CN106841815B - Power line iron tower grounding resistance on-line tester based on voltage excitation - Google Patents
Power line iron tower grounding resistance on-line tester based on voltage excitation Download PDFInfo
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- 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
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
- G01R27/205—Measuring contact resistance of connections, e.g. of earth connections
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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
- G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
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Abstract
The invention discloses a voltage excitation-based on-line tester for ground resistance of a power line iron tower, which comprises a clip-carrying excitation part, a clip-free excitation part, a current sending electrode, a voltage sampling electrode and a signal processing circuit board, wherein one set of clip-carrying excitation part is arranged on one grounding down lead of the power line iron tower, and one set of clip-free excitation part is respectively arranged on the other grounding down leads. The online measurement function of the invention enables the data of the grounding resistance of the power line iron tower to be directly uploaded in an internet of things mode, realizes network monitoring, effectively replaces the manual inspection mode of the power line iron tower, greatly improves the detection efficiency, and in addition, key parameters are obtained by contact measurement, thereby ensuring the test precision and greatly reducing the production difficulty and cost.
Description
Technical Field
The invention relates to a grounding resistance testing technology of a power line iron tower, in particular to an online tester for the grounding resistance of the power line iron tower based on voltage excitation.
Background
As is well known, in order to ensure the safe and stable operation of high-voltage transmission lines and reduce the harm caused by lightning stroke, grounding networks are laid on high-voltage transmission iron towers. In order to improve the grounding effect, besides the grounding network of a single iron tower, the iron towers are sequentially communicated through the overhead line, and grounding current flows into the ground through the grounding network of the single iron tower and also flows into the ground through the grounding network of the adjacent iron tower through the overhead line. Obviously, the grounding resistance of each iron tower needs to be controlled within a certain range. The method mainly comprises two measurement modes of the grounding resistance of the iron tower, one is to disconnect the grounding down lead of the iron tower, the mechanical megger type or electronic ground resistance meter is adopted to measure by a three-wire method, the other is to measure by a clamp meter which appears in recent years, the problem of measuring by using the existing three-wire method is that the grounding down lead must be disconnected, which leads to manual participation, so that the detection efficiency is low, each iron tower can only detect limited times every year, the measurement of the clamp meter assumes that the parallel resistance of other iron towers is extremely small, the assumption does not accord with the actual situation, and meanwhile, when the iron tower has double grounding down leads or even multiple grounding down leads, the measurement cannot be carried out due to the influence of the down leads.
The internet of things is adopted to monitor the resistance value of the ground grid of each iron tower, the traditional manual inspection working mode can be replaced, the detection efficiency, the frequency and the flexibility are greatly improved, the detection method is a practical requirement, the problem of manual participation must be solved at first, and the most important premise is that the grounding down lead is not disconnected.
In order to solve the problem that the grounding resistance of the iron tower can be measured without disconnecting the grounding down conductor, the method for measuring the current of each down conductor by adding the current detection coil on the basis of the three-wire method is proposed in the prior patent, and is feasible in principle, but the measurement method requires that the current detection coil needs high precision when measuring the current, so the measurement method is relatively complex in implementation. Meanwhile, the traditional earth resistance tester cannot accurately test the grounding resistance of the electric iron tower under the condition of not disconnecting the down lead.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an on-line tester for the grounding resistance of a power line iron tower based on voltage excitation.
In order to solve the technical problems, the invention provides the following technical scheme:
the invention relates to a voltage excitation-based on-line tester for ground resistance of a power line iron tower, which comprises a ground resistance tester, wherein the ground resistance tester comprises a belt-clip excitation component, a non-clip excitation component, a current sending electrode, a voltage sampling electrode and a signal processing circuit board, the belt-clip excitation component comprises an upper sampling clip, an excitation coil and a lower sampling clip from top to bottom, is arranged on a grounded downlead of the power line iron tower, is not in contact with the grounded downlead, is fixedly connected with the grounded downlead, only comprises one excitation coil, is arranged on the other grounded downlead of the power line iron tower and is not in contact with the grounded downlead, only needs one non-clip excitation component under the condition of double grounded downleads, and under the condition of multiple grounded downleads, the method comprises the following steps that except for the grounding downlead provided with the excitation component with the clamp head, a non-clamp head excitation component is required to be arranged on each of the other grounding downleads, the distance between the current sending electrode and the voltage sampling electrode is determined according to the traditional three-wire method grounding test standard and then the grounding downlead is inserted into the ground to a certain depth, the test under the single sine wave frequency is divided into two stages, in the first stage, the tested iron tower, other iron towers and inter-tower connecting lines form an electric loop, a loop model comprises two resistors, one resistor is a grounding resistor Rg of the tested iron tower, the other resistor is an equivalent resistor Rt formed by other iron towers except the tested iron tower and overhead lines, the current sending electrode is disconnected and does not work in the stage, an excitation coil in the excitation component with the clamp head and an excitation coil in the non-clamp head excitation component excite electromotive force in the loop, and at the moment, the upper sampling clamp, the voltage signal taken out by the lower sampling chuck is the electromotive force excited by the coil, the voltage taken out by the voltage sampling electrode is the voltage drop on the grounding resistance of the tested iron tower, the two signals are sent into the signal processing board for processing, the ratio of two resistances Rg and Rt in the loop model can be obtained, in the second stage, the exciting coil and the upper sampling chuck are disconnected and do not work, the current sending electrode, the voltage sampling electrode and the lower sampling chuck are communicated, the resistances Rg and Rt are connected in parallel in the stage, the measured resistance is the parallel value Ra of the two resistances Rg and Rt, thereafter, a grounding resistance value Rg of the tested iron tower can be calculated by utilizing the series-parallel relation of the two stages, in order to improve the anti-interference capability, the test process is repeated by adopting a plurality of random frequencies to obtain a series of grounding resistance values, and through statistical processing, and giving an optimal detection result as a measurement output value of the grounding resistance of the tested iron tower.
As a preferred embodiment of the present invention, the excitation coils of the excitation member with a collet and the excitation member without a collet are both composed of an iron core and a plurality of turns of enameled wires wound outside, and the excitation member with a collet and the excitation member without a collet are both structurally composed of two independent and identical semi-cylindrical members.
In a preferred embodiment of the present invention, the parameters of the excitation coils in the excitation member with a collet and the excitation member without a collet are also required to be as identical as possible, and the respective excitation coils are driven by the same driving source.
In a preferred embodiment of the present invention, the driving voltage signal of the exciting coil is a sine wave signal, which is provided by the signal processing circuit board and can excite a sine wave electromotive force in the circuit.
As a preferred technical scheme of the invention, signal frequency is randomly set in the passband of the band-pass filter, a resistance value sequence is obtained by processing the same flow under a plurality of sine wave signals with different frequencies, and then statistical processing is carried out.
The working principle of the invention is as follows: due to the existence of the overhead line, when the grounding down lead of the tested iron tower is not disconnected, the power line iron tower is equivalent to a circuit loop containing two resistors, one resistor is the grounding resistor Rg of the tested iron tower, the other resistor is an equivalent resistor Rt generated by the combined action of other iron towers except the tested iron tower and the overhead line, an exciting coil is adopted to excite electromotive force in the loop, and then a proper voltage measuring point is selected, so that the ratio rho of the two resistors Rt and Rg can be measured; after the ratio of the two resistors and the parallel resistance value of the two resistors are obtained, the resistance value Rg of the grounding network of the tested iron tower can be obtained through calculation; through testing under the condition of a plurality of random frequencies, a series of resistance value calculation results can be obtained, and an optimized estimated value is given to the results by adopting a statistical processing algorithm, so that the anti-interference capability can be improved; the testing process under each frequency is divided into two stages, wherein in the first stage, the signal processor controls the relay to enable the exciting coil, the upper sampling chuck, the lower sampling chuck and the voltage sampling electrode to be connected, the rest of the connection wires are disconnected, no sampling resistor Rs is arranged between the common ground of the lower sampling chuck and the signal processing circuit board, the upper sampling chuck is communicated with the ground of the signal processing circuit board, the exciting coil is driven by sine waves, voltage signals vd and vp1 are respectively taken from the lower sampling chuck and the voltage sampling electrode and are sent into the signal processor through band-pass filtering and A/D conversion, the ratio rho of the two resistors is Rt/Rg (vd-vp1)/vp1 is obtained through processing, in the second stage, the signal processor controls the relay to enable the current sending electrode, the voltage sampling electrode and the lower sampling chuck to be connected, the rest of the connection wires are disconnected, the lower sampling chuck is connected with a sampling resistor Rs to the common ground of the signal processing circuit board, the sine wave is sent out by a signal current sending electrode, voltage signals vp2 and vs are picked up from a voltage sampling electrode and a sampling resistor Rs, and are sent to a signal processor through a band-pass filter and an A/D conversion circuit in the same stage, and resistance value conversion Ra-Rt-Rg-Rs (vp2/vs-1) of two resistors connected in parallel is calculated; obtaining the grounding resistance Rg (Ra x) (1+ 1/rho) of the tested iron tower based on the series-parallel connection relation; one down lead of the iron tower is provided with an excitation component with a clamp head, the other down leads are respectively provided with an excitation component without the clamp head, the excitation coils in the excitation components are driven by the same driving source, and the parameters of the excitation coils are as consistent as possible, so that the difference between the potential at the lower sampling clamp head and the potential at the connecting point of the down lead and the grounding network can be ignored, and the difference between the potential at the upper sampling clamp head and the potential of the iron tower can be ignored.
Compared with the prior art, the invention has the following beneficial effects:
1. the online measurement function of the invention enables the data of the grounding resistance of the power line iron tower to be directly uploaded in an Internet of things mode, realizes network monitoring, effectively replaces a manual inspection mode of the power line iron tower, greatly improves the detection efficiency, frequency and flexibility, and enables the grounding resistance monitoring of the power line iron tower to be more convenient and reliable.
2. The invention determines the resistance ratio and the resistance value of the parallel connection of the resistors by measuring the voltage ratio, the key parameters are obtained by contact measurement, the test precision is ensured, and theoretically, the size of the electromotive force excited by the exciting coil has no quantitative requirement, and the test requirement can be met only by a certain amplitude, so the invention is simpler and more reliable to realize, and the difficulty and the cost in production are greatly reduced.
3. The method can further improve the anti-interference capability, can obtain a more accurate grounding resistance test result of the tested iron tower even if a plurality of iron towers are simultaneously measured, ensures that the grounding down lead is not required to be disconnected with the iron tower to measure in the test principle, and achieves the aim of directly testing the magnitude of the resistance value of the grounding network on line.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and 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 and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram of a test connection of the present invention;
FIG. 2 is a schematic diagram of the equivalent resistance of the measurement loop of the present invention;
FIG. 3 is a signal flow diagram of a coil excitation phase test of the present invention;
FIG. 4 is a signal flow diagram of a test during the excitation phase of a wireless coil of the present invention;
in the figure: 1. a ground resistance tester; 2. a belt clip energizing member; 3. a chuck-less energizing member; 4. a current transmitting electrode; 5. a voltage sampling electrode; 6. a signal processing circuit board; 7. an upper sampling chuck; 8. an excitation coil; 9. a lower sampling chuck; 10. a band pass filter.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Example 1
As shown in fig. 1-4, the present invention provides an online tester for ground resistance of a power line iron tower based on voltage excitation, which comprises a ground resistance tester 1, wherein the ground resistance tester 1 comprises a band-clip excitation component 2, a non-clip excitation component 3, a current transmitting electrode 4, a voltage sampling electrode 5 and a signal processing circuit board 6, the band-clip excitation component 2 comprises an upper sampling clip 7, an excitation coil 8 and a lower sampling clip 9 from top to bottom, and is installed on a grounded down-lead of the power line iron tower, the excitation coil 8 is not in contact with the grounded down-lead, both the upper sampling clip 7 and the lower sampling clip 9 are tightly connected with the grounded down-lead, the non-clip excitation component 3 only comprises one excitation coil 8 and is installed on the other grounded down-lead of the power line iron tower and is not in contact with the grounded down-lead, and only one non-excitation clip component 3 is needed for the case of double grounded down-leads, for the case of multiple grounding downleads, except the grounding downlead provided with the driving component 2 with the clamp head, each of the other grounding downleads needs to be provided with a non-clamp head driving component 3, the distance of the current transmitting electrode 4 and the voltage sampling electrode 5 is determined according to the traditional three-wire method grounding test standard and then the grounding downlead is inserted into the ground to a certain depth, the test under the single sine wave frequency is divided into two stages, in the first stage, the tested iron tower, other iron towers and the overhead line form an electric circuit, the circuit model comprises two resistors, one is the grounding resistor Rg of the tested iron tower, the other is the equivalent resistor Rt formed by other iron towers and the overhead line except the tested iron tower, the current transmitting electrode 4 is disconnected and does not work in the first stage, the exciting coil 8 in the driving component 2 with the clamp head and the exciting coil 8 in the driving component 3 without the clamp head excite electromotive force in the circuit, at this time, the upper sampling chuck 7 is communicated with the ground of the signal processing board 6, the voltage signal taken out by the lower sampling chuck 9 is the electromotive force excited by the coil, the voltage taken out by the voltage sampling electrode 5 is the voltage drop on the grounding resistance of the iron tower to be tested, the two signals are sent into the signal processing board 6 to be processed, the ratio of the two resistors Rg and Rt in the loop model can be obtained, in the second stage, the exciting coil 8 and the upper sampling chuck 7 are disconnected and do not work, the current sending electrode 4, the voltage sampling electrode 5 and the lower sampling chuck 9 are communicated, the resistors Rg and Rt are connected in parallel in the stage, the measured resistor is the parallel value Ra of the two resistors Rg and Rt, then, by utilizing the series-parallel relation of the two stages, the grounding resistance value of the iron tower to be tested can be solved, in order to improve the anti-interference capability, the testing process is repeated by adopting a plurality of random frequencies, and obtaining a series of grounding resistance values, and giving an optimal detection result as a measurement output value of the grounding resistance of the tested iron tower through statistical processing.
The excitation coil 8 in the excitation member 2 with the chuck and the excitation member 3 without the chuck are both composed of an iron core and a plurality of circles of enameled wires wound outside, and the excitation member 2 with the chuck and the excitation member 3 without the chuck are both structurally composed of two independent and same semi-cylindrical components which are fastened into a complete assembly after being mounted on a grounding down conductor, thereby playing the same function as a complete excitation member.
The parameters of the excitation coils 8 in the chucked excitation member 2 and the chuckless excitation member 3 are also required to be as identical as possible, and the respective excitation coils 8 are driven by the same drive source.
The driving voltage signal of the exciting coil 8 is a sine wave signal which is provided by the signal processing circuit board 6, and the electromotive force of the sine wave can be excited in a loop, so that the anti-interference capability can be effectively improved.
The band-pass filter 10 randomly sets signal frequency in the pass band, and a resistance value sequence is obtained by processing the same flow under a plurality of sine wave signals with different frequencies, and then statistical processing is carried out.
Specifically, as shown in fig. 1: the two grounding down wires are respectively provided with a clamping head exciting component 2 and a non-clamping head exciting component 3, the installation direction is not inverted, and a current transmitting electrode 4 (corresponding to a current pole C) and a voltage sampling electrode 5 (corresponding to a voltage pole P) are inserted in a wiring mode of a traditional grounding instrument. The excitation part 2 with the clamp head, the excitation part 3 without the clamp head, the current sending electrode 4 and the voltage sampling electrode 5 are connected with a tester host machine through connectors by leads, and a signal processing circuit board 6 is arranged in the tester host machine. The parameters of the excitation coil 8 in the chuckless excitation member 2 and the chuckless excitation member 3 are to be as consistent as possible. The belt-grip actuating member 2 and the non-grip actuating member 3 are separate members and should include additional parts such as fastening, waterproofing, etc. in addition to the key upper sampling grip 7, the actuating coil 8, the sampling grip and the lead-out wires to ensure convenient and reliable installation and long-term use in the field.
As shown in fig. 2: one resistor is the grounding resistor Rg of the tested iron tower, and the other resistor is the equivalent resistor Rt formed by the grounding resistors of other iron towers, overhead lines and the like. When the upper sampling chuck 7 is communicated with the ground of the signal processing circuit board 6, an electromotive force is excited in a loop by the exciting coil 8, similarly to the fact that a voltage source is added in the loop, and the ratio of the voltages on the two resistors Rg and Rt is equal to the ratio of the two resistors. If the action of the exciting coil 8 and the upper voltage sampling electrode 5 is cancelled, and the current is sent by the current sending electrode 4, and the current returns to the ground of the signal processing circuit board 6 after passing through a sampling resistor Rs from the lower sampling chuck 9, at this time, the two resistors Rg and Rt are in parallel connection in a new loop, and the resistance Ra (Rt) of the two resistors Rg and Rt in parallel connection can be calculated through the ratio of the voltage vs on the sampling resistor Rs and the voltage vp2 taken from the voltage sampling electrode 5. The resistance ratio and the parallel resistance obtained by the two conditions are combined with the series-parallel relation, and the grounding resistance Rg (Ra x) (1+ 1/rho) of the tested iron tower can be converted.
As shown in fig. 3: at this time, the loop model is that the resistors Rg and Rt are connected in series, and the exciting coil 8 generates an electromotive force in the loop. Taking FPGA as an example of a signal processing chip, entering a first stage, namely a coil excitation stage, controlling a relay by the FPGA to enable the excitation coil 8, the upper sampling chuck 7, the lower sampling chuck 9 and the voltage sampling electrode 5 to be connected, disconnecting the rest connecting wires, and connecting the upper sampling chuck 7 with the ground of the signal processing circuit board 6; after the filter is switched on stably, the FPGA generates a sine wave data sequence, and a D/A conversion circuit outputs a sine wave, wherein the frequency of the sine wave has randomness but is positioned in a gain flat area of a band-pass filter; the converted sine wave is then passed through a drive circuit to provide a sufficiently large current and a nearly standard sine wave waveform to simultaneously drive the excitation coils 8 in the chuckless excitation member 3 and the chuckless excitation member 2; voltage signals vp1 acquired at the voltage sampling electrode 5 are sent into the FPGA after being subjected to one path of band-pass filtering and one path of A/D conversion, and voltage signals vd acquired at the lower voltage sampling electrode 5 are sent into the FPGA after being subjected to the other path of band-pass filtering and the other path of A/D conversion; the FPGA adopts a Fourier transform algorithm to solve, and the ratio rho of two resistances Rg and Rt in the loop model is obtained through conversion, wherein Rt/Rg is (vd-vp1)/vp 1.
As shown in fig. 4: at the moment, the loop model is that the resistors Rg and Rt are connected in parallel. Entering a second stage, namely a coil excitation-free stage, the FPGA controls the relay to make the connection of the lower sampling chuck 9, the current sending electrode 4 and the voltage sampling electrode 5 connected, and the rest of the connection is disconnected, and at the moment, the lower sampling chuck 9 is connected with a sampling resistor Rs to the ground of the signal processing circuit board 6; after the relay is switched on, the FPGA still uses the same circuit to generate a sine wave signal, the signal passes through the current sending electrode 4 to the ground, passes through the ground network Rg and the equivalent resistor Rt, then passes through the lower sampling chuck 9 and then returns to the ground of the signal processing circuit board 6 through the sampling resistor Rs, and at the moment, the resistors Rg and Rt form a parallel structure; voltage signals vp2 obtained by the voltage sampling electrode 5 are sent to the FPGA after bandpass filtering and A/D conversion, and voltage signals vs on the sampling resistor Rs are sent to the FPGA after another path of bandpass filtering and A/D conversion; the FPGA processes the two paths of signals and converts the signals to obtain a value Ra ═ Rt | | | Rg ═ Rs · (vp2/vs-1) of the parallel resistor. After the two-stage test is completed, the ratio rho of the two resistances obtained by the first stage calculation and the value Ra of the parallel resistance obtained by the second stage are Rt/Rg, and a measured value Rg of the tested iron tower earth resistance is obtained by calculating according to the series-parallel relation, wherein the measured value Rg is Ra x (1+ 1/rho).
Changing sine wave frequency and then carrying out the same measurement, wherein the flow is completely the same, only the sine wave frequency is changed randomly, the FPGA randomly generates a new sine wave data sequence according to the data input by the A/D, the frequency of the new sine wave data sequence is still limited within the range, and a new measurement value of the grounding resistance of the tested iron tower is obtained according to the process; a sequence set of the ground resistance of the tested iron tower can be obtained by reciprocating in this way, and the resistance finally output by the tested iron tower is obtained through a statistical processing mode.
The measuring circuits at two stages in the measurement are integrated, and the respective circuit functions are achieved only by controlling the on-off of the relay. When not measuring, each relay is disconnected, the circuit board is disconnected with all external connecting wires, and a piezoresistor is added behind the relay to further protect the circuit board.
The signal processor can adopt FPGA, also can adopt chips such as singlechip, DSP, no matter adopt any chip, all require to be able to accomplish the calculation of Fourier transform, resistance value and statistical method and obtain final resistance calculation result.
In addition, the same driving source excites the exciting coils 8 with the same parameters in each exciting part arranged on the grounding down lead by a sine wave, then the upper sampling chuck 7, the lower sampling chuck 9 and the voltage sampling electrode 5 are matched with the ratio rho of the resistor in the test loop model to be Rt/Rg, the parallel resistance Ra of the two resistors in the test loop is measured by the current sending electrode 4, the voltage sampling electrode 5, the lower sampling chuck 9 and the sampling resistor, and the resistance Rg of the tested iron tower is obtained by solving the series-parallel connection relation.
1. The online measurement function of the invention enables the data of the grounding resistance of the power line iron tower to be directly uploaded in an Internet of things mode, realizes network monitoring, effectively replaces a manual inspection mode of the power line iron tower, greatly improves the detection efficiency, frequency and flexibility, and enables the grounding resistance monitoring of the power line iron tower to be more convenient and reliable.
2. The invention determines the resistance ratio and the resistance value of the parallel connection of the resistors by measuring the voltage ratio, the key parameters are obtained by contact measurement, the test precision is ensured, and theoretically, the size of the electromotive force excited by the exciting coil has no quantitative requirement, and the test requirement can be met only by a certain amplitude, so the invention is simpler and more reliable to realize, and the difficulty and the cost in production are greatly reduced.
3. The method can further improve the anti-interference capability, can obtain a more accurate grounding resistance test result of the tested iron tower even if a plurality of iron towers are simultaneously measured, ensures that the grounding down lead is not required to be disconnected with the iron tower to measure in the test principle, and achieves the aim of directly testing the magnitude of the resistance value of the grounding network on line.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The utility model provides a power line iron tower ground resistance on-line measuring appearance based on voltage excitation, includes ground resistance tester (1), its characterized in that, ground resistance tester (1) includes area chuck excitation part (2), no chuck excitation part (3), current transmitting electrode (4), voltage sampling electrode (5) and signal processing circuit board (6), area chuck excitation part (2) top-down contains sample chuck (7), exciting coil (8) and lower sample chuck (9), and installs on a ground connection downlead of power line iron tower, exciting coil (8) and ground connection downlead contactless, go up sample chuck (7) and lower sample chuck (9) and all with ground connection downlead fastening connection, no chuck excitation part (3) then only contains one exciting coil (8), and install on the other ground connection downlead of power line iron tower, the grounding downlead is in non-contact with the grounding downlead, only one non-chuck exciting component (3) is needed for the double-grounding downlead, for the multi-grounding downlead, except the grounding downlead provided with the chuck exciting component (2), the rest grounding downlead needs to be provided with one non-chuck exciting component (3) for each grounding downlead, the current transmitting electrode (4) and the voltage sampling electrode (5) determine the distance according to the traditional three-wire method grounding test standard and then are inserted into the ground to a certain depth, the test under the single sine wave frequency is divided into two stages, in the first stage, the tested iron tower, other iron towers and connecting lines among the iron towers form an electric loop, a loop model comprises two resistors, one is the grounding resistance Rg of the tested iron tower, the other is the equivalent resistor Rt formed by other iron towers except the tested iron tower and an overhead line, and the current transmitting electrode (4) is disconnected and plays no role in the first stage, an exciting coil (8) in the exciting part (2) with the clamp head and an exciting coil (8) in the exciting part (3) without the clamp head excite electromotive force in a loop, at the moment, an upper sampling clamp head (7) is communicated with the ground of a signal processing plate (6), a voltage signal taken out by a lower sampling clamp head (9) is the electromotive force excited by the coils, a voltage taken out by a voltage sampling electrode (5) is the voltage drop on the grounding resistance of a tested iron tower, the two signals are sent into the signal processing plate (6) for processing, the ratio of two resistors Rg and Rt in a loop model can be obtained, in the second stage, the exciting coil (8) and the upper sampling clamp head (7) are disconnected and do not work, the current sending electrode (4), the voltage sampling electrode (5) and the lower sampling clamp head (9) are communicated, and the resistors and the Rt are connected in parallel in the stage, the measured resistance is the parallel value Ra of the two resistors Rg and Rt, then, a grounding resistance Rg of the measured iron tower can be calculated by utilizing the series-parallel relation of the two stages, in order to improve the anti-interference capacity, the test process is repeated by adopting a plurality of random frequencies to obtain a series of grounding resistance values, and an optimal detection result is given out through statistical processing and is used as a measurement output value of the grounding resistance of the measured iron tower.
2. The voltage excitation-based on-line tester for ground resistance of power line iron tower according to claim 1, wherein the exciting coil (8) in the excitation part (2) with the clamp and the excitation part (3) without the clamp are both composed of an iron core and a plurality of turns of enameled wires wound outside, and the excitation part (2) with the clamp and the excitation part (3) without the clamp are both structurally composed of two independent and same semi-cylindrical parts.
3. The on-line tester for the ground resistance of the power line iron tower based on the voltage excitation as claimed in claim 2 is characterized in that the parameters of the excitation coils (8) in the excitation part (2) with the clamp head and the excitation part (3) without the clamp head are required to be the same as much as possible, and each excitation coil (8) is driven by the same driving source.
4. The on-line tester for ground resistance of power line iron tower based on voltage excitation as claimed in claim 3, wherein the driving voltage signal of the excitation coil (8) is a sine wave signal, which is provided by the signal processing circuit board (6) and can excite the electromotive force of sine wave in the loop.
5. The on-line tester for ground resistance of power line iron tower based on voltage excitation according to claim 1, characterized in that signal frequency is randomly set in the pass band of the band-pass filter (10) on the signal processing circuit board (6), a resistance value sequence is obtained by processing the same flow under a plurality of sine wave signals with different frequencies, and then statistical processing is carried out.
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| CN109085387A (en) * | 2018-07-25 | 2018-12-25 | 深圳供电局有限公司 | A kind of fast joint type electric system earthmeter termination |
| CN109374976A (en) * | 2018-10-19 | 2019-02-22 | 中国人民解放军空军勤务学院 | A kind of online ground resistance Fast measurement system |
| CN109490635B (en) * | 2018-12-25 | 2021-11-26 | 国网江苏省电力有限公司南京供电分公司 | Online monitoring system and online monitoring method for tower grounding resistance |
| CN109765432B (en) * | 2018-12-29 | 2021-08-10 | 国网山东省电力公司高唐县供电公司 | Real-time monitoring system for ground resistance of public power distribution station area and implementation method thereof |
| CN109782071B (en) * | 2019-03-11 | 2020-10-16 | 重庆大学 | Pole tower grounding resistance measurement method based on earth surface voltage |
| CN110261680B (en) * | 2019-07-08 | 2024-04-12 | 金茂联合(北京)科技发展有限公司 | Method, device and system for detecting resistance parameters of grounding system and monitoring network |
| CN112254766B (en) * | 2020-10-19 | 2022-02-08 | 三峡大学 | Iron tower stress and vibration detection device |
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