Power transmission line fault location method and system based on simulation
By establishing a simulation model of the transmission line and collecting time differences, and performing data fitting, the problem of inaccurate fault location in the existing technology of transmission lines was solved, and rapid and accurate fault location was achieved, thus improving the accuracy of the distance measurement.
Patent Information
- Application Number
- CN202511345488.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-19
- Publication Date
- 2026-02-03
AI Technical Summary
Among existing methods for fault location in transmission lines, the impedance method has a large error, while the traditional two-end traveling wave method does not consider wave velocity error, resulting in inaccurate distance measurement and making it difficult to meet the requirements for high precision.
A simulation model of the transmission line is established, multiple fault locations are set, and the time difference between the arrival of the initial fault traveling wave at the two measurement points is collected. The functional relationship between the fault location and the time difference is obtained through data fitting, so as to achieve accurate fault location.
It eliminates the need to rely on traveling wave velocity, reduces ranging errors, enables rapid and accurate location of transmission line faults, shortens maintenance time, and reduces power outage losses.
Smart Images
Figure CN121457067A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of fault location, in particular to a power transmission line fault location method and system based on simulation. BACKGROUND
[0002] The power line is the lifeline of the power system, and bears the important responsibility of transmitting electric energy. Therefore, the operation reliability of the power line affects the power supply reliability of the power system. The working environment of the power line is extremely harsh, and it is the place where faults occur most frequently in the power system, and the fault location is usually extremely difficult to find. Therefore, after the line fails, quickly and accurately finding the fault point, i.e. fault location, is not only crucial for timely repairing the line and quickly restoring power supply, but also has important significance for the safe and stable and economic operation of the power system. Quickly and accurately determining the fault point after the power transmission line fails is a key technology to ensure the safe and stable operation of the power grid, and is also one of the main problems that have long plagued the operation of the power grid.
[0003] At present, there are two types of fault location algorithms for power transmission line location devices. One is impedance method, which is an algorithm for directly calculating fault impedance or its percentage. The other is traveling wave method, which uses high-frequency fault transient current, voltage traveling wave, etc. to determine the distance of the fault point from the measurement point. The impedance method is suitable for AC systems, and is easily affected by fault location, fault type and transition resistance, resulting in large measurement error, and is not suitable for high-precision DC line fault location. For the traveling wave method, the traditional double-end traveling wave fault location method widely used at present uses a unified wave speed to determine the time difference of the arrival of the initial traveling wave at the two ends of the measurement point for fault location, which is a relatively accurate method among existing methods. However, this method does not consider the case where the wave speed cannot be accurately obtained in actual situations. Since the wave speed is close to the speed of light, a slight wave speed error will cause a relatively large fault location error. SUMMARY
[0004] The technical problem to be solved by the present application is to provide a power transmission line fault location method and system based on simulation, which can effectively improve the accuracy of power transmission line fault location.
[0005] To solve the above technical problems, the technical scheme adopted by the present application is: A power transmission line fault location method based on simulation, comprising the steps of: establishing a power transmission line simulation model according to the parameters of the power transmission line; setting 1 to N fault locations in the power transmission line simulation model, and collecting the time difference of the arrival of the initial fault traveling wave at the two ends of the measurement point of the power transmission line simulation model for each fault location; data fitting according to each fault location and the time difference to obtain the functional relationship between the fault location and the time difference. The fault position of the fault transmission line is obtained according to the function relationship based on the time difference of the fault transmission line.
[0006] To solve the above technical problems, another technical solution adopted by the present application is: A simulation-based transmission line fault location system, comprising a memory, a processor and a computer program stored in the memory and running on the processor, and the processor implements the following steps when executing the computer program: A transmission line simulation model is established according to the parameters of the transmission line; In the transmission line simulation model, 1 to N fault positions are set, and the time difference of the initial fault traveling wave reaching the two end measurement points of the transmission line simulation model is collected for each fault position; Data fitting is performed according to each fault position and the time difference to obtain a function relationship between the fault position and the time difference; The fault position of the fault transmission line is obtained according to the function relationship based on the time difference of the fault transmission line.
[0007] The beneficial effects of the present application are that a transmission line simulation model is established according to the parameters of the transmission line, 1 to N fault positions are set in the transmission line simulation model, the time difference of the initial fault traveling wave reaching the two end measurement points of the transmission line simulation model is collected for each fault position, data fitting is performed according to each fault position and the time difference, the fault position of the fault transmission line is obtained according to the function relationship based on the time difference of the fault transmission line, so that the fault location error caused by the fixed wave speed of the double-end traveling wave location method is reduced without relying on the wave speed, and the function relationship between the fault position and the time difference obtained by multiple simulation fitting is only needed to input the time difference of the initial fault traveling wave reaching the two end measurement points of the fault transmission line during fault location, so that the fault position of the fault transmission line can be accurately located, thereby effectively improving the accuracy of the transmission line fault location. BRIEF DESCRIPTION OF DRAWINGS
[0008] Figure 1 A flowchart of a simulation-based transmission line fault location method according to an embodiment of the present application; Figure 2 A schematic diagram of a simulation-based transmission line fault location system according to an embodiment of the present application; Figure 3 A schematic diagram of the wave speed varying with frequency in a simulation-based transmission line fault location method according to an embodiment of the present application; Figure 4 A schematic diagram of the single-core cable structure and parameters in a simulation-based transmission line fault location method according to an embodiment of the present application; Figure 5 Fig. 3 is a schematic diagram of DC voltage variation of two end measurement points in a simulation-based power transmission line fault location method according to an embodiment of the present application. DETAILED DESCRIPTION
[0009] To make the technical contents, purposes and effects of the present application clear, the following will be explained in combination with the embodiments and the accompanying drawings.
[0010] Before the embodiments of the present application are described in detail, some related concepts will be explained first: Initial fault traveling wave: the initial fault traveling wave is an initial electromagnetic disturbance signal generated at the fault point when a fault occurs in a power system; Pole mode transformation: a decoupling method in a metal return bipolar DC system, which is derived from the transformation condition of matrix diagonalization and used to eliminate the inter-pole coupling problem; Wavelet transform: a new transform analysis method, which inherits and develops the localization idea of short-time Fourier transform, and overcomes the shortcomings that the window size does not change with frequency, etc., and can provide a "time-frequency" window that changes with frequency, which is an ideal tool for signal time-frequency analysis and processing; Interpolation algorithm: a mathematical method for constructing a mathematical function through known data points to estimate the numerical value of unknown points.
[0011] In the prior art, the impedance method is suitable for AC systems and is easily affected by fault location, fault type and transition resistance, resulting in large fault location error, which is not suitable for high-precision DC line fault location. As for the traveling wave method, the traditional double-end traveling wave fault location method widely used at present uses a unified wave speed to determine the time difference of the arrival of the initial fault traveling wave at the two end measurement points of the line for fault location, without considering the case where the wave speed cannot be accurately obtained in the actual situation. Since the wave speed is close to the speed of light, slight wave speed error will cause relatively large fault location error.
[0012] To at least solve the above problems, please refer to Figure 1 The embodiments of the present application provide a simulation-based power transmission line fault location method, which comprises the following steps: establishing a power transmission line simulation model according to the parameters of the power transmission line; setting 1 to N fault locations in the power transmission line simulation model, and collecting the time difference of the arrival of the initial fault traveling wave at the two end measurement points of the power transmission line simulation model for each fault location; performing data fitting according to each fault location and the time difference to obtain the functional relationship between the fault location and the time difference; The fault position of the fault transmission line is obtained according to the time difference of the fault transmission line based on the function relationship.
[0013] From the above description, the beneficial effects of the present application are that: a transmission line simulation model is established according to the parameters of the transmission line, 1 to N fault positions are set in the transmission line simulation model, the time difference of the initial fault traveling wave reaching the two end measurement points of the transmission line simulation model at each fault position is collected, data fitting is performed according to each fault position and the time difference, and the fault position of the fault transmission line is obtained according to the function relationship based on the time difference of the fault transmission line, so that the fault position of the fault transmission line can be accurately positioned by inputting the time difference of the initial fault traveling wave reaching the two end measurement points of the fault transmission line without relying on the wave speed, thereby effectively improving the accuracy of the fault distance measurement of the transmission line.
[0014] Further, collecting the time difference of the initial fault traveling wave reaching the two end measurement points of the transmission line simulation model at each fault position comprises: obtaining the positive and negative DC voltages and the positive and negative DC currents of the two end measurement points of the transmission line simulation model within a preset time window before and after the fault occurrence at each fault position; decoupling the positive and negative DC voltages and the positive and negative DC currents of each end measurement point using pole module transformation to obtain line modulus; performing wavelet transformation on the line modulus to obtain a modulus maximum value; taking the time corresponding to the first modulus maximum value among all the modulus maximum values as the time of the initial fault traveling wave reaching the measurement point; performing difference calculation on the time of the initial fault traveling wave reaching the measurement point to obtain the time difference of the initial fault traveling wave reaching the two end measurement points of the transmission line simulation model at each fault position.
[0015] From the above description, it can be known that the phenomenon when the fault traveling wave propagates to the measurement point is voltage mutation, and the signal at this time is a discontinuous and singular signal. Wavelet transformation is a mathematical tool of time frequency domain transformation, which can effectively depict the singularity of the signal and reflect the time of signal mutation. Pole module transformation is used to eliminate the coupling between the positive and negative poles and the ground, which can effectively eliminate the interference caused by coupling. The time difference of the initial fault traveling wave reaching the two end measurement points of the line calculated by performing wavelet transformation on the signal after pole module transformation is more accurate, thereby ensuring the accuracy of fault distance measurement.
[0016] Further, obtaining the fault location of the fault transmission line based on the time difference of the fault transmission line according to the function relationship comprises: obtaining the time difference of the initial fault traveling wave of the fault transmission line reaching the two end measuring points of the fault transmission line; substituting the time difference of the initial fault traveling wave of the fault transmission line reaching the two end measuring points of the fault transmission line into the function relationship to obtain the fault location of the fault transmission line.
[0017] As can be seen from the above description, when fault location of the fault transmission line is performed, only the time difference of the initial fault traveling wave reaching the two end measuring points of the fault transmission line needs to be obtained, and the time difference is substituted into the function relationship of the fitting obtained fault location and time difference, so that the fault location can be determined, the fault location of the transmission line can be quickly and accurately positioned, the maintenance time can be shortened, and the power loss can be reduced.
[0018] Further, establishing a transmission line simulation model according to the parameters of the transmission line comprises: if the transmission line includes an overhead line, establishing a transmission line simulation model according to the arrangement positions and electrical conductivities of the conductor and ground wire of the overhead line; if the transmission line includes a cable, establishing a transmission line simulation model according to the geometric radius, electrical conductivity and insulation rate of each layer of the cable.
[0019] As can be seen from the above description, due to the values of the line sequence resistance, inductance and capacitance, such parameters are electrical parameters calculated according to the line geometric size, and if such parameters are used for modeling, the accuracy of the transmission line simulation model will be reduced. Therefore, if the transmission line includes an overhead line, a transmission line simulation model is established according to the arrangement positions and electrical conductivities of the conductor and ground wire of the overhead line, and if the transmission line includes a cable, a transmission line simulation model is established according to the geometric radius, electrical conductivity and insulation rate of each layer of the cable. In this way, the actual geometric parameters of the transmission line are used for modeling, so that the transmission line simulation can be maximally consistent with the actual application scenario, and the reliability of subsequent data fitting is ensured.
[0020] Further, in the transmission line simulation model, setting 1 to N fault locations comprises: setting the fault location and fault occurrence time of the transmission line simulation model; setting the simulation total time length and simulation step length; simulating the transmission line simulation model according to the fault location, the fault occurrence time, the simulation total time length and the simulation step length; returning to execute the setting the fault location and fault occurrence time of the transmission line simulation model step to perform simulation for multiple times until the current simulation number reaches a preset simulation number.
[0021] From the above description, according to the set fault position, fault occurrence time, simulation total time length and simulation step length, the power transmission line simulation model is simulated multiple times, a plurality of groups of data are obtained, and the accuracy of the function relationship of the subsequent obtained fault position and time difference is ensured.
[0022] Further, the function relationship of the fault position and the time difference is obtained by fitting data according to each of the fault positions and the time differences. The function relationship of the fault position and the time difference is obtained by fitting data according to each of the fault positions and the time differences using an interpolation algorithm.
[0023] From the above description, the function relationship of the fault position and the time difference is fitted using an interpolation algorithm, the relationship between the fault position and the time difference of the initial fault traveling wave reaching the measuring points at both ends of the line can be simply and accurately mined.
[0024] Please refer to Figure 2 Another embodiment of the present application provides a simulation-based power transmission line fault location system, comprising a memory, a processor and a computer program stored on the memory and running on the processor, and the processor implements the following steps when executing the computer program: establishing a power transmission line simulation model according to the parameters of the power transmission line; in the power transmission line simulation model, setting 1 to N fault positions, collecting the time difference of the initial fault traveling wave reaching the measuring points at both ends of the power transmission line simulation model for each of the fault positions; fitting data according to each of the fault positions and the time differences, and obtaining the function relationship of the fault position and the time difference; obtaining the fault position of the fault power transmission line based on the time difference of the fault power transmission line according to the function relationship.
[0025] From the above description, the beneficial effects of the present application are as follows: a power transmission line simulation model is established according to the parameters of the power transmission line, 1 to N fault positions are set in the power transmission line simulation model, the time difference of the initial fault traveling wave reaching the measuring points at both ends of the power transmission line simulation model is collected for each fault position, data is fitted according to each fault position and time difference, and the fault position of the fault power transmission line is obtained based on the time difference of the fault power transmission line according to the function relationship. In this way, without relying on the traveling wave speed, the fault location error caused by the fixed wave speed of the double-ended traveling wave location method is reduced. Only the function relationship of the fault position and the time difference obtained by multiple simulation fitting is needed, and when fault location is performed, the time difference of the initial fault traveling wave reaching the measuring points at both ends of the fault power transmission line is input, and the precise positioning of the fault position of the fault power transmission line is realized, thereby effectively improving the precision of the power transmission line fault location.
[0026] Further, the time difference of initial fault traveling wave reaching the two end measurement points of the power transmission line simulation model of each of the fault positions comprises: obtaining the positive and negative DC voltages and the positive and negative DC currents of the two end measurement points of the power transmission line simulation model within a preset time window before and after the fault of each of the fault positions; decoupling the positive and negative DC voltages and the positive and negative DC currents of each of the measurement points using pole-mode transformation to obtain line modulus; performing wavelet transformation on the line modulus to obtain mode maxima; taking the time corresponding to the first mode maximum among all the mode maxima as the time of initial fault traveling wave reaching the measurement point; calculating the time difference of initial fault traveling wave reaching the two end measurement points of the power transmission line simulation model of each of the fault positions by difference calculation of the time of initial fault traveling wave reaching the measurement points.
[0027] As can be known from the above description, the phenomenon when the fault traveling wave propagates to the measurement point is voltage mutation, and the signal at this time is a discontinuous and singular signal. Wavelet transformation is a mathematical tool of time-frequency domain transformation, which can effectively depict the singularity of the signal and reflect the time of signal mutation. Pole-mode transformation is used to eliminate the mutual coupling among the positive and negative pole conductors and the ground, which can effectively eliminate the interference caused by the coupling. The signal after pole-mode transformation is subjected to wavelet transformation again, which can make the time difference of initial fault traveling wave reaching the two end measurement points of the line more accurate, thereby ensuring the accuracy of fault location.
[0028] Further, the fault position of the fault power transmission line based on the time difference of the fault power transmission line according to the function relationship comprises: obtaining the time difference of initial fault traveling wave reaching the two end measurement points of the fault power transmission line; substituting the time difference of initial fault traveling wave reaching the two end measurement points of the fault power transmission line into the function relationship to obtain the fault position of the fault power transmission line.
[0029] As can be known from the above description, when performing fault location of the fault power transmission line, only the time difference of initial fault traveling wave reaching the two end measurement points of the fault power transmission line needs to be obtained, and the function relationship of the fault position and the time difference fitted is substituted into the function relationship, so that the fault position can be determined, the fault position of the power transmission line is quickly and accurately located, the maintenance time is shortened, and the power loss is reduced.
[0030] Further, the power transmission line simulation model is established according to the parameters of the power transmission line, which comprises: If the power transmission line comprises overhead lines, a power transmission line simulation model is established according to the arrangement positions and electrical conductivities of the conductors and ground wires of the overhead lines; If the power transmission line comprises cables, a power transmission line simulation model is established according to the geometric radii, electrical conductivities and insulation rates of the layers of the cables.
[0031] As can be known from the above description, due to the sequence resistance, inductance and capacitance values of the line, such parameters are electrical parameters calculated according to the geometric dimensions of the line, and if such parameters are used for modeling, the accuracy of the power transmission line simulation model will be reduced, therefore, if the power transmission line comprises overhead lines, a power transmission line simulation model is established according to the arrangement positions and electrical conductivities of the conductors and ground wires of the overhead lines, and if the power transmission line comprises cables, a power transmission line simulation model is established according to the geometric radii, electrical conductivities and insulation rates of the layers of the cables, so as to model by using the actual geometric parameters of the power transmission line, so that the power transmission line simulation can be most consistent with the actual application scenario, and the reliability of subsequent data fitting is ensured.
[0032] The above-mentioned power transmission line fault location method and system based on simulation are suitable for the fault location scene of the power transmission line, and the following will be described through specific implementation manners: The traditional double-end traveling wave fault location method is to calculate the fault location by using the time difference of the arrival of the fault traveling wave at the two ends of the line, and the calculation formula is: ; In the formula, l b represents the distance between the fault location and the measurement point at the end, L represents the given full length of the line, t b and t e respectively represent the time when the initial fault traveling wave arrives at the measurement point at the end of the line and the measurement point at the opposite end, v represents the wave speed of the traveling wave on the given line.
[0033] The order of magnitude of the wave speed is 10 8 m / s, and the given wave speed v whether accurate is an important factor affecting the location accuracy, and in fact, since the wave speed is calculated according to the line parameters under a fixed frequency, it is also impossible to obtain an accurate wave speed. As Figure 3 shown, the wave speed varies with the frequency, and there is coupling between the conductors, so calculating with a fixed wave speed will inevitably cause errors.
[0034] Based on the location formula, assuming that the actual wave speed is , and the wave speed given for calculation is , then , represents the wave velocity error. Then, the error of fault location .
[0035] If the effective decimal places of wave velocity in calculation is 2, then the wave velocity error brought by this item only , represents the time difference of initial fault wave arriving at the measuring points at both ends of the line, when the fault occurs at a position farther away from the midpoint of the line, the absolute value of is larger. Assuming that the fault occurs at the end of the line with a total length of 100 km, and assuming , 83.3 m. It can be seen that the wave velocity error has a great influence on the error of fault location result.
[0036] Although it is difficult to obtain an accurate wave velocity, it can be determined that the time of initial fault wave transmission and the fault location are in one-to-one correspondence after the fault occurs. Therefore, the present application establishes an accurate simulation model of the line and performs fault simulation, and finally fits the relationship between the fault location x and the time difference , which is used to replace the above-mentioned double-end wave fault location formula relying on wave velocity for calculation. Specifically, as shown below: Please refer to Figure 1 , an embodiment of the present application is: A simulation-based fault location method for a power transmission line, comprising the steps of: S1, establishing a simulation model of the power transmission line according to the parameters of the power transmission line, specifically comprising S11-S12: S11, if the power transmission line comprises an overhead line, establishing a simulation model of the power transmission line according to the arrangement positions and electrical conductivities of the conductors and ground wires of the overhead line.
[0037] S12, if the power transmission line comprises a cable, establishing a simulation model of the power transmission line according to the geometric radii, electrical conductivities and insulation rates of the layers of the cable.
[0038] For example, a simulation model of the power transmission line is established using PSCAD (electromagnetic transient simulation) software, assuming that a simulation model of the cable is established, first, the length, steady-state working frequency and the like of the cable line are input, then, a model type is selected from a lumped parameter model, a Bergeron model and a frequency-dependent model, the three model types increase in precision in turn, and the simulation time also increases in turn, since the frequency-dependent model can most truly simulate the propagation process of the traveling wave, the frequency-dependent model is selected as the model type, then, parameters of each layer including the conductor layer, the insulation layer, the sheath layer, the semiconductor layer, the armor layer and the like are set for the cable frequency-dependent model, the parameters include the center radius width, the electrical conductivity and the insulation rate of each layer, at the same time, the depth of cable burial, the distance between cables and the like can be set.
[0039] S2, in the power transmission line simulation model, set 1 to N fault locations, collect the time difference of the initial fault traveling wave of each fault location reaching the two end measurement points of the power transmission line simulation model.
[0040] Wherein, in the power transmission line simulation model, setting 1 to N fault locations comprises: Set the fault location and fault occurrence time of the power transmission line simulation model; Set the total simulation time and simulation step; According to the fault location, the fault occurrence time, the total simulation time and the simulation step, simulate the power transmission line simulation model; Return to execute the setting fault location and fault occurrence time of the power transmission line simulation model step for multiple times of simulation until the current simulation times reaches the preset simulation times.
[0041] Each simulation sets a fault location, and the value of N can be set according to actual needs.
[0042] For example, setting the fault location can be realized by setting the line length before the fault point and the line length after the fault point, and the line length before the fault point and the line length after the fault point are equal to the total length of the line. The fault occurrence time is set by setting the "simulation time" and "resistance value" of the fault branch element to control when the fault occurs. The resistance value is set to be very small, indicating that the branch is conducting, which means that the fault occurs.
[0043] In order to reflect the propagation process of traveling wave, the simulation step should be as small as possible. In an optional embodiment, the simulation step is not greater than 1 / 3 of the total length of the traveling wave on the line.
[0044] In an optional embodiment, the output results of each simulation are named, and the naming reflects the position of the fault point. Multiple simulations are realized in python, and the corresponding PSCAD file is located by the system file position; the fault branch and cable line are located according to the element number of the PSCAD file (the number corresponds to the element in the model); the parameters of each element are modified, and the above various parameter settings are referred to; PSCAD is run through python; the results are named and saved.
[0045] Collecting the time difference of the initial fault traveling wave of each fault location reaching the two end measurement points of the power transmission line simulation model comprises: Obtain the positive and negative DC voltage and positive and negative DC current of the two end measurement points of the power transmission line simulation model within a preset time window before and after the fault of each fault location; decoupling the positive and negative DC voltages and the positive and negative DC currents of each end of the measurement point using polar modulus transformation to obtain a line modulus; wavelet transforming the line modulus to obtain a modulus maximum value; taking the time corresponding to the first modulus maximum value among all the modulus maximum values as the time when the initial fault traveling wave reaches the measurement point; calculating the time difference between the times when the initial fault traveling wave reaches the measurement points at both ends of the power transmission line simulation model by difference calculation.
[0046] S3, data fitting is performed according to each of the fault positions and the time differences to obtain a functional relationship between the fault positions and the time differences.
[0047] Specifically, an interpolation algorithm is used to perform data fitting according to each of the fault positions and the time differences to obtain a functional relationship between the fault positions and the time differences.
[0048] For example, after simulation is completed, N fault positions and time differences are obtained, and an interpolation algorithm is used to perform data fitting according to the N fault positions and time differences to obtain a functional relationship between the fault positions x and time differences . .
[0049] In an optional embodiment, the interpolation algorithm includes linear interpolation, cubic spline interpolation, cubic piecewise Hermite interpolation, etc.
[0050] S4, the fault position of the fault power transmission line is obtained according to the functional relationship based on the time difference of the fault power transmission line, and specifically includes S41-S42: S41, obtaining the time difference between the times when the initial fault traveling wave reaches the measurement points at both ends of the fault power transmission line.
[0051] Specifically, the positive and negative DC voltages and the positive and negative DC currents of the measurement points at both ends of the fault power transmission line within a preset time window before and after the fault occurrence are obtained, the positive and negative DC voltages and the positive and negative DC currents of each end of the measurement point are decoupled using polar modulus transformation to obtain a line modulus, the line modulus is wavelet transformed to obtain a modulus maximum value, the time corresponding to the first modulus maximum value among all the modulus maximum values is taken as the time when the initial fault traveling wave reaches the measurement point, and the time difference between the times when the initial fault traveling wave reaches the measurement points at both ends of the fault power transmission line is obtained by difference calculation.
[0052] S42, the time difference of initial fault traveling wave of the fault transmission line reaching two end measurement points of the fault transmission line is substituted into the function relationship, to obtain the fault position of the fault transmission line.
[0053] Taking a DC cable line as an example, the specific process of applying the above method to the DC cable line is described in detail: (1) A bipolar cable model is established in PSCAD software according to cable parameters. The structure and parameters of a single-core cable are shown in FIG. 1. Figure 4
[0054] The bipolar cable model includes a conductor layer (conductor), an insulating layer (insulator), a sheath layer (sheath), a semiconductor layer (SC layer), etc. The center radius width of each layer and the conductivity and insulation rate of each layer can be set. At the same time, the depth of cable burial and the distance between bipolar cables can be set. The simulation model can most accurately reflect the actual installation line condition on site.
[0055] (2) The cable length is 15 km, and the fault is set at an interval of 0.5 km, obtaining a total of 29 groups of data.
[0056] For example, one group of data is: when the fault occurs at 10 km, the time difference of the two end measurement points obtained by simulation is 27.1499 . As shown in FIG. 2, the fault occurs at t=0.01s, the DC voltage is measured at the beginning b and the end e of the line, and the time when the voltage suddenly changes is taken as the initial fault traveling wave arrival time, Figure 5 The time difference of the two end measurement points is about 29.1499 microseconds.
[0057] (3) The 29 groups of data are subjected to cubic spline interpolation to obtain the function relationship between the fault position and the time difference .
[0058] At this time, in order to verify the accuracy of the distance measurement formula, 10 groups of faults are randomly generated again, the time difference is extracted, and the interpolation algorithm is substituted to obtain the predicted fault distance. The specific results are shown in Table 1.
[0059] Table 1 Comparison of fault distance measurement error
[0060] According to Table 1, the average error is 0.0038 km, the maximum error is 0.010 km, the minimum error is 0.000 km, and the root mean square error is 0.0049 km.
[0061] In comparison, the wave speed of the cable is 1.84*10 8 m / s. The calculated results and errors are shown in Table 2.
[0062] Table 2 Error comparison results of traditional double-ended traveling wave fault location
[0063] According to Table 2, the average error is 0.0048 km, the maximum error is 0.0084 km, the minimum error is 0.008 km, and the root mean square error is 0.0056 km.
[0064] Therefore, the above-mentioned method effectively improves the accuracy of the power transmission line fault location compared with the traditional double-ended traveling wave fault location method.
[0065] In summary, the above-mentioned power transmission line fault location method based on simulation according to the parameters of the power transmission line establishes a power transmission line simulation model, sets 1 to N fault positions in the power transmission line simulation model, collects the time difference of the initial fault traveling wave reaching the two end measurement points of the power transmission line simulation model at each fault position, performs data fitting according to each fault position and the time difference, and obtains the fault position of the fault power transmission line based on the function relationship of the time difference of the fault power transmission line. In this way, without relying on the wave speed, the fault location error caused by the fixed wave speed of the double-ended traveling wave location method is reduced. Only the function relationship of the fault position and the time difference obtained by multiple simulation fitting is needed, and when the fault location is performed, the time difference of the initial fault traveling wave reaching the two end measurement points of the fault power transmission line is input, so that the accurate positioning of the fault position of the fault power transmission line is realized, thereby effectively improving the accuracy of the power transmission line fault location. In addition, the wavelet transform is a mathematical tool of time-frequency domain transform, which can effectively depict the singularity of the signal and reflect the time of signal mutation. The pole module transform is used to eliminate the mutual coupling between the positive and negative pole conductors and the ground, which can effectively eliminate the interference caused by the coupling. The wavelet transform of the signal after the pole module transform can make the calculated time difference of the initial fault traveling wave reaching the two end measurement points of the line more accurate. Furthermore, the actual geometric parameters of the power transmission line are used for modeling, so that the power transmission line simulation can be consistent with the actual application scene to the greatest extent, and the reliability of the subsequent data fitting is ensured.
[0066] According to a further aspect of the present application, Figure 2 is a schematic diagram showing a power transmission line fault location system based on simulation according to an embodiment of the present application. The system comprises a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements each step of the power transmission line fault location method based on simulation as described above when executing the computer program.
[0067] The above merely illustrates the embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent variation or direct or indirect application in the related technical field made with the content of the present application specification and drawings shall be included in the patent protection scope of the present application.
Claims
1. A method for fault location on a power transmission line based on simulation, characterized in that, The method comprises the steps of: establishing a power transmission line simulation model according to parameters of the power transmission line; in the power transmission line simulation model, setting 1 to N fault positions, collecting the time difference of initial fault traveling wave at each fault position reaching two end measurement points of the power transmission line simulation model; performing data fitting according to each fault position and the time difference to obtain a functional relationship between the fault position and the time difference; obtaining the fault position of the fault power transmission line based on the time difference of the fault power transmission line according to the functional relationship.
2. A method for fault location on a transmission line based on simulation according to claim 1, characterized in that, The collection of the time difference of initial fault traveling wave at each fault position reaching two end measurement points of the power transmission line simulation model comprises: obtaining the positive and negative DC voltages and the positive and negative DC currents of the two end measurement points of the power transmission line simulation model within a preset time window before and after the occurrence of each fault position; decoupling the positive and negative DC voltages and the positive and negative DC currents of each end measurement point using pole mode transformation to obtain line modulus; performing wavelet transformation on the line modulus to obtain modulus maxima; taking the time corresponding to the first modulus maxima among all the modulus maxima as the time of initial fault traveling wave reaching the measurement point; performing difference calculation on the time of initial fault traveling wave reaching the measurement point to obtain the time difference of initial fault traveling wave at each fault position reaching two end measurement points of the power transmission line simulation model.
3. The method for simulated transmission line fault location as claimed in claim 1 wherein, The obtaining of the fault position of the fault power transmission line based on the time difference of the fault power transmission line according to the functional relationship comprises: obtaining the time difference of initial fault traveling wave at two end measurement points of the fault power transmission line; substituting the time difference of initial fault traveling wave at two end measurement points of the fault power transmission line into the functional relationship to obtain the fault position of the fault power transmission line.
4. The method for simulated transmission line fault location as claimed in claim 1 wherein, The establishment of the power transmission line simulation model according to parameters of the power transmission line comprises: if the power transmission line comprises overhead lines, establishing the power transmission line simulation model according to the arrangement positions and electrical conductivities of the conductors and ground wires of the overhead lines; if the power transmission line comprises cables, establishing the power transmission line simulation model according to the geometric radii, electrical conductivities and insulation rates of the layers of the cables.
5. The method for simulated transmission line fault location as claimed in claim 1 wherein, The setting of 1 to N fault positions in the power transmission line simulation model comprises: setting the fault positions and fault occurrence times of the power transmission line simulation model; setting the total simulation time and simulation step; simulating the power transmission line simulation model according to the fault positions, the fault occurrence times, the total simulation time and the simulation step; returning to the setting of the fault positions and fault occurrence times of the power transmission line simulation model to perform simulation for multiple times until the current simulation number reaches a preset simulation number.
6. The method of claim 1, wherein, The data fitting according to each fault position and the time difference to obtain the functional relationship between the fault position and the time difference comprises: performing data fitting according to each fault position and the time difference using an interpolation algorithm to obtain the functional relationship between the fault position and the time difference.
7. An emulated power line fault location system comprising a memory, a processor, and a computer program stored on the memory and running on the processor, wherein, The processor implements the following steps when executing the computer program: According to the parameters of the power transmission line, a power transmission line simulation model is established; In the power transmission line simulation model, 1 to N fault positions are set, and the time difference of initial fault traveling wave arriving at the two end measurement points of the power transmission line simulation model is collected for each fault position; According to each fault position and the time difference, data fitting is performed to obtain a functional relationship between the fault position and the time difference; Based on the time difference of the fault power transmission line, the fault position of the fault power transmission line is obtained according to the functional relationship.
8. An emulated power line fault location system according to claim 7, wherein, Collecting the time difference of initial fault traveling wave arriving at the two end measurement points of the power transmission line simulation model for each fault position includes: Obtaining the positive and negative DC voltages and currents of the two end measurement points of the power transmission line simulation model within a preset time window before and after the occurrence of each fault position; Using pole mode transformation to decouple the positive and negative DC voltages and currents of each end measurement point to obtain line modulus; Performing wavelet transform on the line modulus to obtain modulus maxima; Taking the time corresponding to the first modulus maxima among all the modulus maxima as the time of initial fault traveling wave arriving at the measurement point; Difference calculation is performed on the time of initial fault traveling wave arriving at the measurement point to obtain the time difference of initial fault traveling wave arriving at the two end measurement points of the power transmission line simulation model for each fault position.
9. An emulated power line fault location system as claimed in claim 7, wherein, Based on the time difference of the fault power transmission line, the fault position of the fault power transmission line is obtained according to the functional relationship includes: Obtaining the time difference of initial fault traveling wave arriving at the two end measurement points of the fault power transmission line; Substituting the time difference of initial fault traveling wave arriving at the two end measurement points of the fault power transmission line into the functional relationship to obtain the fault position of the fault power transmission line.
10. An emulated power line fault location system as claimed in claim 7, wherein, According to the parameters of the power transmission line, a power transmission line simulation model is established includes: If the power transmission line includes overhead lines, a power transmission line simulation model is established according to the arrangement positions and electrical conductivities of the conductors and ground wires of the overhead lines; If the power transmission line includes cables, a power transmission line simulation model is established according to the geometric radii, electrical conductivities and insulation rates of the layers of the cables.