CN109283385B - Lightning arrester monitoring data online processing method and system - Google Patents

Lightning arrester monitoring data online processing method and system Download PDF

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Publication number
CN109283385B
CN109283385B CN201811210554.9A CN201811210554A CN109283385B CN 109283385 B CN109283385 B CN 109283385B CN 201811210554 A CN201811210554 A CN 201811210554A CN 109283385 B CN109283385 B CN 109283385B
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current
frequency
phase
signal
voltage
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CN109283385A (en
Inventor
曾国辉
梁武民
兰五胜
和红伟
毛丽娜
路光辉
雍明超
周水斌
王伟杰
王青山
郭宏燕
陈磊
杨芳
李超
云亚文
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State Grid Corp of China SGCC
Xuji Group Co Ltd
XJ Electric Co Ltd
Xuchang XJ Software Technology Co Ltd
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State Grid Corp of China SGCC
Xuji Group Co Ltd
XJ Electric Co Ltd
Xuchang XJ Software Technology Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2506Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
    • G01R19/2509Details concerning sampling, digitizing or waveform capturing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16Spectrum analysis; Fourier analysis
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2688Measuring quality factor or dielectric loss, e.g. loss angle, or power factor
    • G01R27/2694Measuring dielectric loss, e.g. loss angle, loss factor or power factor

Abstract

The invention relates to an online processing method and system for monitoring data of an arrester, which solve the initial phase angle by carrying out full cycle Fourier transform on signals acquired by a current acquisition unit and a voltage acquisition unit, correct the initial phase angle according to the change of power frequency, and then utilize a least square method to fit a straight line to solve the final initial phase angle and frequency of each phase current signal and each related bus voltage signal, thereby eliminating the periodic change of the phase angle between the current and the voltage and solving the problems of poor interference and inaccurate result of the existing online monitoring data processing method for the arrester.

Description

Lightning arrester monitoring data online processing method and system
Technical Field
The invention belongs to the technical field of online monitoring of lightning arresters, and particularly relates to an online processing method and system for lightning arrester monitoring data.
Background
The lightning arrester is an important electrical device for protecting power equipment from overvoltage in a power grid, and the operational reliability of the lightning arrester directly influences the safety of a power system. In recent years, explosion accidents caused by deterioration of electrical performance of an alternating-current gapless oxide lightning arrester in operation of a transformer substation due to aging of a valve plate sometimes occur, huge loss is brought to national economy, and serious threat is brought to safe operation of a power grid. The lightning arrester is monitored on line, internal defects of the lightning arrester can be effectively monitored in time, faults can be found and eliminated as soon as possible, explosion of the lightning arrester is avoided, and safe operation of an electric power system is guaranteed.
In order to monitor the nonlinear resistance characteristic of the valve plate of the alternating-current gapless oxide arrester, the best method is to monitor the resistive current. To obtain accurate resistive current, the full current and the bus voltage of the arrester need to be synchronously acquired. In the prior art, Fourier transform and least square fitting are generally adopted to calculate, frequency and phase angle. However, the current and the actual bearing voltage of the lightning arrester have different frequencies, which causes the phase angle between the current and the voltage to change periodically and the frequency to fluctuate continuously, resulting in inaccurate calculation results.
Disclosure of Invention
The invention aims to provide an online processing method and system for lightning arrester monitoring data, and aims to solve the problem that the calculation result of the existing online processing method for lightning arrester monitoring data is inaccurate.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides an online processing method of lightning arrester monitoring data, which comprises the following steps:
1) synchronously acquiring each phase current signal and each related bus voltage signal of the lightning arrester, and performing full-cycle Fourier operation on the acquired signals of at least two cycles every N sampling points;
2) calculating the amplitude and initial phase angle of each phase current and each related bus voltage according to the operation result of the step 1);
3) correcting the initial phase angle of each phase current signal and each related bus voltage signal obtained by the operation in the step 2), subtracting the k initial phase angles alpha k from the initial phase angles alpha k +1 obtained by k +1 times of calculation,
if α [ k +1] - α [ k ] > β, α [ k +1] ═ α [ k +1] -360 °,
if α [ k +1] - α [ k ] < - β, α [ k +1] ═ α [ k +1] +360 °;
wherein k is 1,2,3, β is related to the power frequency and the highest frequency of power frequency variation;
4) for each set of k and α [ k ], a straight line y is fitted by the least square method to ax + b, coefficients a and b are obtained, b is the final initial phase angle of each phase current and each relevant bus voltage, and the signal frequency is obtained from a.
The invention also provides an online processing system of the lightning arrester monitoring data, which comprises a current acquisition unit, a voltage acquisition unit, a processor and a memory, wherein the processor receives signals of the current acquisition unit and the voltage acquisition unit; the processor executes instructions stored in the memory to implement the method steps of:
1) synchronously acquiring each phase current signal and each related bus voltage signal of the lightning arrester, and performing full-cycle Fourier operation on the acquired signals of at least two cycles every N sampling points;
2) calculating the amplitude and initial phase angle of each phase current and each related bus voltage according to the operation result of the step 1);
3) correcting the initial phase angle of each phase current signal and each related bus voltage signal obtained by the operation in the step 2), subtracting the k initial phase angles alpha k from the initial phase angles alpha k +1 obtained by k +1 times of calculation,
if α [ k +1] - α [ k ] > β, α [ k +1] ═ α [ k +1] -360 °,
if α [ k +1] - α [ k ] < - β, α [ k +1] ═ α [ k +1] +360 °;
wherein k is 1,2,3, β is related to the power frequency and the highest frequency of power frequency variation;
4) for each set of k and α [ k ], a straight line y is fitted by the least square method to ax + b, coefficients a and b are obtained, b is the final initial phase angle of each phase current and each relevant bus voltage, and the signal frequency is obtained from a.
The invention has the beneficial effects that:
the initial phase angle is obtained by performing full cycle Fourier transform on the signals acquired by the current acquisition unit and the voltage acquisition unit, the initial phase angle is corrected according to the change of power frequency, then a least square method is used for fitting a straight line, and the final initial phase angle and the frequency of each phase current signal and each related bus voltage signal are obtained, so that the periodic change of the phase included angle of the current and the voltage is eliminated, and the problem of inaccurate calculation result of the existing lightning arrester online monitoring data processing method is solved.
And further, the method also comprises the step 5) of judging an effective operation fixed value of the current and the voltage, calculating the stability of the dielectric loss value according to the relationship of the passing frequency and the phase, then calculating the phase difference between the current of the lightning arrester and the voltage of the bus according to the calculated phase difference, and then calculating a resistive current according to the phase difference, wherein the magnitude of the resistive current is equal to the cosine of the phase difference between the total current and the voltage.
Furthermore, the system also comprises a communication comprehensive management unit for synchronously acquiring signals.
Drawings
FIG. 1 is a schematic diagram of two cycles of signals according to the method of the present invention;
FIG. 2 is a schematic diagram of two cycle initial phase angles of the method of the present invention;
FIG. 3 is a schematic diagram of the method of the present invention after fitting a straight line by a first phase angle least squares method;
fig. 4 is a schematic diagram of an online monitoring device system for a serial bus-based lightning arrester according to the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.
The method provided by the invention comprises the following specific implementation steps:
as shown in fig. 1, the current collection unit and the voltage collection unit synchronously collect 2 cycles at a time and have 512 sampling points, full-wave fourier operation is performed on the two cycles at 16 sampling points, and 16 calculation results can be obtained at 512 sampling points. The full cycle Fourier transform calculates the amplitude of the current and the voltage, further calculates the initial phase angle of the current and the voltage, the obtained initial phase angle of the current is shown in figure 2, and 16 calculation results can be obtained in total.
Correcting the initial phase angle of each phase current signal and each related bus voltage signal obtained by calculation, subtracting the initial phase angle of k times of initial phase angle alpha k from the initial phase angle alpha k +1 obtained by k +1 times of calculation,
if α [ k +1] - α [ k ] > β, α [ k +1] ═ α [ k +1] -360 °,
if α [ k +1] - α [ k ] < - β, α [ k +1] ═ α [ k +1] +360 °;
wherein k is 1,2,3, beta is related to the highest frequency of power frequency and power frequency variation measurement; the power frequency is 50Hz, i.e. one cycle is 0.02s, the angle changes 360 ° in one cycle, when the frequency is 65Hz, one cycle time is 0.01538s corresponding to the angle change 360 °, in the case of 65Hz the angle β corresponding to 0.02/16s is equal to the product of 0.02s/16 and 360 divided by 0.01538 to yield 29.25 °, which is approximately 30 °.
As shown in fig. 3, a straight line y ═ ax + b is fitted to the data of each set k and α [ k ] by the least square method, the final initial phase angle b and signal frequency of each phase current and each associated bus voltage are obtained,
the signal frequency is obtained from the slope a of the straight line, and f is a × 50 ÷ 22.5, and includes the voltage frequency and the current frequency.
The communication comprehensive management unit polls the acquisition unit to receive the message, the processor analyzes the message to obtain corresponding data, the ABC three-phase current acquisition units respectively judge the effective operation fixed value of current and voltage under the condition that the sampling synchronous serial number of the voltage unit is consistent with the actual 1 interval of the lightning arrester, the stability of the dielectric loss value is calculated according to the relationship of frequency and phase, the magnitude of the resistive current is equal to the cosine of the total current multiplied by the current-voltage phase difference according to the phase difference of the calculated lightning arrester current and the bus voltage, and therefore the deterioration degree of the lightning arrester is judged.
The invention also provides an online processing system of the lightning arrester monitoring data, which comprises a current acquisition unit, a voltage acquisition unit, a processor, a memory and a communication management unit. As shown in fig. 4, the communication management unit of the system issues a synchronous acquisition command to the voltage acquisition unit and each arrester current acquisition unit through the RS485 bus, and the acquisition unit FPGA receives the command to trigger AD7606 sampling. And then adding a synchronous sequence number byte into the polling message of the acquisition unit, wherein the message sent by the acquisition unit also carries the synchronous sequence number byte, and the synchronous sequence number is used for distinguishing a synchronous acquisition command which is issued for the second time.
The communication comprehensive management unit polls the acquisition unit to receive the message, the processor analyzes the message to obtain corresponding data, and the ABC three-phase current acquisition unit calculates the phase difference with the corresponding bus voltage according to the voltage ABC three-phase initial phase angle and the current three-phase initial phase angle under the condition that the sampling synchronous sequence number of the voltage unit is consistent with that of the actual 1 interval ABC three-phase current acquisition unit of the lightning arrester, so that the resistive current is finally calculated.
The communication comprehensive management unit is communicated with the station end monitoring platform through MMS, and managers can check the parameter state of the lightning arrester monitoring data online processing system in real time.

Claims (5)

1. An online processing method for lightning arrester monitoring data is characterized by comprising the following steps:
1) synchronously acquiring each phase current signal and bus voltage signal of the lightning arrester, and performing full-cycle Fourier operation on the acquired signals of at least two cycles every N sampling points;
2) calculating the amplitude and initial phase angle of each phase current and the bus voltage according to the operation result of the step 1);
3) correcting the initial phase angle of each phase current signal and the bus voltage signal obtained by the operation in the step 2), subtracting k times of initial phase angle alpha k from the initial phase angle alpha k +1 obtained by k +1 times of calculation,
if α [ k +1] - α [ k ] > β, α [ k +1] ═ α [ k +1] -360 °,
if α [ k +1] - α [ k ] < - β, α [ k +1] ═ α [ k +1] +360 °;
wherein k is 1,2,3, β is related to the power frequency and the highest frequency of power frequency variation;
4) for each group of k and alpha [ k ] data, fitting a straight line y to ax + b by using a least square method, and obtaining coefficients a and b, wherein the b is a final initial phase angle of each phase current and each related bus voltage, the signal frequency is obtained by a, the signal frequency comprises a voltage frequency and a current frequency, and is equal to an angle change value corresponding to two adjacent full-cycle Fourier operations in one change period after the coefficient a is multiplied by a power frequency value.
2. The online processing method for the arrester monitoring data according to claim 1, characterized by further comprising the step 5) of judging an effective operation fixed value of current and voltage, calculating a phase difference between each phase current of the arrester and a bus voltage after calculating the stability of a dielectric loss value through a frequency and phase relation, and then calculating a resistive current according to the phase difference, wherein the magnitude of the resistive current is equal to the total current multiplied by the cosine of the phase difference.
3. An online processing system for lightning arrester monitoring data comprises a current acquisition unit, a voltage acquisition unit, a processor and a memory, wherein the processor receives signals of the current acquisition unit and the voltage acquisition unit; wherein the processor executes instructions stored in the memory to implement the method steps of:
1) synchronously acquiring each phase current signal and bus voltage signal of the lightning arrester, and performing full-cycle Fourier operation on the acquired signals of at least two cycles every N sampling points;
2) calculating the amplitude and initial phase angle of each phase current and the bus voltage according to the operation result of the step 1);
3) correcting the initial phase angle of each phase current signal and the bus voltage signal obtained by the operation in the step 2), subtracting k times of initial phase angle alpha k from the initial phase angle alpha k +1 obtained by k +1 times of calculation,
if α [ k +1] - α [ k ] > β, α [ k +1] ═ α [ k +1] -360 °,
if α [ k +1] - α [ k ] < - β, α [ k +1] ═ α [ k +1] +360 °;
wherein k is 1,2,3, β is related to the power frequency and the highest frequency of power frequency variation;
4) for each group of k and alpha [ k ] data, fitting a straight line y to ax + b by using a least square method, and obtaining coefficients a and b, wherein the b is a final initial phase angle of each phase current and each related bus voltage, the signal frequency is obtained by a, the signal frequency comprises a voltage frequency and a current frequency, and is equal to an angle change value corresponding to two adjacent full-cycle Fourier operations in one change period after the coefficient a is multiplied by a power frequency value.
4. The on-line processing system for arrester monitoring data according to claim 3, further comprising step 5) of judging an effective operating constant value of current and voltage, calculating a phase difference between each phase current of the arrester and a bus voltage after calculating stability of a dielectric loss value through a frequency and phase relation, and then calculating a resistive current according to the phase difference, wherein the magnitude of the resistive current is equal to the total current multiplied by the cosine of the phase difference.
5. The on-line processing system for lightning arrester monitoring data according to claim 3 or 4, characterized by further comprising a communication comprehensive management unit for signal synchronous acquisition.
CN201811210554.9A 2018-10-17 2018-10-17 Lightning arrester monitoring data online processing method and system Active CN109283385B (en)

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CN110244144B (en) * 2019-05-28 2021-11-16 许昌许继软件技术有限公司 Lightning arrester state monitoring method and alternating current data acquisition method
CN111323665A (en) * 2020-03-18 2020-06-23 合肥瀚度电力科技有限公司 Lightning arrester monitoring device, method and system based on GPS time service ratio correction

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JPH02193528A (en) * 1989-01-21 1990-07-31 Giichiro Kato Lightning arrestor for high-sensitivity, large-capacity and low-pressure circuit
CN101587147A (en) * 2009-06-25 2009-11-25 中国电力科学研究院 A kind of synchronous phasor measuring device carries out the method for phasor correction
CN102269803A (en) * 2010-06-04 2011-12-07 北京化工大学 Method for correcting low-frequency components in discrete spectrum based on time delay
CN103091545A (en) * 2013-02-21 2013-05-08 南京磐能电力科技股份有限公司 Sinusoidal signal phasor half-wave computing method irrelevant to frequency
CN104142421A (en) * 2013-05-07 2014-11-12 常州顺创电气科技有限公司 Substation equipment insulation online monitoring system and working method thereof
CN104020350A (en) * 2014-06-23 2014-09-03 哈尔滨同为电气股份有限公司 Voltage fundamental component detection method for overcoming frequency perturbation
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CN105182160A (en) * 2015-09-21 2015-12-23 厦门大恒科技有限公司 On-line SPD microampere current leakage detecting device
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CN106970264A (en) * 2017-03-02 2017-07-21 浙江大学 A kind of improvement phase difference correction method for considering mains frequency rate of change

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