Grounding device and grounding method of conductive concrete pole tower

Abstract

The invention discloses a grounding device and a grounding method of a conductive concrete tower, and belongs to the technical field of power transmission line grounding. The grounding device of the conductive concrete tower comprises a lightning conductor, 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 first compensation resistance can be provided according to the current column combined resistance, the first compensation resistance is connected with the initial basic grounding resistance in parallel, the comprehensive grounding resistance of the main loop is reduced, and the high-voltage current of the lightning conductor is smoothly guided to the earth soil layer. And meanwhile, a current diffusion parameter is calculated according to the soil resistivity and the column combination resistance, a second compensation resistor is provided according to the current current diffusion parameter and the voltage fluctuation probability, the second compensation resistor increases the comprehensive grounding resistance of the main loop, and charge accumulation caused by too low comprehensive grounding resistance due to the current diffusion effect is avoided.

Description

Technical Field

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

[0002] The grounding device of the tower can reduce the risk of lightning strikes on the transmission line and avoid single-phase faults. The grounding resistance is the core parameter of the 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 the charge and is prone to electrical corrosion. Therefore, it is necessary to measure the soil resistivity in the area in advance and set a reasonable grounding resistance range. Chinese Patent Publication No. CN110726879A discloses a transmission line tower grounding resistance monitoring system based on precise measurement technology. The system sets a resistance sensor at each field test end. The resistance sensor includes a trigger power supply and an induction current module. The trigger power supply is connected to the voltage coil to generate a constant AC voltage. The voltage is applied to the measured loop, the induction current module is connected to the current coil, and a current is generated in the measured loop. The grounding resistance value in the loop is measured according to the voltage and current. The existing tower is usually composed of multiple groups of conductive concrete columns fixed in the earth's soil layer. The conductive concrete columns act as grounding electrodes of the grounding device together, and multiple conductive concrete columns are connected in parallel to obtain the combined resistance of the columns.

[0003] Affected by the scattered flow effect, the combined resistance of the column includes the ideal contact resistance of the conductive concrete column and the resistance caused by the scattered flow effect. The resistance caused by the scattered flow effect is connected in parallel with the ideal contact resistance, which further reduces the combined resistance of the column, causing the conductive concrete column to absorb the charge of the soil layer. The scattered flow model is difficult to construct and difficult to measure directly. Chinese Patent Publication No. CN118520542A discloses a grounding calculation method for a combination of a tower and a grounding device. The method uses the moment method to calculate the combined grounding resistance of the tower foundation and the grounding device, obtains the power frequency and impulse grounding resistance, and attempts to solve the problem of complex resistance modeling of the tower concrete column combination. The scattered flow effect reflects the condition of the soil layer and indirectly affects the allowable range of the grounding resistance. Although the prior art provides a method for measuring the combined grounding resistance of the column, it cannot solve the problem that the grounding resistance of the tower changes due to the scattered flow changes in the current soil layer. Therefore, it is necessary to provide a 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-mentioned prior art, the present invention proposes a grounding device and a grounding method for a conductive concrete tower, which combines the contact resistance of the conductive concrete column and the scattered flow effect of the soil layer to compensate for the grounding resistance of the tower, thereby improving the grounding safety and avoiding electrical corrosion of the conductive concrete column.

[0005] The technical solution of the present invention is achieved in this way: A grounding device for a conductive concrete tower, comprising: 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.

[0006] In the present invention, 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.

[0007] In the present invention, a high level period of the second switching signal is generated during a low level period of the first switching signal, a high level period of the third switching signal is generated during a high level period of the second switching signal, and a high level period of the fourth switching signal is generated during a high level period of the third switching signal.

[0008] 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 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.

[0009] In the present invention, 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.

[0010] In the present invention, 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 combination resistance r2=u2 / i2.

[0011] In the present invention, 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.

[0012] In the present invention, the second processing unit counts the number of times N' that the zero-sequence voltage is greater than 10V in a natural cycle, and the voltage fluctuation probability p=N' / N, where N is the number of lightning strikes in the natural cycle.

[0013] In the present invention, 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.

[0014] A grounding method according to the grounding device of the conductive concrete tower comprises the following steps: 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.

[0015] The grounding device and grounding method of the conductive concrete pole tower of the present invention have the following beneficial effects: the present invention can provide a first compensation resistor according to the current column combined resistance, the first compensation resistor is connected in parallel with the initial basic grounding resistance, the comprehensive grounding resistance of the main circuit is reduced, the high-voltage current of the lightning arrester is smoothly guided to the earth soil layer, and the grounding safety is improved. At the same time, the scattered current parameter is calculated according to the soil resistivity and the column combined resistance, and the second compensation resistor is provided according to the current scattered current parameter and the voltage fluctuation probability. The second compensation resistor increases the comprehensive grounding resistance of the main circuit, avoiding the accumulation of charge due to the low comprehensive grounding resistance caused by the scattered current effect, thereby avoiding the electrical corrosion of the conductive concrete column. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of a high voltage transmission line; Figure 2 This is a schematic diagram of the tower flow dispersion effect of high-voltage transmission lines; Figure 3 A block diagram of a grounding device for a conductive concrete tower according to the present invention; Figure 4 is an equivalent circuit diagram of a high voltage transmission line of the present invention; Figure 5 This is a structural diagram of the tower grounding of the present invention; Figure 6 is a schematic diagram of a timing control signal of the present invention; Figure 7 It is a preferred schematic diagram of the main circuit of the present invention; Figure 8 It is a preferred schematic diagram of the calibration loop of the present invention; Fig. 9 Schematic diagram of a preferred detection unit of the present invention; Fig.10 The present invention is a flow chart of a grounding method according to the grounding device of the conductive concrete tower.

[0017] Reference numerals in the accompanying drawings: pole tower 100 , transmission line 200 , lightning arrester 300 , substation 400 , conductive concrete column 500 . DETAILED DESCRIPTION

[0018] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0019] Reference Figures 1 to 5 The high-voltage transmission line includes power equipment such as a pole tower 100, a transmission line 200, a lightning arrester 300, and a substation 400. The lightning arrester 300 is arranged at the top of the pole tower 100 to guide lightning and prevent lightning from directly striking the transmission line 200. The transient current of the lightning arrester 300 is then transmitted to the earth's soil layer through the conductive concrete column 500 at the bottom of the pole tower 100. In theory, the pole tower 100 is regarded as an isolated conductive element. In practice, there is a scattered flow effect between the pole towers 100 and the conductive concrete columns 500 of the pole tower 100. The current will diffuse outward from the grounding electrode to form a gradually expanding current field. The scattered flow effect reduces the actual grounding resistance in the current field. The grounding device and grounding method of the conductive concrete pole tower of the present invention predict the influence of the scattered flow effect of the soil layer on the resistance by measuring the soil resistivity and the comprehensive grounding resistance, and provide resistance compensation in combination with the ideal contact resistance of the conductive concrete column 500, thereby improving the grounding safety and avoiding electrical corrosion. Embodiment 1

[0020] like Figures 3 to 9 The grounding device of the conductive concrete tower of the present invention comprises: a lightning arrester, 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 details are as follows.

[0021] The tower is used to erect transmission lines, and the lightning arrester is fixed on the top of the tower to prevent lightning from directly hitting the transmission lines. Figure 4 , the lightning arrester is grounded, the transmission line is overhead, and the transmission line and the earth can be regarded as a parallel circuit of equivalent resistance and capacitance. The resistance value of the equivalent resistance is affected by the breakdown resistance of the air and the diffusion effect of the soil layer. When a fault such as a lightning strike occurs, the voltages of the three phases of the transmission line are not strictly symmetrical, and a zero-sequence voltage is generated relative to the earth. The zero-sequence voltage can be used to describe the risk of a fault such as a lightning strike.

[0022] Multiple sets of conductive concrete columns are buried in the soil layer, and the top of the conductive concrete column is fixed to the bottom of the tower. Figure 5 . The conductive concrete columns of this embodiment are four groups, which are arranged at the four corners of the tower. The ideal output resistance of the column combination is one quarter of the ideal contact resistance of each conductive concrete column. The reference electrode is buried in the soil layer, and the reference electrode is made of copper alloy, for example. The grounding unit is connected to the lightning protection line, the conductive concrete column and the reference electrode through the main circuit, and the grounding unit includes a basic grounding resistor.

[0023] The calibration unit is connected to the conductive concrete column and the reference electrode via a calibration loop, and is used to collect the column combined resistance and soil resistivity of the conductive concrete column. The first processing unit is used to calculate the scattered current parameter of the soil layer according to the soil resistivity and the column combined resistance.

[0024] The detection unit is connected to the transmission line, and 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 according to the zero-sequence voltage. The present invention predicts the risk of lightning damaging the transmission line through the voltage fluctuation probability, and then adjusts the second compensation resistor accordingly.

[0025] The first compensation unit has a first compensation resistor, which is connected in parallel to the foundation grounding resistor. The second compensation unit has a second compensation resistor, which is connected in series to the column combination resistor. 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 signals from the data analysis unit to adjust the effective access length of the first compensation resistor and the second compensation resistor, thereby adjusting their resistance values.

[0026] The control unit is used to generate a timing control signal, which controls the switch 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. The data analysis unit sends the corresponding output signal to the first compensation unit and the second compensation unit.

[0027] The grounding device of the conductive concrete pole tower of the present invention periodically collects relevant parameters and adjusts the comprehensive grounding resistance to avoid charge accumulation on the conductive concrete column while satisfying grounding safety. Specifically, the control unit generates a timing control signal, and the timing control signal includes a first switch signal for cutting the reference electrode into the calibration loop, a second switch signal for cutting the reference electrode into the main loop, a third switch signal for cutting the conductive concrete column out of the main loop, and a fourth switch signal for cutting the conductive concrete column into the calibration loop. When the first switch signal is executed, the soil resistivity is collected. In order to avoid the main loop being unable to be grounded when the conductive concrete column is cut into the calibration loop, 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 regulation cycle includes four high-level cycles of the switch signals. To ensure the switching safety of each circuit, the high-level cycle of the second switch signal is generated during the low-level cycle of the first switch signal, and the high-level cycle of the third switch signal is generated during the high-level cycle of the second switch signal. To ensure the real-time grounding of the main circuit, the high-level cycle of the fourth switch signal is generated during the high-level cycle 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.

[0028] The present invention measures the current combined resistance of the columns, and provides a first compensation resistor based on the combined resistance of the columns, so as to timely compensate for the resistance change caused by factors such as corrosion of the conductive concrete columns. The first compensation resistor is connected in parallel with the initial foundation grounding resistance to reduce the comprehensive grounding resistance of the main circuit, smoothly guide the high-voltage current of the lightning conductor to the earth's soil layer, and improve the grounding safety. Furthermore, the resistance effect of the scattered current parameter leads to an unexpected reduction in the comprehensive grounding resistance. The present invention calculates the scattered current parameter based on the soil resistivity and the combined resistance of the columns. A second compensation resistor is provided based on the current scattered current parameter and the voltage fluctuation probability, and the second compensation resistor increases the comprehensive grounding resistance of the main circuit to avoid the accumulation of charge caused by the excessively low grounding resistance due to the scattered current effect, thereby reducing the electrical corrosion of the conductive concrete columns. Embodiment 2

[0029] Reference Figures 7 to 9 , this embodiment further discloses the preferred structures of the grounding unit, the calibration unit, and the detection unit.

[0030] The grounding unit includes a basic grounding resistor, and the resistance value of the basic grounding resistor is, for example, 1Ω to 3Ω. The first compensation resistor is connected in parallel with the basic grounding resistor, and the first compensation resistor can reduce the comprehensive grounding resistance output by the main circuit. The basic grounding resistor is connected in series with the column combination resistance of the conductive concrete column, and the column combination resistance is further connected in series with the second compensation resistor. The second compensation resistor can increase the output comprehensive grounding resistance. The reference electrode can be regarded as a small resistor, which serves as a temporary grounding electrode when the conductive concrete column cuts out the main circuit.

[0031] 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. In 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. In 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.

[0032] The detection unit includes a mutually coupled primary coil and a secondary coil and a zero-sequence measurement module, wherein 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 extinguishing circuit can be incorporated into the neutral point of the primary coil.

[0033] 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. In the high level period of the first switch signal, the control unit controls switch K1 to remain closed, and in the low level period of the first switch signal, the control unit controls switch K1 to remain open; in the high level period of the second switch signal, the control unit controls switch K2 to remain closed, and in the low level period of the second switch signal, the control unit controls switch K2 to remain open; in the low level period of the third switch signal, the control unit controls switch K3 to remain closed, and in the high level period of the third switch signal, the control unit controls switch K3 to remain open; in the high level period of the fourth switch signal, the control unit controls switch K4 to remain closed, and in the low level period of the fourth switch signal, the control unit controls switch K4 to remain open. Embodiment 3

[0034] This embodiment further discloses a preferred algorithm for calculating the first compensation resistor and the second compensation resistor.

[0035] When the first switch signal is in a high level cycle, the calibration unit collects the current value i1 and the voltage value u1. At this time, the resistance between the reference electrode and the voltage electrode is u1 / i1. The reference electrode is small in size and the scattered current effect can be ignored. According to the resistance model of the ideal grounding network, ρ= (u1 / i1) G, where G is the correction parameter. The current electrode and the voltage electrode are regarded as point electrodes, G=2π(s1s2) / (s1+s2). Therefore, 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. Usually three groups of electrodes are arranged in parallel, with the voltage electrode in the middle, s1=18 meters, and s2=12 meters.

[0036] When the fourth switch signal is at a high level, the calibration unit collects the current value i2 and the voltage value u2. At this time, the column combined resistance r2 between the conductive concrete column and the soil layer is measured, r2=u2 / i2. The column combined resistance includes the ideal contact resistance of the four groups of conductive concrete columns in parallel and the resistance caused by the scattered current effect.

[0037] The first processing unit calculates the ideal contact resistance r3. The size parameters of the conductive concrete column cannot be ignored. The conductive concrete column is regarded as a buried cylinder, and the ideal contact resistance of each conductive concrete column is r3=ρln(8h2 / h1-1) / (2πh2), h1 is the diameter of the conductive concrete column, h2 is the length of the conductive concrete column (buried length), usually h1=0.5 meters, h2=2 meters, 8h2>h1. According to the resistance relationship of the parallel circuit, the resistance caused by the scattered flow effect=r3r2 / (r3-mr2), m is the number of conductive concrete columns, and m=4 in this embodiment. The scattered flow effect between the conductive concrete columns cannot be ignored. In this embodiment, the ratio of the scattered flow resistance of the current soil layer to the combined resistance of the column is used as the scattered flow parameter, that is, the scattered flow parameter λ of the soil layer=r3 / (r3-mr2).

[0038] The second processing unit counts the number of times N' that the zero-sequence voltage is greater than 10V in the natural cycle, where 10V is usually the upper limit of the zero-sequence voltage allowed for high-voltage transmission lines. Then the number of lightning strikes N in the natural cycle is read, and the voltage fluctuation probability p= N' / N, where the voltage fluctuation probability is the probability that the transmission line generates a zero-sequence voltage due to lightning weather. The natural cycle is, for example, a year. In this embodiment, the number of times the zero-sequence voltage is greater than 10V and the number of lightning strikes in the current area are counted each year through its own measuring instrument. In a simpler embodiment, the number of days in which the zero-sequence voltage is greater than 10V and the number of lightning strikes in the current area are counted in units of days through an external climate database.

[0039] The first compensation resistor is used to adjust the comprehensive grounding resistance to the design level. The first compensation resistor r' is connected in parallel with the basic grounding resistance r4 to obtain r0-r2. Therefore, the first compensation resistor r'=r4(r0-r2) / (r4-r0+r2), r0 is the design grounding resistance, and r4 is the basic grounding resistance. The design grounding resistance is determined according to the weather environment and the voltage level of the transmission line in the area. Usually, the design grounding resistance of 35kV in mountainous areas is 4Ω.

[0040] Due to the presence of the conductive concrete column, the diffusion effect of the soil layer is increased. The present invention generates a second compensation resistor through the diffusion parameter, and the second compensation resistor is used to compensate for the impedance drop caused by the diffusion effect. The second compensation resistor r''=(r0-r2) / (λe p ), e is a natural number. The scattered current parameter and the voltage fluctuation probability jointly affect the second compensation resistor. The greater the influence of the scattered current effect, the smaller the actual impedance, the smaller the scattered current parameter, the more consideration is needed for the electrical corrosion problem, and the greater the resistance compensation. The greater the voltage fluctuation probability, the greater the risk of lightning strike, the more consideration is needed for grounding safety, and the smaller the resistance compensation.

[0041] In this embodiment, a function of fitting the second compensation resistor is directly based on the scattered current parameter (scattered current resistance) and the voltage fluctuation probability, that is, the second compensation resistor is proportional to the scattered current parameter and inversely proportional to the exponent of the voltage fluctuation probability. The calculation method is simple and easy to implement, and the second compensation resistor can be quickly updated. However, the second compensation resistor is not strictly linearly related to the scattered current parameter and the voltage fluctuation probability.

[0042] In a further embodiment, the model function can be generated by a support vector machine. Specifically, multiple sets of historical data of the current dispersion parameter λ, the voltage fluctuation probability p and the second compensation resistor r'' are collected, and 80% of the historical data are used as a training set and 20% of the historical data are used as a validation set. A support vector machine is constructed, and a polynomial kernel function of the vector machine is selected to map the historical data to a high-dimensional space. Try to find a hyperplane that minimizes the prediction error of the training set, and determine the model function F(λ,p) based on the hyperplane. Use the validation set to evaluate the mean square error of the model function, and determine whether to re-update the model function based on the error value until a model function that meets the error condition is obtained. Embodiment 4

[0043] Reference Fig.10 This embodiment discloses a grounding method according to the grounding device of the conductive concrete tower, comprising the following steps.

[0044] Step 1: Insert the reference electrode into the calibration loop, connect the calibration unit to the reference electrode via the calibration loop, and collect soil resistivity.

[0045] Step 2: Cut the reference electrode into the main circuit, and connect the grounding unit to the reference electrode through the main circuit.

[0046] Step 3: Cut the conductive concrete column out of the main circuit and disconnect the grounding unit from the conductive concrete column.

[0047] 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.

[0048] Step 5: Calculate the bulk flow parameters of the soil layer based on the soil resistivity and the combined resistance of the column.

[0049] Step 6: The detection unit is connected to the transmission line, and the detection unit collects the zero-sequence voltage of the transmission line.

[0050] Step 7: Predict the voltage fluctuation probability of the transmission line based on the zero-sequence voltage at multiple moments.

[0051] 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.

[0052] 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.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in 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 for a 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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