CN111830381B - Watchband-adjustable full-attached cable partial discharge ultrasonic sensor and online monitoring method - Google Patents
Watchband-adjustable full-attached cable partial discharge ultrasonic sensor and online monitoring method Download PDFInfo
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- CN111830381B CN111830381B CN202010887005.6A CN202010887005A CN111830381B CN 111830381 B CN111830381 B CN 111830381B CN 202010887005 A CN202010887005 A CN 202010887005A CN 111830381 B CN111830381 B CN 111830381B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1209—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/04—Housings; Supporting members; Arrangements of terminals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
Abstract
The invention relates to a watchband adjustable full-fitting cable partial discharge ultrasonic sensor, which belongs to the field of on-line monitoring and intelligent diagnosis of power equipment, and comprises a thin metal sheet lining and a rubber watchband, wherein a watchband buckle head is arranged at the end part of the rubber watchband, a grounding metal sealing box is arranged in the middle of the rubber watchband, and grounding polar plates are arranged on the upper surface and the lower surface of the grounding metal sealing box; an ultrasonic signal sensing system, a signal acquisition and processing system, a data analysis and storage system, a device self measurement and control system, a communication system and a power supply system are arranged in the grounding metal sealing box. The size of the watchband can be adjusted according to the size of the power cable, and the watchband is installed and fastened, so that the thin metal sheet is tightly attached to the outer surface of the cable to be tested, the loss of ultrasonic signals during transmission is reduced, and the reliability and the accuracy of measurement data are ensured; the invention can be widely applied to the on-line monitoring scene of the partial discharge of the power cable, in particular to a watchband type design structure, is convenient to install and is suitable for power cables of various types.
Description
Technical Field
The invention belongs to the field of on-line monitoring and intelligent diagnosis of power equipment, and relates to a watchband-adjustable full-lamination cable partial discharge ultrasonic sensor and an on-line monitoring method.
Background
In a power system, partial discharge occurs at a cable insulation defect in the operation process of a high-voltage and ultra-high-voltage power cable, the partial discharge further causes insulation degradation of the power cable, and the cable is damaged when serious, so that large-area power failure accidents occur, and therefore, detection of the partial discharge of the cable is one of important measures for reducing cable faults. The part of the cable where partial discharge occurs can generate ultrasonic waves, and the ultrasonic waves are transmitted to the cable surface on-line monitoring device. When the ultrasonic wave propagates in the device, the surface of the device is slightly deformed, mechanical stress is generated on the PVDF piezoelectric film attached to the surface of the device and converted into a charge signal, and the charge signal is subjected to the actions of a charge amplifier, a trap circuit and a voltage amplifying circuit and then sent to a computer for analysis and processing, so that the degradation degree of the cable is evaluated.
According to the nature of ultrasound, its attenuation in gaseous media is very severe while in metallic and liquid media is weak, even when propagating in short-distance metallic media, it is important to utilize metallic media and exclude air between cable and metal when receiving ultrasound signals. The cable surface is circular arc, and most ultrasonic sensor surfaces are plane, so it is difficult to fit well with the cable surface, and ultrasonic signals cannot be received in the most efficient way. In general, when receiving an ultrasonic signal, the ultrasonic sensor is exposed to the air and is easily interfered by other signals in the external environment, so that it is important to obtain a more accurate result when receiving an ultrasonic wave to eliminate the influence of the external interference signal.
Disclosure of Invention
In view of the above, the invention aims to solve the problems that the existing ultrasonic on-line monitoring method is easily interfered by external environment signals, so that ultrasonic weak signals are covered, monitoring results are inaccurate and the like, and provides an ultrasonic on-line monitoring device based on cable partial discharge and a structure optimization method. According to the invention, the metal box is used for packaging the ultrasonic sensor, the wave trap circuit, the amplifying circuit, the power supply module and the A/D conversion module, and the metal box is coated with materials for reflecting and absorbing the acoustic wave signals, so that the interference of the external environment is eliminated. Meanwhile, a film ultrasonic sensor is attached to the metal excircle, and an ultrasonic coupling layer is arranged between the metal excircle and the sensor so as to enhance ultrasonic signals. The invention aims to improve the anti-interference capability of the on-line monitoring device, eliminate external interference and maximize ultrasonic signal reception, thereby improving the accuracy and precision of the ultrasonic sensor.
The principle of the invention is as follows: the device mainly realizes signal receiving and information acquisition based on an ultrasonic sensing mode. The device mainly comprises a signal receiving and signal processing module and a device accessory. The modularized ultrasonic sensor is a core structure of the device and mainly comprises an ultrasonic signal acquisition structure and a signal conversion structure. The ultrasonic signal acquisition structure is composed of a PVDF polyvinylidene fluoride piezoelectric film sensor, and the PVDF polyvinylidene fluoride piezoelectric film has the following advantages: the piezoelectric voltage constant is high, and when the piezoelectric sensor is used as a sensor, the sensitivity is high; the density is low, the weight is light, and the influence on the original structure is small when the adhesive is adhered to the surface of an object; the dielectric constant is high, and the strong electric field effect can be tolerated; the flexibility and the processability are good, and films with different thicknesses and different shapes can be manufactured according to the requirements; the frequency response is wide and can be 10 -5 ～10 9 An in-range response; meanwhile, the alloy has high chemical stability and fatigue resistance and good thermal stability. Based on the advantages, the PVDF polyvinylidene fluoride piezoelectric film sensor is adopted as a sensor for receiving ultrasonic signals. The PVDF piezoelectric film sensor transmits ultrasonic information through the degree of stress strain of the film due to the surface deformation of the PVDF piezoelectric film sensor when ultrasonic waves pass through the device, and under the condition that an externally applied electric field is zero, the piezoelectric equation of the PVDF piezoelectric film is as follows:
D i ＝d ij T j (1)
wherein: d (D) i Is an electrical displacement; d, d ij Is a piezoelectric constant; t (T) j Is the stress (i=1, 2,3; j=1, 2,3, carrying out 6).
The output charge of a PVDF piezoelectric film is the response of all its directional strains acting in the polarization direction, namely:
Q＝∑d ij Eε j S (2)
wherein: q is the output charge; e is the elastic modulus of the PVDF piezoelectric film; epsilon j Strain (j=1, 2, 3); s is the area covered by the PVDF piezoelectric film.
Under the condition of one-dimensional stress, the output charge of the PVDF piezoelectric film can be expressed as:
Q＝d 31 Eε 1 S (3)
when the PVDF piezoelectric film is used for a sensing function, the PVDF piezoelectric film is a charge generator, and the generated charges are required to be changed into voltage signals through a signal conversion structure so as to be subjected to subsequent processing. The signal conversion structure is a charge amplifier, in fact, the charge amplifier is a high-gain operational amplifier with deep capacitance negative feedback, the charge signal becomes a voltage signal after passing through the signal conversion structure, and the voltage signal can be obtained as follows:
wherein: c (C) f Is the feedback capacitance of the charge amplifier.
Thus, the voltage output of the charge amplifier is linearly dependent on the strain of the structure being measured, while the larger the area covered by the piezoelectric sensor on the cable, the greater the voltage thereof, which is easier to measure.
Because PVDF piezoelectric film itself is easily received electromagnetic interference, wherein with 50 Hz's power frequency interference most obvious, the existence of power frequency interference easily causes signal distortion, consequently adopts the trapper circuit to eliminate the influence of power frequency interference, and the trapper circuit adopts the dual T band elimination filter circuit to realize. And after the charge signal output by the PVDF piezoelectric film is processed by the charge amplifier and the trap circuit, a voltage detection signal is obtained by the voltage amplifying circuit.
Meanwhile, the optimized structure of the invention encapsulates all the parts which are easy to be interfered in the metal box, the metal box is grounded, the external electromagnetic interference can be shielded, a relatively independent space is formed inside, and the surface of the metal box is coated with a layer of material for absorbing and reflecting sound waves, so that the anti-interference level of the device is further enhanced.
In order to achieve the above purpose, the present invention provides the following technical solutions:
on the one hand, the utility model provides a watchband adjustable full laminating cable partial discharge ultrasonic sensor, including thin metal sheet inside lining and rubber watchband, rubber watchband cladding metal sheet inside lining, and be equipped with the watchband buckle in rubber watchband tip, rubber watchband other end pass the watchband buckle to can be locked by the watchband buckle;
the middle part of the rubber watchband is provided with a grounding metal sealing box, the outer surface of the grounding metal sealing box is covered with a layer of coating for absorbing and reflecting electromagnetic waves, and the upper surface and the lower surface of the grounding metal sealing box are provided with grounding polar plates;
an ultrasonic signal sensing system, a signal acquisition and processing system, a data analysis and storage system, a device self measurement and control system, a communication system and a power supply system are arranged in the grounding metal sealing box;
the ultrasonic signal sensing system is used for collecting cable ultrasonic waves and converting the cable ultrasonic waves into voltage signals; the signal acquisition and processing system is used for receiving the voltage signal and performing filtering amplification and time-frequency conversion processing; the data analysis and storage system is used for receiving data for analysis, obtaining ultrasonic signal fluctuation characteristics and cable operation conditions, and storing the data; the device self measurement and control system is used for abnormal condition detection and alarm and is also used for man-machine communication regulation and control; the communication system is used for communicating with an upper computer; the power supply system is used for supplying power to each module.
Further, the ultrasonic signal sensing system comprises a PVDF piezoelectric film sensor and a charge amplifier, wherein a protective film is further arranged on the surface of the PVDF piezoelectric film sensor, and the ultrasonic signal sensing system further comprises the charge amplifier for converting generated charge signals into voltage signals.
Further, the signal acquisition and processing system comprises a trap circuit, a voltage amplifying circuit, a voltage converting circuit, an A/D converter and a signal reading module, wherein the trap circuit is used for carrying out power frequency interference elimination on the voltage signal, then the voltage amplifying circuit is used for obtaining a voltage detection signal, the voltage converting circuit is used for converting the actual voltage amplitude value into the effective interval of the signal acquisition device, and the A/D converter and the signal reading module are used for realizing voltage signal acquisition and storage.
Further, the data analysis and storage system comprises a high-frequency programmable processor core with an FPU, and parameter characteristic identification, time domain correlation calculation and state evaluation algorithms are carried on the high-frequency programmable processor core and are used for mining ultrasonic signal fluctuation characteristics and cable operation conditions, synchronously acquiring ultrasonic signal data of partial discharge of the cable and providing real-time reference information for identification, operation and maintenance and protection of the cable operation conditions; the memory is expanded through the external expansion SDRAM, and the local data storage capacity is expanded through the external expansion NAND FLASH, so that the storage of the local long-period primary data, the secondary data, the identification result and other data is met.
Further, the device self measurement and control system comprises a device abnormality alarm system and a man-machine communication regulation and control system; the device abnormality alarm system comprises a digital distributed temperature sensor for measuring multipoint temperature in the device and an IIC gating chip for transmitting and collecting multipoint temperature information, and is used for judging and alarming the abnormal temperature; the device abnormality alarm system further comprises a power abnormality alarm system, wherein the power abnormality alarm system collects port signal voltage by using a real-time voltage collection circuit, inputs the port signal voltage into a comparison circuit to be compared with a set threshold voltage, and triggers the voltage abnormality alarm circuit when the output voltage is lower than the threshold voltage;
the man-machine communication regulation and control system comprises a display screen, control keys and an indicator lamp and is used for man-machine interaction.
Furthermore, the communication system comprises a standard optical fiber interface, an Ethernet interface, an RS232/485 interface and a connecting wire at the rear end, and the information in the storage unit is directly transmitted to the communication port by utilizing a DMA mode of the central processing unit, and the communication system is matched with an IEC61850 protocol in the station to realize the functions of uploading information, calling real-time information and remote control between the communication system and IDE equipment in the station and a communication server in the station.
Further, the power supply system comprises an external power supply system, an uninterruptible power supply system, a voltage stabilizing system and a digital-analog isolation system; the external power supply system comprises an alternating current-direct current power supply interface, a rectification loop, an inversion frequency conversion circuit, a filter circuit and a multistage voltage division circuit which are connected in sequence; the uninterruptible power supply system comprises a storage battery pack and is used for guaranteeing continuous supply of electric energy under abnormal conditions; the voltage stabilizing system comprises a voltage protection circuit, so that damage to the device under the action of large voltage is avoided; the digital-analog isolation system is used for realizing the isolation of a digital power supply and an analog power supply and avoiding the mutual interference between signals.
Further, the device can realize measurement of the transient value of the cable ultrasonic signal, the local data storage period is 72h, and the depth of expansion storage is 128G; a standard 220V/50Hz ac source or a 15V constant dc source may power the device.
Further, the fixing device is an elastic watchband. The watchband is formed by embedding a metal sheet lining structure and a rubber appearance structure, the metal sheet lining structure is tightly embedded with the rubber appearance by a thin metal sheet, the size of the metal sheet lining structure can be adjusted according to the size of a cable, and when the watchband is installed, the watchband can be loosened, a monitoring device is installed and fixed on the cable to be tested, and then the watchband is tensioned, so that the metal sheet lining and the cable to be tested are tightly adhered together, and the loss of an ultrasonic signal in the transmission process is reduced.
On the other hand, the invention provides an on-line monitoring method, based on the watchband adjustable full-fitting cable partial discharge ultrasonic sensor, comprising the following steps:
(1) Initialization of
After the watchband adjustable full-attaching cable partial discharge ultrasonic sensor is powered on, the system enters initialization setting according to preset setting, a self measurement and control system is started to detect a power supply system and an operation condition, and the system enters an ultrasonic signal acquisition and measurement state after self detection is qualified;
(2) Periodic signal acquisition and processing
The method comprises the steps of entering a signal acquisition and data analysis period, firstly acquiring ultrasonic signals, converting charge signals output by a thin film sensor into voltage signals by utilizing a charge amplifier, inputting the voltage signals into a filter circuit and an amplifying circuit for processing, then transmitting the signals to an A/D high-speed acquisition device, performing digital filtering by utilizing a high-frequency central processing unit, and storing the processed data into a local memory according to date and characteristic types for subsequent processing;
(3) Data analysis and condition identification
The stored data are subjected to call analysis, ultrasonic characteristics including amplitude, frequency and change rate thereof are obtained based on algorithms such as ultrasonic signal characteristic recognition and state evaluation, the characteristic quantity is compared with historical data, or the partial discharge condition of the cable is excavated based on an intelligent algorithm, so that the current cable operation condition is fully identified, and the faults of overheating inside the cable and excessive transient overvoltage are found in advance; when a fault or abnormal operation condition is identified, starting an early warning system, and simultaneously starting a communication function, and sending an abnormal instruction to a station server to realize accurate early warning of the abnormal cable condition; when no fault exists and the station server sends a call command periodically or appointed, the communication interface receives the call command and starts a data call command in the central processing unit, and a required data set is called out from the memory to be subjected to sub-packaging processing and sending, so that uploading of historical monitoring data is realized, and the sampler continuously performs real-time data sampling during the period;
(4) Ending
When the reset period of the device is reached, the device starts refreshing integrally, vacates the memory and the body storage, and enters the step (1); when a closing command of the station control end or closing of the near-earth end is received, the device is interrupted to operate and enters a closing state.
The invention has the beneficial effects that:
1. according to the invention, the adjustable full-fitting cable partial discharge ultrasonic sensor of the watchband is designed firstly, the size of the watchband of the designed device can be adjusted according to the size of the power cable, and the watchband is fastened by adopting the mounting of the watchband, so that the thin metal sheet is tightly fitted with the outer surface of the cable to be tested, the loss of ultrasonic signals during transmission is reduced, and the reliability and the accuracy of measurement data are ensured;
2. the electromagnetic shielding structure formed by coating electromagnetic absorption and reflection materials on the outer surface of the metal box and grounding can enhance the resistance of an internal measurement and control device to external interference signals, so that the device can be used in various severe environments;
3. the power cable ultrasonic signal synchronous sensing system provided by the invention has the functions of intelligent data processing, remote communication, automatic regulation and control and the like, can realize local processing and analysis of original data, finishes information mining by depending on a hardware program, realizes data transmission by utilizing a remote communication module and a station control layer server, and can realize diagnosis and regulation of the running state of the device per se by the developed automatic regulation and control function, so that the problem of unreliable monitoring caused by unreliable device per se is avoided;
4. the device and the system are convenient to use, and the method is simple to operate.
The invention can be widely applied to the on-line monitoring scene of the partial discharge of the power cable, in particular to a watchband type design structure, is convenient to install and is suitable for power cables of various types.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and other advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the specification.
Drawings
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in the following preferred detail with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of the three-dimensional and planar structure of the device of the present invention;
FIG. 2 is a schematic diagram of data acquisition of the apparatus of the present invention;
FIG. 3 is a schematic illustration of a metal box package of the apparatus of the present invention;
FIG. 4 is a schematic block diagram of the apparatus of the present invention;
FIG. 5 is a block diagram of the power supply system of the device of the present invention;
fig. 6 is a flow chart of the apparatus of the present invention.
Reference numerals: 1-a thin sheet metal liner; 2-a rubber watchband; 3-a watchband buckle; 4-a grounded metal seal box; 5-sealing the earcaps; 6-PVDF piezoelectric film sensor; 7-a charge transfer line; 8-a charge amplifier; 9, a voltage signal acquisition line; 10-a voltage acquisition system; 11-a data analysis hardware module; 12-a memory module; 13-a communication system; 14-a power supply system; 15-a storage battery; 16-an external ac power supply system; 17-a metal box upper polar plate; 18-a metal box lower polar plate; 19—a metal box ground loop; 20-anti-interference coating.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the illustrations provided in the following embodiments merely illustrate the basic idea of the present invention by way of illustration, and the following embodiments and features in the embodiments may be combined with each other without conflict.
Wherein the drawings are for illustrative purposes only and are shown in schematic, non-physical, and not intended to limit the invention; for the purpose of better illustrating embodiments of the invention, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the size of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc., that indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but not for indicating or suggesting that the referred device or element must have a specific azimuth, be constructed and operated in a specific azimuth, so that the terms describing the positional relationship in the drawings are merely for exemplary illustration and should not be construed as limiting the present invention, and that the specific meaning of the above terms may be understood by those of ordinary skill in the art according to the specific circumstances.
As shown in fig. 1-5, an adjustable watchband type full-fitting cable partial discharge ultrasonic sensor mainly comprises a watchband type device structure, an ultrasonic signal sensing structure, a signal acquisition and processing system, a data analysis and storage system, a device self measurement and control system, a communication system and a power supply system, and is characterized in that:
the watchband type device structure consists of a watchband and a closed metal box, wherein the watchband is formed by embedding a thin metal sheet liner 1 and a rubber watchband 2, the size of the watchband can be adjusted according to the size of a cable, and the watchband is fastened by a watchband buckle head 3 during installation, so that the thin metal sheet can be tightly attached to cable bodies or joints with different sizes; because of strong transmissibility of ultrasonic wave in metal and a full-lamination type structure, ultrasonic signals are transmitted to the thin metal sheet directly through a coupling agent on the surface of the cable in low loss during measurement, and then are transmitted to the sensor through the annular thin metal sheet rapidly, so that loss of the ultrasonic signals in the transmission process is greatly reduced, and partial discharge ultrasonic sensing under an all-dimensional angle is realized; the metal sealing box 4 is installed in the watchband center, and the sealing box is made of metal entirely, uses screw fastening to seal the fastening to the metal box during the installation, installs sealed earcaps on the metal box, can better seal. The metal box outer surface is smeared with a layer of paint capable of absorbing and reflecting electromagnetic waves, namely an anti-interference coating 20, and the metal box outer surface is further provided with a metal box grounding loop 19 for grounding the metal box, and the upper surface and the lower surface are provided with grounding polar plates, namely an upper metal box polar plate 17 and a lower metal box polar plate 18, so that zero potential is presented on the metal shell, an electromagnetic shielding independent space is constructed between the inside of the metal box and the external environment, and the influence of external interference signals on the inside is reduced.
The ultrasonic signal sensing system mainly comprises a PVDF piezoelectric film sensor 6 and a charge amplifier 8 which are connected through a charge transmission line 7. In order to avoid damaging and polluting the PVDF piezoelectric film in use, a layer of protective film is added on the surface of the PVDF piezoelectric film; secondly, because the PVDF piezoelectric film is a high polymer material, the electrode cannot be directly welded, but the electrode is led out from the PVDF piezoelectric film in a riveting mode. When the ultrasonic wave propagates in the device, the surface of the device is slightly deformed, mechanical stress is generated on the PVDF piezoelectric film attached to the surface of the device, the mechanical stress is converted into a charge signal, the charge signal is converted into a voltage signal through a charge amplifier, and the voltage signal is transmitted to a signal acquisition and processing module for processing.
The signal acquisition and processing system 10 comprises a voltage signal acquisition line 9, signal filtering, signal amplification and time-frequency conversion of signals. In order to avoid electromagnetic interference to the ultrasonic signals, a trap circuit is designed to eliminate the influence of power frequency interference, and the trap circuit is realized by adopting a double-T band-stop filter circuit. The charge signal output by the PVDF piezoelectric film is processed by the charge amplifier and the trap circuit, then the voltage detection signal is obtained by the voltage amplifying circuit, meanwhile, the voltage converting circuit is designed to convert the actual voltage amplitude into the effective interval of the signal collector, and the voltage signal collection and storage are realized by utilizing the high-resolution A/D converter and the high-speed signal reading module, and the voltage signal is directly transmitted to the central controller after collection, so that the data inspection and transmission are realized.
The data analysis and storage system mainly comprises a data analysis hardware module 11, a storage module 12 and a data processing algorithm. The data analysis hardware module 11 is provided with a high-frequency programmable processor core of the FPU, can realize high-precision and high-speed floating point processing, builds a multi-data processing unit by utilizing a programming and program burning mode, and can support multi-type communication interfaces; (2) the external expansion SDRAM12 is selected to expand the memory, so that the computing capacity of the processor is improved, and the requirement of a complex data processing algorithm is met; the large-capacity, long-period and industrial-level external expansion NAND-FLASH are selected to expand the local data storage capacity so as to meet the storage of the local long-period primary data, secondary data, identification results and other data, and a target database is provided for later remote call; (3) the data processing algorithm comprises algorithms such as parameter feature recognition, time domain correlation calculation, state evaluation and the like so as to fully mine information such as ultrasonic signal fluctuation features, cable operation conditions and the like, realize synchronous acquisition of ultrasonic signal data of partial discharge of the cable and provide real-time reference information for identification, operation and maintenance and protection of the cable conditions.
The device self measurement and control system mainly comprises a device abnormality alarm system and a man-machine communication regulation and control system. In the actual running condition, a high-temperature early warning system of the device is designed in order to prevent the external fire source from causing serious damage to the monitoring device. The method comprises the steps of measuring the multipoint temperature inside the device by using a digital distributed temperature sensor, realizing transmission and collection of multipoint temperature information by using a high-speed IIC gating chip, judging abnormal temperature based on an internal temperature early warning method, and controlling an early warning circuit of high temperature abnormality to realize characterization of a temperature abnormality state; (2) in actual operation, when the energy of the independent power supply is insufficient or the power supply loop fails, the output voltage signal is unstable and the detection signal is inaccurate. The power supply abnormality alarm system of the real-time voltage acquisition and comparison circuit and the early warning system with low energy consumption is provided, the port signal voltage is acquired by the real-time voltage acquisition circuit and is input into the comparison circuit to be compared with the set threshold voltage, and when the output voltage is lower than the threshold voltage, the voltage abnormality alarm circuit is triggered; (3) the man-machine communication system comprises a liquid crystal display screen, an indicator light and keys, wherein the liquid crystal display screen is connected with the measurement and control system by a multi-core shielding wire, a user inputs related commands by the keys and sends the related commands to the measurement and control system, the selection of corresponding functions and the equipment debugging are completed, and the measurement and control system sends the working condition and parameter information of the device to the liquid crystal display screen to realize man-machine communication.
The communication system 13 comprises a standard optical fiber interface, an Ethernet interface, an RS232/485 interface, a connecting wire at the rear end and the like of the device, and utilizes a DMA mode of a central processing unit to directly transmit information in a storage unit to a communication port, and the communication system is matched with an IEC61850 protocol in a station to realize the functions of uploading information, calling real-time information, remote control and the like between the device and IDE equipment in the station and between the device and a communication server in the station.
The power supply system 14 comprises an uninterruptible power supply system, and is a storage battery 15, an external power supply system 16, a voltage stabilizing system and a digital-analog isolation system in the embodiment. The AC/DC power supply interface is provided, the AC or DC power supply of the device under different backgrounds can be met, a rectifying circuit, an inversion frequency conversion circuit, a voltage stabilizing circuit, a filtering circuit and a multi-stage voltage dividing circuit are designed, stable output of +/-5V, +/-3V numbers, analog power supply voltage and 200Hz AC voltage can be realized, and a voltage protection circuit is built, so that the device is prevented from being damaged under the action of large voltage; the uninterrupted power supply system of the device is designed by utilizing the battery and the voltage stabilizing circuit, so that the continuous supply of the device power under the condition of poor quality of an external power supply or fault is met; the large ground plane and the digital-analog isolation circuit are designed, the isolation of a digital power supply and an analog power supply is realized, the mutual interference between signals can be avoided, and the signal integrity of a monitoring system is ensured.
Further, the device can realize measurement of the transient value of the cable ultrasonic signal, the local data storage period is 72h, and the depth of expansion storage is 128G; a standard 220V/50Hz ac source or a 15V constant dc source may power the device.
Further, the fixing device is an elastic watchband. The watchband is formed by embedding a metal sheet lining structure and a rubber appearance structure, the metal sheet lining structure is tightly embedded with the rubber appearance by a thin metal sheet, the size of the metal sheet lining structure can be adjusted according to the size of a cable, and when the watchband is installed, the watchband can be loosened, a monitoring device is installed and fixed on the cable to be tested, and then the watchband is tensioned, so that the metal sheet lining and the cable to be tested are tightly adhered together, and the loss of an ultrasonic signal in the transmission process is reduced.
As shown in fig. 6, the present invention further provides a monitoring method, by using the device, to perform measurement of cable partial discharge ultrasonic waves in a programmed manner, wherein the specific method comprises the following steps:
(1) Initialization of
After the device is powered on, the device system enters initialization setting according to preset setting, the device starts a self measurement and control system to detect the power system 14 and the running condition, and enters an ultrasonic signal acquisition and measurement state after self-checking is qualified;
(2) Periodic signal acquisition and processing
After the step (1) is finished, entering a signal acquisition and data analysis period, firstly acquiring an ultrasonic signal, converting a charge signal output by a thin film sensor into a voltage signal by utilizing a charge amplifier (7), inputting the voltage signal into a filter circuit and an amplifying circuit for processing, then transmitting the signal to an A/D high-speed collector, performing digital filtering by utilizing a high-frequency central processing unit 11, and storing the processed data into a local memory 12 according to date and characteristic types for subsequent processing;
(3) Data analysis and condition identification
After the step (2) is completed, carrying out calling analysis on the stored data, acquiring ultrasonic characteristics including amplitude, frequency, change rate and the like based on algorithms such as ultrasonic signal characteristic identification and state evaluation, comparing the characteristic quantity with historical data, or digging partial discharge conditions of the cable based on an intelligent algorithm, so as to fully identify the current cable operation condition and discover faults such as overheating inside the cable, excessive instantaneous overvoltage and the like in advance. When a fault or abnormal operation condition is identified, the device starts the early warning system, and simultaneously starts the communication function 13 to send an abnormal instruction to the station server, so that accurate early warning of the abnormal cable condition is realized; when no fault exists and the station server sends out the call command periodically or appointed, the communication interface receives the call command and starts the data call command in the central processing unit 11, and the data set is called out from the memory 12 for sub-packaging processing and sending, so that uploading of historical monitoring data is realized, and the sampler continuously performs real-time data sampling during the period;
(4) Ending
After the steps (1), 2 and 3) are completed, when the reset period of the device is reached, the whole device starts to refresh, the memory and the body are emptied for storage, and the step (1) is entered; when a closing command of the station control end or closing of the near-earth end is received, the device is interrupted to operate and enters a closing state.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the claims of the present invention.
Claims (3)
1. The utility model provides an ultrasonic sensor is put in cable office with adjustable laminating with watchband which characterized in that: the novel watch band comprises a thin metal sheet lining and a rubber watch band, wherein the rubber watch band is coated with the metal sheet lining, a watch band buckle head is arranged at the end part of the rubber watch band, and the other end part of the rubber watch band penetrates through the watch band buckle head and can be locked by the watch band buckle head; the size of the rubber watchband can be adjusted according to the size of the cable, the watchband is loosened during installation and is installed and fixed on the cable to be tested, and then the watchband is tensioned, so that the thin metal sheet lining is attached to the cable to be tested, and the loss of an ultrasonic signal in the transmission process is reduced;
the middle part of the rubber watchband is provided with a grounding metal sealing box, the outer surface of the grounding metal sealing box is covered with a layer of coating for absorbing and reflecting electromagnetic waves, and the upper surface and the lower surface of the grounding metal sealing box are provided with grounding polar plates;
an ultrasonic signal sensing system, a signal acquisition and processing system, a data analysis and storage system, a device self measurement and control system, a communication system and a power supply system are arranged in the grounding metal sealing box;
the ultrasonic signal sensing system is used for collecting cable ultrasonic waves and converting the cable ultrasonic waves into voltage signals; the signal acquisition and processing system is used for receiving the voltage signal and performing filtering amplification and time-frequency conversion processing; the data analysis and storage system is used for receiving data for analysis, obtaining ultrasonic signal fluctuation characteristics and cable operation conditions, and storing the data; the device self measurement and control system is used for abnormal condition detection and alarm and is also used for man-machine communication regulation and control; the communication system is used for communicating with an upper computer; the power supply system is used for supplying power to each module;
the ultrasonic signal sensing system comprises a PVDF piezoelectric film sensor and a charge amplifier, wherein the PVDF piezoelectric film surface of the PVDF piezoelectric film sensor is also provided with a protective film, and the ultrasonic signal sensing system further comprises the charge amplifier which is used for converting a generated charge signal into a voltage signal;
the signal acquisition and processing system comprises a trap circuit, a voltage amplifying circuit, a voltage converting circuit, an A/D converter and a signal reading module, wherein the trap circuit performs power frequency interference elimination on the voltage signal, then the voltage amplifying circuit obtains a voltage detection signal, the voltage converting circuit converts the actual voltage amplitude into the effective interval of the signal acquisition device, and the A/D converter and the signal reading module are utilized to realize voltage signal acquisition and storage;
the data analysis and storage system comprises a high-frequency programmable processor core with an FPU, and is provided with parameter feature recognition, time domain correlation calculation and a state evaluation algorithm, wherein the parameter feature recognition, time domain correlation calculation and state evaluation algorithm are used for mining ultrasonic signal fluctuation features and cable operation working conditions, synchronously collecting ultrasonic signal data of partial discharge of the cable and providing real-time reference information for recognition, operation maintenance and protection of the cable working conditions; the memory is expanded through the external expansion SDRAM, and the local data storage capacity is expanded through the external expansion NAND FLASH, so that the storage of the local long-period primary data, the secondary data and the identification result data is met;
the device self measurement and control system comprises a device abnormality alarm system and a man-machine communication regulation and control system; the device abnormality alarm system comprises a digital distributed temperature sensor for measuring multipoint temperature in the device and an IIC gating chip for transmitting and collecting multipoint temperature information, and is used for judging and alarming the abnormal temperature; the device abnormality alarm system further comprises a power abnormality alarm system, wherein the power abnormality alarm system collects port signal voltage by using a real-time voltage collection circuit, inputs the port signal voltage into a comparison circuit to be compared with a set threshold voltage, and triggers the voltage abnormality alarm circuit when the output voltage is lower than the threshold voltage;
the man-machine communication regulation and control system comprises a display screen, control keys and an indicator lamp, and is used for man-machine interaction;
the communication system comprises a standard optical fiber interface, an Ethernet interface, an RS232/485 interface and a connecting wire at the rear end, and utilizes a DMA mode of a central processing unit to directly transmit information in a storage unit to a communication port, and the communication system matches with an IEC61850 protocol in a station to realize functions of information uploading, real-time information calling and remote control between the communication system and IDE equipment in the station and a communication server in the station;
the power supply system comprises an external power supply system, an uninterruptible power supply system, a voltage stabilizing system and a digital-analog isolation system; the external power supply system comprises an alternating current-direct current power supply interface, a rectification loop, an inversion frequency conversion circuit, a filter circuit and a multistage voltage division circuit which are connected in sequence; the uninterruptible power supply system comprises a storage battery pack and is used for guaranteeing continuous supply of electric energy under abnormal conditions; the voltage stabilizing system comprises a voltage protection circuit, so that damage to the device under the action of large voltage is avoided; the digital-analog isolation system is used for realizing the isolation of a digital power supply and an analog power supply and avoiding the mutual interference between signals.
2. The watchband-adjustable full-fit cable partial discharge ultrasonic sensor as recited in claim 1, wherein: the measurement of the transient value of the cable ultrasonic signal is realized, the local data storage period is 72h, and the depth of expansion storage is 128G; a standard 220V/50Hz ac source or a 15V constant dc source may power the device.
3. An on-line monitoring method of an adjustable full-fit cable partial discharge ultrasonic sensor based on a watchband according to any one of claims 1-2, comprising the following steps:
(1) Initialization of
Loosening the watchband of the watchband adjustable full-lamination cable partial discharge ultrasonic sensor, installing and fixing the watchband on a cable to be tested, and tensioning the watchband, so that a thin metal sheet lining is laminated with the cable to be tested, after the watchband adjustable full-lamination cable partial discharge ultrasonic sensor is powered on, the system enters initialization setting according to preset, a self measurement and control system is started to detect a power supply system and an operation condition, and after self detection is qualified, the system enters an ultrasonic signal acquisition measurement state;
(2) Periodic signal acquisition and processing
The method comprises the steps of entering a signal acquisition and data analysis period, firstly acquiring ultrasonic signals, converting charge signals output by a thin film sensor into voltage signals by utilizing a charge amplifier, inputting the voltage signals into a filter circuit and an amplifying circuit for processing, then transmitting the signals to an A/D high-speed acquisition device, performing digital filtering by utilizing a high-frequency central processing unit, and storing the processed data into a local memory according to date and characteristic types for subsequent processing;
(3) Data analysis and condition identification
The stored data are subjected to call analysis, ultrasonic characteristics including amplitude, frequency and change rate thereof are obtained based on a parameter characteristic recognition algorithm, a time domain correlation calculation algorithm and a state evaluation algorithm, the characteristic quantity is compared with historical data, or the partial discharge condition of the cable is excavated based on an intelligent algorithm, so that the current cable operation condition is fully identified, and the internal overheat and instant overvoltage faults of the cable are found in advance; when a fault or abnormal operation condition is identified, starting an early warning system, and simultaneously starting a communication function, and sending an abnormal instruction to a station server to realize accurate early warning of the abnormal cable condition; when no fault exists and the station server sends a call command periodically or appointed, the communication interface receives the call command and starts a data call command in the central processing unit, and a required data set is called out from the memory to be subjected to sub-packaging processing and sending, so that uploading of historical monitoring data is realized, and the sampler continuously performs real-time data sampling during the period;
(4) Ending
When the reset period of the device is reached, the device starts refreshing integrally, vacates the memory and the body storage, and enters the step (1);
when a closing command of the station control end or closing of the near-earth end is received, the device is interrupted to operate and enters a closing state.
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| CN113567815B (en) * | 2021-07-21 | 2023-03-21 | 西安交通大学 | Flexible piezoelectric ultrasonic sensing system for monitoring partial discharge of power equipment |
| CN114509651B (en) * | 2022-04-15 | 2022-07-19 | 湖北工业大学 | GIS partial discharge external ultrasonic and ultrahigh frequency integrated sensor and detection method |
| CN115856457B (en) * | 2023-03-02 | 2023-06-13 | 国网湖北省电力有限公司经济技术研究院 | Transformer substation high-frequency electromagnetic noise monitoring system and method |
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