Distribution line inter-phase short circuit fault distance measurement method and device

Abstract

The invention relates to the technical field of power system fault detection and protection, in particular to a distribution line phase-to-phase short-circuit fault distance measurement method and device, and the method comprises the steps: detecting the fault phase voltage and current at an outlet protection installation part of a transformer substation after a preset time period, determining a time-domain voltage differential equation by using a topological structure of the power distribution network to calculate a fault distance, performing successive search based on the fault distance until the fault distance is located in a target fault section, comparing whether an effective value of branch current collected by a circuit breaker arranged at a branch terminal is not matched with branch current identified in a distance measurement equation, and if yes, determining that the fault distance is not matched with the branch current. And identifying a false fault point to obtain a distribution line inter-phase short-circuit fault distance measurement result. Therefore, the problem that the fault area obtained by the fault area positioning method for the single-end impedance distance measurement method of the power distribution line for the time domain equation is large, and the fault branch is difficult to accurately position for the power grid with the branch, so that the distance measurement error is large in the related technology is solved.

Description

Technical Field

[0001] The present application relates to the technical field of power system fault detection and protection, and in particular to a method and device for measuring the distance between phase-to-phase short-circuit faults in distribution lines. Background Art

[0002] In the related technology, due to the singleness of the measurement and control means, the 35kV line adopts single-ended fault distance measurement based on the current and voltage information measured at the busbar at the substation outlet. The distance measurement principle of the single-ended impedance method is to use the linear relationship between the fault distance and the distance measurement impedance. From the form of the distance measurement equation, it can be divided into frequency domain equation and time domain equation. The single-ended impedance method for 35kV lines mainly focuses on the time domain equation. Generally, the fault component information is used to derive the differential equation in the time domain as the distance measurement equation, and the transition resistance, fault distance and other unknown information are unified as parameters to be identified, and the distance measurement result is obtained by solving the equation group.

[0003] However, in the related art, the single-ended impedance ranging method for distribution lines based on time domain equations has the problem that the fault area obtained by the fault area location method is large, it is difficult to accurately locate the fault branch for a branched power grid, and the ranging error is large, which needs to be solved urgently. Summary of the invention

[0004] The present application provides a method and device for measuring the distance between phase-to-phase short-circuit faults in a distribution line, in order to solve the problem in the related art that the single-ended impedance distance measurement method for the distribution line based on the time domain equation has a large fault area obtained by the fault area location method, and it is difficult to accurately locate the fault branch for a power grid with branches, thus resulting in a large distance measurement error.

[0005] The first aspect of the present application provides a method for measuring the distance between phase-to-phase short-circuit faults in distribution lines, comprising the following steps: detecting the fault phase voltage and the fault phase current at the transformer substation outlet protection installation after a preset fault time; calculating the fault distance based on the fault phase voltage and the fault phase current, using the time-domain voltage differential equation between the transformer substation outlet bus and the fault point determined by the topological structure of the distribution network; performing successive searches based on the fault distance until the fault distance is located in the target fault section, comparing the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measurement equation to see if they do not match, so as to identify the pseudo-fault point and obtain the distribution line phase-to-phase short-circuit fault measurement result.

[0006] Through the above technical scheme, the embodiment of the present application can detect the fault phase voltage and fault phase current at the substation outlet protection installation point after a certain period of time as basic data. These data can be directly obtained from the existing protection device of the substation, without the need to install new measuring equipment, thereby reducing costs; the fault distance is calculated by determining the time-domain voltage differential equation between the substation outlet bus and the fault point based on the topological structure of the distribution network, which fully considers the actual connection conditions and electrical characteristics of the distribution line, so that the calculation result is more in line with the actual situation, thereby improving the accuracy of fault distance measurement; based on the calculated fault distance, successive searches are performed until the fault distance is located in the target fault section. The step-by-step approach can systematically check possible fault locations to avoid omissions. At the same time, by comparing the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measurement equation to see if it does not match, the pseudo-fault point is identified, further improving the reliability of the results.

[0007] Optionally, in one embodiment of the present application, the time domain voltage differential equation is:

[0008]

[0009] Among them, phases B and C are fault phases, u Bf 、u Cf is the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of L phase flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

[0010] Through the above technical scheme, the time-domain voltage differential equation of the embodiment of the present application intuitively reflects the relationship between voltage, current, resistance, inductance and distance, comprehensively considers the electrical characteristics in the circuit, and can comprehensively describe the electrical state of the distribution line when the phases are short-circuited. By accurately reflecting the relationship between these physical quantities, the fault distance calculated according to the equation is more accurate, thereby improving the accuracy of fault distance measurement.

[0011] Optionally, in one embodiment of the present application, the sequential searches based on the fault distance are performed until the fault distance is located in the target fault section, and the effective value of the branch current collected by the circuit breaker installed at the branch terminal is compared with the branch current identified in the distance measurement equation to see whether it does not match, so as to identify the pseudo fault point and obtain the distribution line phase-to-phase short circuit fault distance measurement result, including:

[0012] The grid-connected node with n branch lines is taken as the dividing point to determine that the main line is divided into n+1 sections, and the branch lengths are L g1 , L g2 ...Lgn The length of each trunk line is L1, L2...L n , L n+1 ;

[0013] Starting from m=1, we can g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line, so as to use the damped least squares method to fit the optimal solution and obtain the distance measurement result of the mth section, wherein the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data, until the distance measurement result l is in the searched section and the branch current matches, the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, wherein n and m are both positive integers.

[0014] Through the above technical solution, the embodiment of the present application can partition based on the topological structure of the power distribution network, so that the search process can systematically cover the entire line, without missing any possible fault section, and improve the comprehensiveness and accuracy of fault location. The step-by-step search method can systematically check each section, avoid blind search, and improve search efficiency.

[0015] Optionally, in one embodiment of the present application, the calculation formula of the optimal solution is:

[0016] When the fault is located in the nth branch:

[0017]

[0018]

[0019] When the fault is located on the n+1th trunk line:

[0020]

[0021] in, is the current of the nth branch line.

[0022] Through the above technical scheme, the embodiment of the present application provides a method for calculating the optimal solution for the two situations where the fault is located on the nth branch and the n+1th main line, respectively. The design of different fault locations is comprehensively considered, so that the technical scheme can be applied to various possible fault situations. Regardless of whether the fault occurs on the branch line or the main line, the corresponding formula can be used for accurate calculation, which improves the versatility and practicality of the scheme.

[0023] The second aspect of the present application provides a distribution line phase-to-phase short-circuit fault distance measuring device, including: a detection module, used to detect the fault phase voltage and fault phase current at the substation outlet protection installation after a preset fault time; a calculation module, used to calculate the fault distance based on the fault phase voltage and the fault phase current, using the time domain voltage differential equation between the substation outlet bus and the fault point determined by the topological structure of the distribution network; a distance measuring module, used to perform successive searches based on the fault distance until the fault distance is located in the target fault section, compare the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measuring equation to see if they do not match, so as to identify the pseudo fault point and obtain the distribution line phase-to-phase short-circuit fault distance measurement result.

[0024] Through the above technical scheme, the embodiment of the present application can detect the fault phase voltage and fault phase current at the substation outlet protection installation point after a certain period of time as basic data. These data can be directly obtained from the existing protection device of the substation, without the need to install new measuring equipment, thereby reducing costs; the fault distance is calculated by determining the time-domain voltage differential equation between the substation outlet bus and the fault point based on the topological structure of the distribution network, which fully considers the actual connection conditions and electrical characteristics of the distribution line, so that the calculation result is more in line with the actual situation, thereby improving the accuracy of fault distance measurement; based on the calculated fault distance, successive searches are performed until the fault distance is located in the target fault section. The step-by-step approach can systematically check possible fault locations to avoid omissions. At the same time, by comparing the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measurement equation to see if it does not match, the pseudo-fault point is identified, further improving the reliability of the results.

[0025] Optionally, in one embodiment of the present application, the time domain voltage differential equation is:

[0026]

[0027] Among them, phases B and C are fault phases, u Bf 、u Cf is the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of phase C flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

[0028] Through the above technical scheme, the time-domain voltage differential equation of the embodiment of the present application intuitively reflects the relationship between voltage, current, resistance, inductance and distance, comprehensively considers the electrical characteristics in the circuit, and can comprehensively describe the electrical state of the distribution line when the phases are short-circuited. By accurately reflecting the relationship between these physical quantities, the fault distance calculated according to the equation is more accurate, thereby improving the accuracy of fault distance measurement.

[0029] Optionally, in one embodiment of the present application, the distance measurement module includes: a partitioning unit, which is used to use the grid-connected node with n branch lines as a dividing point to determine that the branch trunk line is n+1 sections, and the branch lengths are L g1 , L g2 ...L gn The length of each trunk line is L1, L2...L n , L n+1 ; Calculation unit, used to calculate branch L starting from m=1 g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line, so as to use the damped least squares method to fit the optimal solution and obtain the distance measurement result of the mth section, wherein the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data, until the distance measurement result l is in the searched section and the branch current matches, the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, wherein n and m are both positive integers.

[0030] Through the above technical solution, the embodiment of the present application can partition based on the topological structure of the power distribution network, so that the search process can systematically cover the entire line, without missing any possible fault section, and improve the comprehensiveness and accuracy of fault location. The step-by-step search method can systematically check each section, avoid blind search, and improve search efficiency.

[0031] Optionally, in one embodiment of the present application, the calculation formula of the optimal solution is:

[0032] When the fault is located in the nth branch:

[0033]

[0034] When the fault is located on the n+1th trunk line:

[0035]

[0036] in, is the current of the nth branch line.

[0037] Through the above technical scheme, the embodiment of the present application provides a method for calculating the optimal solution for the two situations where the fault is located on the nth branch and the n+1th main line, respectively. The design of different fault locations is comprehensively considered, so that the technical scheme can be applied to various possible fault situations. Regardless of whether the fault occurs on the branch line or the main line, the corresponding formula can be used for accurate calculation, which improves the versatility and practicality of the scheme.

[0038] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the distribution line phase-to-phase short-circuit fault distance measurement method as described in the above embodiment.

[0039] The fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program. When the program is executed by a processor, it implements the above distribution line phase-to-phase short-circuit fault distance measurement method.

[0040] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, is used to implement the above-mentioned distribution line phase-to-phase short-circuit fault distance measurement method.

[0041] The embodiment of the present application uses the fault phase voltage and current after a certain period of time at the transformer substation outlet protection installation as the basic data, which can be obtained from the existing protection device, without the need for new measuring equipment, thus reducing costs. Secondly, the fault distance is calculated based on the time-domain voltage differential equation of the distribution network topology, taking into account the actual connection and electrical characteristics, and intuitively reflecting the relationship between multiple physical quantities, making the calculation results more accurate and improving the ranging accuracy. Furthermore, based on the fault distance, the pseudo-fault point is identified by searching and comparing the branch currents one by one, gradually approaching the fault location, avoiding omissions and improving the reliability of the results. Then, the partition search is performed according to the distribution network topology structure, covering the entire line, improving the comprehensiveness and accuracy of fault location, and gradually searching to improve efficiency. Finally, the optimal solution calculation method is given for different situations where the fault is located in the branch and the trunk line, which is applicable to a variety of fault situations and improves the versatility and practicality of the solution.

[0042] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0044] Figure 1 A flow chart of a method for measuring the distance between phase short circuit faults in a power distribution line provided according to an embodiment of the present application;

[0045] Figure 2 A schematic diagram of a 35kV distribution line topology according to a specific embodiment of the present application;

[0046] Figure 3 A schematic diagram of an equivalent circuit of a phase-to-phase short circuit in a distribution network according to a specific embodiment of the present application;

[0047] Figure 4 A schematic diagram of the structure of a distribution line interphase short-circuit fault distance measuring device provided according to an embodiment of the present application;

[0048] Figure 5 The figure is a structural example diagram of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0049] The embodiments of the present application 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 intended to be used to explain the present application, and should not be construed as limiting the present application.

[0050] The following describes the distribution line interphase short-circuit fault distance measurement method and device of the embodiment of the present application with reference to the accompanying drawings. In view of the related technologies mentioned in the above background technology center, the single-ended impedance distance measurement method for the time domain equation for the distribution line has the problem that the fault area obtained by the fault area location method is large, and it is difficult to accurately locate the fault branch for the power grid with branches, which leads to a large distance measurement error. The present application provides a distribution line interphase short-circuit fault distance measurement method. In this method, the fault phase voltage and fault phase current after a certain period of time at the fault installation point of the substation outlet protection can be used as basic data. These data can be directly obtained from the existing protection device of the substation, without the need to install new measurement equipment, thereby reducing costs; by using the distribution network-based The topological structure determines the time domain voltage differential equation between the substation outlet bus and the fault point to calculate the fault distance, which fully considers the actual connection and electrical characteristics of the distribution line, so that the calculation result is more in line with the actual situation, thereby improving the accuracy of fault distance measurement; based on the calculated fault distance, a successive search is performed until the fault distance is located in the target fault section. The step-by-step approach can systematically check the possible fault location to avoid omissions. At the same time, by comparing the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measurement equation, the pseudo fault point is identified, further improving the reliability of the result. In this way, the problem that the single-ended impedance distance measurement method for the time domain equation of the distribution line in the related art has the problem that the fault area obtained by the fault area location method is large, and it is difficult to accurately locate the fault branch for the power grid with branches, resulting in a large distance measurement error.

[0051] Specifically, Figure 1 A schematic flow chart of a method for measuring the distance between phase short circuit faults in a power distribution line provided in an embodiment of the present application.

[0052] like Figure 1 As shown, the distribution line interphase short circuit fault distance measurement method includes the following steps:

[0053] In step S101, the fault phase voltage and the fault phase current at the transformer substation outlet protection installation after the fault has occurred for a preset time are detected.

[0054] It is understandable that the detection location is the protection installation at the outlet of the substation. As an important hub for power transmission and distribution, the data at its outlet protection installation is crucial to understanding the operating status of the entire line. The time node of the detection is a pre-set duration, which is determined after a lot of research and practice. At this point in time, the electrical quantities in the line can fully reflect some key characteristics of the fault, providing a perfect data basis for subsequent fault analysis and ranging. The detection objects are the fault phase voltage and fault phase current. In a three-phase power system, there are phases A, B and C. When a fault occurs, it may be that one of the phases has a problem, and it is necessary to specifically detect the voltage and current of the fault phase.

[0055] In the actual implementation process, the phase voltage and phase current data of the substation outlet protection installation 20ms after the fault occurs are measured as input, that is, the bus phase voltage after the fault Bus phase current after fault in Phase: A phase, B phase or C phase.

[0056] The detection location of the embodiment of the present application is at the protection installation point of the substation outlet. Since the substation is a power transmission and distribution hub, the data here can fully reflect the line status and facilitate fault tracing analysis. The detection time node is after 20ms, at which time the electrical quantity can fully reflect the key characteristics of the fault, providing an accurate basis for subsequent fault analysis and ranging, and avoiding the disadvantages of measuring too early or too late. The detection object is the fault phase voltage and current, and the fault phase is specifically detected in the three-phase system, which can improve the efficiency of fault analysis, avoid screening in the normal phase data, and help to accurately locate and range the fault.

[0057] In step S102, based on the fault phase voltage and the fault phase current, the fault distance is calculated using a time domain voltage differential equation between the substation outlet bus and the fault point determined by the topological structure of the distribution network.

[0058] It can be understood that the topological structure of the distribution network describes the connection relationship between the various components in the distribution network (such as substations, busbars, lines, loads, etc.). Understanding the topological structure can determine the connection method of the circuit, the distribution of components and other information, thereby accurately establishing a differential equation that reflects the relationship between voltage and current.

[0059] Optionally, in one embodiment of the present application, the time domain voltage differential equation is:

[0060]

[0061] Among them, phases B and C are fault phases, u Bf 、u Cf is the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of phase C flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

[0062] The following is a specific example for explanation. Figure 2 As shown, Figure 2 It is a schematic diagram of the topology of a 35kV distribution line. The system has four branch lines, which are connected to the 110kV system through a step-down transformer in a substation. The main transformer of the substation adopts a small current grounding method, and the neutral point is grounded through an arc suppression coil. M is the bus side of the transformer station end, and u and i are the fault phase voltage and phase current measured at the outlet of the collector line, respectively. D, E, F, and G are branch points on the collector line, which divide the main line of the line into 5 sections. The length of the main line is 10km, the length of each section is 2km, and the length of each branch line is 2km. The line parameter values ​​are shown in Table 1. The fault distance measuring device of the present application measures the bus voltage and the current value at the outlet of the collector line through PT (Potential Transformer) and CT (Current Transformer). Assume that Figure 2 A phase-to-phase short circuit fault occurs at the midpoint BC of the EF segment. The actual fault distance is 5 km. Figure 3 As shown, Figure 3 is the equivalent circuit diagram of the phase-to-phase short circuit of the distribution network, and Table 1 is the main parameter table of the distribution line. Among them, Table 1 is as follows:

[0063] Table 1

[0064] Line parameters Resistance (Ω / km) Inductance(mH / km) Capacitance (μF / km) Positive sequence 0.17 1.2096 0.0097 Zero sequence 0.23 5.4749 0.006

[0065] Specifically, 400 sets of data (one cycle is 200 sets of data) are taken as input quantity after the fault of the line at the protection installation 20ms later, that is, the phase voltage uB 、u c , phase current i B 、i c , the time-domain voltage differential equation of BC phase short-circuit fault based on the topological structure of the distribution network is the distance measurement equation:

[0066]

[0067] The embodiment of the present application is based on the fault phase voltage and current and uses the distribution network topology to establish a time-domain voltage differential equation to calculate the fault distance, combining the key electrical quantities of the power system with the network structure information, laying the foundation for accurate distance measurement. Secondly, taking the specific 35kV distribution line topology as an example, including clear branch lines, transformer connection methods and other detailed information, the scheme has strong practicality. Furthermore, measuring multiple sets of data 20ms after the fault at the protection installation as input can effectively reflect the fault state. Finally, a specific phase-to-phase short-circuit fault time-domain voltage differential equation is given to clarify the meaning of each parameter in the equation, and combined with actual line parameters, such as resistance, inductance, capacitance, etc., it is helpful to accurately perform fault distance measurement and improve the efficiency and accuracy of power system fault handling.

[0068] In step S103, a successive search is performed based on the fault distance until the fault distance is located in the target fault section, and the effective value of the branch current collected by the circuit breaker installed at the branch terminal is compared with the branch current identified in the distance measurement equation to see if it does not match, so as to identify the pseudo-fault point and obtain the distribution line phase-to-phase short-circuit fault distance measurement result.

[0069] It can be understood that the step-by-step search is to find the exact location where the fault may exist, and gradually narrowing the search range to the target fault section will help to further accurately determine the fault location. By comparing the effective value of the branch current with the branch current identified in the ranging equation to see if it does not match, the pseudo-fault points that may be misjudged as fault points can be identified. After excluding these pseudo-fault points, the final result is a more accurate distribution line phase-to-phase short-circuit fault ranging result.

[0070] Optionally, in one embodiment of the present application, a search is performed successively based on the fault distance until the fault distance is located in the target fault section, and the effective value of the branch current collected by the circuit breaker installed at the branch terminal is compared with the branch current identified in the distance measurement equation to see whether it does not match, so as to identify the pseudo fault point and obtain the distribution line phase-to-phase short circuit fault distance measurement result, including:

[0071] The grid-connected node with n branch lines is taken as the dividing point to determine that the main line is divided into n+1 sections, and the branch lengths are L g1 , L g2 ...L gn The length of each trunk line is L1, L2, ... Ln , L n+1 ;

[0072] Starting from m=1, we can g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line. The damped least squares method is used to fit the optimal solution to obtain the distance measurement result of the mth section, where the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data until the distance measurement result l is in the searched section and the branch current matches, and the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, where n and m are both positive integers.

[0073] In the actual execution process, the calculation formula for the optimal solution is:

[0074] When the fault is located in the nth branch:

[0075]

[0076] When the fault is located on the n+1th trunk line:

[0077]

[0078] in, is the current of the nth branch line.

[0079] Taking the specific embodiment in step S102 as an example, the distance measurement result is obtained by searching in sections step by step. Assuming that the fault point is located in the first section of the main line, the phase voltage u obtained in step S102 is B 、u c , phase current i B 、i c Substitute the following formula:

[0080]

[0081] Assume that the initial value of the fault distance is l_0 = 5km, and use the damped least squares method to find the optimal solution, and calculate l = 4.943km. The fault distance does not match the fault section, so it is determined that it is not in this section, and continue searching. Assuming that the fault point is located on the first branch line, the phase voltage u obtained in step S102 is B 、u c , phase current i B 、i c Substitute the following formula to continue fitting and solving:

[0082]

[0083] The calculated value is l = 5.034 km. The fault distance does not match the fault section. Therefore, it is determined that the fault point is not in this section and the search continues. Assuming that the fault point is located in the second section of the main line, the phase voltage u obtained in step S102 is B 、u c , phase current i B 、i c Substitute the following formula to continue fitting and solving:

[0084]

[0085] The calculated value is l = 5.0543 km. The fault distance does not match the fault section. Therefore, it is determined that the fault point is not in this section and the search continues. Assuming that the fault point is located in the third section of the main line, the phase voltage u obtained in step S102 is B 、u v , phase current i B 、i c Substitute the following formula to continue fitting and solving:

[0086]

[0087] The calculation results show that l=5.0607km, the fault distance is consistent with the fault section, and the search is completed, and the distance measurement result is 5.0607km.

[0088] The embodiments of the present application can search the target fault section based on the fault distance, gradually narrow the search range, and accurately locate the fault location. Secondly, by comparing whether the effective value of the branch current collected by the branch terminal circuit breaker matches the branch current in the ranging equation to identify the pseudo-fault point, it is possible to eliminate misjudgment and improve the accuracy of the ranging results. Furthermore, the number of line sections is divided based on the grid-connected node as the dividing point, and the length of each section is clarified to make the search and calculation more organized. The damped least squares method is used to calculate the optimal solution, and the calculation formulas corresponding to different fault locations are given. Combined with the substitution calculation, assumption judgment and continuous search process in the specific embodiment, the scientificity and practicality of the scheme are demonstrated, and finally the distribution line phase short-circuit fault ranging result can be obtained more accurately.

[0089] According to the distribution line phase-to-phase short-circuit fault distance measurement method proposed in the embodiment of the present application, the fault phase voltage and fault phase current after the fault at the substation outlet protection installation point is detected for a certain period of time can be used as basic data. These data can be directly obtained from the existing protection device of the substation, without the need to install new measuring equipment, thereby reducing costs; the fault distance is calculated by determining the time-domain voltage differential equation between the substation outlet bus and the fault point based on the topological structure of the distribution network, fully considering the actual connection conditions and electrical characteristics of the distribution line, so that the calculation result is more in line with the actual situation, thereby improving the accuracy of fault distance measurement; based on the calculated fault distance, successive searches are performed until the fault distance is located in the target fault section. The step-by-step approach can systematically check possible fault locations to avoid omissions. At the same time, the pseudo-fault point is identified by comparing whether the effective value of the branch current collected by the circuit breaker installed at the branch terminal does not match the branch current identified in the distance measurement equation, thereby further improving the reliability of the results.

[0090] Next, a distribution line interphase short-circuit fault distance measuring device proposed according to an embodiment of the present application is described with reference to the accompanying drawings.

[0091] Figure 4 It is a block diagram of a distribution line phase-to-phase short-circuit fault distance measuring device according to an embodiment of the present application.

[0092] like Figure 4 As shown, the distribution line interphase short circuit fault distance measuring device 10 includes: a detection module 100, a calculation module 200 and a distance measuring module 300.

[0093] Specifically, the detection module 100 is used to detect the fault phase voltage and the fault phase current at the transformer substation outlet protection installation after the fault has occurred for a preset time.

[0094] The calculation module 200 is used to calculate the fault distance based on the fault phase voltage and the fault phase current using the time domain voltage differential equation between the substation outlet bus and the fault point determined by the topological structure of the distribution network.

[0095] The ranging module 300 is used to perform successive searches based on the fault distance until the fault distance is located in the target fault section, compare the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the ranging equation to see if they do not match, so as to identify the pseudo-fault point and obtain the distribution line phase-to-phase short-circuit fault ranging result.

[0096] Optionally, in one embodiment of the present application, the time domain voltage differential equation is:

[0097]

[0098] Among them, phases B and C are fault phases, u Bf 、u Cfis the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of phase C flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

[0099] Optionally, in one embodiment of the present application, the ranging module 300 includes: a partitioning unit and a calculation unit.

[0100] The partition unit is used to take the grid-connected node with n branch lines as the dividing point to determine that the main line is divided into n+1 sections, and the branch lengths are L g1 , L g2 ...L gn The length of each trunk line is L1, L2...L n , L n+1 .

[0101] The calculation unit is used to calculate the branch L starting from m=1. g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line. The damped least squares method is used to fit the optimal solution to obtain the distance measurement result of the mth section, where the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data until the distance measurement result l is in the searched section and the branch current matches, and the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, where n and m are both positive integers.

[0102] Optionally, in one embodiment of the present application, the calculation formula of the optimal solution is:

[0103] When the fault is located in the nth branch:

[0104]

[0105] When the fault is located on the n+1th trunk line:

[0106]

[0107] in, is the current of the nth branch line.

[0108] It should be noted that the above explanation of the embodiment of the distribution line phase-to-phase short-circuit fault distance measurement method is also applicable to the distribution line phase-to-phase short-circuit fault distance measurement device of this embodiment, and will not be repeated here.

[0109] According to the distribution line phase-to-phase short-circuit fault distance measuring device proposed in the embodiment of the present application, the fault phase voltage and fault phase current after detecting the fault at the substation outlet protection installation point for a certain period of time can be used as basic data. These data can be directly obtained from the existing protection device of the substation, without the need to install new measuring equipment, thereby reducing costs; the fault distance is calculated by determining the time-domain voltage differential equation between the substation outlet bus and the fault point based on the topological structure of the distribution network, fully considering the actual connection conditions and electrical characteristics of the distribution line, so that the calculation result is more in line with the actual situation, thereby improving the accuracy of fault distance measurement; based on the calculated fault distance, successive searches are performed until the fault distance is located in the target fault section. The step-by-step approach can systematically check possible fault locations to avoid omissions. At the same time, by comparing whether the effective value of the branch current collected by the circuit breaker installed at the branch terminal does not match the branch current identified in the distance measurement equation, the pseudo-fault point can be identified, further improving the reliability of the result.

[0110] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0111] A memory 501 , a processor 502 , and a computer program stored in the memory 501 and executable on the processor 502 .

[0112] When the processor 502 executes the program, the distribution line interphase short circuit fault distance measurement method provided in the above embodiment is implemented.

[0113] Furthermore, the electronic device further comprises:

[0114] The communication interface 503 is used for communication between the memory 501 and the processor 502 .

[0115] The memory 501 is used to store computer programs that can be executed on the processor 502 .

[0116] The memory 501 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0117] If the memory 501, the processor 502 and the communication interface 503 are implemented independently, the communication interface 503, the memory 501 and the processor 502 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0118] Optionally, in a specific implementation, if the memory 501, the processor 502 and the communication interface 503 are integrated on a chip, the memory 501, the processor 502 and the communication interface 503 can communicate with each other through an internal interface.

[0119] The processor 502 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0120] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned distribution line phase-to-phase short-circuit fault distance measurement method.

[0121] The embodiment of the present application also provides a computer program product, including a computer program, which, when executed, is used to implement the above distribution line phase-to-phase short-circuit fault distance measurement method.

[0122] 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 application. 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 N 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.

[0123] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0124] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0125] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0126] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: 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.

[0127] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0128] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0129] The storage medium mentioned above may be a read-only memory, a disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for measuring the distance between phase short circuit faults in a distribution line, characterized in that: The following steps are involved: Detect the fault phase voltage and fault phase current after the preset fault time at the substation outlet protection installation; Based on the fault phase voltage and the fault phase current, the fault distance is calculated using a time domain voltage differential equation between the substation outlet bus and the fault point determined by the topological structure of the distribution network; Based on the fault distance, a successive search is performed until the fault distance is located in the target fault section, and the effective value of the branch current collected by the circuit breaker installed at the branch terminal is compared with the branch current identified in the distance measurement equation to see if it does not match, so as to identify the pseudo-fault point and obtain the distribution line phase-to-phase short-circuit fault distance measurement result.

2. The method according to claim 1, characterized in that The time domain voltage differential equation is: Among them, phases B and C are fault phases, u Bf 、u Cf is the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of phase C flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

3. The method according to claim 1, characterized in that The method of searching successively based on the fault distance until the fault distance is located in the target fault section, comparing the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the distance measurement equation to see whether it does not match, so as to identify the pseudo fault point and obtain the distribution line phase-to-phase short circuit fault distance measurement result, includes: The grid-connected node with n branch lines is taken as the dividing point to determine that the main line is divided into n+1 sections, and the branch lengths are L g1 , L g2 ...L gn The length of each trunk line is L1, L2...L n , L n+1 ; Starting from m=1, we can g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line, so as to use the damped least squares method to fit the optimal solution and obtain the distance measurement result of the mth section, wherein the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data, until the distance measurement result l is in the searched section and the branch current matches, the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, wherein n and m are both positive integers.

4. The method according to claim 3, characterized in that The calculation formula of the optimal solution is: When the fault is located in the nth branch: When the fault is located on the n+1th trunk line: Where, m = (1, 2, 3, 4…n), is the current of the nth branch line.

5. A distribution line interphase short circuit fault distance measuring device, characterized in that: include: A detection module, used to detect the fault phase voltage and fault phase current after a preset fault time at the transformer substation outlet protection installation location; A calculation module, configured to calculate the fault distance based on the fault phase voltage and the fault phase current, using a time domain voltage differential equation between the substation outlet bus and the fault point determined by the topological structure of the distribution network; The ranging module is used to perform successive searches based on the fault distance until the fault distance is located in the target fault section, compare the effective value of the branch current collected by the circuit breaker installed at the branch terminal with the branch current identified in the ranging equation to see if they do not match, so as to identify the pseudo-fault point and obtain the distribution line phase-to-phase short-circuit fault ranging result.

6. The device according to claim 5, characterized in that The time domain voltage differential equation is: Among them, phases B and C are fault phases, u Bf 、u Cf is the equivalent power supply voltage of the fault circuit, i Bf is the current of phase B flowing from the upstream of the fault point into the fault point, i Cf is the current of phase C flowing from the upstream of the fault point into the fault point, d is the distance between the fault point and the previous branch point, r is the line unit distance resistance parameter, and l is the line unit distance inductance parameter.

7. The device according to claim 5, characterized in that The ranging module comprises: The partition unit is used to use the grid-connected node with n branch lines as the dividing point to determine that the main line is divided into n+1 sections, and the branch lengths are L g1 , L g2 ...L gn The length of each trunk line is L1, L2...L n , L n+1 ; The calculation unit is used to calculate the branch L starting from m=1. g1 The search is performed on the L1 section of the main line, and the initial fitting value of the fault distance l is set to half of the longest distance of the collector line, so as to use the damped least squares method to fit the optimal solution and obtain the distance measurement result of the mth section, wherein the m value increases successively, and the corresponding search section also increases accordingly, and it is judged whether the branch current satisfies the measurement data, until the distance measurement result l is in the searched section and the branch current matches, the distribution line phase-to-phase short-circuit fault distance measurement result is obtained, wherein n and m are both positive integers.

8. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for measuring the distance between phase short circuit faults in a distribution line as described in any one of claims 1 to 4.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the distribution line phase-to-phase short-circuit fault distance measurement method as described in any one of claims 1 to 4.

10. A computer program product, comprising a computer program, characterized in that The computer program is executed to implement the distribution line phase-to-phase short-circuit fault location measurement method according to any one of claims 1 to 4.

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