6V, it is necessary to convert the voltage of +5V to +3.3V, and the capacitor acts as a filter here. The analog ground and digital ground are distinguished by resistor R16. LED0 is the working status indicator of the circuit. When the LED is on, it means that the circuit is working normally. If it is not on, it means that there is a problem with the circuit and needs to be checked.

As shown in Figure 14, since the front-end analog op amp is powered by dual power supplies, a -5V voltage is required. Therefore, the LMC7660IM voltage conversion chip is used to realize the conversion of +5V voltage into -5V voltage. The role of the capacitor is also filtering.

The alarm circuit, as shown in Figure 15, after the detected signal reaches a certain level, it needs to light up the LED and output a light alarm to remind the staff to check the detected section. The p2.3 in the figure is the single chip microcomputer I/O interface.

Finally, it should be noted that: the above is only a preferred embodiment of the utility model, and is not intended to limit the utility model, although the utility model has been described in detail with reference to the foregoing embodiments, for those skilled in the art , it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (8)

1. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position, it is characterized in that, comprise the calibrate AE sensor, signal deteching circuit, signal processing circuit, electric power management circuit and the warning circuit that are close on GIS outer wall, described calibrate AE sensor signal passes to signal processing circuit through signal deteching circuit, described electric power management circuit provides direct supply, and described warning circuit is electrically connected with signal processing circuit;

Described signal deteching circuit comprises charge-voltage converting unit, pre-amplification unit, filter unit, rearmounted amplifying unit and RMS-DC converter unit; Connect successively in described charge-voltage converting unit, pre-amplification unit, filter unit, rearmounted amplifying unit and RMS-DC converter unit.

2. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1, is characterized in that, described calibrate AE sensor adopts PVDF piezoelectric film material.

3. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, it is characterized in that, described charge-voltage converting unit, comprise transport and placing device U8, resistance R 8, capacitor C 8, resistance R 18, capacitor C 7 and resistance R 6, described resistance R 8, capacitor C 8 and resistance R 18 are connected on the inverting input of transport and placing device U8, described resistance R 6 one end are connected on a node, the other end of resistance R 6 is connected with the output terminal of transport and placing device U8, described capacitor C 7 one end are connected on b node, and the other end of this capacitor C 7 is connected with the output terminal of transport and placing device U8.

4. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, it is characterized in that, described pre-amplification unit comprises transport and placing device U7, resistance R 26, resistance R 7 and adjustable resistance R29, described resistance R 26 is connected on the inverting input of transport and placing device U7, described resistance R 7 one end are connected with the inverting input of transport and placing device U7, the other end of this resistance R 7 is connected with the output terminal of transport and placing device U7, described adjustable resistance R29 is offset compensation rheostat, two stiff ends of this adjustable resistance R29 are connected with two current potential adjustable sides of transport and placing device U7, the adjustable end of this adjustable resistance R29 is connected with the positive voltage end of transport and placing device U7.

5. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, it is characterized in that, described filter unit adopts the circuit of high-pass filtering circuit and low-pass filter circuit stack, described high-pass filtering circuit comprises transport and placing device U6B, capacitor C 41, capacitor C 42 and resistance R 21, described capacitor C 41 and capacitor C 42 are connected on the in-phase input end of transport and placing device U6B, and described resistance R 21 is connected between the inverting input of transport and placing device U6B and the output terminal of transport and placing device U6B;

Described low-pass filter circuit comprises transport and placing device U6A, capacitor C 39, capacitor C 37, capacitor C 40 and resistance R 5, described capacitor C 39 and capacitor C 37 are connected between the in-phase input end of transport and placing device U6A and the output terminal of transport and placing device U6A, described capacitor C 40 is connected with the output terminal of transport and placing device U6A, and described resistance R 5 is connected between the inverting input of transport and placing device U6A and the output terminal of transport and placing device U6A.

6. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, it is characterized in that, described rearmounted amplifying unit comprises that transport and placing device U10, resistance R 62 and resistance R 61, described resistance R 62 are connected between the inverting input of transport and placing device U10 and the output terminal of transport and placing device U10, and described resistance R 61 is connected with the inverting input of transport and placing device U10.

7. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, is characterized in that, described RMS-DC converter unit adopts AD637 RMS-DC converter chip.

8. the system based on flexible piezoelectric membraneous material monitoring GIS partial discharge position according to claim 1 and 2, is characterized in that, described signal processing circuit adopts single-chip microcomputer.