CN110794216A - Grounding state detection device and detection method thereof - Google Patents
Grounding state detection device and detection method thereof Download PDFInfo
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- CN110794216A CN110794216A CN201911115665.6A CN201911115665A CN110794216A CN 110794216 A CN110794216 A CN 110794216A CN 201911115665 A CN201911115665 A CN 201911115665A CN 110794216 A CN110794216 A CN 110794216A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
Abstract
The invention relates to a grounding state detection device and a detection method thereof, belonging to the technical field of grounding grid state detection. The device comprises a variable frequency test power supply, a test electrode, an electrode included angle adjusting device, a temperature and humidity detection module, a signal conditioning module, an acquisition module and a microprocessor; the output end of the variable-frequency test power supply is connected with the input end of the test electrode; the signal conditioning module amplifies a current signal on the test electrode and transmits the amplified current signal to the acquisition module; the acquisition module acquires current data of the test electrode, temperature and humidity data of the temperature and humidity detection module and voltage data of the variable-frequency test power supply, the acquired data are subjected to analog-to-digital conversion and then transmitted to the microprocessor, and the microprocessor analyzes the data according to the data transmitted by the acquisition module to obtain the state of the ground grid. The method can detect the severity of corrosion of a corrosion area or a specific corrosion area, is favorable for more accurately implementing the corrosion prevention and resistance reduction work of the ground network, and improves the fine management capability of the ground network.
Description
Technical Field
The invention belongs to the technical field of ground network state detection, and particularly relates to a ground state detection device and a ground state detection method.
Background
The traditional grounding state testing technology adopting a tripolar method or a quadrapole method can not provide more accurate information aiming at the area and the severity of corrosion except for judging the grounding state corrosion by changing a test source (steady sine, frequency conversion or shock wave). The existing ground resistance testing method has certain randomness, namely the influence of the positions of different testing electrodes on the test is not fully considered, single dependent impedance value is difficult to obtain technical support which is related to the corrosion state of a ground grid and has persuasiveness, such as different electrode directions, temperature and humidity influences and the like, the final data model is not considered, and if the soil condition and the temperature and the humidity are simply tested and the good correlation with the testing data is not carried out, only a very rough conclusion can be obtained. Therefore, in order to improve the fine management of state maintenance and improve the quality of ground grid treatment, it is necessary to detect the severity of corrosion in a corrosion area or a specific corrosion area, and provide a set of reasonable and practical models for highly sensitive development of tests and analysis of the grounding state by combining the influence of temperature, humidity and electrode direction.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provides a grounding state detection device and a grounding state detection method.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a grounding state detection device is characterized by comprising a variable frequency test power supply, a test electrode, an electrode included angle adjusting device, a temperature and humidity detection module, a signal conditioning module, an acquisition module and a microprocessor;
the output end of the variable-frequency test power supply is connected with the input end of the test electrode;
the device comprises a plurality of test electrodes, wherein each test electrode is provided with a temperature and humidity detection module;
the electrode included angle adjusting device is connected with the test electrodes and is used for adjusting included angles among the plurality of test electrodes;
the signal conditioning module is connected with the test electrode and used for amplifying the current signal on the test electrode and transmitting the amplified current signal to the acquisition module;
the acquisition module is respectively connected with the signal conditioning module, the temperature and humidity detection module and the variable-frequency test power supply and is used for acquiring current data of the test electrode, temperature and humidity data of the temperature and humidity detection module and voltage data of the variable-frequency test power supply, and transmitting the acquired data to the microprocessor after analog-to-digital conversion;
and the microprocessor is respectively connected with the variable-frequency test power supply and the acquisition module, is used for controlling the work of the variable-frequency test power supply and is also used for analyzing according to the data transmitted by the acquisition module to obtain the state of the ground network.
Further, it is preferable that there are 3 test electrodes, and an angle between two adjacent test electrodes is 45 to 50 °.
Further, preferably, the acquisition module is an a/D converter.
The invention also provides a ground network state detection method, which adopts the ground state detection device and comprises the following steps:
step (1), when the soil humidity is less than 60% and the soil temperature is less than 45 ℃, under the control of a microprocessor, a variable frequency test power supply generates a voltage signal from dozens of hertz to hundreds of kilohertz;
and (2) acquiring a voltage signal of each frequency of the variable frequency test power supply and current signals of the plurality of test electrodes by the acquisition system, then respectively calculating impedance values of the plurality of test electrodes corresponding to each frequency signal, and drawing an impedance frequency characteristic curve.
Step (3), analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, and if the impedance peak value of the impedance spectrum characteristic curve in the range of being lower than 5000Hz does not exceed a specified value, the impedance peak characteristics of the plurality of test electrodes are consistent in height, and the impedance angle peak value is less than 5 degrees, determining that the ground grid state is healthy and no corrosion phenomenon exists; otherwise, corrosion phenomena exist.
Further, preferably, if the impedance peak value in the range of the impedance spectrum curve lower than 5000Hz does not exceed a specified value, the impedance angle peak value is less than 5 degrees, and the impedance peak characteristic heights of a plurality of test electrodes are inconsistent, searching for the electrode with the highest impedance peak value in the range of 500Hz-5000Hz, and corroding the electrode in the direction where the electrode is located;
analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, if the impedance peak characteristics of a plurality of test electrodes in the range of the impedance spectrum curve lower than 5000Hz are not consistent in height, and the impedance peak value of part of the electrodes exceeds a specified value, searching the electrode with the highest impedance peak value in the range of 500Hz-5000Hz, and corroding the electrode in the direction where the electrode is located; or the impedance peak characteristics of a plurality of test electrodes in the range of impedance spectrum curve lower than 5000Hz are slightly inconsistent, namely the difference is +/-5%, and the impedance or impedance angle consistency is increased along with the frequency increase, searching the electrode with the highest impedance peak value or the largest impedance angle in the range of 500Hz-5000Hz, and corroding the electrode in the direction of the electrode.
Further, it is preferable that the method further comprises a step of correcting the impedance spectrum curve by soil temperature and humidity, the steps are as follows:
when the average soil humidity value measured by the temperature and humidity detection module is greater than 60%, the impedance spectrum curve needs to be corrected:
(1) calculating a humidity correction coefficient, wherein rho = (rho-0.6)/rho t, and rho t is an actually measured soil humidity value;
calculating a temperature correction coefficient Kr = (Kt-25)/Kt, wherein Kt is an actually measured soil temperature value;
(2) the impedance spectrum correction method comprises the following steps:
Zc(f)=Zt1(f)*(1-α*ρr+β/Kr+tan(△Φ));
zt1(f) = a + B (f) j, Zt1(f) is the complex value of the impedance measured at the corresponding frequency f, where a is the real part, B is the imaginary part, f is the frequency value, △ Φ = the angle Φ -30 ° between the electrodes.
Frequency less than 500Hz, 0.8< α <1, β = cos (α), preferably α = 0.9;
frequency greater than 500Hz, 0.4< α <0.8, β = cos (α), preferably α = 0.6.
Further, it is preferable that the waveform of the test output signal of the variable frequency test source includes a sine wave, a square wave, and a triangular wave.
The structure of the electrode included angle adjusting device is not particularly limited, and the electrode included angle adjusting device can be used for adjusting the angle of the test electrode.
The technical scheme provided by the invention is beneficial to improving the accuracy of corrosion detection, provides a more practical data correction method in the field of analyzing the health state of the ground grid, is beneficial to reducing the experience dependence of field personnel, improves the diagnosis capability of the ground grid, and simultaneously provides a technical basis for accurate ground grid treatment.
Compared with the prior art, the invention has the beneficial effects that:
this patent has adopted the multi-electrode structure, has solved the precision problem of earth mat state test, has not only provided earth mat health status detection means, still provides more accurate status information for earth mat administers, and this solution helps anticorrosive and the resistance reduction work of more accurate implementation earth mat, promotes the fine-grained manageability of earth mat.
For example, the power frequency value is 8 ohms through a traditional ground resistance test, and the data is 10 ohms under the power frequency condition. Although the grounding resistance is qualified in the power frequency range, 8 ohms cannot reflect whether the grounding grid is corroded, for example, when the corrosion degree is low, the contribution rate to the overall resistance is very small, so that the total grounding resistance cannot truly reflect the health state of the grounding grid. When a lightning stroke signal comes, a strong self-inductance effect is generated possibly due to the action of ground surface corrosion, and the grounding resistance (such as 200 ohms) is raised, and at the moment, the grounding resistance is seriously excessive, so that the safety of a line is directly influenced. In addition, the traditional field test does not generally consider the environmental temperature and humidity, and even if temperature and humidity data are tested, the test resistance value is not better corrected for the following reasons: (1) the difference of the earth surface conditions of the earth network is large, and possibly, the temperature and the humidity are not constant and uniform, and the acquired data still represent the earth network state incompletely by adopting a single electrode mode or a single current injection mode. (2) If the injection electrode is moved, no accurate reference means is provided (for example, the repeatability of a frequency conversion source for testing can affect a test result, even if the same test frequency and power are adopted at the same position, data fluctuation exists, if the direction of the test electrode is moved for retesting, uncertainty is added to the change of the test source and the change of the position), the angle value of the moving electrode is indicated or measured, the influence of the angle on the test result is still in the fuzzy analysis range, the angle is only used for roughly analyzing whether the change of the angle has influence on the grounding resistance, and the correlation between the influence degree and the ground grid is from the fact that relevant researches are not explicitly carried out due to the fact that an instrument and soil condition change and the like.
This patent has designed radial, but angle of adjustment's three electrode mode to above problem, and observation that can be synchronous is the ground net ground connection impedance state under same test source, the test frequency condition to the analysis of impedance modulus value and impedance angle has been combined, the effectual test and the analytical ability that has promoted ground net health state, and the contrastive analysis of combination impedance curve makes the state prediction ability of ground net obtain showing and improving.
Drawings
FIG. 1 is a schematic structural diagram of a grounding state detection device according to the present invention;
FIG. 2 is a schematic diagram of the connection of a variable frequency test power supply and a test electrode of the present invention;
wherein, 1, a variable frequency test power supply; 2. a test electrode; 3. an electrode included angle adjusting device; 4. a temperature and humidity detection module; 5. a signal conditioning module; 6. an acquisition module; 7. a microprocessor; the arrow direction is the data or signal trend;
FIG. 3 is a graph showing the frequency characteristic of the impedance of an example of the application of the present invention; the range of the abscissa is 40-40000 Hz.
Detailed Description
The present invention will be described in further detail with reference to examples.
It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The specific techniques, connections, conditions, or the like, which are not specified in the examples, are performed according to the techniques, connections, conditions, or the like described in the literature in the art or according to the product specification. The materials, instruments or equipment are not indicated by manufacturers, and all the materials, instruments or equipment are conventional products which can be obtained by purchasing.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. Further, "connected" as used herein may include wirelessly connected.
In the description of the present invention, "a plurality" means two or more unless otherwise specified. The terms "inner," "upper," "lower," and the like, refer to an orientation or a state relationship based on that shown in the drawings, which is for convenience in describing and simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "provided" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. To those of ordinary skill in the art, the specific meanings of the above terms in the present invention are understood according to specific situations.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
As shown in fig. 1-2, a grounding state detection device comprises a variable frequency test power supply 1, a test electrode 2, an electrode included angle adjusting device 3, a temperature and humidity detection module 4, a signal conditioning module 5, an acquisition module 6 and a microprocessor 7;
3 test electrodes 2 are arranged;
the output end of the variable frequency test power supply 1 is connected with the input end of the test electrode 2; the output voltage of the variable frequency test power supply 1 is connected to three test electrodes 2 in parallel, and the three electrodes extend in a radial mode and are injected into a grounding grid;
each test electrode 2 is provided with a temperature and humidity detection module 4; the temperature and humidity detection module 4 is used for collecting the temperature and humidity of the soil contacted with the test electrode 2;
the electrode included angle adjusting device 3 is connected with the test electrodes 2 and is used for adjusting included angles among the test electrodes 2;
the signal conditioning module 5 is connected with the test electrode 2 and used for amplifying the current signal on the test electrode 2 and transmitting the amplified current signal to the acquisition module 6;
the acquisition module 6 is respectively connected with the signal conditioning module 5, the temperature and humidity detection module 4 and the variable frequency test power supply 1, and is used for acquiring current data of the test electrode 2, temperature and humidity data of the temperature and humidity detection module 4 and voltage data of the variable frequency test power supply 1, performing analog-to-digital conversion on the acquired data and transmitting the data to the microprocessor 7;
the microprocessor 7 is respectively connected with the variable frequency test power supply 1 and the acquisition module 6, and is used for controlling the work of the variable frequency test power supply 1 and analyzing according to the data transmitted by the acquisition module 6 to obtain the state of the earth network.
Preferably, there are 3 test electrodes 2, and the included angle between two adjacent test electrodes 2 is 45-50 °.
Preferably, the acquisition module 6 is an a/D converter.
A ground network state detection method, which adopts the ground state detection device, comprises the following steps:
step (1), when the soil humidity is less than 60% and the soil temperature is less than 45 ℃, under the control of a microprocessor, a variable frequency test power supply generates a voltage signal from dozens of hertz to hundreds of kilohertz;
and (2) acquiring a voltage signal of each frequency of the variable frequency test power supply and current signals of the plurality of test electrodes by the acquisition system, then respectively calculating impedance values of the plurality of test electrodes corresponding to each frequency signal, and drawing an impedance frequency characteristic curve.
Step (3), analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, and if the impedance peak value of the impedance spectrum characteristic curve in the range of being lower than 5000Hz does not exceed a specified value, the impedance peak characteristics of the plurality of test electrodes are consistent in height, and the impedance angle peak value is less than 5 degrees, determining that the ground grid state is healthy and no corrosion phenomenon exists; otherwise, corrosion phenomena exist.
The specific method for judging the corrosion phenomenon comprises the following steps:
if the impedance peak value in the range of the impedance frequency spectrum curve lower than 5000Hz does not exceed the specified value, the impedance angle peak value is less than 5 degrees, and the impedance peak characteristic heights of a plurality of test electrodes are inconsistent, searching for the electrode with the highest impedance peak value in the range of 500Hz-5000Hz, and corroding the electrode in the direction where the electrode is located;
analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, if the impedance peak characteristics of a plurality of test electrodes in the range of the impedance spectrum curve lower than 5000Hz are not consistent in height, and the impedance peak value of part of the electrodes exceeds a specified value, searching the electrode with the highest impedance peak value in the range of 500Hz-5000Hz, and corroding the electrode in the direction where the electrode is located; or the impedance peak characteristics of a plurality of test electrodes in the range of impedance spectrum curve lower than 5000Hz are slightly inconsistent, namely the difference is +/-5%, and the impedance or impedance angle consistency is increased along with the frequency increase, searching the electrode with the highest impedance peak value or the largest impedance angle in the range of 500Hz-5000Hz, and corroding the electrode in the direction of the electrode.
The method for correcting the impedance frequency spectrum curve through the soil temperature and the soil humidity comprises the following steps:
when the average soil humidity value measured by the temperature and humidity detection module is greater than 60%, the impedance spectrum curve needs to be corrected:
(1) calculating a humidity correction coefficient, wherein rho = (rho-0.6)/rho t, and rho t is an actually measured soil humidity value;
calculating a temperature correction coefficient Kr = (Kt-25)/Kt, wherein Kt is an actually measured soil temperature value;
(2) the impedance spectrum correction method comprises the following steps:
Zc(f)=Zt1(f)*(1-α*ρr+β/Kr+tan(△Φ));
zt1(f) = a + B (f) j, Zt1(f) is the complex value of the impedance measured at the corresponding frequency f, where a is the real part, B is the imaginary part, f is the frequency value, △ Φ = the angle Φ -30 ° between the electrodes.
The frequency is less than 500Hz, 0.8< α <1, β = cos (α), and the value of α is closer to 1 when the frequency is closer to 0.
Frequency greater than 500Hz, 0.4< α <0.8, β = cos (α).
For further simplification, the median value in the 500Hz range can be calculated, α being 0.9.
In the frequency range above 500Hz α is taken to be 0.6.
The two cases are combined, and the average value is taken to be 0.75.
α, the values of other conditions can be compared with data under standard laboratory conditions and field data, or a more matched α value can be selected reasonably according to the change track of the impedance spectrum curve when the temperature and humidity of the simulated soil under the laboratory conditions are changed.
The waveforms of the test output signals of the variable frequency test source include sine waves, square waves and triangular waves.
Application example 1
The included angle between the three electrodes is set to be 50 degrees in sequence, the output of the frequency conversion test source is 40Hz-400KHz, and an impedance frequency characteristic curve atlas acquired by an acquisition module and calculated by a microprocessor is shown in figure 3:
as shown in fig. 3, it is found by comparison that impedance peak characteristics of the three test electrodes are highly inconsistent, and therefore, the state of the earth screen is considered to be unhealthy, and a corrosion phenomenon exists. It can be seen from the figure that the characteristic impedance of the first test electrode is the greatest overall trend, so that it can be determined that there is a more significant corrosion phenomenon in the electrode direction of the channel a.
For further analysis, the electrode placement direction can be changed and the test re-run until the data for the three channels are substantially identical and the impedance peaks are close to the highest values of the historical test data, resulting in a relatively accurate erosion location. If the peak value on the impedance frequency characteristic curve is continuously refreshed after the electrode arrangement direction is changed, the adjustment should be continuously carried out towards the electrode direction of the highest peak impedance until the data of the three channels are stabilized and basically consistent, and the peak impedance is close to the historical highest value.
As can be seen from this application example, the present invention solves two problems:
(1) the problem of conventional analysis through the resistance value of single frequency point is solved. As found in the three-channel approach, there is still a difference in impedance at different locations that does not change in temperature and humidity to an affected amount (since all three channels are under the same temperature and humidity and test conditions). Therefore, the conventional testing method only uses the data obtained by randomly selecting the test points as the judgment basis and is a whole concept, but lacks of a local concept.
(2) The problem of sensitivity is solved. The traditional test method has single frequency, but the method has wider test bandwidth, and the curve observation shows that the impedance does not show linear characteristics along with the frequency change, particularly when the grounding grid is corroded, the impedance of the grounding grid is not pure resistance, but a reactance part exists, so that the nonlinear characteristics along with the frequency change curve are obvious, and the corrosion state of the grounding grid can be analyzed according to the characteristics. In the same way, the depth of the injection electrode is changed, and the difference of data captured by observation is compared, so that the depth and the position of the corrosion of the ground grid can be tracked, and the power grid management work can be carried out more accurately.
In conclusion, the three-electrode structure is adopted, the precision problem of the ground grid state test is solved, a ground grid health state detection means is provided, more accurate state information is provided for ground grid management, the solution is beneficial to more accurately implementing ground grid corrosion prevention and resistance reduction work, and the fine management capability of the ground grid is improved.
Application example 2: impedance peak value specified value selection method
The peak specification values on the impedance spectrum curves are mentioned in the claims and the description of the invention. It should be noted that the specified value of the impedance peak value may be determined by testing the same ground surface environment, for example, the tower and ground network of the same line, and the obtained average peak value is used as the specified value, and if the peak impedance obtained after testing 10-base towers in the range of 5000Hz is 300 ohms, 300 ohms is used as the specified value; it should be noted that, the examined frequency ranges are different, for example, 1Hz to 1000Hz and 2000Hz to 5000Hz have different peak impedances, and the processing is performed according to actual situations. According to experience, the specified value of 1000 ohms is not usually exceeded, but some ground surface environments are special, even though the operation experience value can also belong to a normal range, so that the specified value has obvious line characteristics in practice, the examined frequency range is wide, the ground electrode state of the ground net has high sensitivity to the soil and rock stratum conditions of the ground net, the specified value is reasonably selected in combination with the actual condition, and the selection of the specified value is of course recommended to be carried out on newly-built lines or lines with short operation period.
An impedance spectrum curve test is carried out on a 10-base tower of a 10kV line which runs for no more than 3 years, and the total line length of the 10-base tower is 20 kilometers. The impedance spectrum curve is tested by a wide frequency method, namely from 1Hz to 100kHz, and the highest peak value in the whole frequency band range is observed firstly. If the frequency point with the highest peak is in the range of 4.1kHz-4.9kHz and the average value of the impedance peak of the 10-base tower is 960 ohms, 960 ohms can be used as a specified value. When the frequency of subsequent test data is not more than 4.9kHz (or 5kHz upper limit is roughly adopted), and the frequency exceeds 960 ohms, the grounding state of the tower should be observed with emphasis, measures such as adjusting the electrode direction and the like are adopted, and whether the situation with higher peak impedance exists is tested, so as to judge whether the more serious grounding body corrosion exists.
It should be noted that although the patent designs 5kHz as the analysis upper limit, in practical application, the upper limit of the frequency can be considered (for example, 300kHz) or the frequency starting point lower than 1Hz (for example, 0.01Hz-0.5 Hz) can be considered, and will not be described in detail here.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. 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 (7)
1. A grounding state detection device is characterized by comprising a variable frequency test power supply (1), a test electrode (2), an electrode included angle adjusting device (3), a temperature and humidity detection module (4), a signal conditioning module (5), an acquisition module (6) and a microprocessor (7);
the output end of the variable frequency test power supply (1) is connected with the input end of the test electrode (2);
the device is characterized in that the number of the test electrodes (2) is multiple, and each test electrode (2) is provided with a temperature and humidity detection module (4);
the electrode included angle adjusting device (3) is connected with the test electrodes (2) and is used for adjusting included angles among the test electrodes (2);
the signal conditioning module (5) is connected with the test electrode (2) and is used for amplifying the current signal on the test electrode (2) and transmitting the amplified current signal to the acquisition module (6);
the acquisition module (6) is respectively connected with the signal conditioning module (5), the temperature and humidity detection module (4) and the variable-frequency test power supply (1) and is used for acquiring current data of the test electrode (2), temperature and humidity data of the temperature and humidity detection module (4) and voltage data of the variable-frequency test power supply (1), and transmitting the acquired data to the microprocessor (7) after performing analog-to-digital conversion;
the microprocessor (7) is respectively connected with the variable frequency test power supply (1) and the acquisition module (6) and is used for controlling the work of the variable frequency test power supply (1) and analyzing according to data transmitted by the acquisition module (6) to obtain the state of the earth network.
2. The ground state detecting device according to claim 1, wherein there are 3 test electrodes (2), and an angle between two adjacent test electrodes (2) is 45-50 °.
3. The ground condition detection device according to claim 1, characterized in that the acquisition module (6) is an a/D converter.
4. A grounding state detection method using the grounding state detection device of any one of claims 1 to 3, comprising the steps of:
step (1), when the soil humidity is less than 60% and the soil temperature is less than 45 ℃, under the control of a microprocessor, a variable frequency test power supply generates a voltage signal from dozens of hertz to hundreds of kilohertz;
and (2) acquiring a voltage signal of each frequency of the variable frequency test power supply and current signals of the plurality of test electrodes by the acquisition system, then respectively calculating impedance values of the plurality of test electrodes corresponding to each frequency signal, and drawing an impedance frequency characteristic curve.
Step (3), analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, and if the impedance peak value of the impedance spectrum characteristic curve in the range of being lower than 5000Hz does not exceed a specified value, the impedance peak characteristics of the plurality of test electrodes are consistent in height, and the impedance angle peak value is less than 5 degrees, determining that the ground grid state is healthy and no corrosion phenomenon exists; otherwise, corrosion phenomena exist.
5. The method for detecting the state of the earth screen as claimed in claim 4, wherein the nonlinear characteristic of the impedance spectrum characteristic curve is analyzed, if the impedance peak value in the range of the impedance spectrum curve lower than 5000Hz does not exceed a specified value, the impedance angle peak value is less than 5 degrees, and the impedance peak characteristics of a plurality of test electrodes are highly inconsistent, the electrode with the highest impedance peak value in the range of 500Hz-5000Hz is searched, and the corrosion phenomenon exists in the direction of the electrode;
analyzing the nonlinear characteristics of the impedance spectrum characteristic curve, if the impedance peak characteristics of a plurality of test electrodes in the range of the impedance spectrum curve lower than 5000Hz are not consistent in height, and the impedance peak value of part of the electrodes exceeds a specified value, searching the electrode with the highest impedance peak value in the range of 500Hz-5000Hz, and corroding the electrode in the direction where the electrode is located; or the impedance peak characteristics of a plurality of test electrodes in the range of impedance spectrum curve lower than 5000Hz are slightly inconsistent, namely the difference is +/-5%, and the impedance or impedance angle consistency is increased along with the frequency increase, searching the electrode with the highest impedance peak value or the largest impedance angle in the range of 500Hz-5000Hz, and corroding the electrode in the direction of the electrode.
6. The method for detecting the state of the ground network as claimed in claim 4, further comprising a method for correcting the impedance spectrum curve by soil temperature and humidity, comprising the following steps:
when the average soil humidity value measured by the temperature and humidity detection module is greater than 60%, the impedance spectrum curve needs to be corrected:
(1) calculating a humidity correction coefficient, wherein rho = (rho-0.6)/rho t, and rho t is an actually measured soil humidity value;
calculating a temperature correction coefficient Kr = (Kt-25)/Kt, wherein Kt is an actually measured soil temperature value;
(2) the impedance spectrum correction method comprises the following steps:
Zc(f)=Zt1(f)*(1-α*ρr+β/Kr+tan(△Φ));
zt1(f) = a + B (f) j, Zt1(f) is the complex value of the impedance measured at the corresponding frequency f, where a is the real part, B is the imaginary part, f is the frequency value, △ Φ = the angle Φ -30 ° between the electrodes.
Frequency less than 500Hz, 0.8< α <1, β = cos (α);
frequency greater than 500Hz, 0.4< α <0.8, β = cos (α).
7. The method of claim 4, wherein the test output signal of the variable frequency test source has a waveform comprising a sine wave, a square wave, and a triangular wave.
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| CN111077350A (en) * | 2019-12-16 | 2020-04-28 | 云南电网有限责任公司西双版纳供电局 | Galvanized electrode system for pole tower grounding state test and detection method |
| CN111880008A (en) * | 2020-08-07 | 2020-11-03 | 中国南方电网有限责任公司超高压输电公司梧州局 | Comprehensive tester for ground net conduction |
| CN113325238A (en) * | 2021-06-25 | 2021-08-31 | 重庆璀陆探测技术有限公司 | Integrated detection method and system for grounding impedance and corrosion of grounding grid |
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| CN111077350A (en) * | 2019-12-16 | 2020-04-28 | 云南电网有限责任公司西双版纳供电局 | Galvanized electrode system for pole tower grounding state test and detection method |
| CN111077350B (en) * | 2019-12-16 | 2021-09-28 | 云南电网有限责任公司西双版纳供电局 | Galvanized electrode system for pole tower grounding state test and detection method |
| CN111880008A (en) * | 2020-08-07 | 2020-11-03 | 中国南方电网有限责任公司超高压输电公司梧州局 | Comprehensive tester for ground net conduction |
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| CN113325238A (en) * | 2021-06-25 | 2021-08-31 | 重庆璀陆探测技术有限公司 | Integrated detection method and system for grounding impedance and corrosion of grounding grid |
| CN113325238B (en) * | 2021-06-25 | 2023-04-07 | 重庆璀陆探测技术有限公司 | Integrated detection method and system for grounding impedance and corrosion of grounding grid |
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