CN112285425B - Grounding resistance calculation method and device of tower grounding device and terminal equipment - Google Patents

Grounding resistance calculation method and device of tower grounding device and terminal equipment Download PDF

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CN112285425B
CN112285425B CN202011180379.0A CN202011180379A CN112285425B CN 112285425 B CN112285425 B CN 112285425B CN 202011180379 A CN202011180379 A CN 202011180379A CN 112285425 B CN112285425 B CN 112285425B
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tower
grounding
current
resistance
grounding device
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李谦
胡晓晖
魏俊涛
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Electric Power Research Institute of Guangdong Power Grid Co Ltd
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    • 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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Abstract

The invention relates to a method, a device and terminal equipment for calculating the ground resistance of a tower grounding device, which are applied to a transmission tower. The grounding resistance testing device does not need field wiring in the grounding resistance measuring process of the pole tower grounding device, and the non-contact measurement enables the operation to be simple and the field implementation to be easy.

Description

Grounding resistance calculation method and device of tower grounding device and terminal equipment
Technical Field
The invention relates to the technical field of lightning protection grounding, in particular to a method and a device for calculating grounding resistance of a tower grounding device and terminal equipment.
Background
The overhead transmission line is an important component of a power grid, and because the overhead transmission line is exposed to the atmospheric environment for a long time and operates in the atmospheric environment, the overhead transmission line becomes the weakest ring of lightning stroke in power equipment, the lightning protection operation reliability directly determines the operation safety of a power system, and particularly, in southern areas with strong lightning activity in China, the power transmission line has frequent lightning damage, so that the lightning protection operation becomes the most basic operation of the power transmission line.
The existing effective dredging of lightning current on a power transmission line is the key of lightning protection work of the power transmission line, so that tower grounding becomes an important foundation stone for safe operation of the power transmission line. For the pole tower grounding, the resistance reduction of the grounding device and the accurate measurement of the grounding resistance are two important lightning protection basic works.
The grounding resistance is a main means for knowing the running state and performance evaluation of the tower grounding device, the design, handover acceptance and preventive test standards and regulations related to tower grounding at present all require accurate measurement of power frequency grounding resistance, and the complicated environmental conditions of the power transmission line tower and the hidden engineering characteristics of grounding engineering cause the accurate measurement of the tower grounding resistance to become a technical problem which puzzles basic units for a long time.
At present, a three-pole method and a voltage-current method are adopted for measuring the grounding resistance of the tower grounding device, the three-pole method is based on the definition of the grounding resistance, and the grounding resistance of the grounding device is tested by three electrodes consisting of the tower grounding device, a current electrode and a voltage electrode, but in practical application, the following problems also exist: firstly, the hidden engineering characteristics of the grounding device make the position of the extension grounding wire unknown, so that a voltage electrode and a current electrode for testing are arranged near an extension grounding ray of the grounding device, and a large measurement error is caused; secondly, the wiring length is difficult to meet the measurement requirement, so that the test result is smaller. In the existing tower grounding resistance measuring method, the tripolar method is poor in operability and large in actual measuring error. Secondly, the loop resistance is measured by adopting a clamp meter method, and is approximate to the grounding resistance of the grounding network of the measured pole tower under certain conditions, so that the limitation exists in principle, and the test data is seriously distorted due to the complex environment on site in site measurement, so that the clamp meter method has strict use conditions, and except for the fact that a test pole is required to have a multi-base pole tower parallel loop in principle, the important point is that no other branch circuits are required on the loop, specifically, no electric conduction exists between a pole tower natural grounding body and a grounding device to be measured, namely, no other branch circuits such as a natural grounding body and the like are required in the loop, and the measurement accuracy is influenced.
Disclosure of Invention
The invention provides a method and a device for calculating the grounding resistance of a tower grounding device and terminal equipment, which are used for solving the technical problem that the resistance value of the grounding resistance measured by a tripolar method or a clamp meter method for the tower grounding resistance in the prior art is inaccurate.
In order to achieve the above purpose, the invention provides the following technical scheme:
a method for calculating the grounding resistance of a tower grounding device is applied to a transmission tower, a grounding resistance testing device is adopted to test the current of the tower grounding device, the tower grounding device comprises a tower framework, and the tower framework at least comprises four tower feet and a tower body; the method for calculating the grounding resistance of the tower grounding device comprises the following steps:
s1, selecting one tower foot of a tower grounding device as a measuring point, disconnecting grounding wires of the other three tower feet of the tower grounding device from a tower framework, connecting the grounding wires of the four tower feet to form a down lead, and forming a multi-port network by the tower grounding device and the grounding resistance testing device;
s2, applying different voltage excitation signals on a tower body of the tower framework through a power source in three wiring modes, and measuring the current of the tower grounding device by adopting a current measuring unit to obtain three groups of measured current data;
s3, analyzing and calculating the ground resistance of the two tower grounding devices according to the three groups of measured current data, and taking the average value of the ground resistance of the two tower grounding devices as the ground resistance of the tower grounding device;
wherein, in S2, obtaining three sets of measured current data specifically includes:
s21, in a first wiring mode, the down lead is in short circuit with one tower body, a first voltage excitation signal is applied to the tower body, and the current of the down lead, the current of the tower body above the down lead, the current of the tower body below the down lead and the currents of the other three tower bodies are measured through the current measuring unit to obtain a first group of measured current data;
s22, in a second wiring mode, applying a second power supply excitation potential signal between a tower body and a grounding wire of a tower foot corresponding to the measuring point, and measuring the current flowing through the down lead, the current of the tower body positioned below the down lead and the currents of the other three tower bodies through the current measuring unit to obtain a second group of measured current data;
s23, in a third wiring mode, the down lead is disconnected from one tower body, a third voltage excitation signal is applied to the tower body, the current of the tower body above the down lead and the current of the tower body below the down lead are measured through the current measuring unit, and a third group of measured current data is obtained.
Preferably, the method for calculating the grounding resistance of the tower grounding device further comprises: analyzing and calculating to obtain R according to the first group of measured current dataHe1、Re1And RE1(ii) a The method specifically comprises the following steps:
Figure GDA0003642264240000031
Figure GDA0003642264240000032
Figure GDA0003642264240000033
I14＝I13-I15
in the formula, Re1Grounding resistance, R, for the natural grounding body of the towerE1As ground resistance, R, of tower earthing devicesHe1Is the equivalent mutual resistance between naturally grounded bodies, I12Measuring the current of the down conductor for a current measuring unit, I13For the current of the tower below the down conductor, I15For currents of three other towers than the tower at the measuring point, E1The voltage of the first voltage excitation signal.
Preferably, the method for calculating the grounding resistance of the tower grounding device further includes: analyzing and calculating to obtain R according to the second group of measured current dataH2And RE2(ii) a The method specifically comprises the following steps:
Figure GDA0003642264240000034
Figure GDA0003642264240000035
I22＝I21-I23
in the formula I23For the current of the tower below the down conductor, RE2Is the grounding resistance, R, of the tower grounding deviceH2Is the equivalent mutual resistance of the grounding device and the natural grounding body, I21For the current to flow through the down conductor, E2The voltage of the second voltage excitation signal.
Preferably, the method for calculating the grounding resistance of the tower grounding device further includes: based on RH2、RE2And analyzing and calculating the third group of measured current data to obtain RHe3And Re3The method specifically comprises the following steps:
Re3＝E3/I33，I32×(RH2+RE2)＝E3，I33＝I31-I34-I32；
in the formula, RHe3Is the equivalent mutual resistance between the natural earthed bodies, Re3Grounding resistance of natural grounding body for tower, I31For currents in the tower above the down conductor, I34Is the current of the tower body below the down conductor.
Preferably, the method for calculating the grounding resistance of the tower grounding device further comprises a current measuring unit for measuring the current of the tower grounding device by using an excitation jaw sleeve at a metal part of the tower framework.
Preferably, the method for calculating the grounding resistance of the tower grounding device further comprises: and the power source is used for providing a voltage excitation signal for the tower grounding device through inductive coupling or direct contact.
The invention also provides a grounding resistance calculating device of the tower grounding device, which is applied to a transmission tower, and adopts a grounding resistance testing device to test the current of the tower grounding device, wherein the tower grounding device comprises a tower framework, the tower framework at least comprises four tower feet and a tower body, the grounding resistance calculating device of the tower grounding device comprises a measuring wiring unit, a current measuring unit and an analyzing and calculating unit, and the current measuring unit comprises a first measuring subunit, a second measuring subunit and a third measuring subunit;
the measurement wiring unit is used for selecting one tower foot of the tower grounding device as a measurement point, grounding wires of the other three tower feet of the tower grounding device are disconnected with the tower framework, grounding wires of the four tower feet are connected to form a down-lead wire, and the tower grounding device and the grounding resistance testing device form a multi-port network;
the current measuring unit is used for applying different voltage excitation signals to the tower body of the tower framework through a power source in three wiring modes, and measuring the current of the tower grounding device by adopting the current measuring unit to obtain three groups of measured current data;
the analysis and calculation unit is used for analyzing and calculating the grounding resistances of the two tower grounding devices according to the three groups of measured current data, and taking the average value of the grounding resistances of the two tower grounding devices as the grounding resistance of the tower grounding device;
the first measuring subunit is configured to, in a first connection manner, short-circuit the down conductor to one of the tower bodies, apply a first voltage excitation signal to the tower body, and measure, by the current measuring unit, a current of the down conductor, a current of the tower body located above the down conductor, a current of the tower body located below the down conductor, and currents of the other three tower bodies, so as to obtain a first set of measured current data;
the second measuring subunit is used for applying a second power excitation potential signal between a tower body and a grounding wire of a tower foot corresponding to the measuring point in a second wiring mode, and measuring the current flowing through the down lead, the current of the tower body positioned below the down lead and the currents of the other three tower bodies through the current measuring unit to obtain a second group of measured current data;
and the third measuring subunit is configured to, in a third connection mode, disconnect the down conductor from one of the tower bodies and apply a third voltage excitation signal to the tower body, and measure, by the current measuring unit, a current of the tower body located above the down conductor and a current of the tower body located below the down conductor, so as to obtain a third set of measured current data.
Preferably, R is analytically calculated from the first set of measured current dataHe1、Re1And RE1(ii) a The method comprises the following specific steps:
Figure GDA0003642264240000051
Figure GDA0003642264240000052
Figure GDA0003642264240000053
I14＝I13-I15
in the formula, Re1Grounding resistance, R, for the natural grounding body of the towerE1As ground resistance, R, of tower earthing devicesHe1Is the equivalent mutual resistance between naturally grounded bodies, I12Measuring the current of the down conductor for a current measuring unit, I13For the current of the tower below the down conductor, I15For currents of three other towers than the tower at the measuring point, E1A voltage that excites the signal for the first voltage;
analyzing and calculating to obtain R according to the second group of measured current dataH2And RE2(ii) a The method specifically comprises the following steps:
Figure GDA0003642264240000054
Figure GDA0003642264240000055
I22＝I21-I23
in the formula I23For the current of the tower below the down conductor, RE2As ground resistance, R, of tower earthing devicesH2Is the equivalent mutual resistance of the grounding device and the natural grounding body, I21For the current to flow through the down conductor, E2A voltage that excites the signal for the second voltage;
based on RH2、RE2And the thirdAnalyzing and calculating the group measurement current data to obtain RHe3And Re3The method specifically comprises the following steps: r ise3＝E3/I33，I32×(RH2+RE2)＝E3，I33＝I31-I34-I32(ii) a In the formula, RHe3Is the equivalent mutual resistance between the natural earthed bodies, Re3Grounding resistance of natural grounding body for tower, I31For currents in the tower above the down conductor, I34Is the current of the tower body below the down conductor.
The invention also provides a computer-readable storage medium for storing computer instructions, which when run on a computer, cause the computer to execute the above method for calculating the grounding resistance of the tower grounding device.
The invention also provides a terminal device, comprising a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
and the processor is used for executing the grounding resistance calculation method of the tower grounding device according to the instructions in the program codes.
According to the technical scheme, the embodiment of the invention has the following advantages: according to the method and the device for calculating the grounding resistance of the tower grounding device and the terminal equipment, under three wiring modes and different voltage excitation signals, the non-contact current measuring unit is adopted to measure the current of the tower grounding device, three groups of measured current data are obtained, and the three groups of measured current data are analyzed and calculated to obtain the grounding resistance of the tower grounding device. According to the method for calculating the grounding resistance of the tower grounding device, the influence of mutual resistance is shielded in the process of measuring by adopting three wiring modes, so that the obtained grounding resistance value data of the tower grounding device is accurate, and the technical problem that the existing grounding resistance value measured by adopting a tripolar method or a clamp meter method for the tower grounding resistance is inaccurate is solved. The grounding resistance testing device does not need field wiring in the grounding resistance measuring process of the pole tower grounding device, and the non-contact measurement enables the operation to be simple and the field implementation to be easy.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive labor.
Fig. 1 is a flowchart illustrating steps of a method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of an equivalent resistance network for ground resistance testing of the method for calculating the ground resistance of the tower grounding device according to the embodiment of the invention.
Fig. 3 is a first multi-terminal network circuit model diagram of the tower grounding device according to the method for calculating the grounding resistance of the tower grounding device in the embodiment of the invention.
Fig. 4 is a second multi-terminal network circuit model diagram of the tower grounding device according to the method for calculating the grounding resistance of the tower grounding device in the embodiment of the present invention.
Fig. 5 is a third multi-terminal network circuit model diagram of the tower grounding device according to the method for calculating the grounding resistance of the tower grounding device in the embodiment of the invention.
Fig. 6 is a schematic diagram illustrating that the resistance of the tower grounding device according to the embodiment of the present invention is affected by a natural grounding body.
Fig. 7 is a schematic diagram of a clamp meter method measurement when the tower grounding device according to the embodiment of the invention is naturally grounded.
Fig. 8 is a multi-port network diagram of the tower grounding device according to the embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
At present, related design, handover acceptance and preventive test standards and regulations on transmission towers all require measurement of power frequency grounding resistance, and accurate measurement of tower grounding resistance is a main means for knowing the operation state and performance evaluation of tower grounding devices, so that the method not only provides a basis for lightning trip fault analysis, but also provides basic data for making and checking lightning protection countermeasures of transmission lines, and can be said that accurate measurement of tower grounding device grounding resistance becomes a basis in the foundation of lightning protection work of overhead transmission lines.
However, in many power transmission line lightning trip fault analyses, the ground resistance of a tower grounding device actually measured in high soil resistivity areas such as karst rock zones is only several Ω, even less than 1 Ω, which is seriously inconsistent with the actual situation, and thus, difficulties are brought to the formulation of countermeasures such as accident analysis and line lightning protection transformation, and the lightning protection transformation is difficult to achieve with a certain goal; and the lack of accurate basic data greatly reduces the effectiveness of lightning protection simulation calculation of the power transmission line.
At present, a three-pole method is adopted for measuring the grounding resistance of the tower grounding device, but the three-pole method is complicated in test, so that the test labor intensity is high, and particularly in areas with complex terrains such as mountainous areas, wiring is very difficult. Therefore, in recent years, a method for testing the tower grounding resistance based on the principle of a single-clamp loop resistance tester appears, the physical significance of the method is clearly different from that of a tripolar method, the clamp meter method is used for obtaining the grounding resistance value based on an approximate method that the loop resistance is close to the grounding resistance, and is only suitable for specific occasions of the tower grounding device of the overhead transmission line with the overhead lightning conductor and a plurality of tower lightning conductors which are directly grounded, and the testing principle and the testing method refer to the standard DL/T887 + 2004 tower power frequency grounding resistance measurement in the power industry. The method is characterized in that auxiliary electrodes (a current electrode and a voltage electrode) are not required to be arranged, the connection of tower grounding bolts is not required to be completely disconnected, and voltage and current auxiliary measuring lines are not required to be arranged, so that the measuring operation is simple.
For the resistance measurement of the tower grounding device, the standard DL475-2017 "grounding device characteristic parameter measurement guide rule" in the power industry requires a tripolar method, and the measurement result of the tripolar method is used as a reference; although the clamp meter method is simple, it can only be used as an auxiliary measurement method, and the comparison of the three-pole method is used as a precondition, and when there is doubt about the test result, the three-pole method should be used for verification. Although the tripolar method is a principle method, the following problems are also present in the application: firstly, earthing device's hidden engineering characteristic for the position of extension earth connection can't know, shaft tower earthing device is generally for the square style of calligraphy net around four tower feet, in addition four extension earth connections, because the complexity of on-the-spot topography condition, the many nimble selections of actual construction according to the on-the-spot condition of extension earth connection probably cause the voltage pole and the electric current pole of test usefulness just to arrange near earthing device's extension ground connection ray, cause measuring error very big. Secondly, the wiring length is difficult to meet the measurement requirement, and the size of the grounding device is inaccurate to estimate due to the uncertainty of the position and the length of the extension grounding wire. The wiring length of current utmost point and voltage utmost point is based on earthing device's size in the actual measurement, and the limitation of on-the-spot wiring line warp often causes wiring length not enough, and the measuring result is littleer. Thirdly, wiring is difficult, because the transmission line is often erected along the mountain, the pole tower is often on the mountain head, the periphery is not a bush forest, namely a rock steep slope, and the field wiring is very difficult.
Therefore, the three-pole method for measuring the grounding resistance of the tower is poor in operability, the willingness of the base unit to measure by adopting the three-pole method is not high, and in addition, certain test experience is required for the implementation of the three-pole method, so that the accuracy of measurement by the base team and team cannot be guaranteed.
The clamp meter method has the advantages of simple instrument, convenient operation and simple test method, more importantly, the method does not need paying off, has low labor intensity, has obvious advantages compared with the tripolar method, is widely popular in the basic unit and is rapidly popularized and applied. The clamp meter method is characterized in that the clamp meter method is actually used for measuring loop resistance, and the loop resistance is approximate to the grounding resistance of a grounding network of a measured pole tower under certain conditions, so that the clamp meter method has great limitation in principle, and can cause serious distortion of test data due to a complex field environment in field measurement. In practical measurement, because the natural grounding resistance of the tower foundation connected in parallel with the grounding grid of the tested pole tower is generally not large enough (in the order of one hundred Ω), and is especially lower under the condition of soil wetting after rain or in rainy season, the shunt of the test current directly affects the correctness of the measurement result, which is one of the reasons why the clamp meter method should be used with caution or even forbidden.
The schematic diagram of the part (the down-lead position of the tower to be measured) when the tower ground resistance is measured by the clamp meter method is shown in fig. 6, and is converted into the test schematic diagram shown in fig. 7. When R isHAnd ROThe sum of the two (called "mutual resistance between tower natural grounding body and grounding device", and R)j+ Δ R is in parallel relation) with RjWhen the magnitude of the current is the same or smaller, the current is more, the influence on the measurement result is larger, and when the foundation bolt is directly connected with the foundation reinforcement cage (R)O0), the natural grounding body has a greater influence on the measurement result; the condition that the tower foundation reinforcement cage is directly welded with the grounding device exists on site (R)H0), if rag bolt and foundation reinforcement cage also direct connection simultaneously, the condition that the test result is less than 1 omega can appear, is the metal loop resistance of ground connection downlead, rag bolt, reinforcement cage in essence. The mutual resistance of the tower natural grounding body and the grounding device is obviously reduced under the condition of soil wetting after raining or in rainy season, and the correctness of the measurement result is directly influenced. Therefore, the principle error exists in the grounding resistance measurement result due to the fact that shunting formed by the tower natural grounding body and the mutual resistance between the tower natural grounding body and the tower grounding device is not considered. Wherein R isjThe grounding resistance (self-existing ground resistance) of the tower grounding device is set; rHThe resistor is connected in parallel with a plurality of base towers.
In summary, in the existing tower grounding resistance measurement method, the tripolar method is poor in operability, and the actual measurement error is large; the clamp meter method does not consider shunt formed by a tower natural grounding body and mutual resistance between the tower natural grounding body and a tower grounding device, so that a larger principle error exists in a grounding resistance measurement result.
The circuit model of the grounding device of the transmission tower can be equivalent to a multi-port network shown in fig. 8, wherein R isEAs ground resistance of the grounding means, ReGrounding resistance, R, for the natural grounding body of the towerHIs the equivalent mutual resistance, R, of the grounding device and the natural grounding bodyHeAnd the delta R is equivalent mutual resistance between natural grounding bodies, is parallel equivalent resistance of other grounding electrodes connected with the tested pole tower, and is small enough and can be ignored when the number of parallel branches is large enough. For testing the grounding resistance of the transmission tower, the grounding resistance R of the tower grounding device is mainly usedEAnd the tower natural grounding body grounding resistance Re and the mutual resistance R of the grounding device and the natural grounding bodyHThen it is influencing RETwo major factors of measurement accuracy, Re and RHThe formed shunt branch is the main reason that the difference between the clamp meter method measured value and the actual value of the grounding resistance of the grounding device is far. Along with different underground moisture degrees and different cement foundation degradation degrees, Re can be changed, and the variable Re is an unstable equivalent grounding resistance influenced by multiple factors; r isHUnderground is invisible, is a distribution parameter, the size of which depends on the state of underground soil medium, the soil moisture degree, the spacing distance between the grounding device and the natural grounding body and the like, and is also unstable equivalent connected resistance influenced by multiple factors.
In order to realize accurate measurement of tower grounding resistance, the embodiment of the application provides a method, a device and a terminal device for calculating the grounding resistance of a tower grounding device based on a multi-terminal network circuit model shown in fig. 8, measures each current parameter in the tower grounding device, applies voltage excitation under different wiring modes, and obtains current measurement values of internal response of a multi-terminal network under different excitation conditions by using a state parameter method, so that specific values of internal state resistance parameters in the tower grounding device are analyzed and calculated, accurate grounding resistance values of the tower grounding device are obtained, accurate evaluation can be made on the state of the tower grounding device of a power transmission line, and the technical problem that the existing grounding resistance values measured by using a three-pole method or a clamp meter method for the tower grounding resistance are inaccurate is solved.
The first embodiment is as follows:
fig. 1 is a flow chart of steps of a method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention, fig. 2 is a circuit diagram of an equivalent resistance network for testing a ground resistance of the method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention, fig. 3 is a model diagram of a first multi-terminal network circuit of the tower grounding device according to the method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention, fig. 4 is a model diagram of a second multi-terminal network circuit of the tower grounding device according to the method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention, and fig. 5 is a model diagram of a third multi-terminal network circuit of the tower grounding device according to the method for calculating a ground resistance of a tower grounding device according to an embodiment of the present invention.
As shown in fig. 1 and 2, an embodiment of the present invention provides a method for calculating a ground resistance of a tower grounding device, which is applied to a transmission tower, and is used for testing a current of the tower grounding device by using a ground resistance testing device, wherein the tower grounding device includes a tower framework, the tower framework at least includes four tower feet and a tower body, and the method for calculating the ground resistance of the tower grounding device includes the following steps:
s1, selecting one tower foot of a tower grounding device as a measuring point, disconnecting grounding wires of the other three tower feet of the tower grounding device from a tower framework, connecting the grounding wires of the four tower feet to form a down lead, and forming a multi-port network by the tower grounding device and a grounding resistance testing device;
s2, applying different voltage excitation signals on a tower body of a tower framework through a power source in three wiring modes, and measuring the current of a tower grounding device by adopting a current measuring unit to obtain three groups of measured current data;
s3, analyzing and calculating the ground resistance of the two tower grounding devices according to the three groups of measured current data, and taking the average value of the ground resistance of the two tower grounding devices as the ground resistance of the tower grounding devices;
wherein, in S2, obtaining three sets of measured current data specifically includes:
s21, in a first wiring mode, a down lead is in short circuit with one tower body, a first voltage excitation signal is applied to the tower body, and current flowing through the down lead, current of the tower body above the down lead, current of the tower body below the down lead and current of the other three tower bodies are measured through a current measuring unit to obtain a first group of measured current data;
s22, in a second wiring mode, applying a second power supply excitation potential signal between a tower body and a grounding wire of a tower foot corresponding to the measuring point, and measuring current flowing through the down lead, the current of the tower body positioned below the down lead and the currents of the other three tower bodies through the current measuring unit to obtain a second group of measured current data;
s23, in a third wiring mode, the down lead is disconnected from one tower body, a third voltage excitation signal is applied to the tower body, the current of the tower body above the down lead and the current of the tower body below the down lead are measured through the current measuring unit, and a third group of measured current data is obtained.
In step S1 of the embodiment of the present invention, a wiring preparation is mainly performed before testing the grounding resistance of the tower grounding device.
In step S2 of the embodiment of the present invention, based on the wiring in step S1, as shown in fig. 2 to 4, a voltage excitation signal is applied to a tower grounding device in an equivalent multi-port network in two different wiring modes, and the response distribution and the parameter state of the tower grounding device are measured, so as to obtain measured current data based on state parameters under different excitation conditions.
The ground resistance testing device is provided with an excitation source and a current measuring unit.
In step S21 of the embodiment of the present invention, as shown in fig. 3, the down conductor is first shorted with the tower body, and a voltage excitation signal E is applied from the tower body1Measuring multiport netsThe in-line current includes a current I flowing through the down conductor12And current I of the tower body above the down conductor11And a current I of the tower body below the down conductor13And the currents I of the other three towers15The tower grounding device in the wiring state can shield the influence of mutual resistance, and the measured current mainly reflects the grounding resistance of the tower grounding device and a natural grounding body.
In addition, a down lead of a tower foot of a measuring point is in short circuit with a tower body, and a voltage excitation signal E is applied from the tower body on the upper part of a grounding wire by using a power source1Measuring the multiport network internal current comprises: measuring the current I flowing through the down conductor using the jaws of a current measuring unit12Measuring the current I of the tower body above the down conductor by using the air core coil of the current measuring unit11Current I of the tower below the down conductor13And the currents I of the other three towers15The tower grounding device in the wiring state can shield the influence of mutual resistance, and the measured current mainly reflects the grounding resistance of the tower grounding device and a natural grounding body. The number of the air coils of the current measuring unit is enough (5 coils are needed at most), and the power source excitation is kept stable through simultaneous measurement, so that the accuracy of the measured current data is ensured.
In step S22 of the embodiment of the present invention, as shown in fig. 4, a voltage excitation signal E is applied between the down conductor of the tower foot and the tower body corresponding to the selected measurement point2Measuring the internal current of the multiport network comprises: current I flowing through the down conductor21And current I of tower body below down lead23And I25And the currents I of the other three towers26The tower grounding device in the wiring state can reflect the influence of mutual resistance from shunt measurement current data.
In step S23 of the embodiment of the present invention, as shown in fig. 5, the down conductor is disconnected from the tower body, and a voltage excitation signal E is applied to the tower body3Measuring the internal current of the multiport network comprises: current I of tower body above down conductor31And the current I of the tower body below the down conductor34The tower grounding device in the wiring state can obtain a natural grounding bodyGround resistance Re3。
In step S3 of the embodiment of the present invention, for the three sets of measured current data obtained in the three connection manners, the three sets of measured current data are analyzed and calculated to obtain specific values of all independent parameters in the tower grounding device, so as to obtain a numerical value of the grounding resistance of the tower grounding device.
It should be noted that the grounding resistance R of the tower natural grounding body is obtained by analyzing and calculating the first group of measured current datae1Grounding resistance R of tower grounding deviceE1And the equivalent mutual resistance R between the natural grounding bodiesHe1. The grounding resistance R of the tower grounding device is obtained by analyzing and calculating the second group of measured current dataE2And equivalent mutual resistance R of grounding device and natural grounding bodyH2. Grounding resistance R of tower grounding deviceEHas a value of RE＝(RE1+RE2)/2. The grounding resistance calculation method of the tower grounding device adopts three wiring modes to connect the grounding resistance test device with the tower grounding device, three groups of measured current values of the tower grounding device are obtained, each group of measured current data is analyzed and calculated to obtain resistance parameters of the tower grounding device, corresponding parameters are taken to obtain resistance values under different wiring modes to calculate an average value, and the resistance value of the resistance of the tower grounding device is obtained.
In this embodiment, as can be seen from fig. 3, the analysis of the first set of measured current data specifically includes: resistance RHThe two ends are equipotential, so the branch is in a short circuit state, according to the theorem of KCL (kirchhoff current law) and KVL (kirchhoff voltage law) of the circuit, the main nodes for analyzing the node current and the loop voltage in the multiport network are respectively A1, B1, C1 and D1, and the main meshes are (i), (ii) and (iii).
According to the KCL theorem, the currents at nodes a1, B1, C1 and D1 are as follows:
Figure GDA0003642264240000131
the current that can be measured directly is I11，I12，I13And I15The resulting current I can then be calculated14And I16The following are:
I14＝I13-I15
I16＝I11-I15
according to the KVL theorem, the voltage equations of meshes (i), (ii) and (iii) are as follows:
Figure GDA0003642264240000132
since the voltage of the voltage excitation signal E1 and the current of the individual branches can be measured or calculated, the resistance variable can be determined as follows:
Figure GDA0003642264240000133
Figure GDA0003642264240000134
Figure GDA0003642264240000135
the above calculation formula yields RHe1Can also yield RE1And Re1For indirectly calculating RE1Or Re1。
The above equation system can be further simplified, when the parallel resistance of the remote multi-stage tower is negligible (Δ R ═ 0), Re1Solving the corresponding equations can be simplified, resulting in the following results:
Figure GDA0003642264240000141
based on the calculation result and RE1And Re1Can be further calculated to obtain RE1：
Figure GDA0003642264240000142
The resistance R can be obtained from the first set of measured current dataHe1、Re1And RE1The resistance value of (2). RHe1The method is obtained by calculating directly measured voltage and current, and the reliability is higher; but R ise1And RE1Are all obtained by indirect calculation, and the error of the calculation is probably large.
As can be seen from fig. 4, the analysis of the second set of measured current data specifically includes: the main nodes are A2, B2 and C2, and the main meshes are (r), (g) and (g). According to KCL, the currents at nodes a2, B2 and C2 are as follows:
Figure GDA0003642264240000143
the branch current that can be directly measured is I21、I25And I26And I is22、I23And I24It needs to be solved by linear equations. Since the number of the independently measured branch currents is only 3 and the unknown variables are also three, I is found through matrix transformation22、I23And I24Is not exclusive, and specifically:
transforming the equation set of the above formula into AX ═ 0;
Figure GDA0003642264240000144
the matrix A is then transformed through the elementary row to obtain the solved relational expression as follows
Wherein each column in matrix a represents, I ═ I (I)21、I22、I23、I24、I25、I26) The coefficient is obtained by the method,
Figure GDA0003642264240000145
the matrix (1) equation is obtained by adding the 2 nd and 3 rd rows to the 1 st row
Figure GDA0003642264240000151
Multiplying the 3 rd row by (-2), adding to the first row to obtain a matrix (3) formula,
Figure GDA0003642264240000152
finally, multiplying the 3 rd row by (-1) to obtain a matrix (4),
Figure GDA0003642264240000153
the row transformed matrix (4) can be solved as, equation (5),
Figure GDA0003642264240000154
from the matrix (4), it is known that the rank of the matrix a is 3, and if r (a) is 3<6, there is an infinite solution. According to the KVL of the circuit, the voltage equations of meshes (i), (ii) and (iii) are as follows:
Figure GDA0003642264240000155
the following can be solved by the KVL equation:
Figure GDA0003642264240000156
Figure GDA0003642264240000157
Figure GDA0003642264240000158
the above equation set, due to the current I22，I23，I24Without a definite solution, further simplification is required to solve for the relevant parameters.
When the parallel resistance of the remote multi-stage tower is negligible (Δ R ═ 0), it can be derived from fig. 4 that the short-circuited branch has RHe2And Re2Thus, the corresponding system of KCL equations can be simplified as follows:
Figure GDA0003642264240000161
the branch current which can be directly measured is I21And I25By calculation, I can be obtained22，I22＝I21-I25。
Then according to KVL of the circuit, the equation of the mesh is as follows;
Figure GDA0003642264240000162
due to the voltage excitation signal E2The voltage and the current of each branch can be measured or calculated, and the resistance parameters that can be obtained are as follows:
Figure GDA0003642264240000163
Figure GDA0003642264240000164
calculating the resistance R from the second set of measured current dataH2And RE2The resistance value of (2).
As can be seen from fig. 5, the analysis of the third set of measured current data specifically includes: the main nodes are A3, B3 and C3, and the main meshes are (r), (g) and (g);
the current equations for nodes A3, B3, and C3, according to KCL, are as follows:
Figure GDA0003642264240000165
the branch current that can be directly measured is I31And I34。
According to KVL, the voltage equations for meshes (r), (g) and (g) are as follows:
Figure GDA0003642264240000166
r can be obtained by direct calculationHe3The resistance value of (2).
The remaining resistances cannot be directly calculated and need further simplification. In this embodiment, different voltage excitation signals are applied to the tower body, corresponding circuit currents are different, but the ground resistance parameter is not changed in different excitation states, so that the resistance R calculated by using the first set of measured current data or the second set of measured current data can be usedH、REThe resistance value of (a) can participate in the operation of the above equation, and then can be further solved. When the parallel resistance of the far-end multi-stage tower is negligible (Δ R ═ 0), the voltage of the node (c) of the mesh can be simplified as follows: I.C. A32×(RH3+RE3)＝E3. Due to E3Known as RH2、RE2Can be calculated by the second group of measured current data, thereby indirectly calculating I32Further, current I31、I34Obtained by measurement, current I32Obtained by calculation, so that the current I can be calculated33(ii) a Finally, can be through E3And I33Calculate Re3＝E3/I33。
In this embodiment, based on the first set of measured current data, the second set of measured current data, and the third set of measured current dataThree sets of measured current data, which are calculated to obtain one or more RE、Re、RH、RHeThe resistance value of (1); and for the resistor with a plurality of resistance values, calculating the average value of the resistance values of the resistor as the resistance value of the resistor, thereby obtaining the numerical value of the grounding resistance of the tower grounding device.
It should be noted that, the method for calculating the grounding resistance of the tower grounding device needs to obtain the measured current data of the corresponding state in three wiring modes sequentially through conversion wiring, voltage excitation signals and measuring points, has the advantages of simple measurement and easy operation, avoids the measurement difficulty and measurement error caused by the arrangement of current poles and voltage poles in the field by a tripolar method and corresponding current lines and voltage lines, and also avoids the principle error caused by the shunt of self resistance and mutual resistance of a tower natural grounding body in a clamp meter method, thereby accurately measuring the grounding resistance of the tower grounding device.
According to the method for calculating the grounding resistance of the tower grounding device, provided by the invention, the currents of the tower grounding device are measured by adopting a non-contact current measuring unit under three wiring modes and different voltage excitation signals, so as to obtain three groups of measured current data, and the three groups of measured current data are analyzed and calculated to obtain the grounding resistance of the tower grounding device. According to the method for calculating the grounding resistance of the tower grounding device, the influence of mutual resistance is shielded in the process of measuring by adopting three wiring modes, so that the obtained grounding resistance value data of the tower grounding device is accurate, and the technical problem that the grounding resistance value measured by adopting a tripolar method or a pincerlike meter method for the tower grounding resistance is inaccurate in the prior art is solved. The grounding resistance testing device does not need field wiring in the grounding resistance measuring process of the pole tower grounding device, and the non-contact measurement enables the operation to be simple and the field implementation to be easy.
In an embodiment of the present invention, the method for calculating the grounding resistance of the tower grounding device further includes: and a power source for providing a voltage excitation signal to the tower grounding device through inductive coupling or direct contact.
It should be noted that the power source is also referred to as a voltage excitation unit or an induced potential excitation unit, and is used for applying a voltage excitation signal with sufficient energy to the tower grounding device through inductive coupling or direct contact.
It should be noted that, the power source (voltage excitation source) induces a larger current signal in the measurement loop by reducing the frequency of the excitation signal and using the power amplification circuit, and the frequency is between 50Hz and 1kHz, so that the power frequency can be avoided, the measurement result can be closer to the power frequency, and the power frequency equivalence of the measurement result is improved. The power source also has a power amplification function, the energy of the induction signal is greatly improved through power amplification in the measurement process of the tower grounding device, the measurement current with the magnitude of more than 10mA is induced in the measurement loop, and the signal-to-noise ratio is improved. In the embodiment, the power source has a direct output mode and a coupling output mode, the output frequency range is 50 Hz-1 kHz, the maximum output current level is 300mA, and the power source in the coupling output mode has a large-caliber jaw, so that the requirement of applying induced potential on a tower metal framework is met.
In an embodiment of the invention, the method for calculating the grounding resistance of the tower grounding device further comprises a current measuring unit for measuring the current of the tower grounding device by using the exciting jaw sleeve at the metal part of the tower framework.
It should be noted that the current measuring unit is used for measuring the current of the tower grounding device, the current measuring unit measures the current of the down conductor by using a split-core ammeter tester, the current measuring unit further forms a closed loop by using an air-core coil to surround the tower body or the tower legs, and the current measuring unit obtains the current of the tower body by measuring the current flowing through the air-core coil in the closed loop. The current measuring unit is an induced current measuring unit and is used for measuring induced currents at different positions of the tower grounding device, and the tower grounding device has high enough sensitivity and has the capability of resisting field interference. The current measuring unit is provided with a jaw with an iron core and an air coil. The current measuring unit is measuring equipment of a non-contact measuring mode, and a jaw with an iron core and an air coil are arranged on the measuring equipment. The air-core coil is a flexible Rogowski coil and is used for measuring the current of the metal framework. A current measuring unit with a jaw is used for measuring the current of the down conductor branch. In this embodiment, since the sectional areas of the tower body and the tower legs in the tower framework are large, the current measuring unit needs to use a flexible rogowski coil to surround the tower body or the tower legs to form a closed loop for measuring the current flowing through the closed loop; furthermore, in order to improve the current measurement accuracy, several turns may be wound, and the measurement result is divided by the number of turns to obtain a current value. The jaw is provided with the triple magnetic shielding layers, so that co-frequency interference in the voltage jaw and electromagnetic interference in an external environment can be effectively isolated or weakened, and the accuracy of measured data is improved. Most of the existing clamp meters do not use a shielding layer or only use one layer of shielding, the flow jaw is very easily influenced by an external electromagnetic field in actual measurement, and particularly when the current jaw is close to a voltage jaw, the coupled interference can seriously distort an induction signal. The jaw in the voltage measuring unit of the embodiment of the application adopts the design of multiple shielding layers, so that the co-channel interference in the voltage jaw and the electromagnetic interference in the external environment can be effectively isolated or weakened. However, materials with high magnetic permeability are used for obtaining high shielding performance, saturation is easy to occur in a strong magnetic field environment of a power transmission line, materials which are not easy to saturate are selected, the magnetic permeability is low, and the shielding requirement cannot be met. In order to solve the contradiction, a triple magnetic shielding layer structure is adopted, and particularly, a first magnetic shielding layer is made of a high-saturation magnetic flux low-magnetic permeability material and attenuates the intensity of interfering magnetic field to a lower level; the second magnetic shielding layer is made of a low saturation magnetic flux high magnetic permeability material and plays a main shielding role. The third layer adopts a high-conductivity layer for realizing electric field shielding. The smaller the resistance of the shielding material is, the larger the eddy current generated is, the larger the diamagnetic field is, and the better the shielding effect is. Meanwhile, the good conductor has larger reflection loss to the low-frequency electric field. The shielding layers are respectively connected with different grounds, and air needs to be separated or other insulating media need to be filled between the shielding layers.
The second embodiment:
the embodiment of the invention also provides a grounding resistance calculating device of the tower grounding device, which is applied to a transmission tower, the grounding resistance measuring device is adopted to test the current of the tower grounding device, the tower grounding device comprises a tower framework, the tower framework at least comprises four tower feet and a tower body, the grounding resistance calculating device of the tower grounding device comprises a measuring wiring unit, a current measuring unit and an analyzing and calculating unit, and the current measuring unit comprises a first measuring subunit, a second measuring subunit and a third measuring subunit;
the measurement wiring unit is used for selecting one tower foot of the tower grounding device as a measurement point, grounding wires of the other three tower feet of the tower grounding device are disconnected with the tower framework, the grounding wires of the four tower feet are connected to form a down lead, and the tower grounding device and the grounding resistance testing device form a multi-port network;
the current measuring unit is used for applying different voltage excitation signals on a tower body of a tower framework through a power source in three wiring modes, and measuring the current of the tower grounding device by adopting the current measuring unit to obtain three groups of measured current data;
the analysis and calculation unit is used for analyzing and calculating the grounding resistance of the two tower grounding devices according to the three groups of measured current data, and taking the average value of the grounding resistances of the two tower grounding devices as the grounding resistance of the tower grounding device;
the first measuring subunit is used for short-circuiting the down conductor with one tower body in a first wiring mode, applying a first voltage excitation signal to the tower body, and measuring the current of the down conductor, the current of the tower body above the down conductor, the current of the tower body below the down conductor and the currents of the other three tower bodies through the current measuring unit to obtain a first group of measured current data;
the second measuring subunit is used for applying a second power excitation potential signal between a tower body and a grounding wire of the tower foot corresponding to the measuring point in a second wiring mode, and measuring the current flowing through the down lead, the current of the tower body positioned below the down lead and the currents of the other three tower bodies through the current measuring unit to obtain a second group of measured current data;
and the third measuring subunit is used for disconnecting the down conductor from one tower body in a third wiring mode, applying a third voltage excitation signal to the tower body, and measuring the current of the tower body positioned above the down conductor and the current of the tower body positioned below the down conductor through the current measuring unit to obtain a third group of measured current data.
Preferably, R is analytically calculated from the first set of measured current dataHe1、Re1And RE1(ii) a The method specifically comprises the following steps:
Figure GDA0003642264240000201
Figure GDA0003642264240000202
Figure GDA0003642264240000203
I14＝I13-I15
in the formula, Re1Grounding resistance, R, for the natural grounding body of the towerE1As ground resistance, R, of tower earthing devicesHe1Is the equivalent mutual resistance between naturally grounded bodies, I12Measuring the current of the down conductor for a current measuring unit, I13For the current of the tower below the down conductor, I15For currents of three other towers than the tower at the measuring point, E1A voltage which is a first voltage excitation signal;
obtaining R by analyzing and calculating the second group of measured current dataH2And RE2(ii) a The method specifically comprises the following steps:
Figure GDA0003642264240000204
Figure GDA0003642264240000205
I22＝I21-I23
in the formula I23For the current of the tower below the down conductor, RE2For earthing of tower earthing devicesResistance, RH2Is the equivalent mutual resistance of the grounding device and the natural grounding body, I21For the current to flow through the down conductor, E2A voltage that excites the signal for the second voltage;
based on RH2、RE2And analyzing and calculating the third group of measured current data to obtain RHe3And Re3The method specifically comprises the following steps: re3＝E3/I33，I32×(RH2+RE2)＝E3，I33＝I31-I34-I32(ii) a In the formula, RHe3Is the equivalent mutual resistance between the natural earthed bodies, Re3Grounding resistance of natural grounding body for tower, I31For currents in the tower above the down conductor, I34Is the current of the tower body positioned below the down conductor.
In the embodiment of the present invention, the units in the second apparatus are arranged corresponding to the steps in the first method, the steps in the first method have been described in detail, and the units in the second apparatus are not described in detail again.
Example three:
the embodiment of the invention also provides a computer-readable storage medium, which is used for storing computer instructions, and when the computer instructions are run on a computer, the computer is enabled to execute the method for calculating the grounding resistance of the tower grounding device.
Example four:
the embodiment of the invention also provides a terminal device, which comprises a processor and a memory:
a memory for storing the program code and transmitting the program code to the processor;
and the processor is used for executing the grounding resistance calculation method of the tower grounding device according to the instructions in the program codes.
Illustratively, a computer program may be partitioned into one or more modules/units, which are stored in a memory and executed by a processor to accomplish the present application. One or more modules/units may be a series of computer program instruction segments capable of performing certain functions, the instruction segments being used to describe the execution of the computer program in the device.
The device may be a computing device such as a desktop computer, a notebook, a palm top computer, a cloud server, and the like. The device may include, but is not limited to, a processor, a memory. Those skilled in the art will appreciate that the device is not limited and may include more or fewer components than those shown, or some components may be combined, or different components, e.g., the device may also include input output devices, network access devices, buses, etc.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable gate array (FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage may be an internal storage unit of the computer device, such as a hard disk or a memory of the computer device. The memory may also be an external storage device of the computer device, such as a plug-in hard disk, a Smart Memory Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. provided on the computer device. Further, the memory may also include both internal storage units and external storage devices of the computer device. The memory is used for storing computer programs and other programs and data required by the computer device. The memory may also be used to temporarily store data that has been output or is to be output.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, methods and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system and method may be implemented in other ways. For example, the above-described system embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed coupling or direct coupling or communication connection between each other may be through some interfaces, indirect coupling or communication connection of systems or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in the form of hardware, or may also be implemented in the form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A method for calculating the grounding resistance of a tower grounding device is applied to a transmission tower, a grounding resistance testing device is adopted to test the current of the tower grounding device, the tower grounding device comprises a tower framework, and the tower framework at least comprises four tower feet and a tower body, and is characterized by comprising the following steps:
s1, selecting one tower foot of a tower grounding device as a measuring point, disconnecting grounding wires of the other three tower feet of the tower grounding device from a tower framework, connecting the grounding wires of the four tower feet to form a down lead, and forming a multi-port network by the tower grounding device and the grounding resistance testing device;
s2, applying different voltage excitation signals on a tower body of the tower framework through a power source in three wiring modes, and measuring the current of the tower grounding device by adopting a current measuring unit to obtain three groups of measured current data;
s3, analyzing and calculating each group of measured current data to obtain resistance parameters of the tower grounding device, and obtaining resistance value calculation average values of the corresponding parameters in different wiring modes to obtain the resistance value of the resistance of the tower grounding device;
wherein, in S2, obtaining three sets of measured current data specifically includes:
s21, in a first wiring mode, the tower body corresponding to the measuring point is in short circuit with the down lead, a first voltage excitation signal is applied to the tower body, and the current of the down lead, the current of the tower body above the down lead, the current of the tower body below the down lead and the currents of the other three tower bodies are measured through the current measuring unit to obtain a first group of measured current data;
s22, in a second wiring mode, applying a second voltage excitation signal between a tower body and a grounding wire of a tower foot corresponding to the measuring point, and measuring the current flowing through the down lead, the current of the tower body positioned below the down lead and the currents of the other three tower bodies through the current measuring unit to obtain a second group of measured current data;
and S23, in a third wiring mode, disconnecting the tower body corresponding to the measuring point from the down lead, applying a third voltage excitation signal to the tower body, and measuring the current of the tower body above the down lead and the current of the tower body below the down lead through the current measuring unit to obtain a third group of measured current data.
2. The method for calculating the grounding resistance of the tower grounding device according to claim 1, further comprising: analyzing and calculating to obtain R according to the first group of measured current dataHe1、Re1And RE1(ii) a The method specifically comprises the following steps:
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；
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；
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；
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；
in the formula, Re1Grounding resistance, R, for the natural grounding body of the towerE1As ground resistance, R, of tower earthing devicesHe1Is the equivalent mutual resistance between naturally grounded bodies, I12Measuring the current of the down conductor for a current measuring unit, I13For the current of the tower below the down conductor, I15For currents of three other towers than the tower at the measuring point, E1The voltage of the first voltage excitation signal.
3. The method for calculating the grounding resistance of the tower grounding device according to claim 1, further comprising: analyzing and calculating to obtain R according to the second group of measured current dataH2And RE2(ii) a The method specifically comprises the following steps:
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；
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；
Figure 737970DEST_PATH_IMAGE007
；
in the formula I23For the current of the tower below the down conductor, RE2As ground resistance, R, of tower earthing devicesH2Is the equivalent mutual resistance of the grounding device and the natural grounding body, I21For the current to flow through the down conductor, E2The voltage of the second voltage excitation signal.
4. The method for calculating the grounding resistance of the tower grounding device according to claim 3, further comprising: based on RH2、RE2And analyzing and calculating the third group of measured current data to obtain RHe3And Re3The method specifically comprises the following steps:
Re3=E3/I33，I32×(RH2+RE2)=E3，I33=I31-I34-I32；
in the formula, RHe3Is the equivalent mutual resistance between the natural earthed bodies, Re3Grounding resistance of natural grounding body for tower, I31For currents in the tower above the down conductor, I34For the current of the tower located below the down conductor, E3The voltage of the third voltage excitation signal.
5. The method for calculating the grounding resistance of the tower grounding device according to claim 1, further comprising: and a power source for providing a voltage excitation signal to the tower grounding device through inductive coupling or direct contact.
6. The method for calculating the grounding resistance of the tower grounding device according to claim 1, further comprising a current measuring unit for measuring the current of the tower grounding device by using an excitation jaw sleeve on a metal part of the tower framework.
7. A grounding resistance calculating device of a tower grounding device is applied to a transmission tower, and adopts a grounding resistance testing device to test the current of the tower grounding device, wherein the tower grounding device comprises a tower framework which at least comprises four tower feet and a tower body;
the measurement wiring unit is used for selecting one tower foot of the tower grounding device as a measurement point, grounding wires of the other three tower feet of the tower grounding device are disconnected with the tower framework, grounding wires of the four tower feet are connected to form a down-lead wire, and the tower grounding device and the grounding resistance testing device form a multi-port network;
the current measuring unit is used for applying different voltage excitation signals to the tower body of the tower framework through a power source in three wiring modes, and measuring the current of the tower grounding device by adopting the current measuring unit to obtain three groups of measured current data;
the analysis and calculation unit is used for analyzing and calculating each group of measured current data to obtain resistance parameters of the tower grounding device, and obtaining resistance value calculation average values of the corresponding parameters in different wiring modes to obtain the resistance values of the resistance of the tower grounding device;
the first measuring subunit is configured to short-circuit the tower body corresponding to the measuring point with the down conductor in a first connection manner, apply a first voltage excitation signal to the tower body, and measure, by the current measuring unit, a current of the down conductor, a current of the tower body located above the down conductor, a current of the tower body located below the down conductor, and currents of the remaining three tower bodies to obtain a first set of measured current data;
the second measuring subunit is configured to apply a second voltage excitation signal between a tower body and a ground line of the tower foot corresponding to the measuring point in a second connection manner, and measure, by the current measuring unit, a current flowing through the down conductor, a current of the tower body located below the down conductor, and currents of the remaining three tower bodies to obtain a second set of measured current data;
and the third measuring subunit is configured to, in a third connection mode, disconnect the tower body corresponding to the measuring point from the downlead, apply a third voltage excitation signal to the tower body, and measure, by the current measuring unit, a current of the tower body located above the downlead and a current of the tower body located below the downlead, to obtain a third set of measured current data.
8. The tower grounding device grounding resistance calculation device of claim 7, wherein R is obtained by analyzing and calculating the first set of measured current dataHe1、Re1And RE1(ii) a The method comprises the following specific steps:
Figure 272857DEST_PATH_IMAGE001
；
Figure 448623DEST_PATH_IMAGE002
；
Figure 436171DEST_PATH_IMAGE003
；
Figure 722795DEST_PATH_IMAGE004
；
in the formula, Re1Grounding resistance, R, for the natural grounding body of the towerE1As ground resistance, R, of tower earthing devicesHe1Is the equivalent mutual resistance between naturally grounded bodies, I12Measuring the current of the down conductor for a current measuring unit, I13For the current of the tower below the down conductor, I15For currents of three other towers than the tower at the measuring point, E1A voltage that excites the signal for the first voltage;
obtaining R by analyzing and calculating the second group of measured current dataH2And RE2(ii) a The method specifically comprises the following steps:
Figure 846609DEST_PATH_IMAGE005
；
Figure 193277DEST_PATH_IMAGE006
；
Figure 668121DEST_PATH_IMAGE007
；
in the formula I23For the current of the tower below the down conductor, RE2As ground resistance, R, of tower earthing devicesH2As grounding means and natureEquivalent mutual resistance of the ground body, I21For the current flowing through the down conductor, E2The voltage of the second voltage excitation signal;
based on RH2、RE2And analyzing and calculating the third group of measured current data to obtain RHe3And Re3The method specifically comprises the following steps: re3=E3/I33，I32×(RH2+RE2)=E3，I33=I31-I34-I32；
In the formula, RHe3Is the equivalent mutual resistance between the natural earthed bodies, Re3Grounding resistance of natural grounding body for tower, I31For currents in the tower above the down conductor, I34For the current of the tower located below the down conductor, E3The voltage of the third voltage excitation signal.
9. A computer-readable storage medium, characterized in that the computer-readable storage medium is used for storing computer instructions, which when run on a computer, cause the computer to perform the method for calculating the grounding resistance of a tower grounding device according to any one of claims 1 to 6.
10. A terminal device, comprising a processor and a memory:
the memory is used for storing program codes and transmitting the program codes to the processor;
the processor is used for executing the grounding resistance calculation method of the tower grounding device according to any one of claims 1-6 according to the instructions in the program code.
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