A method for measuring grounding resistance of transmission tower

Abstract

The present invention discloses a method for measuring the grounding resistance of a transmission tower. The method comprises: short-circuiting the grounding down conductors corresponding to the pole legs of the tower under test, retaining the connection between the grounding down conductor and one of the pole legs, and disconnecting the grounding down conductor from the remaining pole legs to build a test model; measuring the down conductor current value and the current value of each grounding body under a first working condition and a second working condition, and calculating the branch current of the remote multi-level grounding body; calculating the grounding resistance of the tower under test based on the down conductor current value and the current value of each grounding body under the first working condition and the second working condition, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body. The present invention builds a test model, measures the current value of each loop of the equivalent circuit under the first working condition and the second working condition, and calculates the grounding resistance of the tower under test in combination with the preset parallel equivalent resistance of the remote multi-level grounding body; thereby improving the accuracy of the grounding resistance measurement.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power supply and distribution technology, and in particular to a method for measuring the grounding resistance of a transmission tower. Background Art

[0002] As voltage levels and transmission capacity continue to increase, the requirements for measuring transmission tower grounding devices are also increasing. In traditional transmission tower grounding models, grounding is typically achieved by installing grounding bodies at the foot of each tower. Several grounding bodies work together to form a grounding grid, thereby achieving grounding of the transmission tower.

[0003] Traditional ground resistance measurement methods are based on the existing transmission tower grounding model, with a single equivalent circuit model. The primary measurement methods are the three-pole method and the clamp meter method. These two methods fail to account for the presence of soil between the tower base and the tower's metal downconductor. Due to soil's high conductivity, soil resistance can easily affect tower ground resistance measurements, causing deviations between test data and true values. The measured value cannot reflect the tower's true ground resistance. Furthermore, the three-pole method introduces significant uncertainty regarding the size of the on-site grounding device and the routing of the extended grounding wire, complicating construction and wiring. While the clamp meter method simplifies wiring, the measured resistance is the loop resistance, not the tower ground resistance. Summary of the Invention

[0004] The present invention provides a method for measuring the grounding resistance of a transmission tower, so as to improve the measurement accuracy of the grounding resistance of the transmission tower.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for measuring the grounding resistance of a transmission tower, comprising:

[0007] Short-circuit the grounding down conductors corresponding to the pole legs of the tower under test, retain the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs;

[0008] The down conductor current value corresponding to the current flowing through the grounding down conductor and the grounding body current value corresponding to the current flowing through the natural grounding body of each pole foot are measured respectively under a first operating condition and a second operating condition, and the branch current of the remote multi-level grounding body connected to the measured tower is calculated based on the down conductor current value and each grounding body current value under the first operating condition and the second operating condition respectively; wherein, under the first operating condition, an excitation voltage source is applied to the short-circuited node of the grounding lead, and under the second operating condition, a voltage source is applied to the tower body of the transmission tower;

[0009] The grounding resistance of the measured tower is calculated based on the down conductor current value under the first working condition and the second working condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body.

[0010] Optionally, the method of measuring the down conductor current value corresponding to the current flowing through the grounding down conductor under the first operating condition and the second operating condition, and measuring the grounding body current value corresponding to the current flowing through the natural grounding body of each pole foot, and calculating the branch current of the remote multi-level grounding body connected to the measured tower according to the down conductor current value and each grounding body current value under the first operating condition and the second operating condition, respectively, includes:

[0011] Under the first operating condition, a first down conductor current value flowing through the short-circuited node of the grounding down conductor, a current flowing through a pole foot connected to the grounding down conductor are measured as a first grounding body current value, and a natural grounding body current of each of the remaining pole feet are measured as a second grounding body current value; and a first branch current of a remote multi-level grounding body connected to the measured tower under the first operating condition is calculated based on the first down conductor current value, the first grounding body current value, and the second grounding body current value;

[0012] Under the second operating condition, the second down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor is measured as the third grounding body current value, and the natural grounding body current of the remaining pole feet is measured as the fourth grounding body current value. According to the second down conductor current value, the third grounding body current value and the fourth grounding body current value, the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition is calculated.

[0013] Optionally, calculating the first branch current of the remote multi-level grounding body connected to the measured tower under the first working condition according to the first down conductor current value, the first grounding body current value, and the second grounding body current value includes calculating the first branch current using the following first branch circuit calculation formula:

[0014] I4=I1-I2-I3;

[0015] Among them, I1 represents the first down conductor current value, I2 represents the first grounding body current value, I3 represents the second grounding body current value, and I4 represents the first branch current.

[0016] Optionally, calculating the second branch current of the remote multi-level grounding body connected to the measured tower under the working condition according to the second down conductor current value, the third grounding body current value, and the fourth grounding body current value includes calculating the second branch current using the following second branch circuit calculation formula:

[0017] I8=I5+I6-I7;

[0018] Among them, I5 represents the second down conductor current value, I6 represents the third grounding body current value, I7 represents the fourth grounding body current value, and I8 represents the second branch current.

[0019] Optionally, the calculating the grounding resistance of the measured tower according to the down conductor current value under the first operating condition and the second operating condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body includes:

[0020] Determining the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body;

[0021] Analytically obtaining the grounding resistance of the measured tower according to the first KVL equation satisfied under the first working condition and the second KVL equation satisfied under the second working condition;

[0022] The first KVL equation includes:

[0023]

[0024]

[0025]

[0026] The second KVL equation includes:

[0027] U2=I7R5+I6R4,

[0028]

[0029] Among them, U1 represents the voltage of the excitation voltage source under the first working condition, U2 represents the voltage of the excitation voltage source under the second working condition, R1 is the grounding resistance of the artificial grounding body corresponding to the grounding down conductor, R2 is the grounding resistance of the natural grounding body of the pole foot connected to the grounding down conductor; R3 is the mutual resistance between the artificial grounding body and the natural grounding body; R4 is the equivalent resistance of the pole foot connected to the grounding down conductor; R5 is the equivalent resistance of the remaining pole feet of the measured tower; R6 is the parallel equivalent resistance of the remote multi-level grounding body.

[0030] Optionally, determining the final parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body includes:

[0031] The parallel equivalent resistance of the remote multi-level grounding body is determined by using a preset empirical value of the parallel equivalent resistance of the remote multi-level grounding body.

[0032] Optionally, determining the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body includes:

[0033] Finding an optimal solution for the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body;

[0034] The optimal solution of the parallel equivalent resistance of the remote multi-level grounding body is determined as the parallel equivalent resistance of the remote multi-level grounding body.

[0035] Optionally, the finding of an optimal solution for the parallel equivalent resistance of the remote multi-level grounding body includes:

[0036] Step 1: Presetting an initial value of the parallel equivalent resistance of the remote multi-level grounding body;

[0037] Step 2: Input the voltage of the excitation voltage source under the first working condition, the first down conductor current value, the first grounding body current value, the second grounding body current value, the first branch current, and the voltage of the excitation voltage source under the second working condition, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, the second branch current, and the initial value of the parallel equivalent resistance of the remote multi-level grounding body into the corresponding first branch current calculation formula, the second branch current calculation formula, the first KVL equation, and the second KVL equation to obtain an intermediate analytical value of the grounding resistance of the measured tower;

[0038] Step 3: inputting the intermediate analytical value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor in the intermediate analytical value of the grounding resistance of the measured tower, the voltage of the excitation voltage source under the first working condition, the first down conductor current value, the first grounding body current value, the second grounding body current value, the first branch current, and the voltage of the excitation voltage source under the second working condition, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, and the second branch current into the corresponding first branch current calculation formula, the second branch current calculation formula, the first KVL equation, and the second KVL equation to obtain the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body;

[0039] Step 4: updating the initial value of the parallel equivalent resistance of the remote multi-level grounding body to the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body, and calculating the loss function. When the loss function is greater than or equal to the set threshold, returning to step 2, and continuing to perform the subsequent steps of step 2 until the loss function is less than the set threshold;

[0040] Step 5: determining an intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body when the loss function is less than the set threshold as the parallel equivalent resistance of the remote multi-level grounding body;

[0041] Among them, the loss function is the error mean change between the predicted value and the true value of the grounding resistance of the artificial grounding body corresponding to the grounding lead between the parallel equivalent resistance values ​​of each of the remote multi-level grounding bodies. The parallel equivalent resistance value of the remote multi-level grounding body includes the initial value of the parallel equivalent resistance of the remote multi-level grounding body and the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body.

[0042] Optionally, before presetting the initial value of the parallel equivalent resistance of the remote multi-level grounding body, the method further includes:

[0043] Setting the value range and value difference of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor;

[0044] The true value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor is determined based on the voltage of the excitation voltage source, the first down conductor current value, the first grounding body current value, the second grounding body current value, and the first branch current under the first working condition when the grounding resistance of the artificial grounding body of the grounding down conductor takes different values, and the voltage of the excitation voltage source, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, and the second branch current under the second working condition.

[0045] Optionally, the excitation voltage source is applied by voltage coupling.

[0046] The technical solution of the embodiment of the present invention is to build a test model by short-circuiting the grounding down conductors corresponding to the pole legs of the measured tower on the basis of the existing transmission tower grounding model, retaining the connection between the grounding down conductor and one of the pole legs and disconnecting the grounding down conductor from the remaining pole legs, and converting it into an equivalent circuit model that can be calculated. An excitation voltage source is applied to the short-circuited node of the grounding lead as a first working condition, and a voltage source is applied to the tower body of the transmission tower as a second working condition. The current values ​​of each loop of the equivalent circuit under the first working condition and the second working condition are measured respectively, and the grounding resistance of the measured tower is calculated in combination with the parallel equivalent resistance of the preset remote multi-level grounding body; thus, the operation is made simpler and the accuracy of the grounding resistance measurement is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of a method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention;

[0048] Figure 2 This is a schematic structural diagram of a transmission tower grounding resistance measurement model provided by an embodiment of the present invention;

[0049] Figure 3 Schematic diagram of a grounding resistance equivalent circuit model of a transmission tower provided by an embodiment of the present invention;

[0050] Figure 4 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention;

[0051] Figure 5 Schematic diagram of a grounding resistance equivalent circuit model of a transmission tower under a first operating condition provided by an embodiment of the present invention;

[0052] Figure 6 is a schematic diagram of an equivalent circuit model of the grounding resistance of a transmission tower under a second working condition provided by an embodiment of the present invention;

[0053] Figure 7 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention;

[0054] Figure 8 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention;

[0055] Figure 9 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention;

[0056] Figure 10 This is a flow chart for finding an optimal solution for the parallel equivalent resistance of remote multi-level grounding bodies provided by an embodiment of the present invention.

[0057] In the picture:

[0058] Pole tower 11, pole foot 12, grounding down conductor 13, first cement pier A, second cement pier B, third cement pier C, fourth cement pier D. DETAILED DESCRIPTION

[0059] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0060] An embodiment of the present invention provides a method for measuring the grounding resistance of a transmission tower. The method is applicable to measuring the grounding resistance of a transmission tower. Figure 1 This is a flow chart of a method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention. Figure 1 , the method comprising:

[0061] S101. Short-circuit the grounding down conductors corresponding to the pole legs of the measured tower, keep the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs.

[0062] Specifically, Figure 2 This is a schematic diagram of a transmission tower grounding resistance measurement model provided by an embodiment of the present invention. Figure 2 The tower 11 can have four cement piers connected to the pole foot 12: the first cement pier A, the second cement pier B, the third cement pier C, and the fourth cement pier D. A grounding down conductor 13 is connected to the pole foot 12. The grounding down conductor can be a metal conductor that connects electrical equipment to the grounding body. The grounding body can be a metal conductor buried below the ground and directly in contact with the soil. It can be divided into natural grounding bodies and artificial grounding bodies. Natural grounding bodies can be metal conductors that are directly in contact with the earth and are used as grounding for components, equipment, etc.; artificial grounding bodies can be metal conductors buried in the ground specifically for grounding. R6 is the parallel equivalent resistance of the remote multi-level grounding bodies, that is, the parallel equivalent resistance of the grounding resistance of the multi-base tower connected in parallel with the measured tower 11. Short-circuit the grounding down conductors corresponding to each pole foot of the measured tower, keep the grounding down conductor connected to one pole foot, and disconnect the grounding down conductor from the remaining pole feet to build a transmission tower grounding resistance measurement model. Compared with the traditional three-pole method, the model construction of this solution has a simpler wiring method and is easier to operate. Figure 3 This is a schematic diagram of an equivalent circuit model of the grounding resistance of a transmission tower provided by an embodiment of the present invention. According to the grounding resistance measurement model of the transmission tower, it can be obtained Figure 3 The equivalent circuit model of the grounding resistance of the transmission tower shown in Figure 3 , R1 is the grounding resistance of the artificial grounding body corresponding to the grounding down conductor 13, R2 is the grounding resistance of the natural grounding body of the pole foot 12 connected to the grounding down conductor 13; R3 is the mutual resistance between the artificial grounding body and the natural grounding body, that is, the soil resistance; R4 is the equivalent resistance of the first cement pier A of the pole foot 12 connected to the grounding down conductor 13; R5 is the equivalent resistance of the cement piers of the remaining pole feet 12 of the tower 11, the second cement pier B, the third cement pier C, and the fourth cement pier D; R6 is the parallel equivalent resistance of the remote multi-level grounding body connected to the tower 11 under test.

[0063] S102. Measure the down conductor current value corresponding to the current flowing through the grounding down conductor under the first operating condition and the second operating condition, and measure the grounding body current value corresponding to the current flowing through the natural grounding body of each pole foot, and calculate the branch current of the remote multi-level grounding body connected to the measured tower according to the down conductor current value and the grounding body current value under the first operating condition and the second operating condition, respectively; wherein, under the first operating condition, an excitation voltage source is applied to the short-circuit node of the grounding lead, and under the second operating condition, a voltage source is applied to the tower body of the transmission tower.

[0064] Specifically, an excitation voltage source is applied based on the actual location of the excitable point on site. In the first operating condition, the excitation voltage source can be applied to the short-circuited node of the ground lead, while in the second operating condition, the voltage source can be applied to the body of the transmission tower. The current values ​​of each equivalent circuit loop are measured under the first and second operating conditions. For example, a Rogowski coil can be used to directly measure the current in each loop of the equivalent circuit. A Rogowski coil, also known as a current measurement coil or differential current sensor, is a toroidal coil uniformly wound around a non-ferromagnetic material.

[0065] S103, calculating the grounding resistance of the measured tower according to the down conductor current value under the first working condition and the second working condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body.

[0066] Specifically, the measured down conductor current values ​​under the first working condition and the second working condition, the current values ​​of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body are substituted into the formula of the analytical algorithm to calculate the grounding resistance of the measured tower, where the analytical algorithm may include the KVL equations satisfied under the first working condition and the second working condition respectively.

[0067] The technical solution of this embodiment is to build a test model by short-circuiting the grounding down conductors corresponding to the pole legs of the measured tower on the basis of the existing transmission tower grounding model, retaining the connection between the grounding down conductor and one of the pole legs and disconnecting the grounding down conductor from the remaining pole legs, and thus converting it into an equivalent circuit model that can be calculated. An excitation voltage source is applied to the short-circuited node of the grounding lead as a first working condition, and a voltage source is applied to the tower body of the transmission tower as a second working condition. The current values ​​of each equivalent circuit loop under the first working condition and the second working condition are measured respectively, and the grounding resistance of the measured tower is calculated in combination with the preset parallel equivalent resistance of the remote multi-level grounding body. Compared with the traditional three-pole method, the wiring method is simplified, the operation is simpler, and the accuracy of the test results is improved.

[0068] Figure 4 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention. Figure 4 Optionally, the method for measuring the grounding resistance of a transmission tower provided in this embodiment includes:

[0069] S201. Short-circuit the grounding down conductors corresponding to the pole legs of the measured tower, keep the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs.

[0070] S202. Under the first operating condition, measure the first down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the first grounding body current value, and the natural grounding body current of the remaining pole feet as the second grounding body current value; and calculate the first branch current of the remote multi-level grounding body connected to the measured tower under the first operating condition based on the first down conductor current value, the first grounding body current value and the second grounding body current value.

[0071] Specifically, Figure 5 is a schematic diagram of an equivalent circuit model of the grounding resistance of a transmission tower under the first working condition provided by an embodiment of the present invention, see Figure 5 , I1 represents the current value of the first down conductor, I2 represents the current value of the first grounding body, I3 represents the current value of the second grounding body, and I4 represents the current of the first branch. The calculation formula for the current of the first branch can be:

[0072] I4=I1-I2-I3 (1).

[0073] S203. Under the second operating condition, measure the current value of the second down conductor flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the third grounding body current value, and the natural grounding body current of the remaining pole feet as the fourth grounding body current value; and calculate the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition based on the second down conductor current value, the third grounding body current value and the fourth grounding body current value.

[0074] Specifically, Figure 6 is a schematic diagram of the equivalent circuit model of the grounding resistance of a transmission tower under the second working condition provided by an embodiment of the present invention, see Figure 6 , I5 represents the current value of the second down conductor, I6 represents the current value of the third grounding body, I7 represents the current value of the fourth grounding body, and I8 represents the second branch current; the calculation formula for the second branch current can be:

[0075] I8=I5+I6-I7 (2).

[0076] S204 , calculating the grounding resistance of the tower under test according to the down conductor current value under the first working condition and the second working condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body.

[0077] Figure 7 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention. Figure 7 Optionally, the method for measuring the grounding resistance of a transmission tower provided in this embodiment includes:

[0078] S301. Short-circuit the grounding down conductors corresponding to the pole legs of the measured tower, keep the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs.

[0079] S302. Under the first operating condition, measure the first down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the first grounding body current value, and the natural grounding body current of the remaining pole feet as the second grounding body current value; and calculate the first branch current of the remote multi-level grounding body connected to the measured tower under the first operating condition based on the first down conductor current value, the first grounding body current value and the second grounding body current value.

[0080] S303. Under the second operating condition, measure the current value of the second down conductor flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the third grounding body current value, and the natural grounding body current of the remaining pole feet as the fourth grounding body current value; and calculate the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition based on the second down conductor current value, the third grounding body current value and the fourth grounding body current value.

[0081] S304: Determine the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body.

[0082] Specifically, according to the preset parallel equivalent resistance of the remote multi-level grounding body, an appropriate parallel equivalent resistance of the remote multi-level grounding body is determined through an iterative algorithm.

[0083] S305 , analytically obtaining the grounding resistance of the measured tower according to the first KVL equation satisfied under the first working condition and the second KVL equation satisfied under the second working condition.

[0084] Specifically, U1 represents the voltage of the excitation voltage source under the first working condition, U2 represents the voltage of the excitation voltage source under the second working condition, R1 is the grounding resistance of the artificial grounding body corresponding to the grounding down conductor, R2 is the grounding resistance of the natural grounding body of the pole foot connected to the grounding down conductor; R3 is the mutual resistance between the artificial grounding body and the natural grounding body; R4 is the equivalent resistance of the pole foot connected to the grounding down conductor; R5 is the equivalent resistance of the remaining pole feet of the measured tower; R6 is the parallel equivalent resistance of the remote multi-level grounding bodies.

[0085] The first KVL equation includes:

[0086]

[0087]

[0088]

[0089] The second KVL equation includes:

[0090] U2=I7R5+I6R4 (6),

[0091]

[0092] Formulas (3) to (7) can be formulas of analytical algorithms.

[0093] Figure 8 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention. Figure 8 Optionally, the method for measuring the grounding resistance of a transmission tower provided in this embodiment includes:

[0094] S401. Short-circuit the grounding down conductors corresponding to the pole legs of the measured tower, keep the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs.

[0095] S402. Under the first operating condition, measure the first down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the first grounding body current value, and the natural grounding body current of the remaining pole feet as the second grounding body current value; and calculate the first branch current of the remote multi-level grounding body connected to the measured tower under the first operating condition based on the first down conductor current value, the first grounding body current value and the second grounding body current value.

[0096] S403. Under the second operating condition, measure the current value of the second down conductor flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the third grounding body current value, and the natural grounding body current of the remaining pole feet as the fourth grounding body current value; and calculate the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition based on the second down conductor current value, the third grounding body current value and the fourth grounding body current value.

[0097] S404: Determine a preset empirical value of the parallel equivalent resistance of the remote multi-level grounding body as the parallel equivalent resistance of the remote multi-level grounding body.

[0098] Specifically, the parallel equivalent resistance R6 of the remote multi-base grounding body is the parallel equivalent resistance of the grounding resistance of the multi-level tower, and R6 corresponding to each tower can take the same value; the preset parallel equivalent resistance of the remote multi-level grounding body can be set according to experience. For example, the preset parallel equivalent resistance of the remote multi-level grounding body can be 1Ω.

[0099] S405 , analytically obtaining the grounding resistance of the measured tower according to the first KVL equation satisfied under the first working condition and the second KVL equation satisfied under the second working condition.

[0100] Figure 9 This is a flow chart of another method for measuring the grounding resistance of a transmission tower provided by an embodiment of the present invention. Figure 9 Optionally, the method for measuring the grounding resistance of a transmission tower provided in this embodiment includes:

[0101] S501. Short-circuit the grounding down conductors corresponding to the pole legs of the measured tower, keep the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs.

[0102] S502. Under the first operating condition, measure the first down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the first grounding body current value, and the natural grounding body current of the remaining pole feet as the second grounding body current value; and calculate the first branch current of the remote multi-level grounding body connected to the measured tower under the first operating condition based on the first down conductor current value, the first grounding body current value, and the second grounding body current value.

[0103] S503. Under the second operating condition, measure the current value of the second down conductor flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor as the third grounding body current value, and the natural grounding body current of the remaining pole feet as the fourth grounding body current value; and calculate the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition based on the second down conductor current value, the third grounding body current value and the fourth grounding body current value.

[0104] S504 : Finding an optimal solution for the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body.

[0105] Specifically, the optimal solution of the parallel equivalent resistance of the remote multi-level grounding body is calculated by substituting the preset parallel equivalent resistance of the remote multi-level grounding body into the iterative algorithm.

[0106] For example, take a line with 20 towers as an example. Figure 10 This is a flowchart of an optimal solution for finding the parallel equivalent resistance of remote multi-level grounding bodies provided by an embodiment of the present invention. Figure 10 , optionally, a method for finding an optimal solution for the parallel equivalent resistance of remote multi-level grounding bodies, comprising:

[0107] S5041: Preset the initial value of the parallel equivalent resistance of the remote multi-level grounding body.

[0108] Specifically, the initial value of the parallel equivalent resistance of the remote multi-level grounding body may be preset as 1Ω based on an empirical value.

[0109] S5042: Input the voltage of the excitation voltage source under the first working condition, the current value of the first down conductor, the current value of the first grounding body, the current value of the second grounding body, the first branch current, and the voltage of the excitation voltage source under the second working condition, the current value of the second down conductor, the current value of the third grounding body, the current value of the fourth grounding body, the second branch current, and the initial value of the parallel equivalent resistance of the remote multi-level grounding body into the corresponding first branch current calculation formula, second branch current calculation formula, first KVL equation and second KVL equation to obtain the intermediate analytical value of the grounding resistance of the measured tower.

[0110] Specifically, the known U1~U2, I1~I8, and the initial value R6=1Ω of the parallel equivalent resistance of the remote multi-level grounding body are input into formulas (3) to (7), that is, the analytical algorithm, to obtain the intermediate analytical value of the grounding resistance of the measured tower, that is, the value of R1~R5 of each tower.

[0111] S5043: The intermediate analytical value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor in the intermediate analytical value of the grounding resistance of the measured tower, the voltage of the excitation voltage source under the first working condition, the current value of the first down conductor, the current value of the first grounding body, the current value of the second grounding body, the first branch current, and the first branch current calculation formula, the second branch current calculation formula, the first KVL equation and the second KVL equation corresponding to the voltage of the excitation voltage source under the second working condition, the current value of the second down conductor, the current value of the third grounding body, the fourth grounding body current and the second branch current input are used to obtain the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body.

[0112] Specifically, the values ​​of R1 and R2 output by the iterative algorithm, as well as the known values ​​of U1~U2, I1~I8 are input into formulas (3) to (7) again, that is, the analytical algorithm is used for calculation to obtain the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body, that is, the new value of R6.

[0113] S50441: Update the initial value of the parallel equivalent resistance of the remote multi-level grounding body to the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body, and calculate the loss function.

[0114] Specifically, the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body obtained by the iterative algorithm is used as the new parallel equivalent resistance R6 of the remote multi-level grounding body. The intermediate analytical value of the grounding resistance of the measured tower, that is, the value of R1 to R5 of each tower, is compared with the intermediate analytical value of the grounding resistance of the measured tower output by the previous round of iterative algorithm to calculate the loss function.

[0115] S50442: Determine whether the loss function is less than the set threshold. If so, continue to execute S5045; if not, return to S5042 and continue to execute the subsequent steps of S5042 until the loss function is less than the set threshold.

[0116] Specifically, determine whether the loss function is less than a set threshold. The set threshold can be set as needed. For example, the change in the mean analytical error of R1 is less than 0.5%; if the loss function is less than the set threshold, continue to execute step S5045; if the loss function is greater than or equal to the set threshold, return to step S5042, and continue to execute the subsequent steps of step S5042 until the loss function is less than the set threshold.

[0117] For example, the data obtained from the simulation circuit when R1 is 2.9Ω is input into the analytical algorithm for iteration. The intermediate analytical value of the grounding resistance of the measured tower obtained from the first iteration is compared with R1 of 2.9Ω. The obtained data are shown in the following table:

[0118]

[0119] As can be seen from the table above, when the fourth iteration is reached, the mean change in the analytical error of R1 for 20 towers is less than 0.5%, but the data error of the fifth iteration is even smaller and the data is more accurate. The data of the sixth iteration is consistent with the data of the fifth iteration. Therefore, when the fifth iteration is reached, the error is basically stable, and the solution of the fifth iteration is taken as the optimal solution for R6.

[0120] S5045: Determine the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body when the loss function is less than the set threshold as the parallel equivalent resistance of the remote multi-level grounding body; wherein, the loss function is the average change in the error between the predicted value and the true value of the grounding resistance of the artificial grounding body corresponding to the grounding down lead between the parallel equivalent resistance values ​​of each remote multi-level grounding body, and the parallel equivalent resistance value of the remote multi-level grounding body includes the initial value of the parallel equivalent resistance of the remote multi-level grounding body and the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body.

[0121] For example, the iteratively obtained resistance R6 of 0.1399Ω is used as the optimal parameter of the parallel equivalent resistance of the remote multi-level grounding body. The resistance values ​​of each branch of the 20-base tower are obtained by substituting it into the analytical algorithm, as shown in the following table:

[0122] Label R1(Ω) R2(Ω) R3(Ω) R4(Ω) R5(Ω) 1 2.043 99.658 152.770 29.710 33.616 2 2.143 100.046 152.356 29.711 33.617 3 2.243 99.961 151.885 29.710 33.616 4 2.343 99.944 151.467 29.710 33.616 5 2.443 100.713 151.262 29.712 33.618 6 2.543 100.299 150.823 29.711 33.617 7 2.643 100.318 150.504 29.710 33.616 8 2.743 100.860 150.335 29.712 33.618 9 2.843 100.907 150.273 29.612 33.505 10 2.943 100.628 149.749 29.711 33.617 11 3.043 100.617 149.505 29.710 33.616 12 3.143 100.705 149.305 29.711 33.617 13 3.243 100.420 149.025 29.710 33.616 14 3.343 100.570 148.863 29.710 33.616 15 3.443 100.847 148.743 29.710 33.616 16 3.543 100.860 148.572 29.710 33.616 17 3.643 101.099 148.466 29.711 33.617 18 3.743 100.984 148.285 29.711 33.617 19 3.843 100.893 148.114 29.711 33.617 20 3.943 101.000 148.001 29.711 33.617

[0123] The relative error data of R1 to R5 of 20 towers are shown in the following table:

[0124]

[0125]

[0126] As can be seen from the above table, when R6 takes the optimal solution, the errors of R1 and R2 do not exceed 2%, which is acceptable in engineering. This verifies the effectiveness of the analytical algorithm.

[0127] Continue to refer Figure 10 Optionally, before step S5041, the method further includes:

[0128] Step S10, setting a value range and a value difference of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor;

[0129] Specifically, the value range of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor can be set according to the empirical value. For example, the value range of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor can be set to 2Ω~4Ω, and the value difference can be set to 0.1Ω.

[0130] Step S20, determine the true value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor according to the voltage of the excitation voltage source, the first down conductor current value, the first grounding body current value, the second grounding body current value, and the first branch current under the first working condition when the grounding resistance of the artificial grounding body of the grounding down conductor takes different values, and the voltage of the excitation voltage source, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, and the second branch current under the second working condition.

[0131] For example, when the grounding resistance of the artificial grounding body corresponding to the grounding down conductor can be set to a value range of 2Ω to 4Ω and the value difference can be set to 0.1Ω, the following table can be obtained:

[0132]

[0133]

[0134] Specifically, based on soil environmental parameters, when the resistivity is 50 Ω·m, the grounding resistance of the artificial grounding body corresponding to the grounding conductor is 2.9 Ω. R1, 2.9 Ω, is taken as the true value of the grounding resistance of the artificial grounding body. Substituting the voltage and current values ​​corresponding to the grounding resistance of the artificial grounding body corresponding to the grounding conductor into the analytical algorithm yields the following values ​​for R1 to R6: R1 is 2.9 Ω, R2 is 102.465 Ω, R3 is 84.87 Ω, R4 is 29.705 Ω, R5 is 33.61 Ω, and R6 is 0.084 Ω. These values ​​are input as circuit simulation parameters into Multisim for simulation, verifying the accuracy of the analytical algorithm.

[0135] S505: Determine the optimal solution of the parallel equivalent resistance of the remote multi-level grounding body as the parallel equivalent resistance of the remote multi-level grounding body.

[0136] Specifically, determining the optimal solution of the parallel equivalent resistance of the remote multi-level grounding body as the parallel equivalent resistance of the remote multi-level grounding body can make the measurement result of the transmission tower grounding resistance measurement model more accurate.

[0137] S506 , analytically obtaining the grounding resistance of the measured tower according to the first KVL equation satisfied under the first working condition and the second KVL equation satisfied under the second working condition.

[0138] Optionally, the excitation voltage source is applied by voltage coupling.

[0139] Specifically, each equivalent circuit loop shares an excitation voltage source, that is, the excitation voltage source is applied through voltage coupling.

[0140] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for measuring the grounding resistance of a transmission tower, characterized in that: include: Short-circuit the grounding down conductors corresponding to the pole legs of the tower under test, retain the connection between the grounding down conductor and one of the pole legs, and disconnect the grounding down conductor from the remaining pole legs; The down conductor current value corresponding to the current flowing through the grounding down conductor and the grounding body current value corresponding to the current flowing through the natural grounding body of each pole foot are measured respectively under a first operating condition and a second operating condition, and the branch current of the remote multi-level grounding body connected to the measured tower is calculated based on the down conductor current value and each grounding body current value under the first operating condition and the second operating condition respectively; wherein, under the first operating condition, an excitation voltage source is applied to the short-circuited node of the grounding lead, and under the second operating condition, the excitation voltage source is applied to the tower body of the transmission tower; The grounding resistance of the measured tower is calculated based on the down conductor current value under the first working condition and the second working condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body.

2. The method for measuring the grounding resistance of a transmission tower according to claim 1, wherein: The method comprises measuring the down conductor current value corresponding to the current flowing through the grounding down conductor under the first working condition and the second working condition, and measuring the grounding body current value corresponding to the current flowing through the natural grounding body of each pole foot, and calculating the branch current of the remote multi-level grounding body connected to the measured tower based on the down conductor current value and each grounding body current value under the first working condition and the second working condition, respectively. Under the first operating condition, a first down conductor current value flowing through the short-circuited node of the grounding down conductor, a current flowing through a pole foot connected to the grounding down conductor are measured as a first grounding body current value, and a natural grounding body current of each of the remaining pole feet are measured as a second grounding body current value; and a first branch current of a remote multi-level grounding body connected to the measured tower under the first operating condition is calculated based on the first down conductor current value, the first grounding body current value, and the second grounding body current value; Under the second operating condition, the second down conductor current value flowing through the short-circuit node of the grounding down conductor, the current flowing through the pole foot connected to the grounding down conductor is measured as the third grounding body current value, and the natural grounding body current of the remaining pole feet is measured as the fourth grounding body current value. According to the second down conductor current value, the third grounding body current value and the fourth grounding body current value, the second branch current of the remote multi-level grounding body connected to the measured tower under the operating condition is calculated.

3. The method for measuring the grounding resistance of a transmission tower according to claim 2, wherein: Calculating the first branch current of the remote multi-level grounding body connected to the measured tower under the first working condition according to the first down conductor current value, the first grounding body current value, and the second grounding body current value includes calculating the first branch current using the following first branch circuit calculation formula: I4=I1-I2-I3; Among them, I1 represents the first down conductor current value, I2 represents the first grounding body current value, I3 represents the second grounding body current value, and I4 represents the first branch current.

4. The method for measuring the grounding resistance of a transmission tower according to claim 3, wherein: The second branch current of the remote multi-level grounding body connected to the measured tower under the working condition is calculated according to the second down conductor current value, the third grounding body current value, and the fourth grounding body current value, including using the following second branch circuit calculation formula to calculate the second branch current: I8=I5+I6-I7; Among them, I5 represents the second down conductor current value, I6 represents the third grounding body current value, I7 represents the fourth grounding body current value, and I8 represents the second branch current.

5. The method for measuring the grounding resistance of a transmission tower according to claim 4, wherein: The calculating the grounding resistance of the measured tower according to the down conductor current value under the first working condition and the second working condition, the current value of each grounding body, the branch current of the remote multi-level grounding body, and the preset parallel equivalent resistance of the remote multi-level grounding body includes: Determining the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body; Analytically obtaining the grounding resistance of the measured tower according to the first KVL equation satisfied under the first working condition and the second KVL equation satisfied under the second working condition; The first KVL equation includes: The second KVL equation includes: U2=I7R5+I6R4, Among them, U1 represents the voltage of the excitation voltage source under the first working condition, U2 represents the voltage of the excitation voltage source under the second working condition, R1 is the grounding resistance of the artificial grounding body corresponding to the grounding down conductor, R2 is the grounding resistance of the natural grounding body of the pole foot connected to the grounding down conductor; R3 is the mutual resistance between the artificial grounding body and the natural grounding body; R4 is the equivalent resistance of the pole foot connected to the grounding down conductor; R5 is the equivalent resistance of the remaining pole feet of the measured tower; R6 is the parallel equivalent resistance of the remote multi-level grounding body.

6. The method for measuring the grounding resistance of a transmission tower according to claim 5, characterized in that: The determining the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body includes: The preset empirical value of the parallel equivalent resistance of the remote multi-level grounding body is determined as the parallel equivalent resistance of the remote multi-level grounding body.

7. The method for measuring the grounding resistance of a transmission tower according to claim 5, wherein: The determining the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body includes: Finding an optimal solution for the parallel equivalent resistance of the remote multi-level grounding body according to the preset parallel equivalent resistance of the remote multi-level grounding body; The optimal solution of the parallel equivalent resistance of the remote multi-level grounding body is determined as the parallel equivalent resistance of the remote multi-level grounding body.

8. The method for measuring the grounding resistance of a transmission tower according to claim 7, wherein: The step of finding an optimal solution for the parallel equivalent resistance of the remote multi-level grounding body includes: Step 1: Presetting an initial value of the parallel equivalent resistance of the remote multi-level grounding body; Step 2: Input the voltage of the excitation voltage source under the first working condition, the first down conductor current value, the first grounding body current value, the second grounding body current value, the first branch current, and the voltage of the excitation voltage source under the second working condition, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, the second branch current, and the initial value of the parallel equivalent resistance of the remote multi-level grounding body into the corresponding first branch current calculation formula, the second branch current calculation formula, the first KVL equation, and the second KVL equation to obtain an intermediate analytical value of the grounding resistance of the measured tower; Step 3: inputting the intermediate analytical value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor in the intermediate analytical value of the grounding resistance of the measured tower, the voltage of the excitation voltage source under the first working condition, the first down conductor current value, the first grounding body current value, the second grounding body current value, the first branch current, and the voltage of the excitation voltage source under the second working condition, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, and the second branch current into the corresponding first branch current calculation formula, the second branch current calculation formula, the first KVL equation, and the second KVL equation to obtain the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body; Step 4: updating the initial value of the parallel equivalent resistance of the remote multi-level grounding body to the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body, and calculating the loss function. When the loss function is greater than or equal to the set threshold, returning to step 2, and continuing to perform the subsequent steps of step 2 until the loss function is less than the set threshold; Step 5: determining an intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body when the loss function is less than the set threshold as the parallel equivalent resistance of the remote multi-level grounding body; Among them, the loss function is the error mean change between the predicted value and the true value of the grounding resistance of the artificial grounding body corresponding to the grounding lead between the parallel equivalent resistance values ​​of each of the remote multi-level grounding bodies. The parallel equivalent resistance value of the remote multi-level grounding body includes the initial value of the parallel equivalent resistance of the remote multi-level grounding body and the intermediate analytical value of the parallel equivalent resistance of the remote multi-level grounding body.

9. The method for measuring the grounding resistance of a transmission tower according to claim 8, wherein: Before presetting the initial value of the parallel equivalent resistance of the remote multi-level grounding body, the method further includes: Setting the value range and value difference of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor; The true value of the grounding resistance of the artificial grounding body corresponding to the grounding down conductor is determined based on the voltage of the excitation voltage source, the first down conductor current value, the first grounding body current value, the second grounding body current value, and the first branch current under the first working condition when the grounding resistance of the artificial grounding body of the grounding down conductor takes different values, and the voltage of the excitation voltage source, the second down conductor current value, the third grounding body current value, the fourth grounding body current value, and the second branch current under the second working condition.

10. The method for measuring the grounding resistance of a transmission tower according to claim 1, wherein: The excitation voltage source is applied by voltage coupling.

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