CN111044934A - Synchronous acquisition device for leakage current of lightning arrester - Google Patents
Synchronous acquisition device for leakage current of lightning arrester Download PDFInfo
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- CN111044934A CN111044934A CN201911291922.1A CN201911291922A CN111044934A CN 111044934 A CN111044934 A CN 111044934A CN 201911291922 A CN201911291922 A CN 201911291922A CN 111044934 A CN111044934 A CN 111044934A
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Abstract
The invention relates to a synchronous acquisition device for leakage current of a lightning arrester. The method comprises the following steps: the device comprises a configuration unit, a signal acquisition unit and a processing unit; the configuration unit is respectively in communication connection with the signal acquisition unit and the processing unit, and the signal acquisition unit is in communication connection with the processor; the configuration unit is configured to receive a synchronous data packet sent by a switch, analyze the synchronous data packet and record a receiving time mark and a sending time mark of the synchronous data packet, so as to realize time synchronization with the switch; and sending a sampling pulse signal to the signal acquisition unit; the signal acquisition unit is configured to acquire a sampling signal of the lightning arrester according to the sampling pulse signal and send a control pulse signal to the processing unit; the processing unit is configured to acquire the sampling signal from the signal acquisition unit according to the control pulse signal and send the sampling signal to a server through the switch.
Description
Technical Field
The invention relates to the technical field of power internet of things, in particular to a synchronous acquisition device for leakage current of a lightning arrester.
Background
The lightning arrester is an electric appliance which is used for protecting various electric appliances in an electric power system from being damaged by the impact of lightning overvoltage, operation overvoltage and power frequency transient overvoltage. Generally, the types of arrester are a protective gap arrester, a valve type arrester, a magnetic blow arrester, and a zinc oxide arrester.
The zinc oxide arrester is mainly used for protecting a transformer substation and/or a power plant, is used for limiting atmospheric overvoltage in a system of 500KV and below, and can also be used for limiting internal overvoltage or performing backup protection on the internal overvoltage in an ultrahigh voltage system. The zinc oxide lightning arrester is widely applied due to the characteristics of no gap, no follow current, low residual voltage and the like of the ideal volt-ampere characteristic of a zinc oxide valve plate. According to research on lightning arresters in recent decades, a large proportion of fault reasons of fault lightning arresters are moisture intrusion, lightning arrester faults or even explosion caused by performance deterioration of valve plates after the valve plates are affected with damp, and fault processes of the lightning arresters are often accompanied by abnormal rise of temperature and resistive current.
Therefore, on-line monitoring of the resistive component of the leakage current of the arrester is an important means for judging the arrester device. The currently used monitoring methods mainly include a fundamental wave method, a third harmonic wave method and a third harmonic wave compensation method. The fundamental wave method and the third harmonic need to synchronously acquire leakage current signals of the lightning arrester and voltage signals output by the voltage transformer PT, and the basic requirement of the calculation precision is high-precision synchronous sampling, so that a high-precision online monitoring device for the leakage current of the lightning arrester needs to be provided urgently to improve the accuracy of online monitoring of the leakage current of the lightning arrester.
Disclosure of Invention
One object of the present invention is to provide a new solution for the synchronous acquisition of the leakage current of an arrester.
According to an aspect of the present invention, there is provided a synchronous collecting apparatus of leakage current of an arrester, comprising: the device comprises a configuration unit, a signal acquisition unit and a processing unit; the configuration unit is respectively in communication connection with the signal acquisition unit and the processing unit, and the signal acquisition unit is in communication connection with the processor;
the configuration unit is configured to receive a synchronous data packet sent by a switch, analyze the synchronous data packet and record a receiving time mark and a sending time mark of the synchronous data packet, so as to realize time synchronization with the switch; and sending a sampling pulse signal to the signal acquisition unit;
the signal acquisition unit is configured to acquire a sampling signal of the lightning arrester according to the sampling pulse signal and send a control pulse signal to the processing unit;
the processing unit is configured to acquire the sampling signal from the signal acquisition unit according to the control pulse signal and send the sampling signal to a server through the switch.
Optionally, the apparatus further comprises:
the frequency offset calibration unit is respectively connected with the processing unit and the configuration unit in a communication way;
the frequency offset calibration unit is configured to calibrate a frequency in real time according to the frequency control signal output by the processing unit and simultaneously output a clock control frequency to the processing unit and the configuration unit.
Optionally, the processing unit includes a frequency control module and a precise time protocol module; the precise time protocol module is respectively in communication connection with the frequency control module and the configuration unit;
the frequency offset calibration unit includes: an analog conversion unit and a voltage controlled crystal oscillator; the analog conversion unit is in communication connection between the frequency control module and the voltage-controlled crystal oscillator;
the frequency control unit is configured to calculate a crystal oscillator frequency offset according to the time difference output by the precision time protocol module, and output a control word corresponding to the crystal oscillator frequency offset to the analog conversion unit;
the analog conversion unit is configured to convert the control word into the frequency control signal and output the frequency control signal to the voltage controlled crystal oscillator, so that the voltage controlled crystal oscillator implements a calibration frequency according to the frequency control signal.
Optionally, the apparatus further comprises: a photoelectric conversion module disposed between the switch and the configuration unit; the photoelectric conversion module is configured to convert optical signals and electrical signals between the configuration unit and the switch.
Optionally, the signal acquisition unit includes an analog-to-digital conversion module; the analog-to-digital conversion module is respectively in communication connection with the processing unit and the configuration unit; the analog-to-digital conversion module is configured to convert the acquired analog sampling signal into a digital sampling signal.
Optionally, the signal acquisition unit further includes a signal conditioning circuit connected between the signal acquisition module of the lightning arrester and the analog-to-digital conversion module;
the signal conditioning circuit is configured to output a value to the analog-to-digital conversion module after the analog sampling signal is subjected to jitter elimination, filtering, protection and amplification.
Optionally, the signal conditioning circuit includes a plurality of signal conditioning units, and each signal conditioning unit is connected to a signal acquisition module of one lightning arrester.
Optionally, the signal acquisition module of the lightning arrester is a zero-flux small-current sensor.
Optionally, the signal acquisition module of the lightning arrester is a voltage transformer.
In one embodiment of the invention, a configuration unit receives a synchronous data packet sent by a switch, analyzes the synchronous data packet and records a receiving time mark and a sending time mark of the synchronous data packet, so as to realize time synchronization with the switch; and sending a sampling pulse signal to the signal acquisition unit; the signal acquisition unit acquires a sampling signal of the lightning arrester according to the sampling pulse signal and sends a control pulse signal to the processing unit; and the processing unit acquires the sampling signal from the signal acquisition unit according to the control pulse signal and sends the sampling signal to a server through the switch. Therefore, the time setting precision of the signal acquisition unit is improved, a high-precision synchronous sampling signal can be provided for calculating the resistive component of the leakage current of the lightning arrester, and the accuracy of state evaluation of the lightning arrester is improved.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 shows a schematic block diagram of a synchronous acquisition device for arrester leakage current according to a first embodiment of the present invention;
fig. 2 shows a schematic block diagram of a synchronous acquisition device for arrester leakage current according to a second embodiment of the present invention;
fig. 3 is a flow chart illustrating the process of transmitting and receiving the synchronous data packet according to the embodiment of the invention.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be considered a part of the specification where appropriate.
In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
Fig. 1 shows a schematic block diagram of a device for synchronously acquiring leakage current of an arrester according to a first embodiment of the present invention. Fig. 2 shows a schematic block diagram of a device for synchronously acquiring leakage current of an arrester according to a second embodiment of the present invention.
Referring to fig. 1 and 2, the device for synchronously acquiring the leakage current of the lightning arrester in the present embodiment may include: the device comprises a configuration unit, a signal acquisition unit and a processing unit. The configuration unit is in communication connection with the signal acquisition unit and the processing unit respectively, and the signal acquisition unit is in communication connection with the processor.
Specifically, the configuration unit is configured to receive a synchronous data packet sent by a switch, analyze the synchronous data packet, record a receiving time stamp and a sending time stamp of the synchronous data packet, and implement time synchronization with the switch; and sending a sampling pulse signal to the signal acquisition unit; the signal acquisition unit is configured to acquire a sampling signal of the lightning arrester according to the sampling pulse signal and send a control pulse signal to the processing unit; the processing unit is configured to acquire the sampling signal from the signal acquisition unit according to the control pulse signal and send the sampling signal to a server through the switch.
In a possible embodiment, in order to realize the communication between the synchronous acquisition device of the lightning arrester leakage current and a switch, a photoelectric conversion module is arranged between the switch and the configuration unit. The photoelectric conversion module is configured to convert optical signals and electrical signals between the configuration unit and the switch.
Specifically, the optical-to-electrical conversion module may be responsible for converting a baseband signal suitable for optical fiber transmission. The switch and the configuration unit are communicated based on an IEEE1588 protocol, the configuration unit can be used for stamping a time mark on a synchronous data packet from the switch, and the sending clock is synchronous with the receiving clock, so that the phase error of the sending time mark of the sending synchronous data packet and the receiving time mark of the receiving synchronous data packet is ensured to be zero. The configuration unit may also output a periodic sampling pulse signal aligned with a 1pps boundary to the signal acquisition unit as a sampling start signal of the signal acquisition unit.
In one possible embodiment, the signal acquisition unit may include an analog-to-digital conversion module; the analog-to-digital conversion module is respectively in communication connection with the processing unit and the configuration unit; the analog-to-digital conversion module is configured to convert the acquired analog sampling signal into a digital sampling signal.
Furthermore, the signal acquisition unit also comprises a signal conditioning circuit which is connected between the signal acquisition module of the lightning arrester and the analog-to-digital conversion module; the signal conditioning circuit is configured to output a value to the analog-to-digital conversion module after the analog sampling signal is subjected to jitter elimination, filtering, protection and amplification.
The signal conditioning circuit comprises a plurality of signal conditioning units, and each signal conditioning unit is connected with a signal acquisition module of the lightning arrester. Correspondingly, the analog-to-digital conversion module is a parallel analog-to-digital conversion module, and can perform analog-to-digital conversion on analog sampling signals transmitted by a plurality of signal conditioning units at the same time, so that the efficiency is improved. After the conversion is completed, the parallel analog-to-digital conversion module outputs a control pulse signal to the processing unit so that the processing unit starts the DMA to move the converted digital sampling signal.
It should be noted that the signal acquisition module of the lightning arrester is installed at the ground wire of the lightning arrester, and the signal acquisition module of the lightning arrester may be a high-precision zero-flux small-current sensor or a voltage transformer PT. The high-precision zero-flux small current sensor adopts an active zero-flux technology, can effectively improve the detection precision of the small current sensor, selects special alloy with high initial permeability and low loss as an iron core, and also performs full-automatic tracking compensation on the excitation magnetic potential in the iron core by means of an electronic signal processing technology to keep the iron core working in a near-ideal zero-flux state.
In one example, if the signal acquisition module of the lightning arrester is a zero-flux small-current sensor. Correspondingly, the sampling signal is a current sampling signal, and the current sampling signal is processed by the signal conditioning unit, then input into the analog-to-digital conversion module, and converted into a digital current sampling signal by the analog-to-digital conversion module. In another example, if the signal acquisition module of the lightning arrester is a voltage transformer PT. Correspondingly, the sampling signal is a voltage sampling signal, the voltage sampling signal is processed by the signal conditioning unit, then input into the analog-to-digital conversion module, and converted into a digital sampling signal of voltage by the analog-to-digital conversion module.
In one possible implementation, the processing unit may include a frequency control module and a precision time protocol module; the precise time protocol module is respectively in communication connection with the frequency control module and the configuration unit. The precise time protocol module is used for finishing a time synchronization process according to the receiving time mark and the sending time mark of the synchronous data packet. In one example, the processing unit may be a Central Processing Unit (CPU).
Specifically, according to a precise time protocol, the process of completing time initial synchronization with the switch is realized, and the synchronization precision is required to be 1 microsecond. The initial synchronization process is as follows:
setting interval time of exchanger sending SYNC data packet as T, setting synchronous acquisition device to connectThe time stamp of the received n-th packet SYNC data packet is TnThe formula for calculating the initial synchronization error is as follows:
ΔTn＝Tn-1-Tn-T
by cumulatively averaging Δ TnRear output Δ TaveTo adjust the local timer, wait for the average synchronization error Δ TaveThe convergence is below one microsecond, and the average time difference of two continuous received synchronous data packets is output.
Referring to FIG. 3, t1The switch sends the Sync data packet time stamp, t2Is the time stamp of the received Sync packet, t3Is the Delay _ req packet timestamp; t is t4It is the switch that receives the Delay _ req packet timestamp. The calculation formula of the time delay of sending the Sync data packet from the switch to the synchronous acquisition device is as follows:
tmsd＝t2-t1
delay _ req is sent from the synchronous acquisition device to the switch, and the calculation formula is as follows:
tsmd＝t4-t3
because of the symmetry of the communication path, the time delays in the two transmission directions are consistent, so the time difference between the switch and the synchronous acquisition device is as follows:
the configuration unit sends the clock and receives the clock synchronization, eliminates t2And t3Phase error of time mark recording, but tΔErrors caused by crystal frequency drift are not taken into account. In order to eliminate the error caused by the crystal oscillator frequency drift, the device can further comprise: the frequency offset calibration unit is respectively connected with the processing unit and the configuration unit in a communication way; the frequency offset calibration unit is configured to calibrate a frequency in real time according to the frequency control signal output by the processing unit and simultaneously output a clock control frequency to the processing unit and the configuration unit. By automatic frequency control, the frequency offset of the voltage controlled crystal oscillator is eliminated in real time, and high precision is achievedAnd (4) synchronous acquisition is performed, and the synchronous precision can be controlled within 100 nanoseconds.
Specifically, the frequency offset calibration unit includes: an analog conversion unit and a voltage controlled crystal oscillator; the analog conversion unit is communicatively coupled between the frequency control module and the voltage controlled crystal oscillator. The frequency control unit is configured to calculate a crystal oscillator frequency offset according to the time difference output by the precision time protocol module, and output a control word corresponding to the crystal oscillator frequency offset to the analog conversion unit; the analog conversion unit is configured to convert the control word into the frequency control signal and output the frequency control signal to the voltage controlled crystal oscillator, so that the voltage controlled crystal oscillator implements a calibration frequency according to the frequency control signal.
In practical application, the CPU is further provided with a 12-bit digital interface, and the frequency control module is connected to the analog conversion unit through the digital interface. The frequency control module can record t twice according to the precise time protocol module2The time difference is used as input, the difference is filtered and smoothed, and the crystal oscillator frequency offset is calculated, namely:
in a specific implementation, the analog conversion unit is configured to convert the control word input by the frequency unit into an analog voltage and output the analog voltage to a control voltage pin of the vcxo, where the output frequency of the vcxo is linear to the input voltage, and a slope of the input voltage and the output frequency is obtained by the following equation:
and according to the slope k, the CPU fits a calibrated control word table to realize the accurate calibration of the frequency offset, and the frequency accuracy of the voltage-controlled crystal oscillator is below 0.01ppm after the calibration.
Specifically, the frequency control module receives the average time difference Δ TaveThe treatment process comprises the following steps:
mean time difference of conversion Δ TaveTo frequency error
Calculating a control voltage according to a slope formula of the voltage-controlled crystal oscillator;
generating a mapping table of a 12-bit digital value and an analog control voltage according to a slope curve of the voltage-controlled crystal oscillator, inquiring the mapping table to generate a digital control word, and controlling the DA converter to complete frequency control.
The configuration unit outputs periodic sampling pulses aligned with 1PPS boundaries to serve as sampling starting signals of the parallel analog-to-digital conversion unit, and the sampling pulse frequency of the parallel analog-to-digital conversion unit is started, so that the sampling rate is ensured to be the sending interval frequency of SYNC data packets
Integer multiples of.
According to the device, the time setting precision of the configuration unit is improved by improving the time scale recording points of the synchronous data packets with the IEEE1588 protocol and ensuring the synchronization of the sending clock and the receiving clock, and meanwhile, the device can adjust the frequency of the voltage-controlled crystal oscillator according to the time setting errors of two continuous synchronous data packets after the time setting convergence of the initial synchronization, so that the time setting precision is further improved, the time error between synchronous acquisition devices under the same switch is within 100 nanoseconds, high-precision synchronous sampling data are provided for the calculation of the leakage current resistive component of the lightning arrester, and the accuracy of the lightning arrester state evaluation is improved.
Although some specific embodiments of the present invention have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for the purpose of illustration and is not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (9)
1. The utility model provides a synchronous acquisition device of lightning arrester leakage current which characterized in that includes: the device comprises a configuration unit, a signal acquisition unit and a processing unit; the configuration unit is respectively in communication connection with the signal acquisition unit and the processing unit, and the signal acquisition unit is in communication connection with the processor;
the configuration unit is configured to receive a synchronous data packet sent by a switch, analyze the synchronous data packet and record a receiving time mark and a sending time mark of the synchronous data packet, so as to realize time synchronization with the switch; and sending a sampling pulse signal to the signal acquisition unit;
the signal acquisition unit is configured to acquire a sampling signal of the lightning arrester according to the sampling pulse signal and send a control pulse signal to the processing unit;
the processing unit is configured to acquire the sampling signal from the signal acquisition unit according to the control pulse signal and send the sampling signal to a server through the switch.
2. The apparatus of claim 1, further comprising:
the frequency offset calibration unit is respectively connected with the processing unit and the configuration unit in a communication way;
the frequency offset calibration unit is configured to calibrate a frequency in real time according to the frequency control signal output by the processing unit and simultaneously output a clock control frequency to the processing unit and the configuration unit.
3. The apparatus of claim 2, wherein the processing unit comprises a frequency control module and a precision time protocol module; the precise time protocol module is respectively in communication connection with the frequency control module and the configuration unit;
the frequency offset calibration unit includes: an analog conversion unit and a voltage controlled crystal oscillator; the analog conversion unit is in communication connection between the frequency control module and the voltage-controlled crystal oscillator;
the frequency control unit is configured to calculate a crystal oscillator frequency offset according to the time difference output by the precision time protocol module, and output a control word corresponding to the crystal oscillator frequency offset to the analog conversion unit;
the analog conversion unit is configured to convert the control word into the frequency control signal and output the frequency control signal to the voltage controlled crystal oscillator, so that the voltage controlled crystal oscillator implements a calibration frequency according to the frequency control signal.
4. The apparatus of claim 3, further comprising: a photoelectric conversion module disposed between the switch and the configuration unit; the photoelectric conversion module is configured to convert optical signals and electrical signals between the configuration unit and the switch.
5. The apparatus of claim 4, wherein the signal acquisition unit comprises an analog-to-digital conversion module; the analog-to-digital conversion module is respectively in communication connection with the processing unit and the configuration unit; the analog-to-digital conversion module is configured to convert the acquired analog sampling signal into a digital sampling signal.
6. The apparatus of claim 5, wherein the signal acquisition unit further comprises a signal conditioning circuit connected between the signal acquisition module of the lightning arrester and the analog-to-digital conversion module;
the signal conditioning circuit is configured to output a value to the analog-to-digital conversion module after the analog sampling signal is subjected to jitter elimination, filtering, protection and amplification.
7. The device of claim 6, wherein the signal conditioning circuit comprises a plurality of signal conditioning units, and each signal conditioning unit is connected with a signal acquisition module of one lightning arrester.
8. The apparatus of claim 7, wherein the signal acquisition module of the lightning arrester is a zero flux low current sensor.
9. The apparatus of claim 7, wherein the signal acquisition module of the lightning arrester is a voltage transformer.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112858767A (en) * | 2020-12-22 | 2021-05-28 | 国网宁夏电力有限公司检修公司 | High-precision synchronous acquisition device for monitoring extra-high voltage converter station sleeve |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112858767A (en) * | 2020-12-22 | 2021-05-28 | 国网宁夏电力有限公司检修公司 | High-precision synchronous acquisition device for monitoring extra-high voltage converter station sleeve |
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