Distance measurement method and device for inter-phase short circuit fault of power distribution network and medium

Abstract

The invention discloses a power distribution network phase-to-phase short-circuit fault distance measurement method and device and a medium, and the method comprises the steps: carrying out the sampling and obtaining of each phase voltage of the head end of a protection section, and judging whether a starting criterion is satisfied or not according to the obtained voltage; if yes, starting a fault distance measurement method, and injecting a high-frequency current detection signal into the line by the distributed power supply; sampling to obtain three-phase voltage and current of a power frequency period before and after a fault at the head end of the protection section; extracting a power frequency component and a higher harmonic component of each phase of voltage and current by using a fast Fourier algorithm, and calculating a power frequency fault component; the fault type and the fault phase are judged by using the difference between the fault components of the power frequency current between every two phases; and obtaining a fault distance measurement equation according to the fault type, and solving the fault distance measurement equation to obtain a fault distance. The method solves the problem of inter-phase short-circuit fault distance measurement of the power distribution network containing the distributed power supply, and does not need to additionally install a signal injection device. The method can be widely applied to 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 distance measurement method, equipment and medium. Background Art

[0002] The traditional single-ended distance measurement method usually relies on line parameters and the electrical quantity at the local end when the fault occurs for measurement. It is widely used in distribution networks due to its simple and convenient characteristics. However, in the distribution network containing distributed generation (DG), the access of DG changes the distribution network from the original single-power radial network to a complex multi-power network, resulting in changes in the power flow distribution, short-circuit current size and direction of the distribution network, which has a greater impact on the fault distance measurement of the fault point downstream of the grid connection point. In addition, the intermittent and uncertain output of DG further increases the error of single-ended distance measurement, which challenges the traditional single-ended distance measurement method.

[0003] In view of the problem that the traditional single-ended distance measurement method is not accurate enough in the distribution network containing distributed generation, the high controllability of the power electronic equipment in the DG can be fully utilized. Through additional control strategies, the DG can actively output detection signals when a short circuit occurs in the line. Based on the electrical quantity generated by the detection signal, a new fault distance measurement principle is constructed to improve the accuracy of fault distance measurement. Therefore, it is of great significance to study the active injection type distribution network phase-to-phase short circuit fault distance measurement method. Summary of the invention

[0004] In order to solve at least one of the technical problems existing in the prior art to a certain extent, the object of the present invention is to provide a distribution network phase-to-phase short circuit fault distance measurement 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 phase-to-phase short circuit faults in a distribution network comprises the following steps:

[0007] Taking the power frequency cycle as the time window length, sample and obtain the voltage of each phase at the head end of the protection zone, and judge whether the start criterion is met according to the obtained voltage; if it is met, start the fault distance measurement method, 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 algorithm is used to extract the power frequency component and high-order 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] The fault distance equation is obtained according to the fault type, and the fault distance is obtained by solving the fault distance equation.

[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] In the formula, are the phase voltages of the protection zone, U n is the phase voltage rating, 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] The power frequency cycle is used as the time window length to 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 the high-order 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 fault by fast Fourier transform And high 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] In the formula, are the power frequency fault components of each phase voltage, They 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] In the formula, is the difference between the fault components of the power frequency current between phases AB, is the difference of the fault component of the power frequency current between phases BC, is the difference of the fault component of the power frequency current between the CA phases;

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

[0025]

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

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

[0028]

[0029] In the formula, 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, z represent one of the AB phase, BC phase, and CA phase respectively.

[0030] Further, obtaining the 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 the distance measurement equation; the high-frequency current detection signal injected into the line by the distributed power source is used to construct the fault distance measurement equation under the 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 the distance measurement equation; the high-frequency current detection signal injected into the line by the distributed power supply is used to construct the fault distance measurement equation under the high-frequency equivalent circuit.

[0033] Furthermore, the distance measurement 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 end of the protection zone;

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

[0037]

[0038] In the formula, 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 end of the protection zone, 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 section is:

[0040]

[0041] In the formula, is the BC phase power frequency voltage, is the BC phase power frequency current, 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 end of the protection zone;

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

[0043]

[0044] In the formula, 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 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 distribution network interphase short circuit fault distance measurement 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, the 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 distance measurement method as described above.

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

[0050] A computer program product or a 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 the processor executes the computer instructions, so that the computer device executes 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 phase-to-phase short-circuit fault distance measurement in the distribution network containing distributed generation, 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 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.

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

[0057] Figure 2 is a flow chart of a method for measuring the distance between phase short circuit faults in a distribution network based on high frequency current injection in one embodiment of the present invention;

[0058] Figure 3 It is a flow chart of the steps of a distribution network phase-to-phase short-circuit fault location method in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] 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.

[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., 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.

[0061] 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.

[0062] 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.

[0063] Terminology explanation:

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

[0067] Example 1

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

[0069] See also Figure 2 and Figure 3 The present embodiment provides a method for measuring the distance between phase short circuit faults in a distribution network based on high frequency current injection, which specifically includes the following steps:

[0070] S1. Take the power frequency cycle as the time window length, sample and obtain the voltage of each phase at the head end of the protection section. When the starting criterion is met, the fault location method is started, and DG injects 10 high-frequency currents into the line.

[0071] In one embodiment, the fault location method uses the phase voltage at the head end of the protection zone being lower than the starting voltage setting value as the starting criterion:

[0072]

[0073] Where: are the phase voltages of the protection zone, U n is the phase voltage rating, U set is the starting voltage setting value, specifically, U set 0.95 is acceptable.

[0074] S2. Sample and obtain the three-phase voltage and current of one power frequency cycle before and after the fault at the head end of the protection section.

[0075] In one embodiment, the power frequency cycle is used as the time window length to 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 The steady-state current of each phase

[0076] S3. Use the fast Fourier algorithm to extract the power frequency component and high-order harmonic component of each phase voltage and current, and calculate the power frequency fault component.

[0077] In one embodiment, the power frequency components of the voltage and current of each phase after the fault are extracted by fast Fourier transform. And high harmonic components Extract the power frequency components of each phase voltage and current before the fault Then calculate the power frequency fault component:

[0078]

[0079] Where: are the power frequency fault components of each phase voltage, They 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 of the power frequency current fault component between each two phases is first calculated:

[0082]

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

[0084]

[0085] Where: k set1 is the three-phase short-circuit margin coefficient, and a suitable value 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 occurs in the line.

[0086]

[0087] In the formula, k set2 is the two-phase short circuit margin coefficient, and a suitable value can be selected according to the line imbalance and measurement error. In this embodiment, 0.005 is selected. Taking the BC phase fault as an example, when the above formula is satisfied, it is determined that a two-phase short circuit occurs in the line.

[0088] S5. Write the fault distance measurement equation according to the fault type and solve the distance measurement equation by 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 of the back side of the protection zone end. Two equations can be obtained by decomposing the real and imaginary parts of the formula.

[0092] Using the 10-time high-frequency current detection signal injected by 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 end of the protection zone. Similarly, the real and imaginary parts of the equation are decomposed into two equations. By combining the power frequency and high-frequency ranging equations, a total of four equations, the LM algorithm is selected to solve the distance d between the fault point and the head end of the protection zone.

[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] In the formula, 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-time high-frequency current detection signal injected by DG into the line, the ranging equation under the high-frequency equivalent circuit is constructed:

[0099]

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

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

[0102] This embodiment builds the following in PSCAD: Figure 1 The 10 kV low-resistance grounding distribution network model with distributed generation access shown in the figure 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 line is set to have a three-phase short circuit at 0.3s, and the transition resistance is recorded as 0, 10, 20 and 50Ω respectively. The simulation results when the fault point is 10%, 50% and 90% of the total length of the line head end are shown in Table 2.

[0106] Table 2 Three-phase short circuit simulation results

[0107]

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

[0109] Table 3 Two-phase short-circuit simulation results

[0110]

[0111]

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

[0113] Table 4 Three-phase short circuit simulation results when the line is 10km

[0114]

[0115] It can be seen from the above simulation results that when phase-to-phase short circuits with different transition resistances occur at different locations of the protection zone in a 10kV low-resistance grounding system containing distributed power sources, the method of the present invention can accurately calculate the fault location with a calculation error of less than 10%.

[0116] Example 2

[0117] 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 3 A distribution network phase-to-phase short-circuit fault location method is shown.

[0118] 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.

[0119] 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.

[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] 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 3 A distribution network phase-to-phase short-circuit fault location method is shown.

[0123] 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.

[0124] Since the storage medium is a storage medium 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 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.

[0125] Example 4

[0126] 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 a distribution network interphase short circuit fault distance measurement method 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.

[0127] 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.

[0128] 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.

[0129] 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 measuring the distance between phase short circuit faults in a distribution network, 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 it is determined whether the start criterion is met according to the obtained voltage; if it is met, the fault distance measurement method is started, 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 algorithm is used to extract the power frequency component and high-order 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; The fault distance equation is obtained according to the fault type, and the fault distance is obtained by solving the fault distance equation.

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

3. A method for measuring the distance between phase short circuit faults in a distribution network 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 section includes: The power frequency cycle is used as the time window length to 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 phase short circuit faults in a distribution network according to claim 1, characterized in that: The method of extracting the power frequency component and the high-order harmonic component of each phase voltage and current by using the fast Fourier algorithm and calculating the power frequency fault component includes: Extract the power frequency components of each phase voltage and current after fault by fast Fourier transform And high harmonic components Extract the power frequency components of each phase voltage and current before the fault Then calculate the power frequency fault component, specifically: In the formula, are the power frequency fault components of each phase voltage, They are the power frequency fault components of each phase current respectively.

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

6. A method for measuring the distance between phase short circuit faults in a distribution network according to claim 1, characterized in that: The obtaining of the 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 the distance measurement equation; the high-frequency current detection signal injected into the line by the distributed power source is used to construct the fault distance measurement equation under the 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 the distance measurement equation; the high-frequency current detection signal injected into the line by the distributed power supply is used to construct the fault distance measurement equation under the high-frequency equivalent circuit.

7. A method for measuring the distance between phase short circuit faults in a distribution network 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 end of the protection zone; The ranging equation under the high-frequency equivalent circuit is constructed as follows: In the formula, 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 end of the protection zone, and the distance d between the fault point and the head end of the protection zone is obtained by solving the equation.

8. A method for measuring the distance between phase short circuit faults in a distribution network according to claim 6, characterized in that: 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: In the formula, is the BC phase power frequency voltage, is the BC phase power frequency current, 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 end of the protection zone; The ranging equation under the high-frequency equivalent circuit is constructed as follows: In the formula, 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 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.

Images