Grounding device and grounding method for a conductive concrete pole tower

Abstract

The present invention discloses a grounding device and a grounding method for a conductive concrete pole tower, belonging to the technical field of grounding for transmission lines. The grounding device for the conductive concrete pole tower includes: a lightning protection wire, a conductive concrete column, a reference electrode, a grounding unit, a calibration unit, a first processing unit, a detection unit, a second processing unit, a first compensation unit, a second compensation unit, a control unit, and a data analysis unit. The present invention can provide a first compensation resistance according to the current combined resistance of the columns. The first compensation resistance is connected in parallel with the initial basic grounding resistance to reduce the comprehensive grounding resistance of the main circuit and smoothly guide the high-voltage current of the lightning protection wire to the earth soil layer. At the same time, the current dissipation parameters are calculated based on the soil resistivity and the combined resistance of the columns, and a second compensation resistance is provided according to the current dissipation parameters and the voltage fluctuation probability. The second compensation resistance increases the comprehensive grounding resistance of the main circuit to avoid the accumulation of electric charges caused by the too low comprehensive grounding resistance due to the current dissipation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line grounding, and in particular to a grounding device and a grounding method for a conductive concrete pole tower. Background Art

[0002] The grounding device of a pole tower can reduce the lightning strike risk of a transmission line and avoid single-phase faults. The grounding resistance is the core parameter of the pole tower grounding device. If the grounding resistance is too large, the fault current cannot be quickly and effectively discharged to the ground, increasing the risk of electric shock. If the grounding resistance is too small, the grounding electrode absorbs charges and is prone to electrocorrosion. Therefore, it is necessary to measure the soil resistivity of the area in advance and set a reasonable grounding resistance range. Chinese Patent Publication No. CN110726879A discloses a grounding resistance monitoring system for transmission line pole towers based on precise measurement technology. The system sets a resistance sensor at each on-site test end. The resistance sensor includes a trigger power supply and an induced current module. The trigger power supply is connected to a voltage coil to generate a constant AC voltage. The voltage is applied to the measured circuit. The induced current module is connected to a current coil to generate a current in the measured circuit, and the grounding resistance value in the circuit is measured according to the voltage and current. Existing pole towers usually consist of multiple groups of conductive concrete columns fixed in the earth soil layer. The conductive concrete columns jointly act as the grounding electrode of the grounding device, and multiple conductive concrete columns are connected in parallel to obtain the combined resistance of the columns.

[0003] Affected by the current dispersion effect, the combined resistance of the columns includes the ideal contact resistance of the conductive concrete columns and the resistance caused by the current dispersion effect. The resistance caused by the current dispersion effect is connected in parallel with the ideal contact resistance, further reducing the combined resistance of the columns and causing the conductive concrete columns to absorb the charges of the soil layer. It is difficult to construct a current dispersion model and it is difficult to directly measure. Chinese Patent Publication No. CN118520542A discloses a grounding calculation method for a combination of a pole tower and a grounding device. This method uses the moment method to calculate the combined grounding resistance of the pole tower foundation and the grounding device, and obtains the power frequency and impulse grounding resistances, trying to solve the problem of complex resistance modeling of the pole tower concrete column combination. The current dispersion effect reflects the soil layer condition and indirectly affects the allowable range of the grounding resistance. Although the existing technology gives a measurement method for the combined grounding resistance of the columns, it cannot solve the problem that the grounding resistance of the pole tower changes due to the current dispersion change of the current soil layer. Therefore, it is necessary to provide a pole tower grounding device that can adjust the grounding resistance in combination with the grounding electrode and the soil layer condition. Summary of the Invention

[0004] In order to solve the defects of the above existing technology, the present invention proposes a grounding device and a grounding method for a conductive concrete pole tower, which compensate the grounding resistance of the pole tower by combining the contact resistance of the conductive concrete columns and the current dispersion effect of the soil layer, improve the grounding safety, and at the same time avoid the electrocorrosion of the conductive concrete columns.

[0005] The technical solution of the present invention is realized as follows:

[0006] A grounding device for a conductive concrete pole tower, comprising:

[0007] A lightning protection wire fixed to the top of the pole tower;

[0008] At least two groups of conductive concrete columns buried in the soil layer, the tops of the conductive concrete columns being fixed to the bottom of the pole tower;

[0009] A reference electrode buried in the soil layer;

[0010] A grounding unit, the grounding unit being connected to the lightning protection wire, the conductive concrete column and the reference electrode through a main circuit, the grounding unit including a basic grounding resistance;

[0011] A calibration unit, the calibration unit being connected to the conductive concrete column and the reference electrode through a calibration circuit, the calibration unit being used to collect the combined resistance of the column of the conductive concrete column and the soil resistivity;

[0012] A first processing unit, the first processing unit being used to calculate the current dissipation parameter of the soil layer according to the soil resistivity and the combined resistance of the column;

[0013] A detection unit connected to the power transmission line, the detection unit being used to collect the zero-sequence voltage of the power transmission line;

[0014] A second processing unit, the second processing unit being used to predict the voltage fluctuation probability of the power transmission line according to the zero-sequence voltage;

[0015] A first compensation unit, the first compensation unit having a first compensation resistance, the first compensation resistance being connected in parallel to the basic grounding resistance;

[0016] A second compensation unit, the second compensation unit having a second compensation resistance, the second compensation resistance being connected in series to the combined resistance of the column;

[0017] A control unit, the control unit being used to generate a timing control signal, the timing control signal controlling the switching states of the reference electrode and the conductive concrete column;

[0018] A data analysis unit, the data analysis unit being used to calculate the first compensation resistance according to the basic grounding resistance and the combined resistance of the column, and calculate the second compensation resistance according to the current dissipation parameter and the voltage fluctuation probability.

[0019] In the present invention, the timing control signal includes a first switch signal for switching the reference electrode into the calibration circuit, a second switch signal for switching the reference electrode into the main circuit, a third switch signal for switching the conductive concrete column out of the main circuit, and a fourth switch signal for switching the conductive concrete column into the calibration circuit.

[0020] In the present invention, a high-level period of a second switching signal is generated within a low-level period of a first switching signal, a high-level period of a third switching signal is generated within a high-level period of the second switching signal, and a high-level period of a fourth switching signal is generated within a high-level period of the third switching signal.

[0021] In the present invention, the calibration unit includes an excitation module, a current measurement module, a voltage measurement module, a current electrode, and a voltage electrode. The excitation module injects an excitation current into the current electrode, the reference electrode, and the conductive concrete column, and the current measurement module measures the current value of the current electrode.

[0022] In the present invention, when the first switching signal is in a high-level period, the calibration unit acquires the current value i 1 and the voltage value u 1 , and the soil resistivity ρ = 2π(s 1 s 2 )(u 1 / i 1 ) / (s 1 +s 2 ), s 1 is the distance between the reference electrode and the voltage electrode, and s 2 is the distance between the voltage electrode and the current electrode.

[0023] In the present invention, when the fourth switching signal is in a high-level period, the calibration unit acquires the current value i 2 and the voltage value u 2 , and the combined resistance r 2 of the column = u 2 / i 2 .

[0024] In the present invention, the first processing unit calculates the ideal contact resistance r 3 , r 3 = ρln(8h 2 / h 1 -1) / (2πh 2 ), h 1 is the diameter of the conductive concrete column, h 2 is the length of the conductive concrete column, and the scattering parameter λ of the soil layer = r 3 / (r 3 -mr 2 ), where m is the number of conductive concrete columns.

[0025] In the present invention, the second processing unit counts the number N' of times when the zero-sequence voltage is greater than 10V within a natural period, and the voltage fluctuation probability p = N' / N, where N is the number of lightning strikes within the natural period.

[0026] In the present invention, the first compensation unit has a first potentiometer, the second compensation unit has a second potentiometer, and the first compensation resistance r' = r 4 (r 0 -r 2 ) / (r 4 -r 0 +r 2 ),where r 0 is the designed grounding resistance, and r 4 is the basic grounding resistance. The second compensation resistance r'' = (r 0 -r 2 ) / (λe p ), and e is a natural number.

[0027] A grounding method for a grounding device of a conductive concrete pole tower, comprising the following steps:

[0028] Step 1: Cut the reference electrode into the calibration loop. The calibration unit is connected to the reference electrode through the calibration loop, and the calibration unit collects the soil resistivity;

[0029] Step 2: Cut the reference electrode into the main loop. The grounding unit is connected to the reference electrode through the main loop;

[0030] Step 3: Cut the conductive concrete column out of the main loop, and disconnect the grounding unit from the conductive concrete column;

[0031] Step 4: Cut the conductive concrete column into the calibration loop. The calibration unit is connected to the conductive concrete column through the calibration loop, and the calibration unit collects the combined resistance of the columns;

[0032] Step 5: Calculate the current dissipation parameters of the soil layer according to the soil resistivity and the combined resistance of the columns;

[0033] Step 6: Connect the detection unit to the transmission line, and the detection unit collects the zero-sequence voltage of the transmission line;

[0034] Step 7: Predict the voltage fluctuation probability of the transmission line according to the zero-sequence voltage;

[0035] Step 8: Calculate the first compensation resistance according to the basic grounding resistance and the combined resistance of the columns, and calculate the second compensation resistance according to the current dissipation parameters and the voltage fluctuation probability;

[0036] Step 9: Connect the first compensation resistance in parallel with the basic grounding resistance, and connect the second compensation resistance in series with the combined resistance of the columns.

[0037] Implementing the grounding device and method for the conductive concrete pole tower of the present invention has the following beneficial effects: The present invention can provide a first compensation resistance according to the current combined resistance of the columns. The first compensation resistance is connected in parallel with the initial basic grounding resistance to reduce the comprehensive grounding resistance of the main circuit, smoothly guide the high-voltage current of the lightning protection wire to the earth soil layer, and improve the grounding safety. At the same time, the current dissipation parameter is calculated based on the soil resistivity and the combined resistance of the columns, and a second compensation resistance is provided according to the current current dissipation parameter and the voltage fluctuation probability. The second compensation resistance increases the comprehensive grounding resistance of the main circuit, avoids the accumulation of electric charge caused by the too low comprehensive grounding resistance due to the current dissipation effect, and further avoids the electro-corrosion of the conductive concrete columns. Brief Description of the Drawings

[0038] Figure 1 is a schematic diagram of a high-voltage transmission line;

[0039] Figure 2 is a schematic diagram of the current dissipation effect of the pole tower of the high-voltage transmission line;

[0040] Figure 3 is a block diagram of the grounding device of the conductive concrete pole tower of the present invention;

[0041] Figure 4 is an equivalent circuit diagram of the high-voltage transmission line of the present invention;

[0042] Figure 5 is a structural diagram of the pole tower grounding of the present invention;

[0043] Figure 6 is a schematic diagram of the timing control signal of the present invention;

[0044] Figure 7 is a preferred schematic diagram of the main circuit of the present invention;

[0045] Figure 8 is a preferred schematic diagram of the calibration circuit of the present invention;

[0046] Figure 9 is a preferred schematic diagram of the detection unit of the present invention;

[0047] Figure 10 is a flowchart of the grounding method according to the grounding device of the conductive concrete pole tower of the present invention.

[0048] Reference signs in the drawings: pole tower 100, transmission line 200, lightning protection wire 300, substation 400, conductive concrete column 500. Detailed Description of the Preferred Embodiments

[0049] To more clearly understand the purpose, technical solution and advantages of the present application, the present application will be described and illustrated below with reference to the drawings and embodiments.

[0050] Refer toFigures 1 to 5 For a high-voltage transmission line, it includes power equipment such as a pole tower 100, a transmission line 200, a lightning protection wire 300, a substation 400, etc. The lightning protection wire 300 is arranged on the top of the pole tower 100 to guide lightning and prevent the lightning from directly piercing through the transmission line 200. The transient current of the lightning protection wire 300 is then transmitted to the earth soil layer through the conductive concrete column 500 at the bottom end of the pole tower 100. In a theoretical situation, the pole tower 100 is regarded as an isolated conductive element. In an actual situation, there is a current dispersion effect between pole towers 100 and between the conductive concrete columns 500 of the pole tower 100. The current will spread outwards from the grounding electrode, forming an increasingly expanding current field. The current dispersion effect reduces the actual grounding resistance within the current field. The grounding device and grounding method of the conductive concrete pole tower of the present invention measure the soil resistivity and the comprehensive grounding resistance to predict the influence of the current dispersion effect of the soil layer on the resistance, and provide resistance compensation in combination with the ideal contact resistance of the conductive concrete column 500, improving the grounding safety and avoiding electrochemical corrosion at the same time. Embodiment 1

[0051] As Figures 3 to 9 shown, the grounding device of the conductive concrete pole tower of the present invention includes: a lightning protection wire, a conductive concrete column, a reference electrode, a grounding unit, a calibration unit, a first processing unit, a detection unit, a second processing unit, a first compensation unit, a second compensation unit, a control unit, and a data analysis unit. Details are as follows.

[0052] The pole tower is used for erecting the transmission line, and the lightning protection wire is fixed at the top of the pole tower to prevent the lightning from directly hitting the transmission line. As Figure 4 shown, the lightning protection wire is grounded and the transmission line is overhead. The space between the transmission line and the earth can be regarded as a parallel circuit of an equivalent resistance and a capacitor. The resistance value of the equivalent resistance is affected by the air breakdown resistance and the current dispersion effect of the soil layer. When a fault such as a lightning strike occurs, the voltages of the three phase lines of the transmission line are not strictly symmetrical, generating a zero-sequence voltage relative to the earth. The zero-sequence voltage can be used to describe the risk of faults such as lightning strikes.

[0053] Multiple groups of conductive concrete columns are buried in the soil layer, and the top ends of the conductive concrete columns are fixed at the bottom end of the pole tower. Refer to Figure 5 . In this embodiment, there are four groups of conductive concrete columns, which are arranged at the four corners of the pole tower. The ideal output resistance of the column combination is one-fourth of the ideal contact resistance of each conductive concrete column. The reference electrode is buried in the soil layer and is made of, for example, copper alloy. The grounding unit is connected to the lightning protection wire, the conductive concrete column, and the reference electrode through the main circuit, and the grounding unit includes a basic grounding resistance.

[0054] The calibration unit is connected to the conductive concrete column and the reference electrode via a calibration circuit. The calibration unit is used to collect the combined resistance of the column of the conductive concrete column and the soil resistivity. The first processing unit is used to calculate the current dissipation parameter of the soil layer based on the soil resistivity and the combined resistance of the column.

[0055] The detection unit is connected to the transmission line. The detection unit is used to collect the zero-sequence voltage of the transmission line. The second processing unit is used to predict the voltage fluctuation probability of the transmission line based on the zero-sequence voltage. The present invention predicts the risk of lightning damage to the transmission line through this voltage fluctuation probability, and then adjusts the second compensation resistance accordingly.

[0056] The first compensation unit has a first compensation resistance, and the first compensation resistance is connected in parallel to the basic grounding resistance. The second compensation unit has a second compensation resistance, and the second compensation resistance is connected in series to the combined resistance of the column. The first compensation unit also has a first potentiometer, and the second compensation unit also has a second potentiometer. The first potentiometer and the second potentiometer can receive the signal of the data analysis unit, adjust the effective access length of the first compensation resistance and the second compensation resistance, and thus adjust their resistance values.

[0057] The control unit is used to generate a timing control signal, and this timing control signal controls the switching states of the reference electrode and the conductive concrete column. The data analysis unit is used to calculate the first compensation resistance based on the basic grounding resistance and the combined resistance of the column, and calculate the second compensation resistance based on the current dissipation parameter and the voltage fluctuation probability. The data analysis unit sends the corresponding output signal to the first compensation unit and the second compensation unit.

[0058] The grounding device of the conductive concrete tower of the present invention periodically collects relevant parameters and adjusts the comprehensive grounding resistance. Under the condition of meeting the grounding safety, it avoids charge accumulation on the conductive concrete column. Specifically, the control unit generates a timing control signal, and the timing control signal includes a first switch signal for switching the reference electrode into the calibration circuit, a second switch signal for switching the reference electrode into the main circuit, a third switch signal for switching the conductive concrete column out of the main circuit, and a fourth switch signal for switching the conductive concrete column into the calibration circuit. When the first switch signal is executed, the soil resistivity is collected. To avoid the main circuit being unable to be grounded when the conductive concrete column is switched into the calibration circuit, the second switch signal and the third switch signal are executed, and the reference electrode is used as a temporary grounding electrode. When the fourth switch signal is executed, the combined resistance of the column is collected. Refer to Figure 6 , one adjustment period includes the high-level periods of the four switch signals. To ensure the switching safety of each circuit, the high-level period of the second switch signal is generated within the low-level period of the first switch signal, and the high-level period of the third switch signal is generated within the high-level period of the second switch signal. To ensure that the main circuit is grounded in real time, the high-level period of the fourth switch signal is generated within the high-level period of the third switch signal. In addition, the detection unit collects the zero-sequence voltage in real time, so the detection unit does not need to be switched in and out.

[0059] The present invention measures the current combined resistance of the columns, provides a first compensation resistance according to the combined resistance of the columns, and can timely compensate for the resistance change caused by factors such as corrosion of the conductive concrete columns. The first compensation resistance is connected in parallel with the initial basic grounding resistance to reduce the combined grounding resistance of the main circuit, smoothly guide the high-voltage current of the lightning protection wire to the earth soil layer, and improve the grounding safety. Further, the resistance effect of the current dissipation parameter causes an unexpected decrease in the combined grounding resistance. The present invention calculates the current dissipation parameter according to the soil resistivity and the combined resistance of the columns. A second compensation resistance is provided according to the current current dissipation parameter and the voltage fluctuation probability. The second compensation resistance increases the combined grounding resistance of the main circuit, avoids the charge accumulation caused by the too low grounding resistance due to the current dissipation effect, and further reduces the electro-corrosion of the conductive concrete columns. Embodiment 2

[0060] Refer to Figures 7 to 9 , this embodiment further discloses the preferred structures of the grounding unit, the calibration unit, and the detection unit.

[0061] The grounding unit includes a basic grounding resistance, and the resistance value of the basic grounding resistance is, for example, 1 Ω to 3 Ω. The first compensation resistance is connected in parallel with the basic grounding resistance, and the first compensation resistance can reduce the combined grounding resistance output by the main circuit. The basic grounding resistance is connected in series with the combined resistance of the columns of the conductive concrete column, and the combined resistance of the columns is further connected in series with the second compensation resistance. The second compensation resistance can increase the combined grounding resistance output. The reference electrode can be regarded as a small resistance, and this small resistance serves as a temporary grounding electrode when the main circuit is cut out from the conductive concrete column.

[0062] The calibration unit includes an excitation module, a current measurement module, a voltage measurement module, a current electrode, and a voltage electrode. The excitation module injects an excitation current into the current electrode, the reference electrode, and the conductive concrete column. The current measurement module is, for example, an ammeter, and the voltage measurement module is, for example, a voltmeter. During the high-level period of the first switch signal, the current measurement module measures the current value of the current electrode, and the voltage measurement module measures the voltage value between the reference electrode and the voltage electrode. During the high-level period of the fourth switch signal, the current measurement module measures the current value of the current electrode, and the voltage measurement module measures the voltage value between the conductive concrete column and the voltage electrode.

[0063] The detection unit includes a primary coil and a secondary coil that are mutually coupled and a zero-sequence measurement module. The primary coil is connected to the three phase lines of the transmission line, and the secondary coil is connected to the zero-sequence measurement module. The zero-sequence measurement module is, for example, a voltmeter. In order to reduce the influence of the zero-sequence voltage on the transmission line, an arc suppression circuit can be incorporated into the neutral point of the primary coil.

[0064] The grounding unit and the calibration unit are provided with four groups of switching switches. Among them, switch K3 is a normally closed switch, and the other switches are normally open switches. During the high-level period of the first switch signal, the control unit controls switch K1 to remain closed. During the low-level period of the first switch signal, the control unit controls switch K1 to remain open; during the high-level period of the second switch signal, the control unit controls switch K2 to remain closed. During the low-level period of the second switch signal, the control unit controls switch K2 to remain open; during the low-level period of the third switch signal, the control unit controls switch K3 to remain closed. During the high-level period of the third switch signal, the control unit controls switch K3 to remain open; during the high-level period of the fourth switch signal, the control unit controls switch K4 to remain closed. During the low-level period of the fourth switch signal, the control unit controls switch K4 to remain open. Embodiment 3

[0065] This embodiment further discloses a preferred algorithm for calculating the first compensation resistor and the second compensation resistor.

[0066] When the first switch signal is in the high-level period, the calibration unit collects the current value i 1 and the voltage value u 1 . At this time, the resistance between the reference electrode and the voltage electrode is u 1 / i 1 . The volume of the reference electrode is small, and the current dissipation effect can be ignored. According to the resistance model of the ideal grounding network, ρ = (u 1 / i 1 ) G, where G is a correction parameter. The current electrode and the voltage electrode are regarded as point electrodes, and G = 2π(s 1 s 2 ) / (s 1 +s 2 ). Therefore, the soil resistivity ρ = 2π(s 1 s 2 )(u 1 / i 1 ) / (s 1 +s 2 ). s 1 is the distance between the reference electrode and the voltage electrode, and s 2 is the distance between the voltage electrode and the current electrode. Usually, the three groups of electrodes are arranged in parallel, with the voltage electrode in the middle, s 1 = 18 meters, and s 2 = 12 meters.

[0067] When the fourth switch signal is at a high level, the calibration unit collects the current value i 2 and the voltage value u 2 . At this time, the measured resistance of the column combination between the conductive concrete column and the soil layer is r 2 , and r 2 = u 2 / i2 The column combined resistance includes the ideal contact resistance of four groups of conductive concrete columns connected in parallel and the resistance caused by the current dissipation effect.

[0068] The first processing unit calculates the ideal contact resistance r 3 The size parameters of the conductive concrete columns cannot be ignored. The conductive concrete columns are regarded as buried cylinders. The ideal contact resistance r of each conductive concrete column 3 =ρln(8h 2 / h 1 -1) / (2πh 2 ), h 1 is the diameter of the conductive concrete column, h 2 is the length of the conductive concrete column (buried length). Usually, h 1 =0.5 m, h 2 =2 m, 8h 2 >h 1 According to the resistance relationship of the parallel circuit, the resistance caused by the current dissipation effect = r 3 r 2 / (r 3 -mr 2 ), m is the number of conductive concrete columns. In this embodiment, m = 4. The current dissipation effect between the conductive concrete columns cannot be ignored. In this embodiment, the ratio of the current dissipation resistance of the current soil layer to the column combined resistance is used as the current dissipation parameter, that is, the current dissipation parameter λ of the soil layer = r 3 / (r 3 -mr 2 ).

[0069] The second processing unit counts the number N' of times when the zero-sequence voltage is greater than 10V within the natural period. 10V is usually the upper limit of the zero-sequence voltage allowed for high-voltage transmission lines. Then read the number of lightning strikes N within this natural period. The voltage fluctuation probability p = N' / N. The voltage fluctuation probability is the probability that the zero-sequence voltage is generated on the transmission line due to lightning weather. The natural period is, for example, one year. In this embodiment, the number of times when the zero-sequence voltage is greater than 10V per year and the number of lightning strikes in the current area are counted by its own measuring instrument. In a simpler embodiment, in terms of days, the number of days when the zero-sequence voltage is greater than 10V occurs in the current area and the number of lightning days are counted through an external climate database.

[0070] The first compensating resistance is used to adjust the comprehensive grounding resistance to the designed level. The first compensating resistance r' and the basic grounding resistance r 4 are connected in parallel to obtain r 0 -r 2 . Therefore, the first compensating resistance r' = r 4 (r 0 -r 2 ) / (r 4 -r0 +r 2 ),r 0 For the design of the grounding resistance, r 4 is the basic grounding resistance. The design grounding resistance is determined according to the weather environment of the location and the voltage level of the transmission line. Generally, the design grounding resistance for 35 kV in mountainous areas is 4 Ω.

[0071] Due to the presence of the conductive concrete column, the current dissipation effect of the soil layer is increased. The present invention generates a second compensation resistance through the current dissipation parameter, and the second compensation resistance is used to supplement the impedance drop caused by the current dissipation effect. The second compensation resistance r'' = (r 0 -r 2 ) / (λe p ), where e is a natural number. The current dissipation parameter and the voltage fluctuation probability jointly affect the second compensation resistance. The greater the influence of the current dissipation effect, the smaller the actual impedance, the smaller the current dissipation parameter, the more the problem of electrical corrosion needs to be considered, and the greater the resistance compensation. The greater the voltage fluctuation probability, the greater the lightning strike risk, the more the grounding safety needs to be considered, and the smaller the resistance compensation.

[0072] In this embodiment, the function of the second compensation resistance is directly fitted according to the current dissipation parameter (current dissipation resistance) and the voltage fluctuation probability, that is, the second compensation resistance is directly proportional to the current dissipation parameter and inversely proportional to the exponent of the voltage fluctuation probability. This calculation method is simple and easy to implement, and the second compensation resistance can be updated quickly. However, the second compensation resistance is not strictly linearly related to the current dissipation parameter and the voltage fluctuation probability.

[0073] In a further embodiment, the model function can be generated by a support vector machine. Specifically, a plurality of sets of historical data of the current dissipation parameter λ, the voltage fluctuation probability p, and the second compensation resistance r'' are collected. 80% of the historical data is used as the training set, and 20% of the historical data is used as the verification set. A support vector machine is constructed, and the polynomial kernel function of the vector machine is selected to map the historical data to a high-dimensional space. Try to find a hyperplane to minimize the prediction error of the training set, and determine the model function F(λ, p) according to the hyperplane. Use the verification set to evaluate the mean square error of the model function, and determine whether to re-update the model function according to the error value until a model function that meets the error condition is obtained. Embodiment 4

[0074] Refer to Figure 10 , this embodiment discloses a grounding method for the grounding device of the conductive concrete tower, including the following steps.

[0075] Step 1: Cut the reference electrode into the calibration circuit, the calibration unit is connected to the reference electrode through the calibration circuit, and the calibration unit collects the soil resistivity.

[0076] Step 2: Cut the reference electrode into the main circuit, and the grounding unit is connected to the reference electrode through the main circuit.

[0077] Step 3: Cut out the main circuit from the conductive concrete column, and disconnect the grounding unit from the conductive concrete column.

[0078] Step 4: Cut the conductive concrete column into the calibration circuit. The calibration unit is connected to the conductive concrete column via the calibration circuit, and the calibration unit collects the combined resistance of the columns.

[0079] Step 5: Calculate the current dissipation parameters of the soil layer based on the soil resistivity and the combined resistance of the columns.

[0080] Step 6: Connect the detection unit to the power transmission line, and the detection unit collects the zero-sequence voltage of the power transmission line.

[0081] Step 7: Predict the voltage fluctuation probability of the power transmission line based on the zero-sequence voltages at multiple moments.

[0082] Step 8: Calculate the first compensation resistance based on the basic grounding resistance and the combined resistance of the columns, and calculate the second compensation resistance based on the current dissipation parameters and the voltage fluctuation probability.

[0083] Step 9: Connect the first compensation resistance in parallel with the basic grounding resistance, and connect the second compensation resistance in series with the combined resistance of the columns.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A grounding device for a conductive concrete tower, characterized in that: include: Lightning conductor fixed on the top of the tower; At least two groups of conductive concrete columns are buried in the soil layer, and the top ends of the conductive concrete columns are fixed to the bottom ends of the towers; Reference electrode buried in the soil layer; A grounding unit, the grounding unit is connected to the lightning protection wire, the conductive concrete column and the reference electrode through the main circuit, and the grounding unit includes a basic grounding resistor; a calibration unit, the calibration unit being connected to the conductive concrete column and the reference electrode via a calibration loop, and the calibration unit being used to collect the column combined resistance and soil resistivity of the conductive concrete column; A first processing unit, the first processing unit is used to calculate the scattered flow parameters of the soil layer according to the soil resistivity and the combined resistance of the column; A detection unit connected to the transmission line, the detection unit is used to collect the zero-sequence voltage of the transmission line; A second processing unit, the second processing unit is used to predict the voltage fluctuation probability of the transmission line according to the zero-sequence voltage; a first compensation unit, the first compensation unit having a first compensation resistor, the first compensation resistor being connected in parallel to the basic grounding resistor; A second compensation unit, the second compensation unit has a second compensation resistor, and the second compensation resistor is connected in series to the column combination resistor; A control unit, the control unit is used to generate a timing control signal, the timing control signal controls the switching state of the reference electrode and the conductive concrete column; The data analysis unit is used to calculate the first compensation resistance according to the foundation grounding resistance and the column combined resistance, and calculate the second compensation resistance according to the scattered current parameter and the voltage fluctuation probability.

2. The grounding device of the conductive concrete tower according to claim 1, characterized in that: The timing control signal includes a first switch signal for switching the reference electrode into the calibration loop, a second switch signal for switching the reference electrode into the main loop, a third switch signal for switching the conductive concrete column out of the main loop, and a fourth switch signal for switching the conductive concrete column into the calibration loop.

3. The grounding device of the conductive concrete tower according to claim 2, characterized in that: A high level period of the second switch signal is generated during a low level period of the first switch signal, a high level period of the third switch signal is generated during a high level period of the second switch signal, and a high level period of the fourth switch signal is generated during a high level period of the third switch signal.

4. The grounding device for a conductive concrete tower according to claim 3, characterized in that: The calibration unit includes an excitation module, a current measurement module, a voltage measurement module, a current electrode and a voltage electrode. The excitation module injects excitation current into the current electrode, the reference electrode and the conductive concrete column, and the current measurement module measures the current value of the current electrode.

5. The grounding device for a conductive concrete tower according to claim 4, characterized in that: When the first switch signal is in a high level period, the calibration unit collects the current value i1 and the voltage value u1, and the soil resistivity ρ=2π(s1s2)(u1 / i1) / (s1+s2), s1 is the distance between the reference electrode and the voltage electrode, and s2 is the distance between the voltage electrode and the current electrode.

6. The grounding device for a conductive concrete tower according to claim 5, characterized in that: When the fourth switch signal is in a high level period, the calibration unit collects the current value i2 and the voltage value u2, and the column combined resistance r2=u2 / i2.

7. The grounding device for a conductive concrete tower according to claim 6, characterized in that: The first processing unit calculates the ideal contact resistance r3, r3=ρln(8h2 / h1-1) / (2πh2), h1 is the diameter of the conductive concrete column, h2 is the length of the conductive concrete column, the scattered flow parameter λ of the soil layer= r3 / (r3-mr2), and m is the number of conductive concrete columns.

8. The grounding device for a conductive concrete tower according to claim 7, characterized in that: The second processing unit counts the number of times N' that the zero-sequence voltage is greater than 10V in the natural cycle, and the voltage fluctuation probability p=N' / N, where N is the number of lightning strikes in the natural cycle.

9. The grounding device for a conductive concrete tower according to claim 8, characterized in that: The first compensation unit has a first potentiometer, the second compensation unit has a second potentiometer, the first compensation resistor r'=r4(r0-r2) / (r4-r0+r2), r0 is the designed grounding resistor, r4 is the basic grounding resistor, and the second compensation resistor r''=(r0-r2) / (λe p ), e is a natural number.

10. A grounding method for the grounding device of the conductive concrete tower according to claim 1, characterized in that: The following steps are involved: Step 1: Cut the reference electrode into the calibration loop, connect the calibration unit to the reference electrode via the calibration loop, and collect soil resistivity by the calibration unit; Step 2: Cut the reference electrode into the main circuit, and connect the grounding unit to the reference electrode through the main circuit; Step 3: Cut the conductive concrete column out of the main circuit, and disconnect the grounding unit from the conductive concrete column; Step 4: Cut the conductive concrete column into the calibration loop, connect the calibration unit to the conductive concrete column via the calibration loop, and collect the combined resistance of the column by the calibration unit; Step 5: Calculate the scattered flow parameters of the soil layer based on the soil resistivity and the combined resistance of the column; Step 6: The detection unit is connected to the transmission line, and the detection unit collects the zero-sequence voltage of the transmission line; Step 7: Predict the voltage fluctuation probability of the transmission line based on the zero-sequence voltage; Step 8: Calculate the first compensation resistance according to the foundation grounding resistance and the column combined resistance, and calculate the second compensation resistance according to the scattered current parameter and the voltage fluctuation probability; Step 9: Connect the first compensation resistor in parallel with the foundation grounding resistor, and connect the second compensation resistor in series with the column combination resistor.

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