CN111610382A - Non-contact transformer bushing space electric field monitoring device - Google Patents
Non-contact transformer bushing space electric field monitoring device Download PDFInfo
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- CN111610382A CN111610382A CN202010381315.0A CN202010381315A CN111610382A CN 111610382 A CN111610382 A CN 111610382A CN 202010381315 A CN202010381315 A CN 202010381315A CN 111610382 A CN111610382 A CN 111610382A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention discloses a non-contact transformer bushing space electric field monitoring device which comprises an electric field sensor, a receiver, a first transmission unit and a processor, wherein the first transmission unit is connected with the receiver; the input end of the processor is connected with the electric field sensor, the electric field strength around the transformer bushing is obtained, and the electric field strength is processed and modified to obtain an accurate electric field strength value; the output end of the processor is connected with the first transmission unit, the accurate electric field strength value is transmitted to the receiver through the first transmission unit, the receiver conducts reliability verification on the accurate electric field strength value, data subjected to the reliability verification are fed back to the processor, and the processor analyzes the data subjected to the reliability verification and judges whether the electric field strength around the transformer collecting sleeve exceeds a set range. The invention can realize long-term, continuous and non-contact measurement of the transformer bushing space electric field.
Description
Technical Field
The invention belongs to the technical field of transformer monitoring, and particularly relates to a non-contact transformer bushing space electric field monitoring device.
Background
The power transformer is used as a key link of electric energy transmission, and whether the running state of the power transformer is good or not has a great relation with safe and stable running of a power grid. The transformer bushing leads high-voltage and low-voltage leads inside the transformer to the outside of the oil tank, and has important significance in monitoring the running state of the transformer bushing. For the research and application of the transformer bushing on-line monitoring technology, the current main focus is on the measurement of the dielectric loss factor, the capacitance measurement, the frequency domain dielectric spectroscopy and the like.
(1) Dielectric loss factor measurement
Under the action of an alternating current electric field, the dielectric material not only has conductive current (loss) but also has energy consumption caused by polarization of the dielectric. Dielectric loss is an important value for characterizing the insulation state of a device. In order to examine dielectric loss, a circuit is generally simulated by using an insulating material having a loss as a parallel resistor, a capacitor, or the like, as shown in fig. 1 and 2.
When a high voltage is applied to the insulating material, if the insulating state of the material is good, a reactive current I flows through the materialCHigh value of IRThe current value is small and the dielectric loss is also small. However, when the insulating medium is affected with damp or deteriorated, the reactive current is increased and enlarged, and simultaneously the medium loss of the equipment is also multiplied, so that the connection edge characteristic of the equipment can be intuitively reflected through the medium loss factor angle.
(2) Capacitance measurement
The capacitance detection of the transformer bushing can also effectively reflect the local fault defect. According to the capacitance change characteristic of the sleeve, whether the capacitive screen is degraded or not and whether the capacitive screen is discharged or not can be well judged, and if the sleeve capacitive screen is punctured in the detection process, the capacitance can be remarkably increased.
The transformer capacitive bushing comprises a central guide pipe, a capacitor core, external insulation, an installation flange and the like, wherein a tail screen measuring terminal divides the total capacitance of the bushing into two parts, namely a capacitor C1 part and a capacitor C2 part, wherein C1 is the capacitance between the central guide pipe of the bushing and the measuring terminal and is the main insulation capacitor of the bushing, and R1 is the main capacitor insulation resistor (the insulation resistor between a conductive rod and a tail screen); c2 is the capacitance between the measuring terminal (end shield) and the connecting sleeve (flange), and R2 is the insulation resistance between the end shield and the flange, as shown in fig. 3.
(3) Frequency domain dielectric spectroscopy
The frequency domain dielectric spectroscopy is to extend the conventional power frequency dielectric loss and capacitance measurement to low and high frequency bands (e.g., from 0.1mHz to 1kHz), and to evaluate the insulation state of the insulation material by using the parameters of the complex capacitance, complex dielectric constant, dielectric loss factor, etc. of the medium along with the frequency change under a low-voltage sinusoidal alternating electric field, so that the wiring schematic diagram of the polarization and loss conditions in a wider frequency domain range can be reflected as shown in FIG. 4.
The limitations of the quality loss factor measurement are that the result does not reflect all defect types, and only when the insulation fault of the electrical equipment is damp and aged as a whole or partial discharge exists in the insulation, the active current component in the electrical equipment is large, the measured tan is large, and the fractional defects of the electrical equipment can be effectively expressed. In contrast, if the defect types of the electrical equipment are not distributed but concentrated, the measured tan has small change and is relatively insensitive to the reflection of the fault.
The main disadvantage of the transformer bushing capacitance measurement is that the influence of stray capacitance and parasitic capacitance needs to be eliminated during measurement due to the small capacitance of the transformer bushing itself. In addition, the change of the standard capacitance of the measuring instrument can have great influence on the measuring result.
For the frequency domain dielectric spectroscopy, although the method is used as a nondestructive testing means for oil paper insulation aging diagnosis of equipment such as an oil immersed transformer and the like, has certain noise filtering resistance and can carry rich ginger vitamin information, the test result of the method is greatly influenced by the insulation structure, temperature, water distribution and the like of a test article.
In addition, the above test methods are all contact measurement. The transformer is used as high-voltage live equipment, and the contact measurement of the transformer needs to be combined with the power failure plan of a power enterprise, so that the real-time monitoring of the running state of a transformer sleeve is difficult to realize. Meanwhile, the method has relatively complicated operation steps and high price of a test instrument, and is difficult to meet the requirement of continuously monitoring the field equipment for a long time.
Disclosure of Invention
Aiming at the problems, the invention provides a non-contact transformer bushing space electric field monitoring device which can realize long-term, continuous and non-contact measurement of a transformer bushing space electric field.
In order to achieve the technical purpose and achieve the technical effects, the invention is realized by the following technical scheme:
a non-contact transformer bushing space electric field monitoring device, comprising:
the electric field sensor is used for collecting the electric field intensity around the transformer bushing;
a receiver;
the first transmission unit is connected with the receiver;
the input end of the processor is connected with the electric field sensor, the electric field strength around the transformer bushing is obtained, and the electric field strength is processed to obtain an accurate electric field strength value; the output end of the processor is connected with the first transmission unit, the accurate electric field intensity value is transmitted to the receiver through the first transmission unit, the receiver conducts reliability verification on the accurate electric field intensity value, data subjected to the reliability verification are fed back to the processor, the processor analyzes the data subjected to the reliability verification, whether the electric field intensity around the transformer bushing exceeds a set range is judged, and non-contact transformer bushing space electric field monitoring is achieved.
Optionally, the non-contact transformer bushing space electric field monitoring device further includes a second transmission unit, configured to connect to a remote center; and the second transmission unit is also connected with the output end of the processor, receives the accurate electric field intensity value sent by the processor and transmits the accurate electric field intensity value to the remote control center.
Optionally, the non-contact transformer bushing space electric field monitoring apparatus further includes a power supply unit, where the power supply unit includes: the charging module, the rechargeable battery and the DC-DC power supply conversion module are connected in sequence;
the charging module is also used for being connected with an external energy source;
the DC-DC power supply conversion module is used for being connected with the processor.
Optionally, the non-contact transformer bushing space electric field monitoring device further includes a relay switch, and the relay switch is respectively connected to the processor and the DC-DC power conversion module.
Optionally, an amplifier is provided between the electric field sensor and the processor.
Optionally, the number of the electric field sensors is greater than 1, and each electric field sensor is respectively arranged in the transformer bushing space.
Optionally, after the processor receives the electric field strength around the transformer bushing sent by the electric field sensor, the processor rejects interference signals in the received electric field strength to obtain an accurate electric field strength value.
Optionally, after the receiver receives the accurate electric field intensity value, whether the reliability requirement is met according to a protocol written in advance is determined, and data meeting the reliability requirement is sent to the processor.
Optionally, after receiving the data with reliability verified, the processor determines whether the data is in a preset field intensity threshold curve, and if the data crosses the field intensity threshold curve, an alarm signal is sent.
Optionally, the processor is an STM32 single chip microcomputer, and an a/D conversion module is included in the processor; the first transmission unit is a 433 transparent transmission module.
Compared with the prior art, the invention has the beneficial effects that:
the electric field sensor is used for collecting the electric field strength around the transformer bushing and sending the electric field strength to the processor, and the processor processes the electric field strength to obtain an accurate electric field strength value; the processor also transmits the accurate electric field strength value to the receiver through the first transmission unit, the receiver performs reliability verification on the accurate electric field strength value and feeds back the data subjected to reliability verification to the processor, the processor analyzes the data subjected to reliability verification, whether the electric field strength around the transformer bushing exceeds a set range is judged, and long-term, continuous and non-contact measurement on the space electric field of the transformer bushing can be realized.
Drawings
In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a prior art working diagram of an insulating medium;
FIG. 2 is an equivalent model of dielectric loss in the prior art;
FIG. 3 is a prior art bushing capacitor structure;
FIG. 4 is a schematic diagram of prior art mid-frequency domain dielectric spectroscopy connections;
fig. 5 is a schematic diagram of a non-contact transformer bushing space electric field monitoring device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention.
The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.
As shown in fig. 5, the present invention provides a non-contact transformer bushing space electric field monitoring device, which includes:
the electric field sensor is used for collecting the electric field intensity around the transformer bushing;
a receiver;
the first transmission unit is connected with the receiver;
the input end of the processor is connected with the electric field sensor, the electric field strength around the transformer bushing is obtained, and the electric field strength is processed to obtain an accurate electric field strength value; the output end of the processor is connected with the first transmission unit, the accurate electric field intensity value is transmitted to the receiver through the first transmission unit, the receiver conducts reliability verification on the accurate electric field intensity value, data subjected to the reliability verification are fed back to the processor, the processor analyzes the data subjected to the reliability verification, whether the electric field intensity around the transformer bushing exceeds a set range is judged, and non-contact transformer bushing space electric field monitoring is achieved.
In a specific implementation manner of the embodiment of the invention, the processor is an STM32 single chip microcomputer, and the processor internally comprises an a/D conversion module; the first transmission unit is a 433 transparent transmission module; the electric field sensor is a d-dot miniature probe.
In a specific implementation manner of the embodiment of the present invention, an amplifier is disposed between the electric field sensor and the processor, the amplifier may be a differential amplifier circuit, when a common mode interference signal with the same amplitude and phase is input, the difference is zero, and the system determines that the input signal is invalid, so that interference caused by the common mode signal does not need to be considered. And then the difference between the two signals at the input end is used as an effective signal of the differential input circuit, and a voltage input signal can be obtained by designing a reasonable amplification factor. After the input signal passes through the differential circuit, the amplification factor is about 10 times. The amplifier can adopt an AD620 instrument amplifier chip, and the whole working characteristics are as follows: the single power supply works at 4-30V and outputs-10.5V- + 10.5V; power consumption is 0.25 watt; the output voltage range is-10.5V- +10.5V, and the linear range is-10V- + 10V; the precision and the linearity are better than one in a thousand; 4+1 order low-pass filtering can completely filter noise interference higher than 1000 Hz; the maximum input offset voltage is 50 uV; low input offset drift 0.6 μ V/deg.C; inputting a bias current of 1.0 nA; common mode rejection ratio 100 dB; the input voltage noise is 9nV/√ Hz.
In a specific implementation manner of the embodiment of the present invention, the number of the electric field sensors is greater than 1, and each of the electric field sensors is respectively arranged in a space around the transformer bushing.
The STM32 single chip microcomputer is used for realizing logic operation processing of analog and digital signals. The STM32 single chip microcomputer minimum system comprises a crystal oscillator circuit, a power supply module, a JTAG interface module, a serial port ISP downloading module and a system resetting module.
The STM32F103 enhanced family uses a high performance ARM Cortex-M332 bit RISC core, the ARM Cortex-M3 processor being the latest generation of embedded ARM processor, which provides a low cost platform, reduced pin count, lower system power consumption, while providing excellent computing performance and advanced interrupt system response to the needs of MCU. ARM's Cortex-M3 is a 32-bit RISC processor that can provide additional code efficiency, resulting in the high performance of the ARM core over the memory space of typical 8 and 16-bit systems.
The output voltage of the electric field sensor must be converted into digital quantity through A/D (analog/digital) to be processed by a processor, and the digital signal is output after the processor performs data processing.
The 12-bit A/D conversion module configured by STM32 single chip microcomputer is a successive approximation type analog-digital converter. It has 18 channels and can measure 16 external and 2 internal signal sources. The a/D conversion of each channel may be performed in a single, continuous, scanning, or discontinuous mode. The results of the a/D conversion module may be stored in the 16-bit data register in a left-aligned or right-aligned manner.
In summary, the following steps: the working process of the electric field monitoring device in the embodiment of the invention is as follows:
the electric field sensor is used for sending the acquired electric field intensity information to an AC/DC module of the processor to complete analog-digital conversion;
the controller performs information fusion processing and correction (namely denoising processing) on the acquired data to obtain a relatively reliable and accurate electric field intensity value, and the data are packaged and transmitted to the first transmission unit after the processing is finished;
the first transmission unit sends data to the receiver, the receiver judges the reliability of the transmission numerical value according to a protocol compiled in advance after receiving the signal, and then the reliability is fed back to the processor to be analyzed by the processor, so that whether the electric field intensity is in a preset field intensity threshold curve or not is judged, if the electric field intensity exceeds the field intensity threshold curve, an alarm signal is sent out, and the monitoring of the running state is realized.
Example 2
Based on embodiment 1, in the embodiment of the present invention, the non-contact transformer bushing space electric field monitoring apparatus further includes a second transmission unit, which is used for connecting to a remote center; the second transmission unit is also connected with the output end of the processor, receives the accurate electric field intensity value sent by the processor and transmits the accurate electric field intensity value to the remote center.
In a specific implementation manner of the embodiment of the present invention, the second transmission unit employs a USR-GM3 type GPRS module, which provides a serial port-to-GPRS information transmission function, and uploads monitoring information to a server through a 2G network for remote monitoring and calling. The USR-GM3 has the following functional characteristics: the four-frequency GSM850/900 and the DCS1800/1900 are universal globally; support for GSM/GPRS networks; 2G flow of the 2G/3G/4G mobile phone card is supported; the method supports 4-path network connection and online simultaneously, and supports TCP Client and UDPClient; each path of connection supports 4kB data caching, and the cached data can be selected not to be lost when the connection is abnormal; supporting the parameter of a remote short message setting module; a short message transparent transmission mode, a network transparent transmission mode, an HTTPD mode and an UDC mode are supported; supporting a basic instruction set and an extended instruction set; simple instructions are supported to send Chinese/English short messages; the function of supporting similar RFC2217 can dynamically modify the serial port parameters of the module from a network; hardware flow control of a serial port, RTS/CTS is supported; support the UDC protocol; and remote upgrading of the FTP protocol is supported.
Example 3
Based on embodiment 1 or embodiment 2, the non-contact transformer bushing space electric field monitoring apparatus in the embodiment of the present invention further includes a power supply unit, where the power supply unit includes: the charging module, the rechargeable battery and the DC-DC power supply conversion module are connected in sequence;
the charging module is also used for being connected with an external energy source;
the DC-DC power supply conversion module is used for being connected with the processor.
In a specific implementation manner of the embodiment of the invention, the power supply unit is designed by adopting an FR9885S6CTR chip and two SGM2019 chips, is externally connected with 12V direct current, and is connected with an LED (light-emitting diode) which can display the working state of a power supply, and the power supply module can meet the power supply requirement of the whole system in the aspect of real-time measurement.
In the embodiment of the invention, the charging module can be a solar charging module, the rechargeable battery is a lithium battery, the rechargeable battery is used as a supplement of a lithium battery power supply, and if the residual electric quantity of the lithium battery is lower than the early warning level in the outdoor environment, the solar charging module can supply power to the lithium battery.
Example 4
Based on any one of embodiments 1 to 3, in an embodiment of the present invention, the non-contact transformer bushing space electric field monitoring apparatus further includes a relay switch, and the relay switch is respectively connected to the processor and the DC-DC power conversion module.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A non-contact transformer bushing space electric field monitoring device, characterized by, includes:
the electric field sensor is used for collecting the electric field intensity around the transformer bushing;
a receiver;
the first transmission unit is connected with the receiver;
the input end of the processor is connected with the electric field sensor, the electric field strength around the transformer bushing is obtained, and the electric field strength is processed to obtain an accurate electric field strength value; the output end of the processor is connected with the first transmission unit, the accurate electric field intensity value is transmitted to the receiver through the first transmission unit, the receiver conducts reliability verification on the accurate electric field intensity value, data subjected to the reliability verification are fed back to the processor, the processor analyzes the data subjected to the reliability verification, whether the electric field intensity around the transformer bushing exceeds a set range is judged, and non-contact transformer bushing space electric field monitoring is achieved.
2. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: the non-contact transformer bushing space electric field monitoring device also comprises a second transmission unit which is used for being connected with a remote center; and the second transmission unit is also connected with the output end of the processor, receives the accurate electric field intensity value sent by the processor and transmits the accurate electric field intensity value to the remote control center.
3. The non-contact transformer bushing space electric field monitoring device according to claim 1, further comprising a power supply unit, the power supply unit comprising: the charging module, the rechargeable battery and the DC-DC power supply conversion module are connected in sequence;
the charging module is also used for being connected with an external energy source;
the DC-DC power supply conversion module is used for being connected with the processor.
4. The device for monitoring the space electric field of the bushing of the non-contact transformer as claimed in claim 4, further comprising a relay switch, wherein the relay switch is connected to the processor and the DC-DC power conversion module respectively.
5. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: an amplifier is arranged between the electric field sensor and the processor.
6. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: the number of the electric field sensors is more than 1, and the electric field sensors are respectively arranged in the space of the transformer bushing.
7. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: and after the processor receives the electric field strength around the transformer bushing sent by the electric field sensor, eliminating an interference signal in the received electric field strength to obtain an accurate electric field strength value.
8. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: and after the receiver receives the accurate electric field intensity value, whether the reliability requirement is met or not is determined according to a pre-programmed protocol, and the data meeting the reliability requirement is sent to the processor.
9. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: and after receiving the data subjected to reliability verification, the processor judges whether the data is in a preset field intensity threshold curve or not, and if the data crosses the field intensity threshold curve, an alarm signal is sent out.
10. The non-contact transformer bushing space electric field monitoring device of claim 1, wherein: the processor is an STM32 single chip microcomputer and comprises an A/D conversion module inside; the first transmission unit is a 433 transparent transmission module.
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| CN202010381315.0A CN111610382A (en) | 2020-05-08 | 2020-05-08 | Non-contact transformer bushing space electric field monitoring device |
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| CN202010381315.0A CN111610382A (en) | 2020-05-08 | 2020-05-08 | Non-contact transformer bushing space electric field monitoring device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112630638A (en) * | 2020-11-25 | 2021-04-09 | 国网江苏省电力有限公司检修分公司 | Circuit breaker porcelain bushing flashover identification method and system |
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| CN105093154A (en) * | 2015-08-21 | 2015-11-25 | 国网上海市电力公司 | Data transmission method and device for on-line monitoring device quality simulation testing |
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