Power transmission line fault locating method and system based on traveling wave front fitting, and storage medium and electronic device

Abstract

A power transmission line fault locating method and system based on traveling wave front fitting, and a storage medium and an electronic device. The method mainly comprises the following steps: on the basis of electrical parameters and control parameters of an actual project, constructing an electromagnetic transient simulation model for a power transmission system, setting metallic grounding faults along the entire length of a power transmission line at preset step sizes, and performing simulation (S1); recording fault occurrence moments, and, at a preset sampling frequency, collecting a voltage at an installation position of a fault locating device under each fault condition, so as to calculate a line-mode fault voltage under each fault condition (S2); performing function fitting on the line-mode fault voltage calculated at each fault position to obtain a fitting coefficient (S3); performing power function fitting on the fault positions and the fitting coefficients under various preset step size conditions to obtain a fault positioning function (S4); and when a power transmission line protection device of the actual project detects a line fault, performing fitting on a voltage collected by the fault locating device at a target sampling frequency to obtain a fitting coefficient, and substituting the fitting coefficient into the fault locating function to calculate a fault distance (S5).

Description

Transmission line fault location method, system, storage medium and electronic device based on traveling wave front fitting

[0001] Related applications

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on March 20, 2024, with application number 2024103208043 and application name “Transmission line fault location method, system, storage medium and electronic device based on traveling wave front fitting”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of relay protection control of power systems, and in particular to a method, system, storage medium and electronic device for locating faults in power transmission lines based on traveling wave front fitting. Background Art

[0004] With the interconnection of regional power grids in my country, a hybrid AC / DC grid has emerged, posing new challenges to the safe and stable operation of the grid. High-voltage transmission lines, as the medium for transmitting electrical energy within the grid, are subject to the highest failure rates due to variations in climatic conditions and regional characteristics. Accurately locating faults on high-voltage transmission lines is crucial for maintenance personnel to troubleshoot, quickly restore power, shorten outages, and minimize losses. Existing fault location methods primarily fall into three categories: traveling wave method, fault analysis method, and natural frequency method. The traveling wave method, with its advantages of high ranging accuracy, wide applicability, and minimal interference, has been widely used in power systems.

[0005] Traveling wave methods are categorized into single-ended and dual-ended methods. The single-ended method is favored for its simplicity, requiring only single-ended data, and eliminating the need for synchronization. However, the ranging accuracy of the single-ended method is significantly affected by the accurate identification of the traveling wave head and the reflected wave from the fault point. Consequently, extensive research has been conducted on the detection and identification of reflected waves from the fault point in single-ended location methods. However, the single-ended traveling wave location method still requires reliable detection of the reflected wave from the fault point. Furthermore, the fault traveling wave is significantly affected by transition resistance.

[0006] In order to rationally solve the problem that the single-ended traveling wave fault location of the existing transmission line is difficult to accurately identify the reflected wave at the fault point and the problem that the positioning accuracy is greatly affected by the transition to resistance, a new traveling wave-based transmission line fault location method is urgently needed to solve the problems existing in the above-mentioned existing technologies.

[0007] Summary of the Invention

[0008] Each exemplary embodiment of the present application provides a transmission line fault location method based on traveling wave wavefront fitting, so as to at least achieve the technical effect of solving the problem that the existing single-ended traveling wave fault location of the transmission line is difficult to accurately identify the reflected wave at the fault point, and the technical effect of solving the problem that the positioning accuracy is greatly affected by the transition resistance.

[0009] Each exemplary embodiment of the present application provides a transmission line fault location method based on traveling wave front fitting, comprising the following steps:

[0010] Based on the electrical parameters and control parameters of the actual project, an electromagnetic transient simulation model of the power transmission system is constructed. A metallic ground fault is set along the entire length of the transmission line with a preset step size and simulated.

[0011] Record the time of fault occurrence, and collect the voltage at the location where the fault location device is installed under each fault condition at a preset sampling frequency to calculate the sample line mode fault voltage under each fault condition;

[0012] Performing function fitting on the sample line mode fault voltages calculated at the respective fault locations to obtain corresponding fitting coefficients of the sample line mode fault voltages at the respective fault locations;

[0013] Performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function;

[0014] When the transmission line protection device of the actual project detects a line fault, the actual line mode fault voltage is calculated based on the voltage amount collected by the fault location device at a preset sampling frequency, and a function fitting is performed on the actual line mode fault voltage to obtain a fitting coefficient. The fitting coefficient is substituted into the fault location function to calculate the fault distance.

[0015] In another aspect of the present application, a transmission line fault location system based on traveling wave front fitting is proposed, comprising:

[0016] A model simulation module is configured to construct an electromagnetic transient simulation model of the power transmission system based on the electrical parameters and control parameters of the actual project, and to simulate a metallic ground fault along the entire length of the transmission line with a preset step size;

[0017] a fault condition calculation module configured to record the moment of fault occurrence, collect the voltage at the location where the fault location device is installed under each fault condition at a preset sampling frequency, and calculate the sample line mode fault voltage under each fault condition; perform function fitting on the sample line mode fault voltage calculated at each fault location to obtain the corresponding fitting coefficients of the sample line mode fault voltage at each fault location; perform power function fitting on the fault location and the fitting coefficients under each preset step size condition to obtain a fault location function in the form of a power function;

[0018] The target fault calculation module is configured to calculate the actual line mode fault voltage based on the voltage amount collected by the fault location device at a preset sampling frequency when the transmission line protection device of the actual project detects a line fault, and perform function fitting on the actual line mode fault voltage to obtain a fitting coefficient, substitute the fitting coefficient into the fault location function, and calculate the fault distance.

[0019] In another aspect of the present application, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, wherein the computer program is configured to execute the steps of any of the above method embodiments when run.

[0020] In another aspect of the present application, an electronic device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0021] This application has the following beneficial effects:

[0022] (1) Accurately locate the fault location of a high-voltage transmission line. This application collects the voltage of the transmission line, calculates the fault component and line mode fault component of the transmission line, performs logistic function fitting on the sample line mode fault voltage of the full transmission line fault, and obtains a power function expression of the fault location and fitting coefficient. For transmission line faults that occur in actual projects, the logistic function fitting coefficient of the actual line mode fault voltage wavefront data is substituted into the power function expression to obtain the fault location.

[0023] (2) There is no need to accurately determine the velocity of the fault voltage traveling wave. When the fault simulation is performed on the entire high-voltage transmission line with a preset step size, the line-mode fault voltage obtained already includes the effect of the wave velocity on the line-mode fault voltage. Therefore, there is no need to accurately calculate the velocity of the fault voltage traveling wave.

[0024] (3) Not affected by transition resistance. This application simulates metallic faults on the entire line with a step size of Δx kilometers to obtain the line-mode fault voltage traveling wave. When faults with different transition resistances occur at the same location, the line-mode fault voltage traveling wave front has a linear relationship. This application fits the line-mode fault voltage traveling wave front steepness information, so the fitting coefficient is the same under different transition resistances at the same location and is not affected by the transition resistance.

[0025] (4) No need to identify the reverse traveling wave reflected from the fault point. Existing single-ended fault location methods use the time difference between the first traveling wave and the reverse traveling wave reflected from the fault point to locate the fault. This requires accurate identification of the reflected wave from the fault point and the reflected wave from the end of the line. This application fits the line mode fault voltage traveling wavefront, eliminating the need to accurately identify the reverse traveling wave reflected from the fault point. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0027] FIG1 is a schematic diagram of the positioning process of the transmission line fault positioning method based on traveling wave front fitting in this application.

[0028] FIG2 is a schematic diagram of a positioning process of a transmission line fault positioning method based on traveling wave front fitting in an embodiment of the present application.

[0029] FIG3 is a diagram showing the logistic function fitting effect of a transmission line fault location method based on traveling wave front fitting in an embodiment of the present application when 0Ω and 400Ω transition resistances occur at the same location.

[0030] FIG4 is a relationship diagram between the fault distance and the fitting coefficient when a high voltage direct current transmission system is used as an example in an embodiment of the present application, wherein the total length of the direct current transmission line is 1200 km and the fault step length Δx is set to 5.

[0031] FIG5 is a diagram showing the power function fitting effect of the fault distance and the fitting coefficient in one embodiment of the present application.

[0032] FIG6 is a diagram showing the fitting coefficients and power function fitting effects of different DC transmission system topologies in an embodiment of the present application.

[0033] FIG7 is a diagram showing fault location results under different fault conditions in an embodiment of the present application.

[0034] FIG8 is a diagram showing fault location results under different topological structures in an embodiment of the present application.

[0035] FIG9 is a schematic diagram of an optional electronic device structure of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the preferred embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0037] Given the current state of the art, developing a fault location method for transmission lines that is unaffected by transition resistance and eliminates the need to identify reverse-traveling waves at the fault point is a highly research-oriented issue. Previous research has shown that line-mode fault voltages exhibit a linear relationship when varying transition resistance occurs at the same location. This relationship indicates that the fitting coefficients representing the speed of change of line-mode fault voltage curves are the same for varying transition resistances. Therefore, eliminating the influence of transition resistance on fault location accuracy has become a feasible technical approach.

[0038] As shown in Figures 1 and 2, a transmission line fault location method based on traveling wave front fitting includes the following steps:

[0039] S1: Based on the electrical parameters and control parameters of the actual project, an electromagnetic transient simulation model of the transmission system is constructed. A metallic ground fault is set along the entire length of the transmission line with a preset step size and simulated.

[0040] S2, recording the time of fault occurrence, collecting the voltage at the installation location of the fault location device under each fault condition at a preset sampling frequency, and calculating the sample line mode fault voltage under each fault condition;

[0041] S3, performing function fitting on the sample line mode fault voltages calculated at the respective fault locations, and obtaining corresponding fitting coefficients of the sample line mode fault voltages at the respective fault locations;

[0042] S4, performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function;

[0043] S5. When the transmission line protection device of the actual project detects a line fault, the fault location device calculates the actual line mode fault voltage based on the voltage value collected at a preset sampling frequency, performs function fitting on the actual line mode fault voltage to obtain a fitting coefficient, substitutes the fitting coefficient into the fault location function, and calculates the fault distance.

[0044] It should be noted that in S1, the metallic grounding fault at different locations of the transmission line is simulated with a step size of Δx kilometers, where the fault occurs at t0; the preset sampling frequency f is used. a Collect the voltage at the installation location of the fault location device under each fault condition and calculate the sample line mode fault voltage for each fault condition;

[0045] In S3, the sample line mode fault voltage calculated for each fault location is fitted with a logistic function;

[0046] In S4, the fitting coefficient k(i) under the conditions of fault location Δx, 2Δx, 3Δx, ..., τΔx is fitted with a power function to obtain the fault location function x(i) = m·k(i) in the form of a power function. n ,in represents rounding down of ●, L is the length of the transmission line, i = 1, 2, 3, ..., τ, x represents the fault distance, m and n are fitting coefficients;

[0047] In S5, for this actual project, when the transmission line protection device detects a line fault, the fault location device uses the preset sampling frequency f a Collect voltage, calculate the actual line mode fault voltage, and perform logistic function fitting on the actual line mode fault voltage to obtain the fitting coefficient k(x a ), the fitting coefficient k(x a ) is brought into the fault location function of step S3 to calculate the fault distance x meau .

[0048] In the specific embodiment, it should be noted that the step length Δx in step S1 is not greater than 5, and in steps S2 and S5, the sampling frequency f a Not less than 1MHz; in step S1, the fault occurrence time t0 is set to not less than 100ms.

[0049] In an optional embodiment, the voltage amount collected by the fault location device includes: when the transmission line is a DC transmission line, the positive line voltage u p (t) and negative line voltage u n (t); When the transmission line is an AC transmission line, including the A phase voltage u a (t), B phase voltage u b (t) and C phase voltage u c (t); where t is the voltage acquisition time, and the acquisition start time is t s ;

[0050] In the simulation step, the acquisition start time is collected from the first preset time before the fault occurs;

[0051] In the detection of the transmission line protection device in an actual project, data collection starts from a second preset time before the time when the transmission line protection device detects the actual line fault.

[0052] It should be noted that when the transmission line is a DC transmission line, the values ​​of the first preset time and the second preset time are greater than or equal to 10 ms. When the transmission line is an AC transmission line, the values ​​of the first preset time and the second preset time are integer multiples of 20 ms. In this embodiment, the first preset time and the second preset time are both 20 ms for illustration.

[0053] In an optional implementation manner, the method for calculating the sample line-mode fault voltage and the actual line-mode voltage in steps S2 and S5 specifically includes the following steps:

[0054] When the transmission line is a DC transmission line, the positive line voltage u p (t) minus the voltage u of the positive line during normal operation p (t-20ms) to obtain the positive line voltage fault component Δu p (t), the negative line voltage u n (t) minus the voltage u of the negative line during normal operation n (t-20ms) to obtain the negative line voltage fault component Δu n (t); and perform pole mode transformation on the fault components of the DC line voltage at both poles to obtain the line mode fault voltage Δu1(t); the specific calculation formula is:

[0055] When the transmission line is an AC transmission line, the A phase voltage u a (t) minus the voltage u of phase A during normal operation a (t-20ms) Get the A phase voltage fault component Δu a (t), the B phase voltage u b (t) minus the voltage u of phase B during normal operation b (t-20ms) Get the B phase voltage fault component Δu b (t), the C phase voltage u c (t) minus the voltage u of phase C during normal operation c (t-20ms) Get the C phase voltage fault component Δu c (t); and perform phase mode transformation on the three-phase voltage fault component of the AC line to obtain the line mode fault voltage Δu1(t). The specific calculation formula is:

[0056] In an optional embodiment, the sample line mode fault voltage calculated at each fault location is subjected to function fitting, and in the step of obtaining the fitting coefficient of the sample line mode fault voltage at each fault location, the range of the sample line mode fault voltage subjected to logistic function fitting is from From the beginning to the first appearance Ends when.

[0057] In an optional embodiment, in the step of calculating the actual line mode fault voltage and performing function fitting on the actual line mode fault voltage to obtain a fitting coefficient, the actual line mode fault voltage fitted by the logistic function is selected from the range of satisfying the criterion u1(N p+2)<u1(N p +1)<u1(N p ) corresponds to the moment From the beginning to the first appearance of u1(N d +2)>u1(N d +1)>u1(N d ) corresponds to the time End, where N p 、N d For the sampling point.

[0058] In an optional embodiment, in steps S3 and S5, the expression of the logistic function used is Where a, b, and k are fitting coefficients, e is a natural constant, |●| represents the absolute value of ●, and the fitting coefficient k represents the speed of curve change. The square value of the correlation coefficient Rlog between the line mode fault voltage data point and the fitting value is used as the evaluation parameter of the fitting effect.

[0059] It should be noted that when performing logistic function fitting on the line mode fault voltage, the value of the evaluation parameter Rlog of the fitting effect should be no less than 0.95.

[0060] In an optional implementation, in step S4, a power function is fitted to the fault distance x(i) and the fitting coefficient k(i) to obtain the fitting coefficients m and n; and the square value of the correlation coefficient Rpow between the fault distance value set in the simulation and the fitting value is used as an evaluation parameter of the fitting effect.

[0061] It should be noted that, in step S4, when performing power function fitting on the fitting coefficient k(i) and the fault location x(i), the value of the evaluation parameter Rpow of the fitting effect is not less than 0.95.

[0062] In an optional embodiment, in step S5, the actual line mode fault voltage for logistic function fitting is selected from the range of satisfying the criterion u1(N p +2)<u1(N p +1)<u1(N p ) corresponds to the moment From the beginning to the first appearance of u1(N d +2)>u1(N d +1)>u1(N d ) corresponds to the moment End, where N p 、N d For the sampling point.

[0063] In a specific embodiment, the following describes the principle of the method for calculating the line mode fault voltage using a complete working process:

[0064] When the transmission line is a DC transmission line, the positive line voltage u p (t) minus the voltage u of the positive line during normal operation p (t-20ms) to obtain the positive line voltage fault component Δu p (t), the negative line voltage u n (t) minus the voltage u of the negative line during normal operation n (t-20ms) to obtain the negative line voltage fault component Δu n (t); and perform pole mode transformation on the fault components of the DC line voltage at both poles to obtain the line mode fault voltage Δu1(t). The specific calculation formula is:

[0065] This is because DC transmission lines are generally installed on the same tower, and there is electromagnetic coupling between the positive and negative lines during the transient fault process. The polar mode transformation matrix is ​​used to decouple the bipolar DC transmission lines to further improve the positioning accuracy. The polar mode transformation matrix S of the bipolar DC transmission line is:

[0066] The DC transmission line voltage is decoupled through pole mode transformation to obtain zero modulus and line modulus. The specific calculation formula is:

[0067] Among them, Δu1 is the line mode fault voltage, Δu0 is the zero mode fault voltage, Δu p is the fault voltage of the positive line, Δu n is the fault voltage of the negative line.

[0068] When the transmission line is an AC transmission line, the A phase voltage u a (t) minus the voltage u of phase A during normal operation a (t-20ms) Get the A phase voltage fault component Δu a (t), the B phase voltage u b (t) minus the voltage u of phase B during normal operation b (t-20ms) Get the B phase voltage fault component Δu b (t), the C phase voltage u c (t) minus the voltage u of phase C during normal operation c (t-20ms) Get the C phase voltage fault component Δu c (t); and perform phase mode transformation on the three-phase voltage fault component of the AC line to obtain the line mode fault voltage Δu1(t). The specific calculation formula is:

[0069] This is because AC transmission lines are generally installed on the same tower, and three-phase lines experience electromagnetic coupling during fault transients. Decoupling the three-phase transmission lines using a pole mode transformation matrix yields 0-mode, 1-mode, and 2-mode components, further improving positioning accuracy. Both 1-mode and 2-mode components are line mode components.

[0070] The three-phase line pole mode transformation matrix K of the AC transmission line is:

[0071] The AC transmission line voltage is decoupled through pole mode transformation to obtain zero modulus and line modulus. The specific calculation formula is:

[0072] Among them, u a is the voltage of phase A, u b is the B phase voltage, u c is the C-phase voltage, Δu0 is the zero-mode fault voltage, Δu1 is the one-mode fault voltage, and Δu2 is the two-mode fault voltage.

[0073] The range of the sample line mode fault voltage in the logistic function fitting in step S3 is from From the beginning to the first appearance Ends when.

[0074] In the above steps S3 and S5, the expression of the logistic function used is Where a, b, and k are fitting coefficients, e is a natural constant, |●| represents the absolute value of ●, and the fitting coefficient k represents the speed of curve change. The square value of the correlation coefficient Rlog between the line mode fault voltage data point and the fitting value is used as the evaluation parameter of the fitting effect.

[0075] When a fault occurs on a transmission line, a voltage of equal magnitude and opposite direction is superimposed on the fault point. This voltage propagates through the transmission line to the fault location device. For example, if a ground fault occurs on the transmission line at a distance of x kilometers from the protection installation, the line mode fault voltage traveling waves at the protection installation and the fault point have the following relationship:

[0076] U1(0,s)=e -γ(s)x U1(x,s)

[0077] Where γ(s) is the propagation function. The propagation function is a composite function that cannot be solved directly, so a vector fitting is performed on it. Assuming it to be a rational fraction with a numerator order less than or equal to the denominator order, the approximation is:

[0078] Among them, N is the fitting order, c n is the remainder, a n is the extreme point, cn and a n It can be a real number or a conjugate complex number pair; D and H are constants determined by the fitting.

[0079] Substituting the vector fitting function into the line-mode fault voltage traveling wave transmission function and considering the propagation delay of the transmission line x km as τ = x / v (v is the propagation velocity), we can obtain:

[0080] After performing inverse Laplace transform on the above equation, the time domain expression of the fault voltage line mode component is obtained as follows:

[0081] Where ε(t) is the step function of the fault location.

[0082] From the above voltage expression, we can see that it is an algebraic expression with an exponential form. Since the actual fault location is unknown, the exponential form of the line-mode fault voltage is fitted. The logistic function is an S-shaped curve that imitates population growth in statistics. It has the characteristics of an exponential function that grows exponentially in the initial stage and then becomes saturated and increases slowly. Therefore, the logistic function is used to fit the line-mode fault voltage traveling wave. The logistic function is defined as:

[0083] Among them, K is the final value, P0 is the initial value, and k represents the speed of curve change.

[0084] By transforming the above formula, we can get:

[0085] Wherein, a=1 / K, b=(K-P0) / (KP0).

[0086] A logistic function is fitted to the line-mode fault voltage traveling wave, and the fitting effect is evaluated using the square value of the correlation coefficient between the data point and the fitted value. The square value of the correlation coefficient between the data point and the fitted value is one of the most commonly used metrics in statistics. It can reflect the degree of fitting and the reliability of the data, as well as the correlation between variables. For example, the stronger the correlation between the two sets of data, the closer the square value of the correlation coefficient between the data point and the fitted value is to 1.

[0087] In step S4 above, a power function is fitted to the fault distance x(i) and the fitting coefficient k(i) to obtain the fitting coefficients m and n. The square of the correlation coefficient Rpow between the simulated fault distance value and the fitting value is used as the evaluation parameter for the fitting effect. The specific method for fitting the power function between the fitting coefficient k(i) and the fault location x(i) is as follows:

[0088] According to the mapping relationship between the fitting coefficient k(i) and the fault position x(i), it can be seen that the two are nonlinear, and as the fault position increases, the fitting coefficient becomes smaller, showing a power function attenuation trend. Therefore, this application performs power function fitting on the fitting coefficient k(i) and the fault position x(i), which is in the form of y=m·x n , where m and n are fitting parameters, which are estimated by the least squares method. The values ​​of parameters m and n are obtained when the sum of the squares of the errors between the data points and the fitting curve is minimized.

[0089] In the above step S5, the actual line mode fault voltage for logistic function fitting is selected from the range that satisfies the criterion u1(N p +2)<u1(N p +1)<u1(N p ) corresponds to the time From the beginning to the first appearance of u1(N d +2)>u1(N d +1)>u1(N d ) corresponds to the time End, where N p 、N d The specific method for selecting the line mode fault voltage range is:

[0090] The high-voltage transmission line fault location method is performed after the high-voltage transmission line protection detects that a high-voltage transmission line fault has occurred. According to the criterion u1(N p +2)<u1(N p +1)<u1(N p ) to determine whether the line mode fault voltage continues to decrease. If so, use Determine whether the line mode fault voltage reaches its maximum value. If so, the range of the line mode fault voltage fitting data is from time From the beginning to the first occurrence At the end of the moment, since the line-mode fault voltage is a negative number, the absolute value is taken to obtain the continuously increasing line-mode fault voltage, and the line-mode fault voltage after the absolute value is taken is fitted with a logistic function. p For the sampling point.

[0091] In the above step S1 , the step length Δx is not greater than 5.

[0092] The sampling frequency f of the fault location device in the above steps S1 and S4 is a Not less than 1MHz.

[0093] In the above step S1, the fault occurrence time t0 is set to be no less than 100ms, and the starting time of voltage collection is t0-20ms. The specific method of starting the voltage collection is:

[0094] The fault occurs at t0. After the fault occurs, the line mode fault voltage traveling wave propagates from the fault point to the installation location of the fault location device. In order to accurately obtain the time when the line mode fault voltage traveling wave increases, the sampling frequency f is used. a Collecting voltage data starting from 20ms before the fault occurs is conducive to the extraction of line-mode fault voltage traveling waves.

[0095] In the above step S5, the starting time of voltage acquisition is t s The time when the transmission line protection device detects the line fault minus 20ms. The specific method of starting the voltage acquisition is:

[0096] The fault location device uses a sampling frequency f p Collect voltage. When the transmission line protection device detects a line fault, the fault has already occurred. The time of existing traveling wave protection is generally a few milliseconds. In order to accurately obtain the moment when the line mode fault voltage traveling wave begins to increase, this application starts collecting voltage from 20ms before the protection device detects the line fault, which is conducive to the extraction of the line mode fault voltage traveling wave.

[0097] The present application will be further described in detail below with reference to the accompanying drawings and an embodiment using actual working conditions. It should be understood that the specific embodiment described herein is only used to explain the present application and is not intended to limit the present application.

[0098] It should be noted that the grid-commutated converter high-voltage direct current transmission system is used as an example to verify the method, in which the rated DC voltage is ±400kV, the rated DC current is 5kA, and the total length of the DC transmission line is 1200km. When a fault occurs in the DC transmission line, the DC voltage measured on the rectifier side will decrease. When different transition resistances occur at the same location, the larger the transition resistance, the smaller the value of the DC voltage reduction measured on the rectifier side, but the steepness of the change in the line-mode fault voltage is the same; when the same transition resistance occurs at different locations, the closer the fault location is to the rectifier side, the steeper the change in the line-mode fault voltage, and the farther away from the rectifier side, the flatter the change in the line-mode fault voltage. Since the steepness of the line-mode fault voltage on the rectifier side is the same when different transition resistance faults occur at the same location, this application takes metallic grounding faults as an example. In addition, since the steepness of the line-mode fault voltage traveling wave front detected on the rectifier side is different when a metallic grounding fault occurs at different locations, that is, each fault location corresponds to a wave front steepness, based on this feature, the present application performs logistic function fitting on the wave front of the line-mode fault voltage traveling wave obtained at each fault step, obtains the fitting coefficient k that characterizes the speed of the line-mode fault voltage wave front transformation at each fault location, establishes a mapping relationship between the fitting coefficient k and the fault location, and performs power function fitting on the two to obtain a power function expression based on the fitting coefficient k and the fault location, and obtains the fitting coefficients m and n of the power function. By calculating the line-mode fault voltage using the recorded data of the actual engineering fault, the fitting coefficient k(a) obtained by fitting the line-mode fault voltage is substituted into the power function to obtain the fault location x meau .

[0099] Based on a bipolar simulation model of a high-voltage direct current transmission system built in PSCAD / EMTDC, a 12-pulse grid-commutated converter is used for the positive and negative poles of the rectifier station, and a 12-pulse grid-commutated converter is used for the positive and grading poles of the inverter station. The DC line adopts a frequency-variable parameter model with a total line length of 1200km. 150mH smoothing reactors are connected in series at the outlets of both ends of the DC side of the converter. This application takes the positive pole line fault of the DC transmission line as an example, sets the positive pole line of the DC transmission line to a step size of Δx of 5 to perform full line fault simulation, simulating a metallic ground fault.

[0100] A 0Ω and 400Ω ground fault occurred on the positive line of the HVDC system 600 km from the rectifier side. The line-mode fault voltage curves under the two operating conditions are shown in Figure 3(a), and the logistic function fitting results for the two operating conditions are shown in Figure 3(b) and Figure 3(c), respectively. As shown in Figure 3(a), the amplitude of the line-mode fault voltage varies under different transition resistances. After fitting the two fault conditions, the fitting coefficients a and b for the 0Ω ground fault were 0.002878 and 0.02778, respectively. For the 400Ω ground fault, the fitting coefficients a and b were 0.0123 and 0.1187, respectively. The fitting coefficient k for both operating conditions was 0.05067, and the Rlog after fitting was 0.9934, indicating excellent fitting results.

[0101] A simulation of a HVDC transmission line with a fault step size Δx of 5 was performed. The relationship between the fault location and the fitting coefficient is shown in Figure 4. Figure 4 shows that the farther the fault distance, the denser the fitting coefficients k, while the closer the fault distance is to the rectifier side, the greater the difference between adjacent fitting coefficients. A power function was fitted to the fault location and fitting coefficients, and the fitting effect is shown in Figure 5. The fitting coefficient m is 17.72, n is -1.181, and the squared correlation coefficient Rpow between the data point and the fitted value is 0.9975, indicating an excellent fitting effect.

[0102] Furthermore, in order to verify the performance of the designed HVDC line fault location method, the fault location results when 0Ω and 300Ω ground faults occurred at the positive line of the DC transmission line at 421km, 752km, and 1037km away from the rectifier side are shown in Figure 8. f is the transition resistance, f1-p-421 represents the ground fault that occurs 421 km away from the rectifier side of the DC line positive line, k represents the logistic function fitting coefficient, Rlog represents the square value of the correlation coefficient between the data point and the fitting value, and x meau The fault position located by the proposed method is calculated, and the relative error σ=|x real -x meau | / L*100%, where x real The actual fault location.

[0103] From the simulation results in Figure 8, it can be seen that when faults with different transition resistances occur at the same fault location, since the wavefront steepness of the first line wave of the line-mode fault voltage is the same, the fitting coefficient k of the logistic function fitting of the line-mode fault voltage and the square value of the correlation coefficient Rlog between the data point and the fitting value are the same when 0Ω and 300Ω grounding faults occur at the same location. The positioning results and positioning errors are also the same, further proving that the proposed fault location method is not affected by the transition resistance.

[0104] To further verify the universality of the designed HVDC line fault location method, a simulation model was constructed using the Zhangbei multi-terminal flexible DC transmission system as an example, with a sampling frequency of 100 kHz. The Kangning-Fengning section of the DC transmission line is 205.9 km long. A metallic ground fault was set to occur continuously, starting at 20 km and with a step size of 5. The simulation results show the correspondence between the fault location x and the fitting coefficient k, as shown in the scattered points in Figure 6. A power function was fitted to the fault location x and the fitting coefficient k, as shown in the solid line in the figure. The fitted power function has a coefficient m of 72.8 and n of -1.826, and the squared correlation coefficient Rpow between the data points and the fitted values ​​is 0.9996.

[0105] Figure 8 shows the fault location results for a 200Ω ground fault at 51 km, 107 km, and 196 km from Kangbao Station on the positive DC line from Kangbao to Fengning Converter Station. The simulation results demonstrate that fault location remains reliable even at different fault locations, with a maximum error of no more than 0.5%. Simulations of different DC transmission system topologies reveal that the designed HVDC line fault location method is unaffected by the DC transmission system topology, demonstrating strong adaptability.

[0106] According to another aspect of the present application, a transmission line fault location system based on traveling wave front fitting is provided, comprising:

[0107] A model simulation module is configured to construct an electromagnetic transient simulation model of the power transmission system based on the electrical parameters and control parameters of the actual project, and to simulate a metallic ground fault along the entire length of the transmission line with a preset step size;

[0108] A fault condition calculation module records the time of fault occurrence and collects the voltage at the installation location of the fault location device under each fault condition at a preset sampling frequency to calculate the sample line mode fault voltage under each fault condition; performs function fitting on the sample line mode fault voltage calculated at each fault location to obtain the corresponding fitting coefficient of the sample line mode fault voltage at each fault location; performs power function fitting on the fault location and the fitting coefficient under each preset step size condition to obtain a fault location function in the form of a power function;

[0109] The target fault calculation module is configured to calculate the actual line mode fault voltage based on the voltage amount collected by the fault location device at a preset sampling frequency when the transmission line protection device of the actual project detects a line fault, and perform function fitting on the actual line mode fault voltage to obtain a fitting coefficient, substitute the fitting coefficient into the fault location function, and calculate the fault distance.

[0110] According to another aspect of the present application, an electronic device for a transmission line fault location system based on traveling wavefront fitting is also provided. The electronic device can be, but is not limited to, used in a server. As shown in Figure 9, the electronic device includes a memory 902 and a processor 904. The memory 902 stores a computer program, and the processor 904 is configured to execute the steps of any of the above method embodiments using the computer program.

[0111] Optionally, in this embodiment, the electronic device may be located in at least one network device among a plurality of network devices of a computer network.

[0112] Optionally, in this embodiment, the processor may be configured to execute the following steps through a computer program:

[0113] S1: Based on the electrical parameters and control parameters of the actual project, an electromagnetic transient simulation model of the transmission system is constructed. A metallic ground fault is set along the entire length of the transmission line with a preset step size and simulated.

[0114] S2, recording the time of fault occurrence, collecting the voltage at the installation location of the fault location device under each fault condition at a preset sampling frequency, and calculating the sample line mode fault voltage under each fault condition;

[0115] S3, performing function fitting on the sample line mode fault voltages calculated at the respective fault locations, and obtaining corresponding fitting coefficients of the sample line mode fault voltages at the respective fault locations;

[0116] S4, performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function;

[0117] S5. When the transmission line protection device of the actual project detects a line fault, the actual line mode fault voltage is calculated based on the voltage collected by the fault location device at a preset sampling frequency, and a function fitting is performed on the actual line mode fault voltage to obtain a fitting coefficient. The fitting coefficient is substituted into the fault location function to calculate the fault distance.

[0118] Alternatively, those skilled in the art will appreciate that the structure shown in FIG9 is merely illustrative, and the electronic device may also be a terminal device such as a mobile internet device (MID) or a PAD. FIG9 does not limit the structure of the electronic device. For example, the electronic device may include more or fewer components (such as a network interface) than shown in FIG9 , or may have a configuration different from that shown in FIG9 .

[0119] Among them, the memory 902 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 902 may further include a memory remotely arranged relative to the processor 904, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. As an example, as shown in Figure 9, the above-mentioned memory 902 may include, but is not limited to, a model simulation module, a target fault calculation module, and a fault condition calculation module, etc., which will not be repeated in this example.

[0120] Optionally, the transmission device 906 is used to receive or send data via a network. Specific examples of the network may include wired networks and wireless networks. In one embodiment, the transmission device 906 includes a network interface controller (NIC), which can be connected to other network devices and a router via a network cable to communicate with the Internet or a local area network. In one embodiment, the transmission device 906 is a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0121] In addition, the electronic device further includes: a display 908 for displaying current simulation results; and a connection bus 910 for connecting various module components in the electronic device.

[0122] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when run.

[0123] Optionally, in this embodiment, the storage medium may be configured to store a computer program for performing the following steps:

[0124] S1: Based on the electrical parameters and control parameters of the actual project, an electromagnetic transient simulation model of the transmission system is constructed. A metallic ground fault is set along the entire length of the transmission line with a preset step size and simulated.

[0125] S2, recording the time of fault occurrence, collecting the voltage at the installation location of the fault location device under each fault condition at a preset sampling frequency, and calculating the sample line mode fault voltage under each fault condition;

[0126] S3, performing function fitting on the sample line mode fault voltages calculated at the respective fault locations, and obtaining corresponding fitting coefficients of the sample line mode fault voltages at the respective fault locations;

[0127] S4, performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function;

[0128] S5. When the transmission line protection device of the actual project detects a line fault, the actual line mode fault voltage is calculated based on the voltage collected by the fault location device at a preset sampling frequency, and a function fitting is performed on the actual line mode fault voltage to obtain a fitting coefficient. The fitting coefficient is substituted into the fault location function to calculate the fault distance.

[0129] Optionally, the storage medium is further configured to store a computer program for executing the steps included in the method in the above embodiment, which will not be described in detail in this embodiment.

[0130] Optionally, in this embodiment, a person of ordinary skill in the art may understand that all or part of the steps in the various methods of the above embodiments may be completed by instructing the hardware related to the terminal device through a program, and the program may be stored in a computer-readable storage medium, which may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc.

[0131] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0132] If the integrated units in the above embodiments are implemented in the form of software functional units and sold or used as independent products, they can be stored in the above-mentioned computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling one or more computer devices (which can be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application.

[0133] In the above embodiments of the present application, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0134] In the several embodiments provided in this application, it should be understood that the disclosed client can be implemented in other ways. Among them, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, and can be electrical or other forms.

[0135] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0136] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0137] The above is only a preferred embodiment of the present application. It should be noted that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be considered as the scope of protection of the present application.

[0138] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications based on these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A transmission line fault location method based on traveling wave front fitting, comprising the following steps: Based on the electrical parameters and control parameters of the actual project, an electromagnetic transient simulation model of the power transmission system is constructed. A metallic ground fault is set along the entire length of the transmission line with a preset step size and simulated. Record the time of fault occurrence, and collect the voltage at the location where the fault location device is installed under each fault condition at a preset sampling frequency to calculate the sample line mode fault voltage under each fault condition; Performing function fitting on the sample line mode fault voltages calculated at the respective fault locations to obtain corresponding fitting coefficients of the sample line mode fault voltages at the respective fault locations; Performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function; When the transmission line protection device of the actual project detects a line fault, the actual line mode fault voltage is calculated based on the voltage amount collected by the fault location device at a preset sampling frequency, and a function fitting is performed on the actual line mode fault voltage to obtain a fitting coefficient. The fitting coefficient is substituted into the fault location function to calculate the fault distance.

2. The transmission line fault location method based on traveling wave front fitting according to claim 1, wherein: The function fitting is performed using a logistic function.

3. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: The voltage quantities collected by the fault location device include: When the transmission line is a DC transmission line, the positive line voltage u p (t) and negative line voltage u n (t); When the transmission line is an AC transmission line, including the A phase voltage u a (t), B phase voltage u b (t) and C phase voltage u c (t); where t is the voltage acquisition time, and the acquisition start time is t s ; In the simulation step, the acquisition start time is collected from the first preset time before the fault occurs; In the detection of the transmission line protection device in an actual project, data collection starts from a second preset time before the time when the transmission line protection device detects the actual line fault.

4. The transmission line fault location method based on traveling wave front fitting according to claim 3, wherein: The method for calculating the sample line mode fault voltage and the actual line mode fault voltage, when the transmission line is a DC transmission line, specifically includes the following steps: The positive line voltage u p (t) minus the voltage u of the positive line during normal operation p (t-20ms) to obtain the positive line voltage fault component Δu p (t), the negative line voltage u n (t) minus the voltage u of the negative line during normal operation n (t-20ms) to obtain the negative line voltage fault component Δu n (t); and perform pole mode transformation on the fault components of the voltage at both poles of the DC line to obtain the line mode fault voltage Δu1(t).

5. The transmission line fault location method based on traveling wave front fitting according to claim 3, wherein: The method for calculating the sample line mode fault voltage and the actual line mode fault voltage, when the transmission line is an AC transmission line, specifically includes the following steps: The A phase voltage u a (t) minus the voltage u of phase A during normal operation a (t-20ms) Get the A phase voltage fault component Δu a (t), the B phase voltage u b (t) minus the voltage u of phase B during normal operation b (t-20ms) Get the B phase voltage fault component Δu b (t), the C phase voltage u c (t) minus the voltage u of phase C during normal operation c (t-20ms) Get the C phase voltage fault component Δu c (t); and perform phase mode transformation on the three-phase voltage fault component of the AC line to obtain the line mode fault voltage Δu1(t).

6. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: The sample line mode fault voltage calculated at each fault location is subjected to function fitting, and in the step of obtaining the fitting coefficient of the sample line mode fault voltage at each fault location, the range of the sample line mode fault voltage subjected to logistic function fitting is from From the beginning to the first appearance Ends when.

7. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: In the step of calculating the actual line mode fault voltage and performing function fitting on the actual line mode fault voltage to obtain the fitting coefficient, the actual line mode fault voltage fitted by the logistic function is selected from the range of satisfying the criterion u1(N p +2)<u1(N p +1)<u1(N p ) corresponds to the moment From the beginning to the first appearance of u1(N d +2)>u1(N d +1)>u1(N d ) corresponds to the moment End, where N p 、N d For the sampling point.

8. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: The expression of the logistic function is Where a, b, and k are fitting coefficients, e is a natural constant, |●| represents the absolute value of ●, and the fitting coefficient k represents the speed of curve change. The square value of the correlation coefficient Rlog between the sample line mode fault voltage data point and the fitting value is used as the evaluation parameter of the fitting effect.

9. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: The preset step size is not greater than 5, the preset sampling frequency is not less than 1 MHz; the target sampling frequency of the fault location device is not less than 10 kHz; and the fault occurrence time t0 is set to be not less than 100 ms.

10. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: A power function is fitted to the fault distance x(i) and the fitting coefficient k(i) to obtain the fitting coefficients m and n. The square value of the correlation coefficient Rpow between the fault distance value set in the simulation and the fitting value is used as the evaluation parameter of the fitting effect. The value of the evaluation parameter Rpow of the fitting effect is not less than 0.

95.

11. The transmission line fault location method based on traveling wave front fitting according to claim 2, wherein: When performing logistic function fitting on the line mode fault voltage, the value of the evaluation parameter Rlog of the fitting effect shall not be less than 0.

95.

12. A transmission line fault location system based on traveling wave front fitting, applying the method according to claims 1 to 11, wherein: include: A model simulation module is configured to construct an electromagnetic transient simulation model of the power transmission system based on the electrical parameters and control parameters of the actual project, and to simulate a metallic ground fault along the entire length of the transmission line with a preset step size; Fault condition calculation module; Recording the time of fault occurrence, collecting the voltage at the location where the fault location device is installed under each fault condition at a preset sampling frequency to calculate the sample line mode fault voltage under each fault condition; performing function fitting on the sample line mode fault voltage calculated at each fault location to obtain a corresponding fitting coefficient for the sample line mode fault voltage at each fault location; Performing power function fitting on the fault location and the fitting coefficients under the respective preset step length conditions to obtain a fault location function in the form of a power function; The target fault calculation module is configured to calculate the actual line mode fault voltage based on the voltage amount collected by the fault location device at a preset sampling frequency when the transmission line protection device of the actual project detects a line fault, and perform function fitting on the actual line mode fault voltage to obtain a fitting coefficient, substitute the fitting coefficient into the fault location function, and calculate the fault distance.

13. A computer-readable storage medium, wherein: The storage medium stores a computer program, wherein the computer program is configured to execute the method according to any one of claims 1 to 11 when executed.

14. An electronic device comprising a memory and a processor, wherein: A computer program is stored in the memory, and the processor is configured to run the computer program to perform the method according to any one of claims 1 to 11.

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