CN112013983B - Transformer multipoint temperature and oil pressure combined monitoring device and method based on differential inductive sensor - Google Patents
Transformer multipoint temperature and oil pressure combined monitoring device and method based on differential inductive sensor Download PDFInfo
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- CN112013983B CN112013983B CN202010891826.7A CN202010891826A CN112013983B CN 112013983 B CN112013983 B CN 112013983B CN 202010891826 A CN202010891826 A CN 202010891826A CN 112013983 B CN112013983 B CN 112013983B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/36—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using magnetic elements, e.g. magnets, coils
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
- G01L9/0004—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using variations in inductance
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/40—Structural association with built-in electric component, e.g. fuse
- H01F27/402—Association of measuring or protective means
Abstract
The invention relates to a transformer multipoint temperature and oil pressure monitoring device based on a differential inductive sensor, belonging to the field of on-line monitoring and intelligent diagnosis of electric equipment, and comprising a transient oil pressure-oil temperature sensing module, a multi-channel signal acquisition module, a data processing and analyzing module, a data storage module, a device self measurement and control system, a communication system and a power supply system; the transient oil pressure-oil temperature sensing module is used for acquiring and calculating transient oil pressure data and oil temperature data; the multi-channel signal acquisition module is used for acquiring a voltage difference signal and a multi-channel current signal; the data processing and analyzing module is used for analyzing the fluctuation characteristics of the measured parameters and the information of the operating conditions according to the oil temperature and the oil pressure data of multiple points in the transformer; the data storage module is used for storing local long-period original data, secondary data and analysis result data; the device self-monitoring system is used for monitoring the self state and carrying out high-temperature alarm, power supply abnormity alarm and man-machine communication regulation and control. A monitoring method is also provided.
Description
Technical Field
The invention belongs to the field of on-line monitoring and intelligent diagnosis of electrical equipment, and relates to a transformer multi-point temperature and oil pressure combined monitoring device and method based on a differential inductive sensor.
Background
The oil-immersed power transformer is a key power device in the current power system and plays a role in electric energy transmission. When the transformer is internally discharged due to various reasons in the operation process and then electric arcs are triggered, the oil temperature in the transformer rises, and a large amount of gas is generated at the same time, so that the pressure in the oil tank rises suddenly, and if timely alarming and protection are not performed, the transformer can be damaged. Through carrying out temperature monitoring to the transformer structure, know the inside running state of transformer, in time discover potential fault of transformer or proruption problem, effectively avoid the fault damage, finally realize the steady operation of power supply work, establish good basis for transformer steady operation. At present, the traditional methods of infrared temperature measurement, thermal resistance temperature measurement, thermocouple temperature measurement and the like are mostly adopted for a transformer oil temperature monitoring method, the transmission scale is large, certain deviation is easy to cause, and meanwhile, the transmission scale is long and is easy to be influenced by the outside. Meanwhile, the oil pressure can reflect faults such as internal overheating, local oil surge and local arc discharge, the oil pressure is detected in real time, and reference data can be provided for transformer working condition identification and operation and maintenance management. The oil pressure and temperature characteristics have strong coupling, and the real-time operation condition of the transformer can be fully and accurately identified through synchronous measurement of the oil pressure and the temperature characteristics.
Aiming at the problems of multi-characteristic synchronous measurement, disturbance misdetection, severe operating environment, unreliable monitoring and the like of synchronous measurement of oil pressure and temperature of a transformer, the existing method and the technology cannot fully solve all the problems, and a novel detection mode is required to be provided to realize a real-time monitoring method with double parameters, disturbance resistance and high reliability.
Disclosure of Invention
In view of the above, the present invention provides a device and a method for jointly monitoring the multi-point temperature and the oil pressure of a transformer based on a differential inductive sensor, wherein the device and the method are based on the change of the inductance value to obtain the internal oil temperature and the oil pressure characteristic quantity of the transformer in real time, make full use of the high reliability characteristic of the inductive sensor, remove external disturbance by using a differential bridge structure and a working condition recognition algorithm, and complete the functions of data processing, remote communication and the like by relying on designed intelligent information equipment to realize the anti-disturbance, high reliability and multi-parameter real-time monitoring engineering goal.
The principle of the device of the invention is as follows: the device of the invention is mainly based on the parameter measurement realized by a differential inductive sensing mode. The device mainly comprises an inductive pressure sensor, an eddy current temperature sensor, a signal processing module and device accessories. The modularized inductive sensor is used as a core structure of the device and mainly comprises a sensing structure and a signal acquisition part. The eddy current temperature sensing structure is composed of a measuring coil, a temperature sensing element and a compensating coil, the change of the impedance of the measuring coil is completely dependent on the eddy current effect of a measured metal conductor, the eddy current effect is related to the resistivity, the magnetic permeability and the geometric shape of a measured body, the geometric parameters of the coil, the frequency of exciting current in the coil and the distance between the coil and the conductor, and the resistivity rho of the temperature sensing element changes along with the change of the temperature:
ρ＝ρ0[1+a(t-t0)] (1)
where t represents temperature and a represents temperature coefficient of resistance. When other parameters are not changed, the resistivity of the temperature sensitive element is changed under the condition of only changing the temperature, the eddy current effect is also changed, and the impedance of the measuring coil is further changed. However, the change of temperature also has an influence on the sensing head of the sensor, i.e. the temperature rise or decrease causes the thermal sensitive element to expand with heat and contract with cold, and the change of temperature causes the geometric dimension and the electrical parameter of the sensor coil to change, and the influence of the two aspects causes the output characteristic of the sensor to change, resulting in a measurement error:
where L represents the sensor contact length, α represents the coefficient of thermal expansion, Δ t represents the amount of temperature change, and Δ d represents the amount of contact length change. Therefore, the compensation coil is added, and the differential temperature compensation method is adopted, so that the influence of temperature on the measurement result is reduced, and the wide-range full-system temperature compensation is realized.
The oil pressure sensing structure is by the oil pressure probe, the trace, the coil promotes the structure and surveys the oil pressure elastic coil and constitute, when the oil pressure changes, act on one side of elastic element through the oil pressure probe, and elastic element's opposite side is in inclosed cavity, the produced pressure differential of inequality of outside oil pressure and inside cavity pressure can make elastic element take place deformation, and promote the connecting rod displacement, the displacement of connecting rod can promote the coil and promote the structure, make the coil take place the displacement, the air bed between the coil has changed corresponding magnetic induction intensity and can change, make inductance value change. In order to reduce errors, a differential amplification circuit is used, and the current value of the oil pressure measuring coil and the current value of the compensating coil are used as two input ends, so that the variation of the inductance can be measured more accurately.
The device can accurately and reliably synchronously acquire the characteristic quantities of the oil temperature and the oil pressure in the transformer, and provides more accurate data for identifying the operating condition in the transformer.
In order to achieve the purpose, the invention provides the following technical scheme:
on one hand, the invention provides a transformer multipoint temperature and oil pressure monitoring device based on a differential inductive sensor, which comprises a transient oil pressure-oil temperature sensing module, a multi-channel signal acquisition module, a data processing and analyzing module, a data storage module, a device self measurement and control system, a communication system and a power supply system, wherein the transient oil pressure-oil temperature sensing module is connected with the multi-channel signal acquisition module;
the transient oil pressure-oil temperature sensing module is used for acquiring and calculating transient oil pressure data and oil temperature data;
the multi-channel signal acquisition module is used for acquiring a voltage difference signal and a multi-channel current signal;
the data processing and analyzing module is used for analyzing the fluctuation characteristics of the measured parameters and the information of the operating conditions according to the oil temperature and the oil pressure data of multiple points in the transformer;
the data storage module is used for storing local long-period original data, secondary data and analysis result data;
the device self-monitoring system is used for monitoring the self state and carrying out high-temperature alarm, power supply abnormity alarm and man-machine communication regulation and control;
the communication system is used for connecting an upper computer and carrying out data uploading and remote control;
the power supply system is used for supplying power to each module.
Further, the transient oil pressure-oil temperature sensing module comprises a compensation coil, an oil pressure measuring elastic coil, a coil pushing structure, a closed cavity, a connecting rod, a spring element, an oil pressure probe, a temperature measuring coil, a heat insulation plate and a temperature sensitive element;
the temperature sensing element is connected with a temperature measuring coil through a heat insulation plate, the temperature measuring coil is connected with high-frequency excitation current, an eddy current is formed on the temperature sensing element, and the temperature measuring coil and a compensation coil form the input end of a differential amplification circuit;
the oil pressure probe is sequentially connected with an elastic element, a connecting rod, a coil pushing structure and an oil pressure measuring elastic coil, and the elastic element and the connecting rod are arranged in the closed cavity; the oil pressure measuring elastic coil and the compensating coil form an input end of a differential amplifying circuit.
Furthermore, the multi-path signal acquisition module, the voltage signal acquisition module and the multi-terminal current signal acquisition module lead current signals of the compensation coil, the oil pressure measurement elastic coil and the temperature measurement coil out to the multi-terminal current signal acquisition module through signal leads;
the voltage signal acquisition module comprises a variable frequency power supply, a voltage measurement device and a plurality of measurement bridges, wherein the variable frequency power supply is connected with a temperature measurement coil and provides excitation for the differential amplification circuit; the variable frequency power supply comprises a sine oscillator circuit and a secondary voltage stabilizing circuit, and the voltage conversion circuit converts the actual voltage amplitude value into the effective interval of the signal collector;
the voltage measuring device is connected with the compensating coil, the oil pressure measuring elastic coil and the temperature measuring coil, and a high-resolution A/D converter and a high-speed signal reading module are used for acquiring and storing a voltage difference signal;
the plurality of measuring bridges are respectively arranged opposite to the compensating coil, the oil pressure measuring elastic coil and the temperature measuring coil and are used for realizing current signal conversion by utilizing a current-voltage conversion module according to the current change of the measuring bridges caused by the impedance change of the differential amplifying circuit and then realizing the synchronous acquisition and storage of multi-channel current signals by utilizing a multi-channel high-resolution A/D converter and a high-speed signal reading module;
the system also comprises a fixed frequency gating active filter circuit and a digital filter circuit which are used for filtering the original signal, and the time-frequency transformation of the signal is realized through an FFT algorithm so as to obtain the frequency characteristics of different parameters.
Furthermore, the temperature measuring coil is connected with an oil temperature measuring zero setting resistor, and the oil pressure measuring elastic coil is connected with an oil pressure measuring zero setting resistor in series.
Further, the measuring bridge is an eddy current equivalent circuit.
Furthermore, the data processing and analyzing module is connected with the end current signal acquisition module and the voltage signal acquisition module and is used for mining fluctuation characteristics of the measured parameters and providing real-time reference information for identification, operation and maintenance and protection of transformer working conditions by using a multi-channel characteristic identification, time domain correlation calculation and a state evaluation algorithm.
Further, the data storage module expands the memory through the externally expanded SDRAM and expands the local data storage capacity through the externally expanded NAND-FLASH for storing the local long-period original data, the secondary data and the identification result.
Furthermore, the device self measurement and control system comprises a high-temperature alarm system, a power supply abnormity alarm system and a man-machine communication regulation and control system, wherein the high-temperature alarm system comprises a multipoint digital distributed temperature sensor which is used for detecting the internal temperature and giving an alarm when the temperature is abnormal;
the power supply abnormity alarm system acquires port signal voltage by using a real-time voltage acquisition circuit, inputs the port signal voltage into a comparison circuit to be compared with a set threshold voltage, and triggers a voltage abnormity alarm circuit when the output voltage is lower than the threshold voltage;
the man-machine communication regulation and control system comprises a display screen, an indicator light and a control key and is used for carrying out man-machine interaction on the device.
Furthermore, the communication system is connected with the data storage module, comprises a standard optical fiber interface, an Ethernet interface, an RS232/485 interface, a rear-end connecting line and the like, directly transmits information in the storage unit to the communication port by utilizing a DMA mode of the central processing unit, matches an IEC61850 protocol in the station, and realizes the 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.
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 elastic elements with multiple points simultaneously act on the connecting rod, so that the displacement of the connecting rod is more obvious, and the multi-characteristic information of measuring the temperature extrusion and the like of the power equipment can be expanded.
Furthermore, the device can realize the measurement of the transient value of the oil pressure and the oil temperature, 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.
In another aspect, the present invention provides a method for monitoring the temperature and oil pressure of a transformer at multiple points based on a differential inductive sensor, comprising the steps of:
(1) initialization
After the power supply is switched on, according to the preset initialization setting, a measurement and control system of the device is started to detect a power supply system and an operation condition, and after the self-detection is qualified, the device enters a multi-point temperature and transient oil pressure multi-characteristic measurement state;
(2) periodic signal acquisition and processing
Firstly, injecting a periodic voltage signal, utilizing a multi-terminal current signal acquisition module to acquire current of each loop and input the current to a source filter for filtering, then transmitting the signal to an A/D high-speed acquisition device, utilizing a data analysis hardware module to carry out digital filtering, FFT (fast Fourier transform) feature conversion or identifying a basic bridge difference value depending on a set algorithm, and storing the processed data into a data storage module according to date and feature types for subsequent processing;
(3) data analysis and condition identification
The stored data is called and analyzed, oil temperature characteristics and oil pressure characteristics including oil temperature, oil pressure and change rate thereof are obtained based on multi-channel characteristic identification, a temperature oil pressure reference relation model and a state evaluation algorithm, the characteristic quantity is compared with historical data, or the basic operation condition of the transformer is excavated based on an intelligent algorithm, so that the current operation condition of the transformer is fully identified, and the internal overheating and instantaneous overlarge oil pressure fault of the transformer are found in advance;
when a fault or abnormal operation working condition is identified, starting an early warning system, and simultaneously sending an abnormal instruction to a station-level server through a communication system to realize accurate early warning of the abnormal working condition of the transformer; when no fault exists and the station-level server issues a command for information calling regularly or in a designated manner, the communication system receives the calling command, starts a data calling command in the data processing and analyzing module, calls a required data set from the data storage module 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
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 near-earth end is received, the device is interrupted to run and enters a closing state.
The invention has the beneficial effects that:
1. the differential inductance type multipoint oil temperature and oil pressure sensor is designed firstly, the resistance to external interference can be enhanced through a differential design structure, and the reliability and the accuracy of measured data are guaranteed; meanwhile, the designed device can synchronously acquire oil temperature and oil pressure data of multiple points in the transformer, and provides more sufficient reference data for fully mining the operating condition information of the transformer;
2. the differential inductance type multipoint oil temperature and oil pressure synchronous sensing system 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 the device and avoids the problem of unreliable monitoring caused by the unreliable self-operation of the device;
3. the device and the system are convenient to use, and the method is simple to operate.
4. The invention can be widely applied to various multipoint oil temperature and oil pressure double-parameter measurement scenes, in particular to transformer protection equipment depending on oil temperature and oil pressure characteristics.
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 diagram of a sensing architecture of the present invention;
FIG. 2 is a schematic diagram of a differential circuit of an information acquisition module of the apparatus of the present invention;
FIG. 3 is a schematic block diagram of the apparatus of the present invention;
FIG. 4 is a block diagram of the power supply system of the apparatus of the present invention;
FIG. 5 is a schematic diagram of the apparatus of the present invention.
In the figure: 1-a compensation coil; 2-measuring the oil pressure elastic coil; 3-a coil pushing structure; 4-sealing the cavity; 5-a connecting rod; 6-an elastic element; 7-oil pressure probe; 8-temperature measuring coil; 9-heat insulation board; 10-a temperature sensitive element; 11-signal leads; 12-a multi-terminal current signal acquisition module; 13-a voltage signal acquisition module; 14-a data analysis hardware module; 15-voltage signal acquisition line; 16-a current signal transfer unit; 17-a data storage module; 18-a communication system; 19-a power supply system; 20-an external power supply system; 21-an uninterruptible power supply system; 22-a variable frequency power supply; 23-voltage measuring means; 24-eddy current equivalent circuit; 25-oil temperature measurement zero setting resistance; oil pressure measurement zeroing resistance 26.
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 and 3, a transformer multipoint temperature and oil pressure monitoring device based on differential inductive sensor mainly comprises a transient oil pressure-oil temperature sensing module, a multi-channel signal acquisition module, a data processing and analyzing module, a data storage module, a device self measurement and control system, a communication system and a power supply system, and is characterized in that:
the transient oil pressure-oil temperature sensing module mainly comprises a temperature measuring coil 8, a temperature sensing element 10, an oil pressure measuring elastic coil 2, a coil pushing structure 3, an oil pressure probe 7, an elastic element 6, a linkage rod 5, a compensation coil 1, a heat insulation plate 9 and integral external packaging. Wherein the content of the first and second substances,
firstly, a temperature sensitive element 10 is made of a magnetic material with a larger resistance temperature coefficient after corrosion resistance treatment, the temperature sensitive element is separated from a temperature measuring coil 8 through a heat insulation plate 9, high-frequency excitation current is introduced into the temperature measuring coil 8, the resistivity of the temperature sensitive element 10 is changed along with the change of temperature, so that the eddy current is changed, the reactance value of the temperature measuring coil 8 is further changed, and the change value of the inductance can be solved through the input end of a differential amplification circuit formed by the temperature sensitive element and a compensation coil 1 so as to obtain the temperature;
a connecting rod 5 and an elastic element 6 are both positioned in the closed cavity 4, the elastic element 6 is deformed under pressure, one side of the elastic element 6 is connected with an oil pressure probe 7, the other side of the elastic element is connected with the connecting rod 5, the connecting rod 5 pushes the oil pressure measuring elastic coil 2 to be deformed when the elastic element 6 is deformed through a coil pushing structure 3, so that the inductance value of the oil pressure measuring elastic coil is changed, and the change value of the inductance can be solved through the input end of a differential amplifying circuit formed by the connecting rod 5 and the compensating coil 1 so as to obtain instantaneous oil pressure;
when the oil pressure is higher than the other side of the elastic element 6, namely the pressure in the closed cavity 4, the elastic element 6 can generate larger deformation to push the connecting rod 5 to move;
the signal lead 11 comprises a first lead 11-1, a second lead 11-2 and a third lead 11-3, current signals on the three coils are led out respectively, and each signal wire adopts a parallel packaging form, so that the currents of all loops are ensured not to interfere with each other, and a sensor mounting position is provided for the current signal acquisition 11;
the closed cavity 4 uses low heat conductivity material to reduce the influence of oil temperature on the pressure intensity in the cavity and ensure the measuring accuracy of pressure signal.
As shown in fig. 2, the multi-channel signal acquisition and processing system mainly includes a voltage signal acquisition module 13, a multi-terminal current signal acquisition module 12, signal filtering, and time-frequency conversion of signals. Wherein the single loop comprises an acquisition and processing unit having:
firstly, a stable high-frequency voltage source is built by utilizing a sine oscillator circuit and a secondary voltage stabilizing circuit and is used as the excitation of a differential circuit; a voltage conversion circuit is designed to convert the actual voltage amplitude value into an effective interval of a signal collector, and a high-resolution A/D converter and a high-speed signal reading module are utilized to realize the acquisition and storage of a voltage difference signal;
a temperature measuring coil 8, an oil pressure measuring elastic coil 2 and a compensating coil 1 respectively form a differential amplifying circuit, impedance changes cause changes of corresponding bridge current, current-voltage conversion is achieved through a current-voltage conversion module, and synchronous acquisition and storage of multi-channel current signals are achieved through a multi-channel high-resolution A/D converter and a high-speed signal reading module;
the voltage signal acquisition module 13 comprises a variable frequency power supply 22, a voltage measuring device 23 and a measuring bridge, the temperature measuring coil 8 and the compensating coil 1 form the measuring bridge, and the oil pressure measuring elastic coil 2 and the compensating coil 1 form the measuring bridge; before measuring the oil temperature, the zero setting is carried out through an oil temperature measuring zero setting resistor 25 and an oil pressure measuring zero setting resistor 26, the inductance of the temperature measuring coil 8 and the oil pressure measuring elastic coil 2 is changed due to the change of the oil temperature and the oil pressure during measurement, the electric bridge is in an unbalanced state, the voltage output to the voltage measuring device 23 is not zero, and the oil temperature and the oil pressure can be obtained through measuring the voltage and calculating;
considering the thermal noise and interference signals in the original voltage and current signals, and utilizing a fixed frequency gating active filter circuit and a digital filter circuit to realize the filtering processing of the original signals and reduce the influence of the interference signals;
fifthly, in order to fully excavate information carried in the signals, the time-frequency transformation of the signals is realized by using an FFT algorithm so as to obtain frequency characteristics of different parameters. After the multi-channel data are collected, the multi-channel data are directly input to the central controller, and the multi-point data are detected and transmitted.
The data analysis and storage system is connected with the end current signal acquisition module and the voltage signal acquisition module through a voltage signal acquisition line 15 and a current signal transmission unit 16 respectively, and mainly comprises a data analysis hardware module 14, a storage module 17 and a data processing algorithm. The data analysis hardware module 14 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 using programming and program burning modes, and can support various types of communication interfaces; secondly, an external SDRAM17 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; and the data processing algorithm comprises algorithms such as multi-channel feature identification, time domain correlation calculation, state evaluation and the like so as to fully dig out information such as fluctuation features of the measurement parameters, operation working conditions and the like, realize synchronous acquisition of oil temperature and oil pressure data of multiple points in the transformer and provide real-time reference information for identification, operation and maintenance and protection of the working conditions of the transformer.
The device self-monitoring system mainly comprises a high-temperature alarm system, a power supply 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 18 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 a communication port in a DMA mode of a 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 achieved.
As shown in fig. 4, the power system 19 includes an external power supply system 20, an uninterruptible power system 21, a voltage stabilizing system, and a digital-analog isolation system. 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.
Optionally, the device can realize measurement of the transient value of the oil pressure and the oil temperature, 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 can supply power to the device;
optionally, the elastic element with multiple points simultaneously acts on the connecting rod 5, so that the displacement of the connecting rod is more obvious, and the multi-characteristic information of measuring the temperature extrusion and the like of the power equipment can be expanded;
as shown in fig. 5, a method for monitoring the multi-point temperature and oil pressure of a transformer based on a differential inductive sensor, which utilizes the device to perform the multi-characteristic measurement of the multi-point temperature and the transient oil pressure of the transformer in a programmed manner, is characterized by comprising the following steps:
(1) initialization
The device of claim 1 is powered on, the device system enters initialization setting according to preset setting, the device starts a self-monitoring system to detect the power supply system 19 and the operation condition, and enters a multi-point temperature and transient oil pressure multi-feature measurement state after the self-monitoring is qualified;
(2) periodic signal acquisition and processing
After the step (1) is finished, entering a signal acquisition and data analysis period, firstly injecting a periodic voltage signal, acquiring the current of each loop by using a multi-modular current signal collector 12, inputting the current into a source filter for filtering, then transmitting the signal to an A/D high-speed collector, identifying a basic electric bridge difference value by using a high-frequency central processing unit 14 for digital filtering and FFT (fast Fourier transform) characteristic conversion or depending on a set algorithm, storing the processed data into a local memory (17) according to date and characteristic types, and waiting for subsequent processing;
(3) data analysis and condition identification
After the step (2) is finished, the stored data is called and analyzed, the oil temperature characteristics and the oil pressure characteristics including the oil temperature, the oil pressure, the change rate of the oil temperature and the oil pressure are obtained based on algorithms such as multi-channel characteristic identification, a temperature and oil pressure reference relation model, state evaluation and the like, the characteristic quantity is compared with historical data, or the basic operation condition of the transformer is excavated based on an intelligent algorithm, so that the current operation condition of the transformer is fully identified, and faults such as overheating inside the transformer, overlarge instantaneous oil pressure and the like are found in advance. When a fault or abnormal operation working condition is identified, the device starts an early warning system, simultaneously starts a communication function 21, and sends an abnormal instruction to a station-level server to realize accurate early warning of the abnormal working condition of the transformer; 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 17, calls a required data set from the memory 20 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 a transformer multiple spot temperature and oil pressure monitoring devices based on differential inductance type sensor which characterized in that: the device comprises a transient oil pressure-oil temperature sensing module, a multi-channel signal acquisition module, a data processing and analyzing module, a data storage module, a device self measurement and control system, a communication system and a power supply system;
the transient oil pressure-oil temperature sensing module is used for acquiring and calculating transient oil pressure data and oil temperature data; the transient oil pressure-oil temperature sensing module comprises a compensation coil, an oil pressure measuring elastic coil, a coil pushing structure, a closed cavity, a connecting rod, a spring element, an oil pressure probe, a temperature measuring coil, a heat insulation plate and a temperature sensitive element;
the temperature sensing element is connected with a temperature measuring coil through a heat insulation plate, the temperature measuring coil is connected with high-frequency excitation current, an eddy current is formed on the temperature sensing element, and the temperature measuring coil and a compensation coil form the input end of a differential amplification circuit;
the oil pressure probe is sequentially connected with an elastic element, a connecting rod, a coil pushing structure and an oil pressure measuring elastic coil, and the elastic element and the connecting rod are arranged in the closed cavity; the oil pressure measuring elastic coil and the compensating coil form the input end of a differential amplifying circuit;
the multi-channel signal acquisition module is used for acquiring a voltage difference signal and a multi-channel current signal;
the data processing and analyzing module is used for analyzing the fluctuation characteristics of the measured parameters and the information of the operating conditions according to the oil temperature and the oil pressure data of multiple points in the transformer;
the data storage module is used for storing local long-period original data, secondary data and analysis result data;
the device self-monitoring system is used for monitoring the self state and carrying out high-temperature alarm, power supply abnormity alarm and man-machine communication regulation and control;
the communication system is used for connecting an upper computer and carrying out data uploading and remote control;
the power supply system is used for supplying power to each module.
2. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 1, characterized in that: the multi-path signal acquisition module comprises a voltage signal acquisition module and a multi-terminal current signal acquisition module, and current signals of the compensation coil, the oil pressure measurement elastic coil and the temperature measurement coil are led out to the multi-terminal current signal acquisition module through signal leads;
the voltage signal acquisition module comprises a variable frequency power supply, a voltage measurement device and a plurality of measurement bridges, wherein the variable frequency power supply is connected with a temperature measurement coil and provides excitation for the differential amplification circuit; the variable frequency power supply comprises a sine oscillator circuit and a secondary voltage stabilizing circuit, and the voltage conversion circuit converts the actual voltage amplitude value into the effective interval of the signal collector;
the voltage measuring device is connected with the compensating coil, the oil pressure measuring elastic coil and the temperature measuring coil, and a high-resolution A/D converter and a high-speed signal reading module are used for acquiring and storing a voltage difference signal;
the plurality of measuring bridges are respectively arranged opposite to the compensating coil, the oil pressure measuring elastic coil and the temperature measuring coil and are used for realizing current signal conversion by utilizing a current-voltage conversion module according to the current change of the measuring bridges caused by the impedance change of the differential amplifying circuit and then realizing the synchronous acquisition and storage of multi-channel current signals by utilizing a multi-channel high-resolution A/D converter and a high-speed signal reading module;
the system also comprises a fixed frequency gating active filter circuit and a digital filter circuit which are used for filtering the original signal, and the time-frequency transformation of the signal is realized through an FFT algorithm so as to obtain the frequency characteristics of different parameters.
3. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 2, characterized in that: the temperature measuring coil is connected with an oil temperature measuring zero setting resistor, and the oil pressure measuring elastic coil is connected with an oil pressure measuring zero setting resistor in series.
4. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 3, characterized in that: the measuring bridge is an eddy current equivalent circuit.
5. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 4, wherein: the data processing and analyzing module is connected with the multi-terminal current signal acquisition module and the voltage signal acquisition module and used for mining fluctuation characteristics of the measured parameters and providing real-time reference information for identification, operation and maintenance and protection of transformer working conditions by operating working conditions through multi-channel characteristic identification, time domain correlation calculation and a state evaluation algorithm.
6. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 5, characterized in that: the data storage module expands the memory through the external expansion SDRAM and expands the local data storage capacity through the external expansion NAND-FLASH to store local long-period original data, secondary data and identification results.
7. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 6, characterized in that: the device self-monitoring system comprises a high-temperature alarm system, a power supply abnormity alarm system and a man-machine communication regulation system, wherein the high-temperature alarm system comprises a multipoint digital distributed temperature sensor for detecting the internal temperature and giving an alarm when the temperature is abnormal;
the power supply abnormity alarm system acquires port signal voltage by using a real-time voltage acquisition circuit, inputs the port signal voltage into a comparison circuit to be compared with a set threshold voltage, and triggers a voltage abnormity alarm circuit when the output voltage is lower than the threshold voltage;
the man-machine communication regulation and control system comprises a display screen, an indicator light and a control key and is used for carrying out man-machine interaction on the device.
8. The differential inductive sensor based transformer multipoint temperature and oil pressure monitoring device according to claim 7, wherein: 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.
9. A method of monitoring a multi-point temperature and oil pressure monitoring device for a transformer based on a differential inductive sensor according to any one of claims 1 to 8, comprising the steps of:
(1) initialization
After the power supply is switched on, according to the preset initialization setting, a measurement and control system of the device is started to detect a power supply system and an operation condition, and after the self-detection is qualified, the device enters a multi-point temperature and transient oil pressure multi-characteristic measurement state;
(2) periodic signal acquisition and processing
Firstly, injecting a periodic voltage signal, utilizing a multi-terminal current signal acquisition module to acquire current of each loop and input the current to a source filter for filtering, then transmitting the signal to an A/D high-speed acquisition device, utilizing a data analysis hardware module to carry out digital filtering, FFT (fast Fourier transform) feature conversion or identifying a basic bridge difference value depending on a set algorithm, and storing the processed data into a data storage module according to date and feature types for subsequent processing;
(3) data analysis and condition identification
The stored data is called and analyzed, oil temperature characteristics and oil pressure characteristics including oil temperature, oil pressure and change rate of the oil temperature and the oil pressure are obtained based on multi-channel characteristic recognition, a temperature oil pressure reference relation model and a state evaluation algorithm, the oil temperature characteristic quantity and the oil pressure characteristic quantity are compared with historical data, or the basic operation condition of the transformer is excavated based on an intelligent algorithm, so that the current operation condition of the transformer is fully identified, and the internal overheating and instantaneous overlarge oil pressure fault of the transformer are found in advance;
when a fault or abnormal operation working condition is identified, starting an early warning system, and simultaneously sending an abnormal instruction to a station-level server through a communication system to realize accurate early warning of the abnormal working condition of the transformer; when no fault exists and the station-level server issues a command for information calling regularly or in a designated manner, the communication system receives the calling command, starts a data calling command in the data processing and analyzing module, calls a required data set from the data storage module for subpackage processing and sending, so that uploading of historical monitoring data is realized, and the multi-channel signal acquisition module continuously performs real-time data sampling;
(4) end up
When the reset period of the device is reached, the whole device starts refreshing, empties the memory and the main memory, and enters the step (1); when a closing command of the station control end or the near-earth end is received, the device is interrupted to run and enters a closing state.
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