CN114047554A - Earth resistivity model modeling method and device, computer equipment and storage medium - Google Patents

Abstract

The present application relates to a method, apparatus, computer equipment and storage medium for modeling a ground resistivity model. The method comprises: using the quadrupole method to obtain the first earth resistivity data of the shallow layer, using the controllable source audio frequency magnetotelluric method to measure the second earth resistivity data of the middle layer, and using the magnetotelluric method to measure the deep layer third earth resistivity. Data; inversion of the first earth resistivity data to obtain the first inversion objective function, inversion of the second earth resistivity data to obtain the second inversion objective function, and inversion of the third earth resistivity data to obtain the third inversion Objective function: According to the first, second and third inversion objective functions, the comprehensive inversion objective function is obtained, and the differential evolution algorithm is used to invert the comprehensive inversion objective function, and the comprehensive inversion with the soil parameters after the inversion will be The objective function serves as the earth resistivity model. The method can accurately and uniformly model the earth resistivity covering a wide area covering tens of kilometers from the surface to the ground.

Description

Ground resistivity model modeling method, device, computer equipment and storage medium

technical field

The present application relates to the technical field of power system grounding, and in particular, to a method, apparatus, computer equipment and storage medium for modeling earth resistivity.

Background technique

With the development of power system grounding technology, it is a feasible idea to extend the size of the ground electrode in the vertical direction. When the earth resistivity in the deep part of the electrode site is low, the current can be led to the deep underground. However, the earth resistivity exploration is very complicated due to the large buried depth of the ground electrode and the wide range of strata involved. In order to better study the distribution law of earth resistivity, the earth resistivity modeling method is proposed. However, the traditional earth resistivity modeling method does not take into account the distribution law of earth resistivity at different depths, and cannot accurately and uniformly model the wide area of earth resistivity covering tens of kilometers from the surface to the ground.

SUMMARY OF THE INVENTION

Based on this, it is necessary to provide a method, device, computer equipment and storage medium that can accurately model a wide-area earth resistivity model covering tens of kilometers from the surface to the underground in response to the above technical problems.

A method for modeling a ground resistivity model, the method comprising:

Using the quadrupole method to measure the first earth resistivity data in the shallow layer;

The second earth resistivity data of the middle layer is measured by the controllable source audio frequency magnetotelluric method;

The third earth resistivity data of the deep layer is measured by the magnetotelluric method; the above-mentioned shallow layer, middle layer and deep layer are divided according to the depth;

Inverting the first earth resistivity data to obtain the first inversion objective function;

Inverting the second earth resistivity data to obtain the second inversion objective function;

The third inversion objective function is obtained by inverting the third earth resistivity data;

Obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function and the third inversion objective function;

The differential evolution algorithm was used to invert the soil parameters of the comprehensive inversion objective function, and the comprehensive inversion objective function with the inversion soil parameters was used as the earth resistivity model.

In one embodiment, the step of using the differential evolution algorithm to perform soil parameter inversion on the comprehensive inversion objective function includes:

By setting the inversion initial value of the comprehensive inversion objective function, the population is initialized, and the population refers to the population composed of the individual soil parameters in the comprehensive inversion objective function;

Iteratively executes the steps of performing mutation operation on the individuals in the contemporary population to generate mutant individuals, performing crossover operations on the contemporary population and mutant individuals to generate experimental individuals, and selecting excellent individuals between the experimental individuals and the individuals in the contemporary population to form the next generation population, until When the termination conditions are met, the soil parameters in the latest generation of populations are output as the soil parameters after inversion.

In one embodiment, the step of performing mutation operation on individuals in the contemporary population to generate mutated individuals includes:

Three different individuals in the population are randomly selected, and the vector difference of any two individuals is weighted with the vector of the remaining individual to obtain a mutant individual.

In one embodiment, according to the first inversion objective function, the second inversion objective function and the third inversion objective function, the step of obtaining the comprehensive inversion objective function includes:

configuring the first weight parameter of the first inversion objective function, the second weight parameter of the second inversion objective function, and the third weight parameter of the third inversion objective function;

The first inversion objective function, the second inversion objective function and the third inversion objective function are weighted and summed to obtain a comprehensive inversion objective function.

In one embodiment, the value of the first weight parameter decreases as the sounding increases; the value of the second weight parameter increases first and then decreases with the increase of the sounding; when the value of the second weight parameter increases When the value decreases, the value of the third weight parameter increases with the increase of sounding depth, and remains unchanged when the sounding reaches the maximum sounding depth.

In one embodiment, the method for modeling the earth resistivity model further includes:

The initial value of the first weight parameter is configured as 1; the initial value of the second weight parameter is configured as 0; the initial value of the third weight parameter is configured as 0.

When the sounding gradually increases before the first threshold, the first weight parameter is decreased, and the second weight parameter is increased, and when the sounding increases to the first threshold, the first weight parameter is decreased to 0, and the second weight parameter is decreased to 0. The weight parameter is increased to 1;

When the sounding gradually increases within the range from the first threshold to the second threshold, the second weighting parameter is decreased, and the third weighting parameter is increased, and when the sounding increases to the second threshold, the second weighting parameter Decrease to 0 and increase the third weight parameter to 1.

A device for modeling a ground resistivity model, the device comprising:

The first earth resistivity acquisition module is used to measure the shallow first earth resistivity data by the quadrupole method;

The second earth resistivity acquisition module is used to measure the second earth resistivity data of the middle layer by the controllable source audio frequency magnetotelluric method;

The third earth resistivity acquisition module is used to measure the deep third earth resistivity data by using the magnetotelluric method; the shallow layer, the middle layer and the deep layer are divided according to the depth;

a first inversion function establishment module, configured to invert the first earth resistivity data to obtain a first inversion objective function;

The second inversion function establishment module is used to invert the second earth resistivity data to obtain a second inversion objective function;

A third inversion function establishment module is used to invert the third earth resistivity data to obtain a third inversion objective function;

a comprehensive inversion function establishment module, configured to obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function and the third inversion objective function;

The optimization module is used to perform soil parameter inversion on the comprehensive inversion objective function by using a differential evolution algorithm, and use the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model.

A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the above-mentioned earth resistivity model modeling method are implemented.

A computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, implements the steps of the above-mentioned method for modeling the earth resistivity model.

The above-mentioned earth resistivity modeling method, device, computer equipment and storage medium, by using quadrupole method, controllable source audio magnetotelluric method and magnetotelluric method respectively to measure the earth resistivity at different depths to obtain the earth resistance of different sounding depths Then, the inversion objective function obtained by inversion of the earth resistivity data obtained by the quadrupole method, the inversion objective function obtained by the inversion of the earth resistivity data obtained by the controllable source audio geodetic method, and the The inversion objective function obtained by inversion of the earth resistivity obtained by the electromagnetic method is mixed, and the comprehensive inversion objective function is obtained; The comprehensive inversion objective function of the parameters is used as the earth resistivity model, so as to realize the unified modeling of the wide area earth resistivity covering from the surface to the underground tens of kilometers.

Description of drawings

Fig. 1 is the application environment diagram of the earth resistivity model modeling method in one embodiment;

2 is a schematic flowchart of a method for modeling the earth resistivity model in one embodiment;

Fig. 3 is the measurement schematic diagram of the quadrupole method;

Fig. 4 is the measurement schematic diagram of the controllable source audio frequency magnetotelluric method;

Fig. 5 is the measurement schematic diagram of magnetotelluric method;

6 is a schematic flowchart of steps of a method for modeling the earth resistivity model in one embodiment;

7 is a schematic flowchart of steps of a method for modeling the earth resistivity model in another embodiment;

Figure 8 is a schematic diagram of the measurement of the UHV DC grounding pole position;

Figure 9 is a schematic diagram of the grounding resistance measurement of the ground electrode;

Fig. 10 is a structural block diagram of an apparatus for modeling the earth resistivity model in one embodiment;

11 is a structural block diagram of a comprehensive inversion function establishment module in one embodiment;

12 is a structural block diagram of an optimization module in one embodiment;

Figure 13 is a diagram of the internal structure of a computer device in one embodiment.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

The earth resistivity model modeling method provided in this application can be applied to the application environment shown in FIG. 1 . The terminal 102 communicates with the server 104 through the network. The user can use the mobile terminal 102 to obtain the electric field and electromagnetic data that can characterize the resistivity of the earth based on the quadrupole method, the electric field and electromagnetic data that can characterize the resistivity of the earth based on the controllable source audio Electric field and electromagnetic data characterizing the resistivity of the earth is sent to server 104 . The server 104 performs the steps of the earth resistivity modeling method according to the above electric field and electromagnetic data to model the earth resistivity. The terminal 102 can be, but is not limited to, various personal computers, notebook computers, smart phones, tablet computers and portable wearable devices, and the server 104 can be implemented by an independent server or a server cluster composed of multiple servers.

In one embodiment, as shown in FIG. 2 , a method for modeling earth resistivity is provided, and the method is applied to the server in FIG. 1 as an example for illustration, including the following steps:

S20, using the quadrupole method to measure the first earth resistivity data of the shallow layer.

S40, the second earth resistivity data of the middle layer is measured by the controllable source audio frequency magnetotelluric method.

S60, the third earth resistivity data of the deep layer is measured by the magnetotelluric method.

S80, inverting the first earth resistivity data to obtain a first inversion objective function.

S100, inverting the second earth resistivity data to obtain a second inversion objective function.

S120, inverting the third earth resistivity data to obtain a third inversion objective function.

S140: Obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function, and the third inversion objective function.

S160, using the differential evolution algorithm to perform soil parameter inversion on the comprehensive inversion objective function, and using the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model.

Among them, the above-mentioned shallow layer, middle layer and deep layer are obtained by dividing according to the depth.

The quadrupole method is a measurement method that uses the spatial potential difference formed by current backflow to deduce the subsurface resistivity distribution. The quadrupole method has high sensitivity to shallow ground resistivity, so it is suitable for measuring shallow ground resistivity data.

Specifically, the measurement schematic diagram _of the quadrupole method is shown in Figure _3. P1 and _P4 are current electrodes, P2 and _P3 are voltage electrodes. Taking the measurement center point as the center, a current electrode and a current electrode are respectively arranged on both sides. A voltage electrode, d is the distance between electrodes, b is the depth of the measuring electrode.

The specific measurement process of using the quadrupole method to measure the shallow first earth resistivity data includes the following steps:

Survey the survey location to determine the survey center point.

Keep the position of the measurement center point unchanged, and conduct the equidistant quadrupole method with the wiring in the north-south direction (or any direction), and the polar distance is selected according to the principle of " _1-2-3-5-7 ". .

Keeping the position of the measurement center point unchanged, perform the same measurement in the east-west direction (or perpendicular to the previous measurement direction) wiring method and pole spacing arrangement, and observe the difference in apparent resistivity in the two directions.

After completing the measurement of m ₁ groups of pole distance arrangements according to the above steps, perform one-dimensional inversion of soil parameters according to the first inversion objective function F ₁ :

Among them, ρ _a (d _i ) and ρ _m (d _i ) are the i-th group of measurements, respectively, and the forward and measured values of apparent resistivity when the sounding is di. The calculation method of the forward value of the apparent resistivity of the quadrupole method has been disclosed in other documents, and will not be repeated here.

In addition, when the pole distance of the quadrupole method exceeds 100m, the measurement data will be inaccurate due to the mutual inductance effect of the wires. At the same time, the quadrupole method is difficult to penetrate when it encounters a high resistance layer. Therefore, the maximum measurement pole distance of the quadrupole method is generally It is set to about 100m, that is, the maximum sounding depth of the quadrupole method is 100m, and the earth resistivity cannot be measured when the depth exceeds 100m.

The controllable source audio magnetotelluric method is a frequency domain sounding method developed to overcome the disadvantage of poor signal strength of the magnetotelluric method. It has the characteristics of high signal-to-noise ratio and strong anti-interference ability. However, the controllable source audio magnetotelluric method is greatly affected by the frequency, and it is easy to be interfered when measuring high-frequency shallow data. Therefore, the controllable source audio magnetotelluric method is not as accurate as the quadrupole method for shallow data. Usually, the sounding depth of the controllable source audio magnetotelluric method can reach 2.5km-3km. Therefore, in the embodiment of the present invention, the quadrupole method is used to measure the first ground resistivity data in the shallow layer, and the controllable source audio frequency magnetotelluric method is used to measure the first earth resistivity data. Measure the second earth resistivity data in the middle layer.

Specifically, Figure 4 shows the measurement scheme of the controlled-source audio magnetotelluric method.

The measurement steps of measuring the second earth resistivity data of the middle layer by using the controllable source audio frequency magnetotelluric method include:

The transmitters and sources A and B are arranged, and the electrodes and magnetic poles of the controllable source audio-magnetism are arranged at the measurement points.

Determine the minimum measurement frequency of the pole site to determine the maximum measurement depth.

Measure the data of the apparent resistivity changing with the frequency f _i corresponding to the measurement point, extract the electric field _Ex and the magnetic field _{Hy in the frequency range in the receiving system, and calculate the apparent resistivity corresponding to the frequency f i :}

where Z is the apparent resistivity, T is the period, and f _i is the frequency of the ith measurement.

Take out m ₂ feature points, and perform one-dimensional inversion of soil parameters according to the second inversion objective function F ₂ :

Among them, ρ _a (fi ) and ρ _m (fi _{) are the forward value and the measured value of the apparent resistivity corresponding to the frequency f i of} the _ith feature point, respectively. The calculation method of the forward value of the resistivity has been disclosed in other literatures, and will not be repeated here.

The detection is jointly determined from the inversion result and the above-mentioned measurement data, and whether to repeat the measurement of the above-mentioned steps is determined through the detection.

Move the measurement points and repeat the above steps until all measurement points have been measured.

The detection depth of the magnetotelluric method can theoretically reach 100 kilometers, and the detection depth of this method depends on the lowest frequency that can be received by the measuring field equipment. However, since this method needs to measure the corresponding natural magnetic field and electric field data at low frequencies, the resistivity data of the shallow and middle layers measured by this method are easily submerged in the measurement site. Therefore, in the embodiment of the present invention, only the Magnetotelluric method to measure the deep third earth resistivity data.

Specifically, the arrangement of the magnetotelluric method is shown in FIG. 5 . The steps of using magnetotelluric method to measure deep earth resistivity data include:

The electrodes and magnetic poles are arranged at the measurement center point, and the non-polarized electrodes are arranged in four directions, east, west, northwest, _respectively , and the electrodes are _centered on the receiver. The magnetic poles are arranged in the _x and _y directions of the second and fourth quadrants shown in to measure the two quadrant components Hx and Hy, respectively, components of the magnetic field. The electric fields in the x and y directions measured by the non-polarized electrodes are calculated as:

Among them, Ex is the electric field in the x direction, E _y is the electric field in the _y direction, and D is the distance between two non-polarized electrodes in the same direction.

Monitor the electric field and magnetic field data over a period of time, extract the electric field and magnetic field in the frequency range, and calculate the apparent resistivity corresponding to the frequency f _i :

where Z ₁ ( _fi ) is the apparent resistivity in the xy direction, and Z ₂ ( _fi ) is the apparent resistivity in the yx direction.

Take out m ₃ feature points, and perform one-dimensional inversion of soil parameters according to the third inversion objective function F ₃ :

Among them, ρ _a (fi ) and ρ _m (fi ₎ are the forward value and the measured value of the apparent resistivity corresponding to the frequency fi of the _ith feature point _, respectively. The calculation method of the forward value of the apparent resistivity of the magnetotelluric method has been disclosed in other literatures, and will not be repeated here.

The inversion results and the measurement data are used to determine the sounding, and judge whether the sounding meets the requirements. If not, repeat the magnetotelluric measurement steps above.

The above first inversion objective function, the second inversion objective function and the third inversion objective function are added to obtain the comprehensive inversion objective function, and the comprehensive inversion objective function minF can be expressed as:

minF=F ₁ +F ₂ +F ₃

In one embodiment, as shown in Figure 6, according to the first inversion objective function, the second inversion objective function and the third inversion objective function, the step of obtaining the comprehensive inversion objective function includes:

S141 , configure the first weight parameter of the first inversion objective function, the second weight parameter of the second inversion objective function, and the third weight parameter of the third inversion objective function according to the sounding.

The purpose of configuring the first weight parameter, the second weight parameter and the third weight parameter according to the sounding is to make the value of the resistivity of the earth resistivity model for different depths more inclined to a method that is more accurate for the depth measurement.

S142: Perform a weighted summation on the first inversion objective function, the second inversion objective function, and the third inversion objective function to obtain a comprehensive inversion objective function.

Specifically, the comprehensive inversion objective function minF can be obtained by configuring the first weight parameter, the second weight parameter and the third weight parameter by the following formula:

min F=ω ₁ F ₁ +ω ₂ F ₂ +ω ₃ F ₃

Wherein, ω ₁ , ω ₂ and ω ₃ represent the first weight parameter, the second weight parameter and the third weight parameter, respectively.

The first weight parameter, the second weight parameter and the third weight parameter are all related to the sounding. Specifically, the first weight parameter is related to the polar distance, and the second weight parameter and the third weight parameter are related to the frequency.

In one embodiment, the value of the first weight parameter decreases as the sounding increases, the value of the second weight parameter increases first and then decreases with the increase of the sounding, and the value of the third weight parameter increases with the sounding It increases as the depth increases, and remains unchanged when the sounding reaches the maximum sounding depth.

In one embodiment, the earth resistivity modeling method further includes:

S130 , the initial value of the first weight parameter is configured to be 1, the initial value of the second weight parameter is configured to be 0, and the initial value of the third weight parameter is configured to be 0.

In one embodiment, the step S141 of configuring the values of the first weight parameter, the second weight parameter and the third weight parameter according to the sounding includes:

When the sounding gradually increases before the first threshold, the first weight parameter is decreased, and the second weight parameter is increased, and when the sounding increases to the first threshold, the first weight parameter is decreased to 0, and the second weight parameter is decreased to 0. The weight parameter is increased to 1;

When the sounding gradually increases within the range from the first threshold to the second threshold, the second weighting parameter is decreased, and the third weighting parameter is increased, and when the sounding increases to the second threshold, the second weighting parameter Decrease to 0 and increase the third weight parameter to 1.

The typical sounding range of quadrupole method is 0～100m, the typical sounding range of controllable source audio magnetotelluric method is 10～2500m, and the typical sounding range of magnetotelluric method is 2.5km～100km. Therefore, the typical sounding ranges of the quadrupole method, the controllable source audio magnetotelluric method and the magnetotelluric method overlap each other to a certain extent, and the overlapping part is called the transition layer. For example, the transition layer between the shallow layer and the middle layer is 10m to 100m. By setting the first threshold and the second threshold, the results of the shallow transition layer in the earth resistivity model can be more inclined to the quadrupole method with higher measurement accuracy for the shallow layer, and the results of the middle transition layer can be more inclined to the measurement accuracy of the middle layer. The high controllable source audio frequency magnetotelluric method, and the result of the deep transition layer are more biased towards the magnetotelluric method with higher precision for deep measurement, and finally a more accurate wide-area earth resistivity model is obtained.

Specifically, in the shallow layer, the earth resistivity model mainly refers to the measurement results of the quadrupole method. The output results of the model are related to the first weight parameter and the second weight parameter. The initial value of the first weight parameter is set to 0, and the second weight parameter is set to 0. The initial value is set to 1. As the sounding increases, the first weight parameter gradually decreases, and the second weight parameter gradually increases. When the sounding increases to the first threshold for distinguishing the shallow layer and the middle layer, the first weight parameter decreases to 0, and the second weight parameter increases to 1. At this time, as the sounding continues to increase, the second weight parameter It gradually decreases, and the third weight parameter increases from 0. The earth resistivity model mainly refers to the measurement results of the controllable source audio magnetotelluric method. The model output results are related to the second weight parameter and the third weight parameter. When the sounding increases to the second threshold for distinguishing between the middle layer and the deep layer, the second weight parameter decreases to 0, and the third weight parameter increases to 1. At this time, as the sounding continues to increase, the third weight parameter remains Invariant, the earth resistivity model mainly refers to the measurement results of the magnetotelluric method. The above-mentioned shallow layer, middle layer and deep layer can be divided according to the measurement depth, and the first threshold value and the second threshold value are set according to the actual measurement environment.

In one embodiment, as shown in FIG. 7 , the step S160 of using the differential evolution algorithm to perform soil parameter inversion on the comprehensive inversion objective function includes:

S161, initialize the population by setting the initial inversion value of the comprehensive inversion objective function.

Among them, the population refers to the population composed of the individual soil parameters in the above-mentioned comprehensive inversion objective function. The above-mentioned initial value of inversion includes parameters such as the first weight parameter, the second weight parameter, the third weight parameter, the maximum number of inversion layers, the depth, and the inversion precision, which need to be preset with initial values.

Specifically, N D-dimensional vectors are generated in the search space and cover the entire search space.

Among them, G represents the evolutionary algebra, the initial population G=0, and the individual s can be expressed as:

S162, iteratively execute the steps of performing mutation operation on individuals in the contemporary population to generate mutant individuals, performing crossover operations on the contemporary population and mutant individuals to generate experimental individuals, and selecting excellent individuals between the experimental individuals and individuals in the contemporary population to form the next generation population , until the termination condition is met, the soil parameters in the latest generation of populations are output as the soil parameters after inversion.

Specifically, the steps of performing mutation operation on individuals in the contemporary population to generate mutated individuals can be as follows:

Three different individuals in the population are randomly selected, and the vector difference of any two individuals is weighted and superimposed with the vector of the remaining one to obtain the variant individual.

Specifically, the process of generating mutant individuals can be expressed as follows:

Among them, r ₁ , r ₁ , r ₁ ∈ (1, 2, . . . , N) and different from i, and k is a scaling factor.

Then, crossover operations are performed on contemporary populations and mutant individuals to generate experimental individuals.

The above crossover operation can be expressed as follows:

为变异个体，rand(j)为[0,1]之间均匀分布随机数；CR∈[0,1]为交叉概率；rnbr(i)为{1,2,...,D}之间随机整数。in,

is a mutant individual, rand(j) is a uniformly distributed random number between [0,1]; CR∈[0,1] is the crossover probability; rnbr(i) is between {1,2,...,D} random integer.

Select excellent individuals between experimental individuals and individuals in the contemporary population to form the next generation population.

If it is determined that the termination condition is met, the soil parameters in the latest generation of populations are output as the soil parameters after inversion.

Among them, if the algorithm reaches the preset inversion accuracy, it is considered that the termination condition is met, and a feasible solution is output; if the algorithm exceeds the preset calculation amount and does not reach the preset inversion accuracy, it is considered to meet the termination condition. , output the current optimal solution. The preset inversion precision includes the inversion precision F1 of the first inversion objective function, the inversion precision F2 of the second inversion objective function, the inversion precision F3 of the third inversion objective function, and the inversion precision of the comprehensive inversion objective function. Inversion accuracy F.

The preset calculation amount includes the number of iterations and the running time of the algorithm.

In one of the embodiments, F ₁ , F ₂ , and F ₃ are all set to 6%, and F is set to 18%. When F ₁ , F ₂ and F ₃ are all less than 6% and F is less than 18%, it is considered that the above differential evolution algorithm satisfies the termination condition, and a feasible solution is output.

If it is determined that the termination condition is not satisfied, iteratively executes S162.

Since the quadrupole method is an electrical method, the controllable source audio magnetotelluric method and the magnetotelluric method are electromagnetic methods, the inversion theory of the electrical method and the electromagnetic method cannot be applied across methods, and the normalization of different data to a unified size is a joint inversion. In order to solve this problem, the technical solution in the embodiment of the present application first obtains the comprehensive inversion objective function, and uses the differential evolution algorithm to invert the comprehensive inversion objective function, so as to realize the quadrupole method-based, controllable The measurement data obtained by the source audio magnetotelluric method and the magnetotelluric method are normalized to a unified size to complete the inversion of soil parameters.

Differential evolution algorithm has the advantages of fast convergence, few control parameters, simple setting and good robustness. Therefore, using the differential evolution algorithm to invert the soil parameters of the comprehensive inversion objective function can make the modeling process of the earth resistivity model more efficient, that is, the algorithm can be converged with fewer iterations.

It should be understood that although the various steps in the flowchart of FIG. 2 or FIG. 6 or FIG. 7 are sequentially displayed according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, the execution of these steps is not strictly limited to the order, and these steps may be performed in other orders. Moreover, at least a part of the steps in FIG. 2 or FIG. 6 or FIG. 7 may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but may be executed at different times. Alternatively, the order of execution of the stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least a portion of the steps or stages in the other steps.

In addition, the earth resistivity model modeling method proposed in the embodiment of the present application can be applied to the earth resistivity modeling of the UHV DC ground electrode.

As an important part of the UHVDC transmission system, the DC ground electrode acts to clamp the neutral point potential during the operation of the system, and provides a ground connection for the rated current during unipolar extreme operation or the unbalanced current during bipolar asymmetrical operation. channel etc. When the DC system runs on a single pole, the powerful rated current of the system flows into the ground through the ground electrode to increase the surface potential, and the current spreads in the ground to cause the surrounding soil to heat up. If the temperature is too high, the stable operation of the ground electrode will be seriously affected. Therefore, it is very important to select the ground electrode location in the design stage of DC engineering. Due to the strict requirements of the key performance indicators of the DC ground electrode, it is necessary to have a large enough diffusion area for the ground electrode. At present, land resources are tight, and most conventional DC grounding electrodes are large in size, which leads to the increasingly prominent problems of difficult site selection and land acquisition for DC grounding electrodes.

Therefore, it is a feasible idea to extend the size of the ground electrode to the vertical direction in practical engineering. When the earth resistivity of the deep electrode site is low, the current can be led to the deep underground, which has certain advantages in reducing the grounding resistance and step voltage, and also reduces the floor space. It is an effective grounding electrode arrangement. Program. At present, the buried depth of the DC ground electrode may be in the range of hundreds to thousands of kilometers, and the electrical and thermal characteristics of the ground electrode will be largely determined by the earth resistivity within 10 times the buried depth.

However, at present, traditional earth resistivity modeling methods do not take into account the distribution law of earth resistivity at different depths, and cannot accurately model a wide area of earth resistivity covering tens of kilometers from the surface to the ground. . Therefore, in the embodiments of the present application, a combined measurement method and a geodetic resistivity modeling method that comprehensively use the terrestrial method, the controllable source audio frequency magnetotelluric method, and the magnetotelluric method are proposed, so that the coverage from the surface to the underground can be more accurately measured. Unified modeling of the wide-area earth resistivity of kilometers.

Specifically, the content of the embodiments of the present invention will be described in detail by using an ultra-high voltage DC ground pole address.

The ground pole site requires detection of earth resistivity at least 10km deep. According to the different advantageous detection depths of the three methods, the earth resistivity test is divided into three different depth sections, and different methods are used for testing. The quadrupole method is used to measure the earth resistivity data of 0m-100m, the controllable source audio magnetotelluric method is used to measure the earth resistivity data of 0m-3km, and the magnetotelluric method is used to measure the earth resistivity data of 0-68km. The schematic diagram of the pole address measurement is shown in Figure 8. Due to the limitation of on-site measurement conditions, the wiring of the four-pole method in the horizontal and vertical directions adopts the method of three vertical and one horizontal, that is, S1-S4 in the figure, and the maximum pole spacing is 100m. The controllable source audio magnetotelluric method adopts the straight-line method arrangement, that is, L2-L6 in the figure. The distance between L2 and L3 is 70m, and the distance between L3-L6 is 50m. The length of each measurement line is 700m, and the interval between measurement points in each line is 12.5m. It basically covers the local area of the ground electrode. Depending on the on-site interference situation, it is difficult to arrange all the magnetotelluric measurement points in a straight line. Therefore, the magnetotelluric method has four measurement points, which are M1-M4 in the figure.

The first earth resistivity data in the shallow layer, the second earth resistivity data in the middle layer, and the third earth resistivity data in the deep layer are measured by the method in the embodiment of the present application based on the quadrupole method, the controllable source audio frequency magnetotelluric method and the magnetotelluric method. The comprehensive inversion objective function is obtained from the earth resistivity data, and the differential evolution algorithm is used to invert the soil parameters for the comprehensive inversion objective function. The initial value of the number of large formations in the above differential evolution algorithm is set to 8. If "minF < 18%, F ₁ < 6%, F ₂ < 6% and F ₃ <6%" are satisfied, a feasible solution is output. "minF<18%, F ₁ <6%, F ₂ <6% and F ₃ <6%", then add 1 to the number of soil layers and continue the inversion until the preset algorithm stopping conditions are met. According to this inversion idea, a single measurement point is inverted.

By configuring the first weight parameter, the second weight parameter and the third weight parameter according to the sounding, the geodetic resistivity model is more inclined to the quadrupole method data for the depth of 0-100m, and the depth of 100m-3000m is more inclined to the controllable source audio magnetotelluric The magnetotelluric method is more inclined below the depth of 3km, and finally the wide-area earth resistivity model of the deep well ground electrode site is obtained, as shown in Table 1.

Table 1 Wide-area earth resistivity model for deep well ground electrode sites

In order to verify the accuracy of the earth resistivity measurement method and the modeling method proposed in the embodiments of the present application, a ground resistance test is carried out on the DC ground electrode. The three-pole method is used to carry out the grounding resistance test of the grounding electrode. The measurement uses 220V AC power supply, the rectifier converts AC to DC source, and the maximum output is 7A. The voltage is measured at the end of the deep well grounding electrode drainage cable. The schematic diagram of the measurement is shown in Figure 9, and the measurement results are shown in Table 2.

Table 2 The measurement results of the grounding resistance of the deep well grounding electrode

Using the earth resistivity model obtained in the examples of this application, the grounding resistance of the grounding electrode is calculated in the CDEGS simulation software, and the calculation result is 0.138Ω. Compared with the actual measured value, the error is only 0.036Ω, which proves that The reliability of the earth resistivity model obtained by the earth resistivity modeling method in the application examples.

In one embodiment, as shown in FIG. 10 , a device for modeling earth resistivity model is provided, including: a measurement module, a comprehensive inversion function establishment module and an optimization module, wherein:

The first earth resistivity acquisition module 20 is used to measure the shallow first earth resistivity data by using the quadrupole method;

The second earth resistivity acquisition module 40 is used to measure the second earth resistivity data of the middle layer by using the controllable source audio frequency magnetotelluric method;

The third earth resistivity acquisition module 60 is used to measure the third earth resistivity data of the deep layer by using the magnetotelluric method; the shallow layer, the middle layer and the deep layer are divided according to the depth;

a first inversion function establishment module 80, configured to invert the first earth resistivity data to obtain a first inversion objective function;

The second inversion function establishment module 100 is configured to invert the second earth resistivity data to obtain a second inversion objective function;

The third inversion function establishment module 120 is configured to invert the third earth resistivity data to obtain a third inversion objective function;

a comprehensive inversion function establishment module 140, configured to obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function and the third inversion objective function;

The optimization module 160 is used to perform soil parameter inversion on the comprehensive inversion objective function by using a differential evolution algorithm, and use the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model.

In one embodiment, as shown in Figure 11, the comprehensive inversion function establishment module includes:

The configuration unit 141 is configured to configure the first weight parameter of the first inversion objective function, the second weight parameter of the second inversion objective function, and the third weight parameter of the third inversion objective function according to the sounding.

The superposition unit 142 is configured to perform a weighted summation of the first inversion objective function, the second inversion objective function and the third inversion objective function to obtain a comprehensive inversion objective function.

In one embodiment, the comprehensive inversion function establishment module further includes:

The weight initial value setting unit 130 is configured to configure the initial value of the first weight parameter as 1, the initial value of the second weight parameter as 0, and the initial value of the third weight parameter as 0.

In one embodiment, the configuration unit 141 includes:

The weight updating unit is used to reduce the first weight parameter and increase the second weight parameter when the sounding gradually increases before the first threshold, and when the sounding increases to the first threshold, the first weight parameter decreases As small as 0, the second weight parameter increases to 1;

When the sounding gradually increases in the range from the first threshold to the second threshold, the second weight parameter is decreased, and the third weight parameter is increased, and when the sounding increases to the second When the threshold is set, the second weight parameter decreases to 0, and the third weight parameter increases to 1.

In one embodiment, as shown in Figure 12, the optimization module package 160 includes:

The initialization unit 161 is configured to initialize the population by setting the inversion initial value of the comprehensive inversion objective function.

The iterative execution unit 162 is used to iteratively execute the mutation operation on the individuals in the contemporary population to generate mutant individuals, perform crossover operations on the contemporary population and the mutant individuals, generate experimental individuals, and select excellent individuals between the experimental individuals and the individuals in the contemporary population to form The steps of the next generation population, until the termination condition is met, output the soil parameters in the latest generation population as the soil parameters after inversion.

In one embodiment, the mutant individual generating unit includes:

The differential weighting unit is used to randomly select three different individuals in the population, and superimpose the vector of any two individuals with the vector of the remaining one after differential weighting to obtain the variant individual.

For the specific limitation of the earth resistivity model modeling device, please refer to the limitation of the earth resistivity model modeling method above, which will not be repeated here. Each module in the above-mentioned earth resistivity model modeling apparatus can be implemented in whole or in part by software, hardware and combinations thereof. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

In one embodiment, a computer device is provided, the computer device may be a terminal, and its internal structure diagram may be as shown in FIG. 13 . The computer equipment includes a processor, memory, a communication interface, a display screen, and an input device connected by a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium, an internal memory. The nonvolatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the execution of the operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for wired or wireless communication with an external terminal, and the wireless communication can be realized by WIFI, operator network, NFC (Near Field Communication) or other technologies. The computer program, when executed by a processor, implements a method of modeling a ground resistivity model. The display screen of the computer equipment may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment may be a touch layer covered on the display screen, or a button, a trackball or a touchpad set on the shell of the computer equipment , or an external keyboard, trackpad, or mouse.

Those skilled in the art can understand that the structure shown in FIG. 13 is only a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer equipment to which the solution of the present application is applied. Include more or fewer components than shown in the figures, or combine certain components, or have a different arrangement of components.

In one embodiment, a computer device is provided, including a memory and a processor, a computer program is stored in the memory, and the processor implements the following steps when executing the computer program:

S20, using the quadrupole method to measure the first earth resistivity data of the shallow layer.

S40, the second earth resistivity data of the middle layer is measured by the controllable source audio frequency magnetotelluric method.

S60, the third earth resistivity data of the deep layer is measured by the magnetotelluric method.

S80, inverting the first earth resistivity data to obtain a first inversion objective function.

S100, inverting the second earth resistivity data to obtain a second inversion objective function.

S120, inverting the third earth resistivity data to obtain a third inversion objective function.

S140: Obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function, and the third inversion objective function.

S160, using the differential evolution algorithm to perform soil parameter inversion on the comprehensive inversion objective function, and using the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model.

Among them, the above-mentioned shallow layer, middle layer and deep layer are obtained by dividing according to the depth.

In one embodiment, the processor further implements the following steps when executing the computer program:

S130 , configure the initial value of the first weight parameter to be 1, configure the initial value of the second weight parameter to be 0, and configure the initial value of the third weight parameter to be 0.

In one embodiment, the processor further implements the following steps when executing the computer program:

S141. Configure a first weight parameter of the first inversion objective function, a second weight parameter of the second inversion objective function, and a third weight parameter of the third inversion objective function.

S142: Perform a weighted summation on the first inversion objective function, the second inversion objective function, and the third inversion objective function to obtain a comprehensive inversion objective function.

In one embodiment, the processor further implements the following steps when executing the computer program:

S161, initialize the population by setting the initial inversion value of the comprehensive inversion objective function.

S162, iteratively execute the steps of performing mutation operation on individuals in the contemporary population to generate mutant individuals, performing crossover operations on the contemporary population and mutant individuals to generate experimental individuals, and selecting excellent individuals between the experimental individuals and individuals in the contemporary population to form the next generation population , until the termination condition is met, the soil parameters in the latest generation of populations are output as the soil parameters after inversion.

If it is determined that the termination condition is not satisfied, S162 is executed.

In one embodiment, a computer-readable storage medium is provided on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

S20, using the quadrupole method to measure the first earth resistivity data of the shallow layer.

S40, the second earth resistivity data of the middle layer is measured by the controllable source audio frequency magnetotelluric method.

S60, the third earth resistivity data of the deep layer is measured by the magnetotelluric method.

S80, inverting the first earth resistivity data to obtain a first inversion objective function.

S100, inverting the second earth resistivity data to obtain a second inversion objective function.

S120, inverting the third earth resistivity data to obtain a third inversion objective function.

S140: Obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function, and the third inversion objective function.

S160, using the differential evolution algorithm to perform soil parameter inversion on the comprehensive inversion objective function, and using the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model.

Among them, the above-mentioned shallow layer, middle layer and deep layer are obtained by dividing according to the depth.

In one embodiment, the computer program further implements the following steps when executed by the processor:

S141. Configure a first weight parameter of the first inversion objective function, a second weight parameter of the second inversion objective function, and a third weight parameter of the third inversion objective function.

S142: Perform a weighted summation on the first inversion objective function, the second inversion objective function, and the third inversion objective function to obtain a comprehensive inversion objective function.

In one embodiment, the computer program further implements the following steps when executed by the processor:

S130 , configure the initial value of the first weight parameter to be 1, configure the initial value of the second weight parameter to be 0, and configure the initial value of the third weight parameter to be 0.

In one embodiment, the computer program further implements the following steps when executed by the processor:

S161, initialize the population by setting the initial inversion value of the comprehensive inversion objective function.

S162, iteratively execute the steps of performing mutation operation on individuals in the contemporary population to generate mutant individuals, performing crossover operations on the contemporary population and mutant individuals to generate experimental individuals, and selecting excellent individuals between the experimental individuals and individuals in the contemporary population to form the next generation population , until the termination condition is met, the soil parameters in the latest generation of populations are output as the soil parameters after inversion.

If it is determined that the termination condition is not satisfied, S162 is executed.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage In the medium, when the computer program is executed, it may include the processes of the above-mentioned method embodiments. Wherein, any reference to memory, storage, database or other media used in the various embodiments provided in this application may include at least one of non-volatile and volatile memory. The non-volatile memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, and the like. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, the RAM may be in various forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM).

The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, all It is considered to be the range described in this specification.

The above-mentioned embodiments only represent several embodiments of the present application, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims (10)

1. a method for modeling earth resistivity model, is characterized in that, described method comprises: Using the quadrupole method to measure the first earth resistivity data in the shallow layer; The second earth resistivity data of the middle layer is measured by the controllable source audio frequency magnetotelluric method; The third earth resistivity data of the deep layer is measured by the magnetotelluric method; the shallow layer, the middle layer and the deep layer are divided according to the depth; Inverting the first earth resistivity data to obtain a first inversion objective function; Inverting the second earth resistivity data to obtain a second inversion objective function; Inverting the third earth resistivity data to obtain a third inversion objective function; Obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function and the third inversion objective function; The differential evolution algorithm is used to invert the soil parameters of the comprehensive inversion objective function, and the comprehensive inversion objective function with the inversion soil parameters is used as the earth resistivity model. 2. method according to claim 1, is characterized in that, the step that described adopting differential evolution algorithm to carry out soil parameter inversion to comprehensive inversion objective function comprises: By setting the inversion initial value of the comprehensive inversion objective function, the population is initialized, and the population refers to the population formed by each soil parameter in the comprehensive inversion objective function as an individual; Iteratively execute the mutation operation on the individuals in the contemporary population to generate mutant individuals, perform crossover operations on the contemporary population and the mutant individuals, generate experimental individuals, and select excellent individuals between the experimental individuals and the individuals in the contemporary population to form the next generation population until the termination condition is met, the soil parameters in the latest generation of populations are output as the inversion soil parameters. 3. The method according to claim 2, wherein the step of performing mutation operation on an individual in the contemporary population to generate a mutation individual comprises: Three different individuals in the population are randomly selected, and the vector difference of any two individuals is weighted and superimposed with the vector of the remaining one to obtain the variant individual. 4. The method according to any one of claims 1-3, wherein, according to the first inversion objective function, the second inversion objective function and the third inversion objective function, obtaining The steps of comprehensive inversion of the objective function include: Configure the first weight parameter of the first inversion objective function, the second weight parameter of the second inversion objective function, and the third weight parameter of the third inversion objective function according to the sounding; The first inversion objective function, the second inversion objective function and the third inversion objective function are weighted and summed to obtain the comprehensive inversion objective function. 5. The method according to claim 4, wherein the value of the first weight parameter decreases as the sounding increases; The value of the second weight parameter first increases and then decreases as the sounding increases; When the value of the second weight parameter decreases, the value of the third weight parameter increases as the sounding depth increases, and remains unchanged when the sounding depth reaches the maximum sounding depth. 6. The method of claim 4, further comprising: The initial value of the first weight parameter is configured as 1; the initial value of the second weight parameter is configured as 0; the initial value of the third weight parameter is configured as 0. 7. The method according to claim 6, wherein the step of configuring the values of the first weight parameter, the second weight parameter and the third weight parameter according to sounding comprises: When the sounding gradually increases before the first threshold, the first weight parameter is decreased, and the second weight parameter is increased, and when the sounding increases to the first threshold, the first weight parameter is increased. A weight parameter decreases to 0, and the second weight parameter increases to 1; When the sounding gradually increases within the range of the first threshold to the second threshold, the second weight parameter is decreased, and the third weight parameter is increased, and when the sounding increases to the second When the threshold is set, the second weight parameter decreases to 0, and the third weight parameter increases to 1. 8. A device for modeling a ground resistivity model, wherein the device comprises: The first earth resistivity acquisition module is used to measure the shallow first earth resistivity data by the quadrupole method; The second earth resistivity acquisition module is used to measure the second earth resistivity data of the middle layer by the controllable source audio frequency magnetotelluric method; The third earth resistivity acquisition module is used to measure the deep third earth resistivity data by using the magnetotelluric method; the shallow layer, the middle layer and the deep layer are divided according to the depth; a first inversion function establishment module, used for inverting the first earth resistivity data to obtain a first inversion objective function; The second inversion function establishment module is used to invert the second earth resistivity data to obtain a second inversion objective function; The third inversion function establishment module is used to invert the third earth resistivity data to obtain a third inversion objective function; a comprehensive inversion function establishment module, configured to obtain a comprehensive inversion objective function according to the first inversion objective function, the second inversion objective function and the third inversion objective function; The optimization module is used to perform soil parameter inversion on the comprehensive inversion objective function by using the differential evolution algorithm, and use the comprehensive inversion objective function with the inversion soil parameters as the earth resistivity model. 9. A computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the method according to any one of claims 1 to 7 when the processor executes the computer program. step. 10. A computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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