High-resistance grounding fault positioning method and system based on double-end electromagnetic time reversal

Abstract

The invention discloses a high-resistance grounding fault positioning method and system based on double-end electromagnetic time reversal, and relates to the technical field of electric power, and the method comprises the steps: injecting high-frequency excitation sources with opposite polarities into two ends of a line in a transmission line simulation model consistent with the reality, setting different guess fault points at equal intervals and recording corresponding transverse branch fault current; transient voltage signals generated by faults are measured at the head end and the tail end of an actual line; and carrying out direct convolution calculation and addition on the fault current and voltage transient signals of the corresponding line end, calculating to obtain the energy of the convolution signal, and realizing fault positioning according to the mirror image minimum criterion of the energy of the convolution signal. According to the invention, accurate positioning of the impedance position of the high-resistance grounding fault of the transmission line in practice can be realized, and the fault repair efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a high-resistance grounding fault locating method and system based on double-terminal electromagnetic time inversion. Background Art

[0002] At present, the section location method for single-phase grounding faults is mainly theoretical research, especially for high-resistance grounding faults grounded by non-metallic conductive media such as branches, grass, asphalt, etc., the transition resistance during the fault is usually above 300Ω, the fault characteristic signal is weak, the detection is difficult, and it is easily disturbed by noise and other disturbances, making it difficult to accurately locate the fault. Summary of the invention

[0003] In view of the above-mentioned problem that it is difficult to accurately locate the fault, the present invention is proposed.

[0004] Therefore, the technical problems solved by the present invention are:

[0005] To solve the above technical problems, the present invention provides the following technical solutions: a high-resistance grounding fault location method based on two-terminal electromagnetic time inversion, comprising: injecting high-frequency excitation sources with opposite polarities into both ends of the line in a transmission line simulation model consistent with the actual situation, setting different guessed fault points at equal intervals and recording the corresponding lateral branch fault currents; measuring the transient voltage signal generated by the fault at both ends of the actual line; performing direct convolution calculation on the fault current and voltage transient signals at the corresponding line ends and adding them, calculating the energy of the convolution signal, and realizing fault location according to the mirror minimum value criterion of the energy of the convolution signal.

[0006] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, wherein: a transmission line model is built for the actual transmission line in the PSCAD / EMTDC electromagnetic transient software, and the inversion-processed signal is injected at the same measurement point; the setting of the different guessed fault points is as follows: after the transmission line model is built in the electromagnetic transient simulation software, transverse branch grounding faults with different impedance values ​​are set at equal intervals along the line.

[0007] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, the calculation process of the transverse branch fault current is as follows: the left and right sides of the transverse fault branch are simplified based on the Thevenin equivalence theorem, the impedance is equivalent, and the equivalent impedance and equivalent voltage source are obtained; the fault current on one side at the fault location is guessed to be:

[0008]

[0009] Among them, U 1r (x' f,w) is the equivalent voltage source, Z in2r is the equivalent input impedance on the right side of the lateral fault branch, Z in1r is the equivalent input impedance on the left side of the lateral fault branch, x' f is the different guessed fault locations, γ is the transmission coefficient of the lossless transmission line, ρ0 is the voltage reflection coefficient, is the hypothetical fault impedance of the lateral fault branch, U1(0,w) is the high-frequency excitation source injected into the left side of the line, and Z in2r is the equivalent impedance on the right side of the transverse fault branch; U1(0,w) is the high-frequency excitation source injected into the left side of the line.

[0010] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, the device for measuring the transient voltage signal is a broadband voltage sensing device; the broadband voltage sensing device realizes real-time online monitoring of transmission line overvoltage by using a combination of a sensing unit, an energy acquisition unit and a wireless acquisition and transmission unit.

[0011] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, the sensing unit includes a high-voltage capacitor and a low-voltage capacitor, and directly collects the overvoltage signal on the medium-voltage insulated line through capacitor voltage division; the energy acquisition unit obtains electric energy from the insulated line through a reasonable value of the capacitor, and transmits it to the rectifier bridge after passing through an isolation transformer to rectify the AC signal; the rectified signal is filtered to remove high-frequency components, and the wireless acquisition and transmission unit is powered by a DC / DC step-down converter.

[0012] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, the voltage division ratio of the sensing unit is:

[0013]

[0014] Among them, C3 is a high-voltage capacitor; C4 is a low-voltage capacitor.

[0015] As a preferred solution of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion described in the present invention, the wireless acquisition and transmission unit includes a wireless acquisition module and a wireless transmission module. The wireless acquisition module analyzes, processes and encrypts the overvoltage signal collected by the sensor unit and transmits it to the wireless transmission module; the wireless transmission module transmits the encrypted overvoltage signal to the background online monitoring system based on the GPRS communication network, and performs real-time online monitoring of the overvoltage of the medium-voltage insulated line.

[0016] Another object of the present invention is to provide a high-resistance grounding fault location system based on two-terminal electromagnetic time inversion, including: a high-resistance grounding fault location system based on two-terminal electromagnetic time inversion, including: a simulation model construction module, used to construct a transmission line simulation model; a fault current signal acquisition module, used to acquire fault current signals on lateral branches of different guessed fault locations in the transmission line simulation model; a transient voltage signal acquisition module, used to measure in real time the transient voltage signal generated according to the high-resistance grounding fault of the transmission line; a transmission line high-resistance grounding fault location determination module, which performs convolution calculation on the fault current signal and the transient voltage signal and determines the location of the high-resistance grounding fault of the transmission line in practice according to the mirror minimum value of the energy of the convolution signal.

[0017] A computer device includes a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion are implemented as described above.

[0018] A computer-readable storage medium stores a computer program thereon, wherein when the computer program is executed by a processor, the steps of the high-resistance grounding fault location method based on double-terminal electromagnetic time inversion as described above are implemented.

[0019] The beneficial effects of the present invention are as follows: the present invention constructs a transmission line simulation model and obtains fault current signals on lateral branches at different guessed fault locations; measures in real time a transient voltage signal generated by a high-resistance grounding fault of the transmission line; finally, convolution calculation is performed on the fault current signal and the transient voltage signal, and the location of the high-resistance grounding fault of the transmission line in practice is determined according to the mirror image minimum value of the energy of the convolution signal; this method is not affected by factors such as external noise and traveling wave velocity, and can achieve accurate positioning of the impedance location of the high-resistance grounding fault of the transmission line in practice, which is beneficial to improving the efficiency of fault repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 The flowchart is a specific example of a high-resistance ground fault location method based on double-terminal electromagnetic time inversion.

[0022] Figure 2 This is the reverse phase model diagram of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion.

[0023] Figure 3 This is the fault current derivation diagram based on the Thevenin equivalent theorem of this application, (a) is step 1, and (b) is step 2.

[0024] Figure 4 This is a structural diagram of a broadband voltage sensing device.

[0025] Figure 5 Schematic diagram of coaxial cable transmission.

[0026] Figure 6 This is the forward phase model diagram of this application.

[0027] Figure 7 This is the derivation diagram of the transient voltage of the transmission line based on the Thevenin equivalent theorem of this application, (a) is step 1, and (b) is step 2.

[0028] Figure 8 It is the normalized distribution diagram of convolution signal energy. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Example 1

[0032] Reference Figure 1 to Figure 7 , is an embodiment of the present invention, and provides a high-resistance ground fault location method based on double-terminal electromagnetic time inversion, such as Figure 1 As shown, the following steps are included:

[0033] S1: In a transmission line simulation model consistent with the actual situation, high-frequency excitation sources with opposite polarities are injected into both ends of the line, different guessed fault points are set at equal intervals, and the corresponding transverse branch fault currents are recorded.

[0034] Specifically, a transmission line model is built for the actual transmission line in the PSCAD / EMTDC electromagnetic transient software, and then the inversion-processed signal is injected at the same measurement point.

[0035] Different guessed fault locations refer to setting up transverse branch grounding faults with different impedance values ​​at equal intervals along the line after building a transmission line model in the electromagnetic transient simulation software.

[0036] In the transmission line simulation model consistent with the actual situation, high-frequency excitation sources with opposite polarities are injected into both ends of the line respectively, and the fault current signal I of each guessed fault location is calculated. f1 and I f2 .

[0037] like Figure 2 As shown, taking the injection excitation source U1 at the left end of the line as an example, the horizontal branch fault current I is calculated f1 , based on the Thevenin equivalence theorem, we simplify Figure 3 The impedances Z1 and Z on the right side of (a) c By performing the equivalent operation, we can obtain the equivalent impedance expression Z on the right side of the lateral fault branch: in2r , the specific expression is shown in the following formula:

[0038]

[0039] Where ρ1 is the voltage reflection coefficient, γ is the transmission coefficient of the lossless transmission line, L is the total length of the transmission line, and x' f For different guesses of fault locations, Z c is the transmission line characteristic impedance;

[0040] Similarly, the left side of the horizontal fault branch is equivalent, such as Figure 3 As shown in (b), the equivalent impedance Z inr1 And the equivalent voltage source U 1r , the formula is as follows:

[0041]

[0042] Among them, x' f is the different guessed fault locations, γ is the transmission coefficient of the lossless transmission line, ρ0 is the voltage reflection coefficient, Z c is the characteristic impedance of the transmission line, and U1(0,w) is the high-frequency excitation source injected from the left side of the line.

[0043] Finally, the fault current I at different guessed fault locations can be derived: f1 :

[0044]

[0045] Among them, U 1r (x' f ,w) is the equivalent voltage source, Z in2r is the equivalent input impedance on the right side of the lateral fault branch, Z in1ris the equivalent input impedance on the left side of the lateral fault branch, x' f is the different guessed fault locations, γ is the transmission coefficient of the lossless transmission line, ρ0 is the voltage reflection coefficient, is the hypothetical fault impedance of the lateral fault branch, and U1(0,w) is the high-frequency excitation source injected into the left side of the line.

[0046] Similarly, the fault current I generated by the reverse excitation source injected at the right end of the line can also be derived: f2 .

[0047] S2: Measure the transient voltage signal generated by the fault at both ends of the actual line.

[0048] Furthermore, the device for measuring transient voltage signals is a broadband voltage sensing device, and the interior of the device is mainly divided into three parts, including a sensing unit, an energy storage unit and a wireless acquisition and transmission unit.

[0049] In terms of voltage sensing, the sampling frequency can reach 400kHz, achieving high-precision measurement of fault transient signals.

[0050] According to the instruction manual Figure 4 The structure diagram of the broadband voltage sensing device, the sensing unit includes a high-voltage capacitor C33 and a low-voltage capacitor C4 4, the energy acquisition unit includes a high-voltage capacitor C1 1, a low-voltage capacitor C2 2, an overvoltage protection circuit 8, an isolation transformer 9, a bridge rectifier circuit 10, an RC low-pass filter circuit 13, a DC / DC buck converter 14 and a backup power supply 19, and the wireless acquisition and transmission unit 17 includes a data acquisition module 15 and a wireless transmission module 16.

[0051] The high and low voltage capacitors utilize the principle of capacitive voltage division to obtain overvoltage signals from the transmission line and convert them into low voltage signals, which are then transmitted to the data acquisition module 15 via the coaxial cable 21 .

[0052] The cable wiring diagram from low voltage signal to data acquisition module is as follows: Figure 5 As shown, R1 and R2 at both ends of the coaxial cable are matching resistors, and their resistance is equal to the cable wave impedance Z. Therefore, the relationship between U5 and U4 is as follows:

[0053]

[0054] In the above formula, U5 is the voltage output from the sensor insulator to the front circuit of the data acquisition module, and U4 is the voltage value on the medium voltage insulation line.

[0055] Transforming the above formula, the initial partial pressure ratio is:

[0056]

[0057] The final voltage divider ratio after reaching stability is:

[0058]

[0059] In order to make the initial voltage division ratio equal to the final voltage division ratio, let C3 = 360pF, C4 = 220nF, and the total capacitance C5 = C3 + C4.

[0060] Therefore, the voltage division ratio of the sensing unit is:

[0061]

[0062] The data acquisition module 15 first attenuates the transmitted low-voltage signal to an acceptable voltage of ±5V, and then analyzes, processes, encrypts and transmits the signal to the wireless transmission module 16 .

[0063] The working principle of the energy acquisition unit is: voltage division through high and low voltage circuits in series, and the voltage division ratio is calculated as follows:

[0064]

[0065] In the above formula, U6 is the output voltage value across the low-voltage capacitor, and K1 is the potential insulator voltage divider ratio.

[0066] The output U3 voltage is transmitted to the bridge rectifier circuit 10 through the isolation transformer 9 to convert the AC signal into a DC signal.

[0067] The isolation transformer 9 electrically isolates the primary circuit from the subsequent circuit. The bridge rectifier circuit 10 is constructed using four diodes and can output the positive and negative half cycles of the AC signal.

[0068] Then the DC signal is filtered through the RC low-pass filter circuit 13 to remove some high-frequency components and interference noise.

[0069] Finally, the DC voltage is stepped down by the DC / DC step-down converter 14 so that the output voltage can provide a stable 12V DC power for the wireless acquisition and transmission unit.

[0070] The wireless transmission module 16 is based on the GPRS communication network and uses the SIM800 communication module as the main communication processing unit to wirelessly transmit the collected overvoltage signal.

[0071] S3: Perform direct convolution calculation on the fault current and voltage transient signals at the corresponding line end and add them together to calculate the energy of the convolution signal, and realize fault location according to the mirror minimum value criterion of the energy of the convolution signal.

[0072] like Figure 6 As shown in the reverse phase, Figure 7 (a) After simplification by Thevenin equivalent, we get Figure 7(b) And obtain the transient voltage U3 at the left end. The specific expression is as follows. The transient voltage at the right end is derived in the same way:

[0073]

[0074] Among them, Z eq is the final equivalent input impedance, γ is the transmission coefficient of the lossless transmission line, and Z in2d is the equivalent input impedance on the right side of the lateral fault branch, ρ f is the transmission line terminal voltage reflection coefficient, x f is the actual fault location, Z0 is the equivalent impedance of the power transformer, U fs is the fault voltage source, Z eq2 is the equivalent input impedance, is the actual fault impedance.

[0075] The fault current I derived from the first two stages is f1 (x' f ,w) and the left-end transient voltage U3, fault current I f2 (x' f ,w) and the right-end transient voltage U4 are convolved to obtain the following formula:

[0076]

[0077] Among them, I f1 (x' f ,w) is the fault current signal on the left side of the high-resistance grounding fault position of the transmission line, I f2 (x' f ,w) is the fault current signal on the right side of the high-resistance grounding fault position of the transmission line, U3(0,w) is the transient voltage measured in real time at the left end of the transmission line, U4(L,w) is the transient voltage measured in real time at the right end of the transmission line, Z in2r is the equivalent input impedance on the right side of the lateral fault branch, Z in1r is the equivalent input impedance on the left side of the lateral fault branch, x' f is the different guessed fault locations, γ is the transmission coefficient of the lossless transmission line, ρ0 is the voltage reflection coefficient, is the hypothetical fault impedance of the lateral fault branch, U1(0,w) is the high-frequency excitation source injected on the left side of the line, ρ1 is the voltage reflection coefficient, L is the total length of the transmission line, and U2(L,w) is the high-frequency excitation source injected on the right side of the line.

[0078] Based on Parseval's theorem, the convolution signal energy P(x f ′,j) can be calculated as follows:

[0079]

[0080] Where N is the number of frequency points, x′ f，j (j=1,2,…,M) are different guessed fault locations, ω k (k=1,2,…,N) is a frequency-dependent function, E(x′ f ,ω k ) is the fault signal at different guessed fault locations, P(x′ f，j ) is the convolution signal energy at different guessed fault locations.

[0081] The minimum energy position of the convolution signal x′ fmin for:

[0082]

[0083] Among them, x f is the actual fault location, x′ fmin is the minimum energy position of the convolution signal, L is the total length of the transmission line, P(x′ f，j ) is the convolution signal energy at different guessed fault locations.

[0084] From the minimum position formula, we know that the actual fault position x f The mirror image position of the minimum convolution energy position relative to the midpoint of the line satisfies the energy mirror minimum property.

[0085] This embodiment also provides a computer device, which is applicable to the case of a high-resistance grounding fault location method based on two-terminal electromagnetic time inversion, including a memory and a processor; the memory can be used to store computer programs, such as the computer program corresponding to the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion in this embodiment, and the processor executes various functional applications and data processing by running the computer program stored in the memory, that is, implementing the above method. The memory may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage systems, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include a memory remotely arranged relative to the processor, and these remote memories may be connected to the terminal via a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0086] The transmission device is used to receive or send data via a network. The above network includes a wireless network provided by a communication provider of the terminal. In one example, the transmission device includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device can be a radio frequency (Radio Frequency, referred to as RF) module, which is used to communicate with the Internet wirelessly.

[0087] Example 2

[0088] Reference Figure 1 to Figure 7 , which is an embodiment of the present invention, provides a high-resistance grounding fault location system based on double-terminal electromagnetic time inversion, comprising:

[0089] Simulation model building module, fault current signal acquisition module, transient voltage signal acquisition module and transmission line high-resistance grounding fault location determination module;

[0090] A simulation model building module, used to build a transmission line simulation model;

[0091] A fault current signal acquisition module is used to acquire fault current signals on lateral branches at different guessed fault locations in a transmission line simulation model;

[0092] A transient voltage signal acquisition module is used to measure in real time the transient voltage signal generated by a high-resistance grounding fault of a transmission line;

[0093] The location determination module of the high-resistance grounding fault of the transmission line performs convolution calculation on the fault current signal and the transient voltage signal and determines the location of the high-resistance grounding fault of the transmission line in practice according to the mirror image minimum value of the energy of the convolution signal.

[0094] Example 3

[0095] Reference Figure 1 to Figure 7 , which is the third embodiment of the present invention, based on the first two embodiments, the embodiment of the present invention provides a computer device, which may be a server. The computer device includes a processor, a memory, and a network interface connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium.

[0096] The database of the computer device is used to store action detection data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in any of the above-mentioned sparse tensor operation acceleration method embodiments are implemented.

[0097] In one embodiment, an embodiment of the present invention provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in any of the above-mentioned sparse tensor operation acceleration method embodiments are implemented.

[0098] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0099] Example 4

[0100] Reference Figure 8 , which is the fourth embodiment of the present invention, provides experimental simulation data of a high-resistance grounding fault location method based on double-terminal electromagnetic time inversion on the basis of the first three embodiments, including:

[0101] A single-phase transmission line with a voltage level of 10 kV was built in the PSCAD simulation software, and a sinusoidal voltage source with an amplitude of 10 kV and a phase angle of 0 was injected. The capacitance, inductance and resistance parameters per unit length of the line were C = 7.10 pF / m, L = 1.56 H / m and R = 0 Ω / m, respectively.

[0102] The equivalent impedance of the power transformer is Z0=Z1=100k.

[0103] Assume that a ground fault occurs at 4 km of the line, and set the guessed locations at equal intervals of 0.5 km.

[0104] The imaginary fault grounding impedance ZfRT and the actual fault grounding impedance ZfDT are set to 1000. In the reverse phase, the arbitrary excitation sources injected at the left and right ends of the line differ only in polarity. Taking the left end injection as an example, the excitation source is selected as a lightning voltage with an amplitude of 10kV and a waveform parameter of 2.6 / 50s.

[0105] like Figure 8 This is the normalized distribution of the convolution signal energy under different guessed fault locations. It can be seen from the figure that the minimum value of the convolution signal energy is at 6 km from the guessed fault location. This position is the mirror image position of the actual fault location (4 km) relative to the midpoint of the line (5 km), which meets the convolution signal energy mirror minimum value criterion and can achieve accurate fault location.

[0106] It can be seen that the present invention constructs a transmission line simulation model and obtains fault current signals on lateral branches at different guessed fault locations, measures the transient voltage signal generated by the high-resistance grounding fault of the transmission line in real time, and finally convolves the fault current signal with the transient voltage signal and determines the location of the high-resistance grounding fault of the transmission line in practice according to the mirror image minimum value of the energy of the convolution signal. This method is not affected by external noise, traveling wave velocity and other factors, and can achieve accurate positioning of the impedance position of the high-resistance grounding fault of the transmission line in practice, which is beneficial to improving the efficiency of fault repair.

[0107] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high-resistance grounding fault location method based on two-terminal electromagnetic time inversion is characterized by: include: In a transmission line simulation model consistent with the actual situation, high-frequency excitation sources with opposite polarities are injected into both ends of the line, different guessed fault points are set at equal intervals, and the corresponding transverse branch fault currents are recorded; Measure the transient voltage signal generated by the fault at both ends of the actual line; The fault current and voltage transient signals at the corresponding line end are directly convolved and added to calculate the energy of the convolution signal, and the fault location is achieved based on the mirror minimum value criterion of the energy of the convolution signal.

2. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 1 is characterized in that: The transmission line model of the actual transmission line is constructed in the PSCAD / EMTDC electromagnetic transient software, and the inversion-processed signal is injected at the same measurement point; The settings of the different guessed fault points are as follows: After building the transmission line model in the electromagnetic transient simulation software, transverse branch grounding faults with different impedance values ​​are set at equal intervals along the line.

3. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 2 is characterized by: The calculation process of the transverse branch fault current is as follows: The left and right sides of the lateral fault branch are simplified based on the Thevenin equivalence theorem, and the impedances are equivalent to obtain equivalent impedances and equivalent voltage sources. The fault current on one side at the fault location is guessed to be: Among them, U 1r (x' f ,w) is the equivalent voltage source, Z in2r is the equivalent input impedance on the right side of the lateral fault branch, Z in1r is the equivalent input impedance on the left side of the lateral fault branch, x' f is the different guessed fault locations, γ is the transmission coefficient of the lossless transmission line, ρ0 is the voltage reflection coefficient, is the hypothetical fault impedance of the lateral fault branch, U1(0,w) is the high-frequency excitation source injected into the left side of the line, and Z in2r is the equivalent impedance on the right side of the transverse fault branch; U1(0,w) is the high-frequency excitation source injected into the left side of the line.

4. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 3 is characterized by: The device for measuring the transient voltage signal is a broadband voltage sensing device; The broadband voltage sensing device realizes real-time online monitoring of overvoltage of the transmission line by using a combination of a sensing unit, an energy storage unit and a wireless acquisition and transmission unit.

5. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 4 is characterized in that: The sensing unit includes a high-voltage capacitor and a low-voltage capacitor, and directly collects overvoltage signals on the medium-voltage insulated line through capacitor voltage division. The energy acquisition unit obtains electrical energy from the insulated line by selecting the appropriate value of the capacitor, and transmits it to the rectifier bridge after passing through the isolation transformer to rectify the AC signal; The rectified signal is filtered to remove high-frequency components and powered by a DC / DC step-down converter to power the wireless acquisition and transmission unit.

6. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 5 is characterized by: The voltage division ratio of the sensing unit is: Among them, C3 is a high-voltage capacitor; C4 is a low-voltage capacitor.

7. The high-resistance grounding fault location method based on two-terminal electromagnetic time inversion as claimed in claim 6 is characterized by: The wireless acquisition and transmission unit includes a wireless acquisition module and a wireless transmission module; The wireless acquisition module analyzes, processes and encrypts the overvoltage signal collected by the sensor unit and transmits it to the wireless transmission module; The wireless transmission module is based on the GPRS communication network and transmits the encrypted overvoltage signal to the background online monitoring system to perform real-time online monitoring of the overvoltage of the medium-voltage insulation line.

8. A high-resistance grounding fault location system based on double-terminal electromagnetic time inversion according to any one of claims 1 to 7, characterized in that: include: A simulation model building module, used to build a transmission line simulation model; A fault current signal acquisition module is used to acquire fault current signals on lateral branches at different guessed fault locations in a transmission line simulation model; A transient voltage signal acquisition module is used to measure in real time the transient voltage signal generated by a high-resistance grounding fault of a transmission line; The location determination module of the high-resistance grounding fault of the transmission line performs convolution calculation on the fault current signal and the transient voltage signal and determines the location of the high-resistance grounding fault of the transmission line in practice according to the mirror image minimum value of the energy of the convolution signal.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the high-resistance grounding fault location method based on two-terminal electromagnetic time inversion according to any one of claims 1 to 7 are implemented.

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