CN111830381A - Watchband-adjustable full-laminated cable partial discharge ultrasonic sensor and online monitoring method - Google Patents
Watchband-adjustable full-laminated cable partial discharge ultrasonic sensor and online monitoring method Download PDFInfo
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- CN111830381A CN111830381A CN202010887005.6A CN202010887005A CN111830381A CN 111830381 A CN111830381 A CN 111830381A CN 202010887005 A CN202010887005 A CN 202010887005A CN 111830381 A CN111830381 A CN 111830381A
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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-laminated cable partial discharge ultrasonic sensor, belonging to the field of power equipment online monitoring and intelligent diagnosis, comprising a thin metal sheet lining and a rubber watchband, wherein a watchband buckle 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 in a watchband type mode, so that the thin metal sheet can be tightly attached to the outer surface of the cable to be measured, the loss of ultrasonic signals in transmission is reduced, and the reliability and accuracy of measured data are guaranteed; the invention can be widely applied to the scene of on-line monitoring of 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 models.
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-laminated cable partial discharge ultrasonic sensor and an on-line monitoring method.
Background
In a power system, a high-voltage power cable and an extra-high voltage power cable can generate a partial discharge phenomenon at a cable insulation defect in the operation process, the partial discharge can further cause insulation degradation of the power cable, the cable can be damaged in serious conditions, and then a large-area power failure accident is caused, so that the detection of the partial discharge of the cable is one of important measures for reducing the cable failure. 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 ultrasonic waves are transmitted 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 equipment, the PVDF piezoelectric film is converted into a charge signal, and the charge signal is sent to a computer for analysis and processing under the action of a charge amplifier, a trap circuit and a voltage amplifying circuit, so that the degradation degree of the cable is evaluated.
According to the ultrasonic wave property, the attenuation of the ultrasonic wave in a gas medium is very serious when the ultrasonic wave propagates, the attenuation of the ultrasonic wave in metal and liquid media is weak, and the attenuation of the ultrasonic wave can be ignored when the ultrasonic wave propagates in a metal medium with a short distance, so that the metal medium is utilized and air between a cable and the metal is excluded when the ultrasonic wave signal is received. The cable surface is a circular arc, and most ultrasonic sensor surfaces are flat, so that it is difficult to adhere well to the cable surface, and the ultrasonic signal cannot be received in the most efficient manner. Generally, when receiving ultrasonic signals, the ultrasonic sensor is exposed in the air and is easily interfered by other signals in the external environment, so that it is very important to obtain a more accurate result when receiving ultrasonic waves and eliminating the influence of external interference signals.
Disclosure of Invention
In view of the above, the present invention provides an ultrasonic online monitoring device based on cable partial discharge and a structure optimization method thereof, aiming at the problems that the existing ultrasonic online monitoring method is easily interfered by external environment signals, so that ultrasonic weak signals are covered, and the monitoring result is inaccurate. The ultrasonic sensor, the trap circuit, the amplifying circuit, the power supply module and the A/D conversion module are packaged by the metal box, and the metal box is coated by a material for reflecting and absorbing sound wave signals, so that the interference of the external environment is eliminated. Meanwhile, the film ultrasonic sensor is attached to the metal excircle, and an ultrasonic coupling layer is arranged between the metal excircle and the sensor to enhance ultrasonic signals. The invention aims to improve the anti-interference capability of an online monitoring device, eliminate external interference and maximize the ultrasonic signal reception, thereby improving the accuracy and precision of an ultrasonic sensor.
The principle of the invention is as follows: the device of the invention is mainly based on the mode of ultrasonic sensing to realize signal receiving and information acquisition. The device mainly comprises a signal receiving module and a signal processing moduleAnd the 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 piezoelectric film has the following advantages: the piezoelectric constant is high, and when the piezoelectric sensor is used as a sensor, the sensitivity is high; the density is small, 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 high-strength electric field can be resisted; the flexibility and the processing performance are good, and films with different thicknesses and shapes can be manufactured according to the requirements; wide frequency response (10)-5～109An in-range response; meanwhile, the chemical stability and fatigue resistance of the material are high, and the material has good thermal stability. Based on the advantages, the PVDF-PVDF piezoelectric film sensor is adopted as the sensor for receiving ultrasonic signals. The PVDF piezoelectric film sensor transmits ultrasonic information by the degree of the stress strain of the film due to the surface deformation of the ultrasonic wave when the ultrasonic wave passes through the device, and under the condition that an external electric field is zero, the piezoelectric equation of the PVDF piezoelectric film is as follows:
Di＝dijTj(1)
in the formula: diIs a potential shift; dijIs the piezoelectric constant; t isjIs the stress (i ═ 1,2, 3; j ═ 1,2,3, ·, 6).
The output charge of a PVDF piezoelectric film is the response of the strain in all directions acting in the polarization direction, namely:
Q＝∑dijEjS (2)
in the formula: q is the output charge; e is the elastic modulus of the PVDF piezoelectric film;jis strain (j ═ 1,2, 3); and S is the area covered by the PVDF piezoelectric film.
Under the condition of one-dimensional stress of the PVDF piezoelectric film, the output charge can be expressed as:
Q＝d31E1S (3)
when the PVDF piezoelectric film is used for a sensing function, the PVDF piezoelectric film is a charge generator, and charges generated by the PVDF piezoelectric film are converted into voltage signals through a signal conversion structure so as to be processed subsequently. The signal conversion structure is a charge amplifier, which is actually a high-gain operational amplifier with deep capacitance negative feedback, the charge signal is converted into a voltage signal through the signal conversion structure, and the voltage signal can be obtained as follows:
in the formula: cfIs the feedback capacitance of the charge amplifier.
Therefore, the voltage output of the charge amplifier is in linear relation with the strain of the measured structure, and meanwhile, the larger the area covered by the piezoelectric sensor on the cable is, the larger the voltage of the piezoelectric sensor is, the easier the measurement is.
Because the PVDF piezoelectric film is easily subjected to electromagnetic interference, wherein the power frequency interference of 50Hz is most obvious, and the existence of the power frequency interference easily causes signal distortion, a trap circuit is adopted to eliminate the influence of the power frequency interference, and the trap circuit is realized by adopting a double-T band-stop filter circuit. After the charge signal output by the PVDF piezoelectric film is processed by a charge amplifier and a trap circuit, a voltage detection signal is obtained by a voltage amplifying circuit.
Meanwhile, all the parts which are easy to interfere are packaged in the metal box in the optimized structure, the metal box is grounded, external electromagnetic interference can be shielded, a relatively independent space is formed inside, and a layer of material for absorbing and reflecting sound waves is coated on the surface of the metal box, so that the interference resistance level of the device is further enhanced.
In order to achieve the purpose, the invention provides the following technical scheme:
on one hand, the ultrasonic sensor for partial discharge of the full-laminated cable with the adjustable watchband comprises a thin metal sheet lining and a rubber watchband, wherein the rubber watchband covers the thin metal sheet lining, a watchband buckle head is arranged at one end of the rubber watchband, and the other end of the rubber watchband penetrates through the watchband buckle head and can be locked by the watchband buckle head;
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 carrying out filtering amplification and time-frequency conversion processing; the data analysis and storage system is used for receiving and analyzing data to obtain 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 charge amplifier is used for converting a generated charge signal into a voltage signal.
Furthermore, the signal acquisition and processing system comprises a trap circuit, a voltage amplification circuit, a voltage conversion circuit, an A/D converter and a signal reading module, wherein the trap circuit eliminates power frequency interference of the voltage signal, the voltage amplification circuit obtains a voltage detection signal, the voltage conversion circuit converts an actual voltage amplitude value into an 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.
Furthermore, the data analysis and storage system comprises a high-frequency programmable processor core with an FPU, and parameter feature identification, time domain correlation calculation and state evaluation algorithms are carried for mining ultrasonic signal fluctuation features and cable operation working conditions, synchronously acquiring ultrasonic signal data of cable partial discharge and providing real-time reference information for identification, operation and maintenance and protection of the cable working conditions; the memory is further expanded through the externally expanded SDRAM, and the storage capacity of local data is expanded through the externally expanded NAND-FLASH so as to meet the storage requirements of data such as local long-period original data, secondary data and identification results.
Furthermore, the device self measurement and control system comprises a device abnormity alarm system and a man-machine communication regulation and control system; the device abnormity 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 abnormity alarm system also comprises a power supply abnormity alarm system, a real-time voltage acquisition circuit is used for acquiring port signal voltage, the port signal voltage is input into a comparison circuit to be compared with a set threshold voltage, and when the output voltage is lower than the threshold voltage, the voltage abnormity alarm circuit is triggered;
the man-machine communication regulation and control system comprises a display screen, a control key and an indicator light 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 line at the rear end, information in the storage unit is directly transmitted to the communication port by utilizing a DMA mode of the central processing unit, an IEC61850 protocol in the station is matched, and the functions of information uploading, real-time information calling and remote control between the communication system and the IDE equipment and the communication server in the station are realized.
Further, the power supply system comprises an external power supply system, an uninterruptible power supply system, a voltage stabilizing system and a digital-to-analog isolation system; the external power supply system comprises an alternating current and direct current power interface, a rectification loop, an inversion frequency conversion circuit, a filter circuit and a multi-stage voltage division circuit which are sequentially connected; the uninterruptible power supply system comprises a storage battery pack and a control module, wherein the storage battery pack is used for guaranteeing the continuous supply of electric energy under abnormal conditions; the voltage stabilizing system comprises a voltage protection circuit, so that the device is prevented from being damaged under the action of large voltage; 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.
Furthermore, the device can realize the measurement of the transient value of the cable ultrasonic signal, the local data storage period is 72h, and the extended storage depth is 128G; a standard 220V/50Hz AC source or a 15V constant DC source may power the device.
Further, the fixing device is a flexible watchband. The watchband is inlayed by foil inside lining structure and rubber outward appearance structure and forms, and its foil inside lining structure is tightly inlayed by foil and rubber outward appearance and is in the same place, and its size can be adjusted according to the size of cable, during the installation, can loosen the watchband, is fixed in on the cable that awaits measuring with monitoring devices installation, and then taut watchband to make foil inside lining and the cable that awaits measuring tightly hug closely together, so that reduce the loss of ultrasonic signal in the transmission process.
On the other hand, the method for monitoring the partial discharge of the full-laminated cable on the basis of the adjustable watchband comprises the following steps of:
(1) initialization
After the watchband adjustable full-laminated cable partial discharge ultrasonic sensor is connected with a power supply, 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 working condition, and the ultrasonic signal acquisition and measurement state is entered after the self-inspection is qualified;
(2) periodic signal acquisition and processing
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 using a charge amplifier, 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 using a high-frequency central processing unit, storing the processed data into a local memory according to date and characteristic types, and waiting for subsequent processing;
(3) data analysis and condition identification
The stored data is called and analyzed, ultrasonic wave characteristics including amplitude, frequency and change rate of the ultrasonic wave characteristics are obtained based on algorithms such as ultrasonic signal characteristic identification 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 faults such as overheating inside the cable and overlarge instantaneous overvoltage are found in advance; when a fault or abnormal operation working condition is identified, starting an early warning system, starting a communication function, and sending an abnormal instruction to a station-level server to realize accurate early warning of the abnormal working condition of the cable; when no fault exists and the station-level server issues a command for information calling regularly or in a designated manner, the communication interface receives the calling command, starts a data calling command of the central processing unit, calls a required data set from the memory for packet 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) end up
When the reset period of the device is reached, the whole device starts refreshing, empties the memory and the body storage, and enters the step (1); when a closing command of the station control end or the close-to-ground end is received, the device interrupts the operation and enters a closing state.
The invention has the beneficial effects that:
1. according to the invention, the watchband adjustable full-fit cable partial discharge ultrasonic sensor is firstly designed, the size of the watchband of the designed device can be adjusted according to the size of the power cable, and watchband type installation and fastening are adopted, so that a thin metal sheet can be tightly fitted with the outer surface of the cable to be measured, the loss of ultrasonic signals in transmission is reduced, and the reliability and accuracy of measured data are ensured;
2. the electromagnetic shielding structure formed by coating the electromagnetic absorption and reflection materials on the surface of the metal box and grounding can enhance the resistance of the 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, completes information mining depending on a hardware program, realizes data transmission by utilizing a remote communication module and a station control layer server, can realize diagnosis and regulation of the running state of a device, and avoids the problem of unreliable monitoring caused by unreliable self-operation of the device;
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 scene of on-line monitoring of 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 models.
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 objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic perspective and plan view of the apparatus of the present invention;
FIG. 2 is a schematic view of the data acquisition of the apparatus of the present invention;
FIG. 3 is a schematic view of a metal can package of the device 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 apparatus of the present invention;
FIG. 6 is a flow chart of the apparatus of the present invention.
Reference numerals: 1-thin sheet metal lining; 2-rubber watchband; 3, a watchband buckle head; 4-a grounded metal seal box; 5, sealing the ear cap; 6-PVDF piezoelectric film sensor; 7-charge transfer line; 8-a charge amplifier; 9-voltage signal collection line; 10-a voltage acquisition system; 11-data analysis hardware module; 12-a storage module; 13-a communication system; 14-a power supply system; 15-a storage battery; 16-external ac power supply system; 17-upper pole plate of metal box; 18-metal box bottom plate; 19-metal box ground return; 20-anti-interference coating.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood 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 numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
As shown in fig. 1-5, a watchband adjustable full-laminated 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 inlaying a thin metal sheet lining 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 using a watchband buckle head 3 during installation, so that the thin metal sheet can be tightly attached to the cable body or the joint to be tested in different sizes; due to the strong propagation property of ultrasonic waves in metal and the full-fit structure, ultrasonic signals are directly propagated to the thin metal sheet through the coupling agent on the surface of the cable in a low-loss manner during measurement and then are rapidly conducted to the sensor through the annular thin metal sheet, so that the loss of the ultrasonic signals in the propagation process is greatly reduced, and the partial-discharge ultrasonic sensing under all-dimensional angles is realized; earthing metal seal box 4 is installed at the watchband center, and the seal box is made by the metal entirely, uses the screw-fastening to seal the fastening to the metal cassette during the installation, installs sealed earcap on the metal cassette, can be better sealed. The coating that the one deck can absorb and reflect the electromagnetic wave is paintd to the metal box surface, anti-interference coating 20 promptly, still includes metal box ground return circuit 19 for the metal box ground connection, the surface all installs the ground connection polar plate about simultaneously, divide into metal box upper plate 17, metal box bottom plate 18, presents zero potential on making the metal-back to construct the independent space of electromagnetic shield between metal box inside and external environment, reduce the influence of external interference signal to inside.
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 made of high polymer materials, the electrode cannot be directly welded, but is led out on the PVDF piezoelectric film in a riveting mode. When the ultrasonic wave is transmitted in the device, the surface of the device can be slightly deformed, mechanical stress is generated on the PVDF piezoelectric film attached to the surface of the equipment, the PVDF piezoelectric film 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 the ultrasonic signals from being subjected to electromagnetic interference, 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 elimination filter circuit. The charge signal output by the PVDF piezoelectric film is processed by a charge amplifier and a trap circuit, then a voltage detection signal is obtained by the voltage amplifier circuit, meanwhile, a voltage conversion circuit is designed to convert the actual voltage amplitude value into the effective interval of a signal collector, a high-resolution A/D converter and a high-speed signal reading module are utilized to realize the acquisition and storage of the voltage signal, and the voltage signal is directly transmitted to a central controller after the acquisition, so that the inspection and the transmission of data 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 an FPU (field programmable unit), can realize high-precision and high-speed floating point processing, builds a multi-data processing unit by using programming and program burning modes, and can support various types of communication interfaces; secondly, an external SDRAM12 is selected to expand the memory, the calculation capacity of the processor is improved, and the requirement of a complex data processing algorithm is met; selecting a high-capacity, long-period and industrial-grade externally-expanded NAND-FLASH to expand the storage capacity of local data so as to satisfy the storage of data such as local long-period original data, secondary data, identification results and the like and provide a target database for later-period remote calling; the data processing algorithm comprises algorithms such as parameter feature recognition, time domain correlation calculation, state evaluation and the like, so that information such as ultrasonic signal fluctuation features and cable operation conditions is fully excavated, synchronous acquisition of ultrasonic signal data of cable partial discharge is realized, and real-time reference information is provided for identification, operation and maintenance and protection of cable conditions.
The device self measurement and control system mainly comprises a device abnormity alarm system and a man-machine communication regulation and control system. In the actual operation condition, in order to prevent an external fire source from causing serious damage to a monitoring device, a high-temperature early warning system of the device is designed. Measuring the internal multipoint temperature of the device by using a digital distributed temperature sensor, realizing the 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 a high-temperature abnormal early warning circuit to realize the representation of a temperature abnormal state; secondly, in actual operation, due to insufficient energy of the independent power supply or failure of the power supply circuit, output voltage signals are unstable and detection signals are inaccurate. The power supply abnormity warning system of the low-energy consumption real-time voltage acquisition and comparison circuit and the early warning system is provided, the real-time voltage acquisition circuit is used for acquiring the port signal voltage, the port signal voltage 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 abnormity warning circuit is triggered; the man-machine communication system comprises a liquid crystal display screen, an indicator light and a key, the liquid crystal display screen adopts a multi-core shielding wire, the measurement and control system is connected, a user inputs related commands to the measurement and control system by the key, the selection and the equipment debugging of corresponding functions are completed, and the measurement and control system sends the working condition and the 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 rear-end connecting line and the like of the device, information in the storage unit is directly transmitted to the communication port in a DMA mode of the central processing unit, an IEC61850 protocol in the station is matched, and functions of information uploading, real-time information calling, remote control and the like between the device and IDE equipment and a communication server in the station are realized.
The power system 14 includes an uninterruptible power system, which is a storage battery 15, an external power supply system 16, a voltage stabilizing system, and a digital-analog isolation system in this embodiment. The alternating current and direct current power supply interfaces are provided, alternating current or direct current power supply of the device under different backgrounds can be met, a rectifier circuit, an inverter frequency conversion circuit, a voltage stabilizing circuit, a filter circuit and a multi-stage voltage dividing circuit are designed, stable output of +/-5V, +/-3V, analog power supply voltage and 200Hz alternating current voltage can be achieved, a voltage protection circuit is built, and damage to the device under the action of large voltage is avoided; an uninterruptible power supply system of the device is designed by using the battery and the voltage stabilizing circuit, so that the continuous supply of electric energy of the device under the condition of poor quality or fault of an external power supply is met; a large ground plane and a digital-analog isolation circuit are designed, so that 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.
Furthermore, the device can realize the measurement of the transient value of the cable ultrasonic signal, the local data storage period is 72h, and the extended storage depth is 128G; a standard 220V/50Hz AC source or a 15V constant DC source may power the device.
Further, the fixing device is a flexible watchband. The watchband is inlayed by foil inside lining structure and rubber outward appearance structure and forms, and its foil inside lining structure is tightly inlayed by foil and rubber outward appearance and is in the same place, and its size can be adjusted according to the size of cable, during the installation, can loosen the watchband, is fixed in on the cable that awaits measuring with monitoring devices installation, and then taut watchband to make foil inside lining and the cable that awaits measuring tightly hug closely together, so that reduce the loss of ultrasonic signal in the transmission process.
As shown in fig. 6, the present invention further provides a monitoring method, which uses the above device to perform the measurement of cable partial discharge ultrasonic wave in a programmed manner, and is characterized in that the specific method steps are as follows:
(1) initialization
After the device is powered on, a device system enters initialization setting according to preset setting, the device starts a self measurement and control system to detect a power supply system 14 and an operation condition, and enters an ultrasonic signal acquisition and measurement state after the device is qualified by self-inspection;
(2) periodic signal acquisition and processing
After the step (1) is finished, entering a signal acquisition and data analysis period, firstly acquiring ultrasonic signals, converting charge signals output by the film sensor into voltage signals by using a charge amplifier (7), 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 using 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
And (3) after the step (2) is finished, calling and analyzing the stored data, acquiring ultrasonic wave characteristics including amplitude, frequency, change rate and the like based on algorithms such as ultrasonic signal characteristic identification, state evaluation and the like, comparing the characteristic quantity with historical data, or excavating partial discharge conditions of the cable based on an intelligent algorithm so as to fully identify the current cable operation condition and find faults such as internal overheating of the cable, excessive instantaneous overvoltage and the like in advance. When a fault or abnormal operation working condition is identified, the device starts an early warning system, simultaneously starts a communication function 13, and sends an abnormal instruction to a station-level server to realize accurate early warning of the abnormal working condition of the cable; when no fault exists and the station level server issues a command for information calling regularly or in a designated manner, the communication interface receives the calling command, starts a data calling command in the central processing unit 11, calls a required data set from the memory 12 for subpackage 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) end up
After the steps (1), (2) and (3) are finished, when the reset period of the device is reached, the whole device starts refreshing, the memory and the body storage are emptied, and the step (1) is entered; when a closing command of the station control end or the close-to-ground end is received, the device interrupts the operation and enters a closing state.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (9)
1. The utility model provides an ultrasonic sensor is put in full laminating cable office with adjustable watchband which characterized in that: the rubber watchband is covered on the metal sheet lining, a watchband buckling head is arranged at one end of the rubber watchband, and the other end of the rubber watchband penetrates through the watchband buckling head and can be locked by the watchband buckling head;
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 carrying out filtering amplification and time-frequency conversion processing; the data analysis and storage system is used for receiving and analyzing data to obtain 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.
2. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 1, characterized in that: 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 charge amplifier is used for converting a generated charge signal into a voltage signal.
3. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 2, characterized in that: the signal acquisition and processing system comprises a trap circuit, a voltage amplifying circuit, a voltage conversion circuit, an A/D converter and a signal reading module, wherein the trap circuit eliminates power frequency interference of the voltage signal, the voltage amplifying circuit obtains a voltage detection signal, the voltage conversion circuit converts an actual voltage amplitude value into an effective interval of a signal acquisition device, and the A/D converter and the signal reading module are used for realizing voltage signal acquisition and storage.
4. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 3, characterized in that: the data analysis and storage system comprises a high-frequency programmable processor core with an FPU (field programmable Unit), and is loaded with parameter feature identification, time domain correlation calculation and a state evaluation algorithm, and is used for mining ultrasonic signal fluctuation features and cable operation working conditions, synchronously acquiring ultrasonic signal data of cable partial discharge and providing real-time reference information for identification, operation and maintenance and protection of the cable working conditions; the memory is further expanded through the externally expanded SDRAM, and the storage capacity of local data is expanded through the externally expanded NAND-FLASH so as to meet the storage requirements of data such as local long-period original data, secondary data and identification results.
5. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 4, characterized in that: the device self-monitoring system comprises a device abnormity alarm system and a man-machine communication regulation system; the device abnormity 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 abnormity alarm system also comprises a power supply abnormity alarm system, a real-time voltage acquisition circuit is used for acquiring port signal voltage, the port signal voltage is input into a comparison circuit to be compared with a set threshold voltage, and when the output voltage is lower than the threshold voltage, the voltage abnormity alarm circuit is triggered;
the man-machine communication regulation and control system comprises a display screen, a control key and an indicator light and is used for man-machine interaction.
6. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 5, characterized in that: the communication system comprises a standard optical fiber interface, an Ethernet interface, an RS232/485 interface and a connecting line at the rear end, information in the storage unit is directly transmitted to the communication port in a DMA mode of the central processing unit, an IEC61850 protocol in the station is matched, and the functions of information uploading, real-time information calling and remote control between the communication system and an IDE device and a communication server in the station are achieved.
7. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 6, characterized in that: the power supply system comprises an external power supply system, an uninterruptible power supply system, a voltage stabilizing system and a digital-analog isolating system; the external power supply system comprises an alternating current and direct current power interface, a rectification loop, an inversion frequency conversion circuit, a filter circuit and a multi-stage voltage division circuit which are sequentially connected; the uninterruptible power supply system comprises a storage battery pack and a control module, wherein the storage battery pack is used for guaranteeing the continuous supply of electric energy under abnormal conditions; the voltage stabilizing system comprises a voltage protection circuit, so that the device is prevented from being damaged under the action of large voltage; 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.
8. The ultrasonic sensor is put in full laminating cable office with adjustable watchband of claim 7, characterized in that: the measurement of the transient value of the cable ultrasonic signal is realized, the local data storage period is 72h, and the extended storage depth is 128G; a standard 220V/50Hz AC source or a 15V constant DC source may power the device.
9. An online monitoring method of the partial discharge ultrasonic sensor of the watchband-adjustable full-attached cable based on any one of claims 1 to 8, comprising the following steps:
(1) initialization
After the watchband adjustable full-laminated cable partial discharge ultrasonic sensor is connected with a power supply, 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 working condition, and the ultrasonic signal acquisition and measurement state is entered after the self-inspection is qualified;
(2) periodic signal acquisition and processing
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 using a charge amplifier, 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 using a high-frequency central processing unit, storing the processed data into a local memory according to date and characteristic types, and waiting for subsequent processing;
(3) data analysis and condition identification
The stored data is called and analyzed, ultrasonic wave characteristics including amplitude, frequency and change rate of the ultrasonic wave characteristics are obtained based on algorithms such as ultrasonic signal characteristic identification 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 faults such as overheating inside the cable and overlarge instantaneous overvoltage are found in advance; when a fault or abnormal operation working condition is identified, starting an early warning system, starting a communication function, and sending an abnormal instruction to a station-level server to realize accurate early warning of the abnormal working condition of the cable; when no fault exists and the station-level server issues a command for information calling regularly or in a designated manner, the communication interface receives the calling command, starts a data calling command of the central processing unit, calls a required data set from the memory for packet 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) end up
When the reset period of the device is reached, the whole device starts refreshing, empties the memory and the body storage, and enters the step (1); when a closing command of the station control end or the close-to-ground end is received, the device interrupts the operation and enters a closing state.
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