Overhead line-cable three-terminal hybrid power transmission line fault segment determination method, device and medium

Abstract

The invention discloses an overhead line-cable three-end hybrid power transmission line fault segment determination method and device and a medium, and the method comprises the steps: obtaining the three-phase voltage and current of the head end of a line, and carrying out the fault phase selection according to the three-phase voltage and current; calculating an admittance matrix of any two-port network in the hybrid power transmission line system, and calculating a node impedance matrix of the system; calculating a frequency domain transient voltage according to the node impedance matrix, and converting the frequency domain transient voltage into a time domain solution through discrete inverse Laplace transformation to obtain an analytic waveform; calculating waveform abrupt change moments in the analytic waveform and the actual waveform, and determining a reference signal and a measured signal for similarity comparison; assuming that a fault occurs at a preset distance between the head end and the tail end of each section of line, solving a transient voltage analysis waveform of a measurement point, and performing cosine similarity comparison with an actual waveform; wherein the section with the maximum similarity is the fault section. The method solves the problem of fault segment determination when the AC power transmission line has a short-circuit fault, and provides a basis for further fault location.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power systems, and in particular to a method, equipment and medium for locating fault sections of an overhead line-cable three-terminal hybrid transmission line. Background Art

[0002] At present, with the gradual increase in the scale of the power system, there are more and more overhead line-cable hybrid three-terminal transmission lines. As a key component of the power system, the transmission line undertakes the important task of transmitting electricity from the power plant to the substation. Once a short circuit fault occurs, it will seriously affect the normal operation of social production and people's lives. It is necessary to quickly troubleshoot and solve the fault to reduce the harm caused by the power outage. Therefore, for the overhead line-cable hybrid three-terminal transmission line, accurate fault segmentation is of great practical significance for further fault distance measurement and timely maintenance by operation and maintenance personnel. Summary of the invention

[0003] In order to solve at least one of the technical problems existing in the prior art to a certain extent, the purpose of the present invention is to provide a method, device and medium for fault location of an overhead line-cable three-terminal hybrid transmission line based on transient voltage waveform similarity.

[0004] The first technical solution adopted by the present invention is:

[0005] A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line comprises the following steps:

[0006] Obtain the three-phase voltage and current at the head end of the line, and select the fault phase based on the three-phase voltage and current;

[0007] Calculate the admittance matrix of any two-port network in a hybrid transmission line system and calculate the node impedance matrix of the system (including fault points);

[0008] Input any transient current source I f As the initial value, the frequency-domain transient voltage is calculated according to the node impedance matrix and converted into the time-domain solution by discrete inverse Laplace transform to obtain the analytical waveform;

[0009] Calculate the waveform mutation moments in the analytical waveform and the actual waveform, and determine the reference signal and the measured signal for similarity comparison;

[0010] Assuming that a fault occurs at a preset distance between the beginning and end of each section of the line, the transient voltage analytical waveform at the measurement point is solved and compared with the actual waveform by cosine similarity; among them, the section with the greatest similarity is the fault section.

[0011] Further, the components in the AC hybrid power transmission line system include power supplies, transformers, overhead lines and cable transmission lines;

[0012] The method of calculating the admittance matrix of any two-port network in the hybrid transmission line system and calculating the node impedance matrix of the system includes:

[0013] For any two-port network, its admittance matrix is ​​expressed as:

[0014]

[0015] Where Y ii , Y jj are the self-admittances of nodes i and j, respectively, and Y ij , Y ji is the mutual admittance between node i and node j;

[0016] Assuming there are n nodes in the system, the node admittance matrix Y of the system is composed according to the two-port network of each device. fault , and then the node admittance matrix Y fault Inverse and get the system's node impedance matrix Z fault .

[0017] Furthermore, the impedance of the transformer is expressed as inductive reactance, and its port admittance matrix is ​​expressed as:

[0018]

[0019] Where, L h is the equivalent inductance of the transformer.

[0020] Furthermore, the line unit length series impedance Z(s) and shunt admittance Y(s) are expressed as:

[0021]

[0022] Construct its port admittance matrix as:

[0023]

[0024] Where T is the eigenvector, A(s) is the diagonal matrix containing the line modal coefficients, l is the line length, and Z(s) and Y(s) are the series impedance and shunt admittance of the line per unit length, respectively.

[0025] Furthermore, the frequency domain transient voltage is calculated according to the node impedance matrix, and converted into a time domain solution by discrete inverse Laplace transform to obtain an analytical waveform, including:

[0026] The transient voltage waveform of the system is expressed as:

[0027] U fault =Z fault(f,:) I f

[0028] In the formula, Z fault(f,:) is the mutual impedance between each node and the fault node, I f It is the transient current source of the system after the fault;

[0029] Because I f It is difficult to obtain directly. Enter any non-zero value as I f The initial value of U fault , because it is a discrete time domain signal, it needs to be converted into a complex frequency domain signal before it can be used in the calculation. Then, the complex frequency domain voltage and current are converted into the time domain through discrete inverse Laplace transform to obtain the analytical waveform of the measurement point.

[0030] Furthermore, the formula for converting the discrete time domain control signal into a discrete complex frequency domain signal is:

[0031]

[0032] Δω=π / T

[0033] Δt=T / N

[0034] c=ln(N 2 ) / T

[0035] The formula for converting frequency domain to time domain is as follows:

[0036]

[0037] In the formula, f n and F m Represent the time domain value and frequency domain value of voltage or current respectively; T is the sampling period: N is the number of sampling points; m, n = 0, 1, ..., N-1; Δt and Δω are the calculation steps in the time domain and frequency domain respectively; c is the damping coefficient, which is used to reduce the aliasing error in the sampling process; σ m is the Hanning window function.

[0038] Further, the calculation of waveform mutation moments in the analytical waveform and the actual waveform to determine the reference signal and the measured signal for similarity comparison includes:

[0039] For the actual waveform, it is subjected to wavelet transformation, and the arrival time t of the traveling wave is extracted according to the wavelet modulus maximum principle. 1 , the time window is [t 1 -5μs,t 1 +500μs];

[0040] For the analytical waveform, at the moment of waveform mutation t 1 ', the value of U(t) is always 0, so the moment corresponding to the first non-zero value is taken as the mutation moment t of the analytical waveform. 1', then the time window is [t 1 '-5μs,t 1 '+500μs]; at this time, the sampling frequency of the analyzed waveform should be consistent with the sampling frequency of the actual recorded waveform.

[0041] Furthermore, the calculation formula of the cosine similarity is:

[0042]

[0043] In the formula, u si (t) and u an (t) represent the fault recording and analytical waveform of the transient voltage waveform, i.e., the reference signal and the measured signal, respectively, and n is the number of sampling points in the time window used for similarity evaluation.

[0044] The second technical solution adopted by the present invention is:

[0045] An electronic device comprises a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line as described above.

[0046] The fourth technical solution adopted by the present invention is:

[0047] A computer-readable storage medium, wherein at least one instruction, at least one program, a code set or an instruction set is stored in the storage medium, wherein the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by a processor to implement a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line as described above.

[0048] The fifth technical solution adopted by the present invention is:

[0049] A computer program product or a computer program, the computer program product or the computer program includes computer instructions, the computer instructions are stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the above-mentioned method for locating the fault section of an overhead line-cable three-terminal hybrid transmission line.

[0050] The beneficial effects of the present invention are as follows: the present invention provides a fault segmentation solution for an overhead line-cable three-terminal hybrid transmission line, solves the fault segmentation problem when a short circuit fault occurs in an AC transmission line, and provides a basis for further fault location. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 is a flow chart of a fault segmentation method according to an embodiment of the present invention;

[0053] Figure 2 Schematic diagram of an overhead line-cable three-terminal hybrid transmission line model in an embodiment of the present invention;

[0054] Figure 3 1 is an example diagram of an analytical waveform and a simulation waveform in an embodiment of the present invention;

[0055] Figure 4 It is a flow chart of the steps of a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0057] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0058] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0059] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0060] In view of the existing technical problems, the present invention provides a fault segmentation solution for overhead line-cable three-terminal hybrid transmission lines based on transient voltage waveform similarity, which aims to solve the fault segmentation problem when a short circuit fault occurs in the overhead line-cable three-terminal hybrid transmission line, and help operation and maintenance personnel to perform accurate fault distance measurement and rapid maintenance. Assuming that a fault occurs 1 km from the beginning and end of each section line, the transient voltage analysis waveform of the measurement point is solved respectively, and the cosine similarity is compared with the actual waveform to achieve a more accurate fault segmentation.

[0061] Example 1

[0062] like Figure 1 and Figure 4 As shown, this embodiment provides a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line, comprising the following steps:

[0063] S1. Obtain the three-phase voltage and current at the head end of the line, and select the fault phase based on the three-phase voltage and current.

[0064] In one embodiment, the line head end can collect the voltage of each phase of the line With each phase current The fault phase can be selected by the traditional phase current difference method.

[0065] Optionally, a Clarke transformation matrix is ​​used for phase transformation:

[0066]

[0067] S2. Calculate the admittance matrix of any two-port network in the hybrid transmission line system and calculate the node impedance matrix of the system (including fault points).

[0068] In one embodiment, the main components of the AC hybrid transmission line are power supply, transformer, overhead line and cable transmission line. For any two-port network, its admittance matrix can be expressed as:

[0069]

[0070] Exemplarily, the admittance matrix corresponding to different components is expressed as follows:

[0071] 1) The impedance of a transformer is generally expressed as inductive reactance, and its port admittance matrix can be expressed as:

[0072]

[0073] Among them, L h are the equivalent inductance of the transformer respectively.

[0074] 2) The line unit length series impedance Z(s) and shunt admittance Y(s) can be expressed as:

[0075]

[0076] The port admittance matrix can be constructed as:

[0077]

[0078]

[0079] Where T is the eigenvector, A(s) contains the diagonal matrix of the line modal coefficients, and l is the line length. Z(s) and Y(s) are the series impedance and shunt admittance of the line per unit length, respectively.

[0080] Assuming there are n nodes in the system, the node admittance matrix Y of the system can be formed according to the two-port network of the above devices: fault , and then invert it to get the node impedance matrix Z of the system fault .

[0081]

[0082] S3, input any transient current source I f As the initial value, the frequency-domain transient voltage is calculated according to the node impedance matrix and converted into a time-domain solution by discrete inverse Laplace transform to obtain an analytical waveform.

[0083] In one embodiment, the system transient voltage waveform can be expressed as:

[0084] U fault =Z fault(f,:) I f

[0085] Among them, Z fault(f,:) is the mutual impedance between each node and the fault node, I f It is the transient current source of the system after the fault. f It is related to the transition resistance and the instantaneous value of the voltage at the fault point when the fault occurs, and only affects the amplitude of the waveform.

[0086] Because I f It is difficult to obtain directly. Enter any non-zero value as I f The initial value of U fault(s), because it is a discrete time domain signal, it needs to be converted into a complex frequency domain signal before it can be used in calculations. The formula for converting a discrete time domain control signal into a discrete complex frequency domain signal is:

[0087]

[0088] Δω=π / T

[0089] Δt=T / N

[0090] c=ln(N 2 ) / T

[0091] The complex frequency domain voltage and current are then converted to the time domain through Laplace inverse transform to obtain the analytical waveform of the measurement point. The specific conversion formula is as follows:

[0092]

[0093] In the formula, f n and F m Represent the time domain value and frequency domain value of voltage or current respectively: T is the sampling period: N is the number of sampling points; m, n = 0, 1, ..., N-1: Δt and 2Δω are the calculation steps in the time domain and frequency domain respectively: c is the damping coefficient, which is used to reduce the aliasing error in the sampling process; σ m is the Hanning window function.

[0094] S4. Calculate the waveform mutation moments in the analytical waveform and the actual waveform, and determine the reference signal and the measured signal for similarity comparison.

[0095] In one embodiment, for the actual waveform, a wavelet transform can be performed on it, and the arrival time t of the traveling wave can be extracted according to the wavelet modulus maximum principle. 1 , the time window is [t 1 -5μs,t 1 +500μs].

[0096] For the analytical waveform, at the moment of waveform mutation t 1 ', the value of U(t) is always 0, so the moment corresponding to the first non-zero value is taken as the mutation moment t of the analytical waveform. 1 ', then the time window is [t 1 '-5μs,t 1 '+500μs]. At this time, the sampling frequency of the analyzed waveform should be consistent with the sampling frequency of the actual recorded waveform.

[0097] S5. Assume that a fault occurs at a preset distance between the beginning and the end of each section of the line, solve the transient voltage analytical waveform of the measurement point, and compare it with the actual waveform by cosine similarity; among them, the section with the greatest similarity is the fault section.

[0098] To reduce the waveform amplitude, that is, I f Regarding the impact on ranging, this embodiment selects cosine similarity to analyze the feature similarity of the waveforms.

[0099] In one embodiment, assuming that a fault occurs 1 km from the beginning and end of each section line, the transient voltage analytical waveform of the measurement point is solved respectively, and the cosine similarity is compared with the actual waveform to obtain S cos Among them, the segment with higher cosine similarity is the fault segment.

[0100]

[0101] In the formula, u si (t) and u an (t) represent the fault recording and analytical waveform of the transient voltage waveform, i.e., the reference signal and the measured signal, respectively, and n is the number of sampling points in the time window used for similarity evaluation.

[0102] The method of this embodiment is further illustrated below through a specific simulation example.

[0103] This embodiment builds the following in PSCAD: Figure 2 The overhead line-cable three-terminal hybrid transmission line model shown in the figure is simulated and tested. The line length is as follows Figure 2 As shown in the figure, S 1 , S 2 and S 3 It is a three-terminal power supply with internal resistance Z s =1Ω. The following example uses a metallic single-phase grounding fault at the midpoint of line 45 and node 3 to test the proposed segmentation method. The fault point analysis waveform and the actual waveform are shown in Figure 2. Figure 3 The simulation results are shown in Table 1 and Table 2.

[0104] Table 1 Simulation results of line 45 fault

[0105]

[0106] Table 2 Node 3 fault simulation results

[0107]

[0108]

[0109] Example 2

[0110] An embodiment of the present invention further provides an electronic device, the electronic device comprising a processor and a memory, the memory storing at least one instruction, at least one program, a code set or an instruction set, the at least one instruction, the at least one program, the code set or the instruction set being loaded and executed by the processor to implement the following Figure 4 A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line is shown.

[0111] It is understood that the memory may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory includes a non-transitory computer-readable storage medium. The memory may be used to store instructions, programs, codes, code sets, or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function, instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data created according to the use of the server, etc.

[0112] The processor may include one or more processing cores. The processor uses various interfaces and lines to connect the various parts of the entire server, and executes various functions of the server and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory. Optionally, the processor can be implemented in at least one hardware form of digital signal processing (DSP), field programmable gate array (FPGA), and programmable logic array (PLA). The processor can integrate one or a combination of a central processing unit (CPU) and a modem. Among them, the CPU mainly processes the operating system and application programs; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor, but implemented separately through a chip.

[0113] Since the electronic device is an electronic device corresponding to a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line in an embodiment of the present invention, and the principle of solving the problem by the electronic device is similar to that of the method, the implementation of the electronic device can refer to the implementation process of the above-mentioned method embodiment, and the repeated parts will not be repeated.

[0114] Example 3

[0115] The embodiment of the present invention further provides a computer-readable storage medium, wherein the storage medium stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, the at least one program, the code set or instruction set is loaded and executed by a processor to implement the following Figure 4 A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line is shown.

[0116] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable rewritable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0117] Since the storage medium is the storage medium corresponding to a method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line in an embodiment of the present invention, and the principle of solving the problem by the storage medium is similar to that of the method, the implementation of the storage medium can refer to the implementation process of the above-mentioned method embodiment, and the repeated parts will not be repeated.

[0118] Example 4

[0119] In some possible implementations, various aspects of the method of the embodiment of the present invention can also be implemented in the form of a program product, which includes a program code. When the program product is run on a computer device, the program code is used to enable the computer device to execute the steps of the method for locating the fault section of an overhead line-cable three-terminal hybrid transmission line according to various exemplary embodiments of the present application described above in this specification. Among them, the executable computer program code or "code" for executing each embodiment can be written in a high-level programming language such as C, C++, C#, Smalltalk, Java, JavaScript, Visual Basic, structured query language (e.g., Transact-SQL), Perl, or in various other programming languages.

[0120] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0121] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0122] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line, characterized in that: The following steps are involved: Obtain the three-phase voltage and current at the head end of the line, and select the fault phase based on the three-phase voltage and current; Compute the admittance matrix of any two-port network in a hybrid transmission line system and compute the nodal impedance matrix of the system; The frequency domain transient voltage is calculated based on the node impedance matrix and converted into a time domain solution through discrete inverse Laplace transform to obtain an analytical waveform; Calculate the waveform mutation moments in the analytical waveform and the actual waveform, and determine the reference signal and the measured signal for similarity comparison; assume that a fault occurs at a preset distance between the beginning and end of each section of the line, solve the transient voltage analytical waveform of the measurement point, and compare it with the actual waveform for cosine similarity; among them, the section with the greatest similarity is the fault section.

2. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 1, characterized in that: The components in the AC hybrid power transmission line system include power supplies, transformers, overhead lines and cable transmission lines; The method calculates the admittance matrix of any two-port network in the hybrid transmission line system and calculates the node impedance matrix of the system. include: For any two-port network, its admittance matrix is ​​expressed as: Where Y ii , Y jj are the self-admittances of nodes i and j, respectively, and Y ij , Y ji is the mutual admittance between node i and node j; Assuming there are n nodes in the system, the node admittance matrix Y of the system is composed according to the two-port network of each device. fault , and then the node admittance matrix Y fault Inverse and get the system's node impedance matrix Z fault .

3. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 2, characterized in that: The impedance of the transformer is expressed as inductive reactance, and its port admittance matrix is ​​expressed as: Where, L h is the equivalent inductance of the transformer.

4. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 2, characterized in that: The line unit length series impedance Z(s) and shunt admittance Y(s) are expressed as: Construct its port admittance matrix as: Where T is the eigenvector, A(s) is the diagonal matrix containing the line modal coefficients, l is the line length, and Z(s) and Y(s) are the series impedance and shunt admittance of the line per unit length, respectively.

5. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 1, characterized in that: The frequency domain transient voltage is calculated according to the node impedance matrix, and converted into a time domain solution by discrete inverse Laplace transform to obtain an analytical waveform, including: The transient voltage waveform of the system is expressed as: U fault =Z fault(f,:) I f In the formula, Z fault(f,:) is the mutual impedance between each node and the fault node, I f It is the transient current source of the system after the fault; Because I f It is difficult to obtain directly. Enter any non-zero value as I f The initial value of U fault , because it is a discrete time domain signal, it needs to be converted into a complex frequency domain signal before it can be used in the calculation. Then, the complex frequency domain voltage and current are converted into the time domain through discrete inverse Laplace transform to obtain the analytical waveform of the measurement point.

6. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 5, characterized in that: The formula for converting discrete time domain control signal into discrete complex frequency domain signal is: Δω=π / T Δt=T / N c=ln(N 2 ) / T The formula for converting frequency domain to time domain is as follows: In the formula, f n and F m Respectively represent the time domain value and frequency domain value of voltage or current; T is the sampling period: N is the number of sampling points; m, n = 0, 1, ..., N-1; Δt and Δω are the calculation steps in the time domain and frequency domain respectively; c is the damping coefficient, which is used to reduce the aliasing error in the sampling process; σ m is the Hanning window function.

7. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 1, characterized in that: The calculation of waveform mutation moments in the analytical waveform and the actual waveform, and determination of a reference signal and a measured signal for similarity comparison, comprises: For the actual waveform, wavelet transform is performed on it, and the arrival time t1 of the traveling wave is extracted according to the wavelet modulus maximum principle; For the analytical waveform, before the waveform mutation moment t1', the value of U(t) is always 0, so the moment corresponding to the first non-zero value is taken as the mutation moment t1' of the analytical waveform; at this time, the sampling frequency of the analytical waveform should be consistent with the sampling frequency of the actual recording.

8. A method for locating fault sections of an overhead line-cable three-terminal hybrid transmission line according to claim 1, characterized in that: The calculation formula of the cosine similarity is: In the formula, u si (t) and u an (t) represent the fault recording and analytical waveform of the transient voltage waveform, i.e., the reference signal and the measured signal, respectively, and n is the number of sampling points in the time window used for similarity evaluation.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the method described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement the method according to any one of claims 1 to 8.

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