A power distribution network phase-to-phase short circuit fault location method, device and medium

Abstract

The application discloses a power distribution network phase-to-phase short-circuit fault distance measurement method, equipment and medium, wherein the method comprises the following steps: sampling and acquiring each-phase voltage at the head of a protection section, and judging whether the starting criterion is met according to the acquired voltage; if yes, starting the fault distance measurement method, and the distributed power supply injects a high-frequency current detection signal into the line; sampling and acquiring three-phase voltage and current of one power frequency cycle before and after the fault at the head of the protection section; extracting power frequency component and high-order harmonic component of each-phase voltage and current by using a fast Fourier algorithm, and calculating the power frequency fault component; judging the fault type and the fault phase by using the difference between the power frequency current fault components of each two phases; obtaining the fault distance measurement equation according to the fault type, solving the fault distance measurement equation, and obtaining the fault distance. The application solves the problem of the fault distance measurement of the power distribution network phase-to-phase short-circuit fault containing the distributed power supply, and does not need to additionally install a signal injection device. The application can be widely applied in the field of power distribution network fault positioning.

Description

Technical Field

[0001] The present invention relates to the field of distribution network fault location, and in particular to a distribution network interphase short circuit fault location method, equipment and medium. Background Art

[0002] Traditional single-ended fault location methods typically rely on measuring line parameters and the electrical quantities at the local end at the time of the fault. Due to their simplicity and convenience, they are widely used in distribution networks. However, in distribution networks with distributed generation (DG), the integration of DG transforms the distribution network from a single-source radial network into a complex multi-source network, resulting in changes in the distribution network's power flow distribution, short-circuit current magnitude, and direction. This significantly impacts fault location for faults located downstream of the grid connection point. Furthermore, the intermittent and uncertain output of DG further increases the error of single-ended fault location, posing challenges to traditional single-ended fault location methods.

[0003] To address the inaccuracy of traditional single-ended fault location methods in distribution networks containing distributed generation (DGs), we can fully utilize the high controllability of the power electronics in the DGs. By implementing additional control strategies, we can enable the DGs to actively output detection signals when a line short circuit occurs. Based on the electrical quantities generated by the detection signals, we can construct a new fault location principle, thereby improving the accuracy of fault location. Therefore, it is of great significance to study active injection-based methods for phase-to-phase short-circuit fault location in distribution networks. Summary of the Invention

[0004] In order to at least solve one of the technical problems existing in the prior art to a certain extent, the purpose of the present invention is to provide a distribution network phase-to-phase short circuit fault location method, device and medium based on high-frequency current injection.

[0005] The first technical solution adopted by the present invention is:

[0006] A method for measuring the distance between phases of a distribution network and a short circuit fault, comprising the following steps:

[0007] Using the power frequency cycle as the time window length, the voltage of each phase at the head end of the protection zone is sampled and obtained. The startup criteria are determined based on the obtained voltage. If so, the fault location method is activated, and the distributed power supply injects a high-frequency current detection signal into the line.

[0008] Sampling and obtaining the three-phase voltage and current of one power frequency cycle before and after the fault at the head end of the protection zone;

[0009] The fast Fourier transform algorithm is used to extract the power frequency component and higher harmonic component of each phase voltage and current, and calculate the power frequency fault component;

[0010] The fault type and fault phase are determined by using the difference in the power frequency current fault component between each two phases;

[0011] Obtain the fault distance equation according to the fault type, solve the fault distance equation, and obtain the fault distance.

[0012] Furthermore, the starting criterion is that the phase voltage at the head end of the protection zone is lower than the starting voltage setting value, specifically:

[0013]

[0014] Where, are the phase voltages of the protection section, U n is the phase voltage rated value, U set It is the starting voltage setting value.

[0015] Furthermore, the sampling and obtaining of the three-phase voltage and current of one power frequency cycle before and after the fault at the head end of the protection zone includes:

[0016] With the power frequency cycle as the time window length, collect the current of each phase in one cycle after the fault at the head end of the protection section Collect the voltage of each phase in the cycle before the fault at the head end of the protection section With each phase current

[0017] Furthermore, the method of extracting the power frequency component and higher harmonic component of each phase voltage and current by using the fast Fourier algorithm and calculating the power frequency fault component includes:

[0018] Extract the power frequency components of each phase voltage and current after the fault by fast Fourier transform and higher harmonic components Extract the power frequency components of each phase voltage and current before the fault Then calculate the power frequency fault component, specifically:

[0019]

[0020] Where, are the power frequency fault components of each phase voltage, are the power frequency fault components of each phase current respectively.

[0021] Furthermore, the method of determining the fault type and the fault phase by using the difference between the power frequency current fault components between each two phases includes:

[0022]

[0023] Where, is the difference between the power frequency current fault components between phases AB, is the difference between the power frequency current fault components between phases BC, is the difference between the power frequency current fault components of the CA phases;

[0024] When formula (2) is satisfied, it is determined that a three-phase short circuit occurs in the line:

[0025]

[0026] Where k set1 is the three-phase short-circuit margin coefficient, and the appropriate value can be selected according to the line imbalance and measurement error;

[0027] When formula (3) is satisfied, it is determined that a two-phase short circuit occurs in the line:

[0028]

[0029] Where k set2 is the two-phase short-circuit margin coefficient, and the appropriate value can be selected according to the line imbalance and measurement error; x, y, and z represent one of the AB phase, BC phase, and CA phase, respectively.

[0030] Furthermore, obtaining a fault distance equation according to the fault type includes:

[0031] When a three-phase short circuit occurs, the power frequency voltage and current of any phase at the head end of the protection zone are used to construct a distance measurement equation. The high-frequency current detection signal injected into the line by the distributed power supply is used to construct a fault distance measurement equation under a high-frequency equivalent circuit.

[0032] When a two-phase short circuit occurs, the power frequency voltage and current of the fault phase at the head end of the protection section are used to construct a distance measurement equation. The high-frequency current detection signal injected into the line by the distributed power supply is used to construct a fault distance measurement equation under a high-frequency equivalent circuit.

[0033] Furthermore, the ranging equation constructed using the power frequency voltage and current of phase A at the head end of the protection zone is:

[0034]

[0035] Where d is the distance between the fault point and the beginning of the protection zone, Z L is the line unit impedance, R f is the transition resistance, l is the length of the protection zone, Z n is the equivalent impedance on the back side of the protection zone end;

[0036] The ranging equation under the high-frequency equivalent circuit is constructed as follows:

[0037]

[0038] Where Z L10 is the high-frequency equivalent unit impedance of the line, Z n10is the high-frequency equivalent impedance on the back side of the protection zone end, and the distance d between the fault point and the head end of the protection zone is obtained by solving the equation.

[0039] Furthermore, the distance measurement equation constructed using the power frequency voltage and current of the fault BC phase at the head end of the protection zone is:

[0040]

[0041] Where, is the BC phase power frequency voltage, is the power frequency current between phases BC, is the difference between the power frequency fault components of the BC phase current, is the difference of the power frequency fault component of the BC phase voltage; Z L is the line unit impedance, R f is the transition resistance, l is the length of the protection zone, Z n is the equivalent impedance on the back side of the protection zone end;

[0042] The ranging equation under the high-frequency equivalent circuit is constructed as follows:

[0043]

[0044] Where, is the high-frequency voltage between phases BC, is the high-frequency current between phases BC; the distance d between the fault point and the beginning of the protection zone is obtained by solving the equation.

[0045] The second technical solution adopted by the present invention is:

[0046] An 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, at least one program, the code set, or the instruction set is loaded and executed by the processor to implement a distribution network phase-to-phase short circuit fault location method as described above.

[0047] The third technical solution adopted by the present invention is:

[0048] A computer-readable storage medium stores at least one instruction, at least one program, a code set, or an instruction set, wherein the at least one instruction, at least one program, the code set, or the instruction set is loaded and executed by a processor to implement a distribution network interphase short circuit fault location method as described above.

[0049] The fourth technical solution adopted by the present invention is:

[0050] A computer program product or computer program includes computer instructions 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 execute the computer instructions, so that the computer device performs the above method.

[0051] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0052] (1) There is no need to install an additional high-frequency signal injection device. It can be achieved by simply adding a high-frequency current injection control strategy based on the original DG control method in the distribution network. This solves the problem of inter-phase short-circuit fault location in the distribution network containing distributed power sources, and has high control accuracy.

[0053] (2) The amplitude and frequency of the injected signal can be adjusted according to actual needs to adapt to different line conditions, with strong flexibility and adaptability.

[0054] (3) It is not affected by the location of the fault point and the fault phase. Regardless of whether the fault point is located at the beginning, middle or end of the line, the error between the distance calculation result and the actual distance is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following introduction is made to the drawings of the embodiments of the present invention or the related technical solutions in the prior art. 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 any creative work.

[0056] Figure 1 This is a schematic diagram of a 10 kV distribution network with low resistance grounding and distributed power sources in one embodiment of the present invention;

[0057] Figure 2 is a flow chart of a method for measuring interphase short circuit fault location in a distribution network based on high-frequency current injection in one embodiment of the present invention;

[0058] Figure 3 The present invention is a flowchart of a method for measuring the distance between phases of a distribution network short circuit fault. DETAILED DESCRIPTION

[0059] The embodiments of the present invention are described in detail below, examples of which 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 limiting the present invention. The step numbers in the following embodiments are provided for ease of explanation only and do not limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0060] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They 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. Therefore, they cannot be understood as limitations on the present invention.

[0061] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0062] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting 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.

[0063] Explanation of terms:

[0064] DG: distribution generation, distributed power supply.

[0065] LM algorithm: Levenberg-Marquardt, is an algorithm for iteratively finding the extreme value of a function.

[0066] In response to existing technical problems, the present invention provides a distribution network phase-to-phase short circuit fault location solution based on high-frequency current injection, aiming to solve the problem of insufficient accuracy of traditional single-ended fault location when a phase-to-phase short circuit occurs in a distribution network containing distributed power sources. The fault location equation is constructed using the power frequency and high-frequency voltage and current at the head end of the line protection section. The LM algorithm is used to solve the equation group to obtain the distance between the fault point and the head end of the protection section, thereby realizing fault location of phase-to-phase short circuits in the distribution network.

[0067] Example 1

[0068] A 10kV distribution network model based on which a high-frequency current injection-based distribution network phase-to-phase short-circuit fault ranging method is based is shown in Figure 1 . Figure 1 The system is a typical 10kV distribution network system with distributed power source access, the neutral point of the system adopts a small-resistance grounding mode, the grounding resistance is 10Ω, the main transformer ratio is 110kV / 10kV, the main transformer capacity is 20MVA, and the protection section MN length is 20km.

[0069] Referring to Figure 2 and Figure 3 , the embodiment provides a high-frequency current injection-based distribution network phase-to-phase short-circuit fault ranging method, and specifically comprises the following steps:

[0070] S1, taking a power frequency cycle as a time window length, sampling to obtain each-phase voltage at the head of a protection section, when a starting criterion is met, the fault ranging method is started, and the DG injects 10 high-frequency currents into the line.

[0071] In one embodiment, the fault ranging method takes the voltage at the head of the protection section being lower than a starting voltage setting value as the starting criterion:

[0072]

[0073] In the formula, U are respectively each-phase voltage of the protection section, U n is a rated value of the phase voltage, U set is the starting voltage setting value, and specifically, U set may be 0.95.

[0074] S2, sampling to obtain three-phase voltage and current at the head of the protection section before and after a fault.

[0075] In one embodiment, taking a power frequency cycle as a time window length, each-phase current at the head of the protection section after a fault is collected each-phase voltage at the head of the protection section before a fault is collected and each-phase steady-state current

[0076] S3, using a fast Fourier algorithm to extract power frequency components and high-order harmonic components of each-phase voltage and current, and calculating a power frequency fault component.

[0077] In one embodiment, the power frequency components of each-phase voltage and current after a fault are extracted by fast Fourier transform and the high-order harmonic components are extracted the power frequency components of each-phase voltage and current before a fault are extracted and then the power frequency fault component is calculated:

[0078]

[0079] Where: are the power frequency fault components of each phase voltage, are the power frequency fault components of each phase current respectively.

[0080] S4. Use the difference in the fault component of the power frequency current between each two phases to determine the fault type and fault phase.

[0081] In one embodiment, the difference between the power frequency current fault components between each two phases is first calculated:

[0082]

[0083] Where: is the difference between the power frequency current fault components between phases AB, is the difference between the power frequency current fault components between phases BC, It is the difference between the AC phase power frequency current fault components.

[0084]

[0085] Where: k set1 is the three-phase short-circuit margin coefficient, which can be selected according to the line imbalance and measurement error. In this embodiment, 0.015 is selected. When the above formula is satisfied, it is determined that a three-phase short circuit has occurred in the line.

[0086]

[0087] Where k set2 is the two-phase short-circuit margin coefficient. An appropriate value can be selected based on line imbalance and measurement error. In this embodiment, 0.005 is selected. Taking a BC phase fault as an example, when the above equation is satisfied, a two-phase short circuit is determined to have occurred in the line.

[0088] S5. Write the fault distance equation according to the fault type and solve the distance equation using the LM algorithm to obtain the fault distance. The fault distance measurement process ends.

[0089] In one embodiment, when a three-phase short circuit occurs, the power frequency voltage and current of any phase (taking phase A as an example) at the head end of the protection zone are used to construct a distance measurement equation:

[0090]

[0091] Where: d is the distance between the fault point and the beginning of the protection zone, Z L is the line unit impedance, R f is the transition resistance, l is the length of the protection zone, Z nis the equivalent impedance on the back side of the protection zone end. Decomposing the real and imaginary parts of this formula yields two equations.

[0092] Using the 10 high-frequency current detection signals injected by the DG into the line, the ranging equation under the high-frequency equivalent circuit is constructed:

[0093]

[0094] Where: Z L10 is the high-frequency equivalent unit impedance of the line, Z n10 is the high-frequency equivalent impedance on the back side of the protected area. Similarly, decomposing the real and imaginary parts of this equation yields two equations. By combining the power frequency and high-frequency ranging equations, a total of four equations, the LM algorithm is used to solve the distance d between the fault point and the beginning of the protected area.

[0095] When a two-phase short circuit occurs, the power frequency voltage and current of the fault phase at the head end of the protection section (taking phases B and C as an example) are used to construct the distance measurement equation:

[0096]

[0097] Where, is the power frequency voltage between phases B and C, is the power frequency current between phases B and C, is the difference between the power frequency fault components of phase B and phase C currents, It is the difference between the power frequency fault components of the B and C phase voltages.

[0098] Using the 10 high-frequency current detection signals injected by the DG into the line, the ranging equation under the high-frequency equivalent circuit is constructed:

[0099]

[0100] Where, is the 10th high frequency voltage between phases B and C, is the 10th-order high-frequency current between phases B and C. By combining the above equations, the LM algorithm is selected to solve and obtain the distance d between the fault point and the beginning of the protection zone.

[0101] The method of the present invention is further illustrated below through a specific simulation example.

[0102] This embodiment builds the following in PSCAD Figure 1 The 10kV low-resistance grounding distribution network model with distributed generation access is simulated and tested, and the specific model parameters are shown in Table 1.

[0103] Table 1 Main parameters of distribution network

[0104] parameter Value System voltage (kV) 10 System impedance (Ω) 1j Neutral point resistance (Ω) 10 Line MN length (km) 20 Line unit positive sequence resistance (Ω / km) 0.125 Line unit positive sequence inductance (mH / km) 1.299 Line unit positive sequence capacitance (μF / km) 0.0096 Line unit zero-sequence resistance (Ω / km) 0.275 Line unit zero-sequence inductance (mH / km) 4.595 Line unit zero-sequence capacitance (μF / km) 0.0054 Line end load impedance (Ω) 100+j0.314

[0105] The simulation results of three-phase short circuit when the line is set at 0.3s, the transition resistance is 0, 10, 20 and 50Ω respectively, and the fault point is 10%, 50% and 90% of the total length from the line head are shown in Table 2.

[0106] Table 2 Simulation results of three-phase short circuit

[0107]

[0108] Similarly, the simulation results of two-phase short circuit when the line is set at 0.3s, the transition resistance is 0, 10, 20 and 50Ω respectively, and the fault point is 10%, 50% and 90% of the total length from the line head are shown in Table 3.

[0109] Table 3 Simulation results of two-phase short circuit

[0110]

[0111]

[0112] The line length of the protection section MN is changed to 10km, the simulation results of three-phase short circuit when the line is set at 0.3s, the transition resistance is 0, 10, 20 and 50Ω respectively, and the fault point is 10%, 50% and 90% of the total length from the line head are shown in Table 4.

[0113] Table 4 Simulation results of three-phase short circuit when the line is 10km

[0114]

[0115] From the simulation results above, when the phase-to-phase short circuit of different sizes and different positions occurs in the 10kV small resistance grounding system containing distributed power supply, the fault position can be accurately calculated by the method, and the calculation error is less than 10%.

[0116] Embodiment 2

[0117] The embodiment of the application also provides an electronic device, which 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 realize the power distribution network phase-to-phase short circuit fault ranging method as shown in Figure 3

[0118] ​It is understood that the memory may include random access memory (RAM) or 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 various method embodiments described above, etc.; the data storage area may store data created based on the use of the server, etc.

[0119] The processor may include one or more processing cores. The processor utilizes various interfaces and circuits to connect various components within the server. It executes various server functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in memory, as well as accessing data stored in memory. Optionally, the processor may be implemented using at least one of the following hardware forms: digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor may integrate one or a combination of a central processing unit (CPU) and a modem. The CPU primarily processes the operating system and application programs, while the modem handles wireless communications. It is understood that the modem may not be integrated into the processor and may be implemented separately via a single chip.

[0120] Since the electronic device is an electronic device corresponding to a distribution network phase-to-phase short-circuit fault distance measurement method 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.

[0121] Example 3

[0122] An 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 3 A method for measuring the distance between phase short circuit faults in a distribution network is shown.

[0123] Those skilled in the art can understand that all or part of the steps of various methods in the above embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer readable storage medium, including Read-Only Memory (ROM), Random Access Memory (RAM), Programmable Read-only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), One-time Programmable Read-Only Memory (OTPROM), Electrically-Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM) or other optical disk storage, magnetic disk storage, magnetic tape storage, or any other medium that can be used to carry or store data in a computer readable manner.

[0124] Since the storage medium is a storage medium corresponding to the power distribution network phase-to-phase short-circuit fault distance measurement method of the embodiments of the present application, and the problem solving principle of 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 method embodiments, and the repeated parts will not be described again.

[0125] Embodiment 4

[0126] In some possible implementation manners, various aspects of the method of the embodiments of the present application can also be implemented in the form of a program product, which includes program codes for causing a computer device to execute the steps of the power distribution network phase-to-phase short-circuit fault distance measurement method according to various exemplary embodiments of the present application described above in the specification when the program product is run on the computer device. The executable computer program codes or "codes" for executing various embodiments can be written in a high-level programming language such as C, C++, C#, Smalltalk, Java, JavaScript, Visual Basic, Structured Query Language (for example, Transact-SQL), Perl, or in various other programming languages.

[0127] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0128] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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 can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0129] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for measuring the distance between phases of a distribution network short circuit fault, characterized in that: The following steps are involved: The voltage of each phase at the head end of the protection zone is sampled and obtained, and the startup criteria are determined based on the obtained voltage. If so, the fault location method is activated, and the distributed power supply injects a high-frequency current detection signal into the line. Sampling and obtaining the three-phase voltage and current of one power frequency cycle before and after the fault at the head end of the protection zone; The fast Fourier transform algorithm is used to extract the power frequency component and higher harmonic component of each phase voltage and current, and calculate the power frequency fault component; The fault type and fault phase are determined by using the difference in the power frequency current fault component between each two phases; Obtain the fault distance equation according to the fault type, solve the fault distance equation, and obtain the fault distance.

2. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 1, characterized in that: The starting criterion is that the phase voltage at the head end of the protection zone is lower than the starting voltage setting value, specifically: Where, are the phase voltages of the protection section, U n is the phase voltage rated value, U set It is the starting voltage setting value.

3. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 1, characterized in that: The sampling and acquisition of the three-phase voltage and current of one power frequency cycle before and after the fault at the head end of the protection zone includes: With the power frequency cycle as the time window length, collect the current of each phase in one cycle after the fault at the head end of the protection section Collect the voltage of each phase in the cycle before the fault at the head end of the protection section With each phase current 4. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 1, characterized in that: The method of extracting the power frequency components and higher harmonic components of each phase voltage and current using the fast Fourier algorithm and calculating the power frequency fault components includes: Extract the power frequency components of each phase voltage and current after the fault by fast Fourier transform and higher harmonic components Extract the power frequency components of each phase voltage and current before the fault Then calculate the power frequency fault component, specifically: Where, are the power frequency fault components of each phase voltage, are the power frequency fault components of each phase current respectively.

5. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 1, characterized in that: The method of determining the fault type and the fault phase by using the difference in the power frequency current fault component between each two phases includes: Where, is the difference between the power frequency current fault components between phases AB, is the difference between the power frequency current fault components between phases BC, is the difference between the power frequency current fault components of the CA phases; When formula (2) is satisfied, it is determined that a three-phase short circuit occurs in the line: Where k set1 is the three-phase short-circuit margin coefficient; When formula (3) is satisfied, it is determined that a two-phase short circuit occurs in the line: Where k set2 is the two-phase short-circuit margin coefficient; x, y, and z represent one of the AB phase, BC phase, and CA phase respectively.

6. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 1, characterized in that: Obtaining a fault distance equation according to the fault type includes: When a three-phase short circuit occurs, the power frequency voltage and current of any phase at the head end of the protection zone are used to construct a distance measurement equation. The high-frequency current detection signal injected into the line by the distributed power supply is used to construct a fault distance measurement equation under a high-frequency equivalent circuit. When a two-phase short circuit occurs, the power frequency voltage and current of the fault phase at the head end of the protection section are used to construct a distance measurement equation. The high-frequency current detection signal injected into the line by the distributed power supply is used to construct a fault distance measurement equation under a high-frequency equivalent circuit.

7. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 6, characterized in that: The distance measurement equation constructed using the power frequency voltage and current of phase A at the head end of the protection zone is: Where d is the distance between the fault point and the beginning of the protection zone, Z L is the line unit impedance, R f is the transition resistance, l is the length of the protection zone, Z n is the equivalent impedance on the back side of the protection zone end; The ranging equation under the high-frequency equivalent circuit is constructed as follows: Where Z L10 is the high-frequency equivalent unit impedance of the line, Z n10 is the high-frequency equivalent impedance on the back side of the protection zone end, and the distance d between the fault point and the head end of the protection zone is obtained by solving the equation; is the A-phase power frequency voltage at the head end of the protection section after the fault, is the A-phase power frequency current at the head end of the protection section after the fault, The A-phase power frequency voltage fault component at the head end of the protection section is is the A-phase power frequency current fault component at the head end of the protection section, The A-phase high-frequency voltage at the head end of the protection section is It is the high-frequency current of phase A at the beginning of the protection section.

8. A method for measuring the distance between phases of a distribution network short circuit fault according to claim 6, characterized in that: The distance measurement equation constructed using the power frequency voltage and current of the fault phase BC at the head end of the protection zone is: Where, is the BC phase power frequency voltage, is the power frequency current between phases BC, is the difference between the power frequency fault components of the BC phase current, is the difference of the power frequency fault component of the BC phase voltage; Z L is the line unit impedance, R f is the transition resistance, l is the length of the protection zone, Z n is the equivalent impedance on the back side of the protection zone end; The ranging equation under the high-frequency equivalent circuit is constructed as follows: Where, is the high-frequency voltage between phases BC, is the high-frequency current between phases BC; the distance d between the fault point and the beginning of the protection zone is obtained by solving the equation.

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 according to 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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