Fault point iterative correction-based power distribution network short-circuit fault distance measurement method and system

Abstract

The invention discloses a power distribution network short-circuit fault distance measurement method and system based on fault point iterative correction, relates to the technical field of power distribution network short-circuit fault distance measurement, and solves the problem that a fault distance measurement result is not accurate enough. According to the method, the calculation process of the fault distance is simplified, the fault distance serves as a unique variable through reasonable assumption to establish a simple distance measurement differential equation, complex simultaneous equation set solving is avoided, and engineering application is more convenient. Moreover, an iterative calculation method is adopted, so that the calculation process is simplified, errors caused by hypothesis can be corrected, and high distance measurement precision can be ensured through multiple iterations. The method is wide in application range, can be used for single-phase grounding faults and inter-phase short-circuit grounding faults, and is high in engineering application value. In addition, the fault voltage variation is adopted to calculate the distance measurement result, the influence of the load current on the distance measurement precision can be eliminated, and the calculation precision can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grids, and in particular to a method and system for measuring short-circuit fault distance in a distribution network based on iterative correction of fault points. Background Art

[0002] 10~35kV is the main voltage level of my country's distribution network, which has a wide distribution range and undertakes the task of directly supplying power to users. Once a distribution network fails, it will directly affect the reliability of power supply. Statistics show that 90% of user power outages are related to distribution network failures. After a distribution network failure occurs, maintenance personnel need to quickly find the fault point to troubleshoot the fault, so accurate fault distance measurement results are needed to assist maintenance personnel to quickly determine the fault location. Due to the complex structure of the distribution network, diverse operating environment, rich line types, and complex fault characteristics, it is difficult to obtain accurate fault distance measurement results. Therefore, the fault distance measurement problem of the distribution network has long plagued the power supply operation department, and a better solution is urgently needed from a technical level.

[0003] Considering the complex structure of the distribution network, it is difficult to obtain multi-point synchronous electrical quantity information. From a practical point of view, it is suitable to use a single-ended distance measurement method, but not suitable to use complex distance measurement methods such as double-ended distance measurement and traveling wave distance measurement. Therefore, a single-ended distance measurement method that is more in line with the actual characteristics of the distribution network and easier to implement is needed. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is that the structure of the distribution network is very complex, and it is difficult to obtain multi-point synchronous electrical quantity information. From a practical point of view, it is suitable to adopt a single-end measurement method, but not suitable to adopt complex measurement methods such as double-end measurement and traveling wave measurement. The fault distance measurement results are not accurate enough due to factors such as the wide distribution range of the distribution network, the complex structure, and the diverse operating environment.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a distribution network short-circuit fault location method based on fault point iterative correction, which includes collecting first parameters of each phase of the distribution network during normal operation and after a fault occurs;

[0008] Determine the fault type and the fault phase according to the fault distance measuring device, and calculate a second parameter corresponding to the fault phase according to the first parameter;

[0009] Constructing a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to the second parameter;

[0010] Setting the initial values ​​of the voltage variation at the fault point and the fault distance according to the first parameter and the second parameter;

[0011] Correcting the values ​​of the voltage variation at the fault point and the fault distance to obtain a first fault distance and a voltage variation at the first fault point;

[0012] Substitute the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance; substitute the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point;

[0013] Determine whether the distance measurement result converges. If so, end the process. If not, return the value of the corrected fault point voltage change and fault distance.

[0014] As a preferred solution of the distribution network short-circuit fault distance measurement method based on fault point iterative correction described in the present invention, wherein: the first parameters of each phase of the distribution network are collected during normal operation and after a fault occurs, the first parameters include the voltage and current of each phase during normal operation of the circuit, the voltage and current of each phase after a single-phase ground short-circuit fault occurs, and the voltage and current between each phase after a phase-to-phase ground short-circuit fault occurs; the second parameters include the change in fault phase voltage and the change in fault phase current.

[0015] As a preferred solution of the distribution network short-circuit fault distance measurement method based on fault point iterative correction of the present invention, wherein: the distance measurement equation of the single-phase grounding fault and the distance measurement equation of the phase-to-phase grounding fault are constructed according to the second parameter, wherein the construction process of the distance measurement equation of the single-phase grounding fault is as follows:

[0016] Assume that the fault occurs in phase A:

[0017] Construct a differential equation with fault distance as the unknown quantity as follows:

[0018]

[0019] Among them, Δi a1 (t), Δi a2 (t), Δi a0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase current variation, Δu f (t) is the voltage change at the fault point, R1 and L1 are the resistance and inductance of line 1 between the busbar and the fault point, R2 and L2 are the resistance and inductance of line 2 between the busbar and the fault point, R0 and L0 are the resistance and inductance of line 0 between the busbar and the fault point, Δu a (t) is the change of fault voltage of phase A;

[0020] Assuming that the line is uniform, that is, the line impedance per unit length is constant, then:

[0021] R1=r1·L,L1=l1·L;

[0022] R2=r2·L,L2=l2·L;

[0023] R0=r0·L,L0=l0·L;

[0024] Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0;

[0025] In addition, when a single-phase grounding fault occurs, the following conditions occur:

[0026]

[0027] Therefore, the distance measurement equation for single-phase ground fault is:

[0028]

[0029] r ∑ =r1+r2+r0,l ∑ =l1+l2+l0

[0030] Among them, Δi a (t) is the change of phase A fault current.

[0031] As a preferred solution of the distribution network short-circuit fault distance measurement method based on fault point iterative correction of the present invention, wherein: the distance measurement equation of the single-phase grounding fault and the distance measurement equation of the phase-to-phase grounding fault are constructed according to the second parameter;

[0032] The construction process of the phase-to-ground fault distance measurement equation is as follows:

[0033] Assume that the fault occurs between phases AB:

[0034] Construct a differential equation with fault distance as the unknown quantity, as follows:

[0035]

[0036] Among them, Δu f (t) is the voltage change at the fault point, Δi ab1 (t), Δi ab2 (t), Δi ab0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase-to-phase current variation, R1 and L1 are the 1-mode resistance and inductance of the line from the bus to the fault point, R2 and L2 are the 2-mode resistance and inductance of the line from the bus to the fault point, R0 and L0 are the 0-mode resistance and inductance of the line from the bus to the fault point, Δu ab(t) is the change of fault voltage between phases AB;

[0037] Assuming that the line is uniform, that is, the line impedance per unit length is constant, then:

[0038] R1=r1·L,L1=l1·L;

[0039] R2=r2·L,L2=l2·L;

[0040] R0=r0·L,L0=l0·L;

[0041] Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0;

[0042] Therefore, the distance equation for phase-to-ground fault is:

[0043]

[0044] Among them, Δi ab (t) Change in fault current between phases AB, r is the line resistance per unit length, l is the line inductance per unit length.

[0045] As a preferred solution of the distribution network short-circuit fault distance measurement method based on fault point iterative correction of the present invention, wherein: the distance measurement equation of the single-phase grounding fault and the distance measurement equation of the phase-to-phase grounding fault are constructed according to the second parameter;

[0046] The calculation process of the second fault distance is as follows:

[0047] Setting the initial values ​​of the voltage variation at the fault point and the fault distance according to the first parameter and the second parameter;

[0048] Correct the initial values ​​of the voltage change at the fault point and the fault distance to obtain the first fault distance and the voltage change at the first fault point, wherein the correction step length of the initial value of the fault distance is +0.1 km, and the correction step length of the initial value amplitude of the voltage change at the fault point is -0.01 kV;

[0049] Taking the fault distance as an unknown, substitute the voltage change at the first fault point into the distance measurement equation to find the second fault distance; Taking the voltage change at the fault point as an unknown, substitute the first fault distance into the distance measurement equation to find the voltage change at the second fault point;

[0050] When the second fault distance needs to be calculated again, the second fault point voltage change and the second fault distance are used as initial values ​​of the fault point voltage change and the fault distance.

[0051] As a preferred solution of the distribution network short-circuit fault distance measurement method based on iterative correction of the fault point according to the present invention, wherein: the determination of whether the distance measurement result converges, if so, the process is terminated, if not, the value of the voltage change amount and the fault distance of the corrected fault point is returned;

[0052] The basis for judging whether the ranging result is convergent is as follows:

[0053] LL′|≤ε

[0054]

[0055] Where L is the fault distance obtained in the previous calculation, L′ is the fault distance obtained in the next calculation, ε is the iterative calculation error, and L total is the total length of the line.

[0056] As a preferred solution of the distribution network short-circuit fault distance measurement method based on iterative correction of fault points described in the present invention, wherein: the fault type and fault phase are determined according to the fault distance measurement device, wherein the fault distance measurement device is installed at the head end of the line, and when a single-phase grounding fault occurs in the line, the voltage sampling value and the current sampling value within a fixed time window before and after the fault occurs are recorded.

[0057] In a second aspect, an embodiment of the present invention provides a distribution network short-circuit fault location system based on fault point iterative correction, which includes:

[0058] A collection module collects the first parameters of each phase of the distribution network during normal operation and after a fault occurs;

[0059] A calculation module, which determines the fault type and the fault phase according to the fault distance measuring device, and calculates a second parameter corresponding to the fault phase according to the first parameter;

[0060] A construction module is used to construct a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to the second parameter;

[0061] A setting module, which sets the initial value of the voltage change at the fault point and the fault distance according to the first parameter and the second parameter;

[0062] A correction module, which corrects the value of the voltage change at the fault point and the fault distance to obtain a first fault distance and a voltage change at the first fault point;

[0063] An iteration module, substituting the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance, and substituting the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point;

[0064] The judgment module judges whether the distance measurement result converges. If so, the process ends; if not, the value of the voltage change at the corrected fault point and the fault distance is returned.

[0065] In a third aspect, an embodiment of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the distribution network short-circuit fault location method based on iterative correction of fault points as described in the first aspect of the present invention are implemented.

[0066] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, the steps of the distribution network short-circuit fault location method based on iterative correction of fault points as described in the first aspect of the present invention are implemented.

[0067] The beneficial effects of the present invention are as follows: the present invention simplifies the calculation process of the fault distance, establishes a simple distance measurement differential equation by taking the fault distance as the only variable through reasonable assumptions, avoids solving complex sets of simultaneous equations, and is more convenient for engineering applications. The iterative calculation method is adopted, which not only simplifies the calculation process, but also can correct the errors caused by the assumptions, and can ensure a high distance measurement accuracy through multiple iterations. The method has a wide range of applications, and can be used not only for single-phase grounding faults, but also for phase-to-phase short-circuit grounding faults, and has high engineering application value. The use of the fault voltage change to calculate the distance measurement result can eliminate the influence of the load current on the distance measurement accuracy; directly using the voltage and current changes of the fault phase or between the fault phases avoids complex decoupling calculations, and is also conducive to improving the calculation accuracy.

[0068] In summary, the present invention simplifies the calculation method of the fault distance by means of reasonable assumptions and iterative calculations, expands the scope of application, improves the distance measurement accuracy, and eliminates the influence of load current, and is worthy of popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0070] Figure 1 It is a flow chart of a distribution network short-circuit fault location method based on iterative correction of fault points;

[0071] Figure 2 A computer equipment diagram for a distribution network short-circuit fault location method based on iterative correction of fault points;

[0072] Figure 3 Schematic diagram of distribution network section positioning based on the distribution network short-circuit fault location method with iterative correction of fault points. DETAILED DESCRIPTION

[0073] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0074] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0075] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0076] Example 1

[0077] Reference Figure 1-2 , which is the first embodiment of the present invention, and provides a distribution network short-circuit fault location method based on fault point iterative correction, comprising:

[0078] S100: collecting the first parameters of each phase of the distribution network during normal operation and after a fault occurs;

[0079] S101: Collecting the first parameters of each phase of the distribution network during normal operation and after a fault occurs. The first parameters include the voltage and current of each phase during normal operation of the circuit, the voltage and current of each phase after a single-phase ground short circuit fault occurs, and the voltage and current between phases after an inter-phase ground short circuit fault occurs. The second parameters include the voltage change of the fault phase and the current change of the fault phase.

[0080] S200: determining the fault type and the fault phase according to the fault distance measuring device, and calculating a second parameter corresponding to the fault phase according to the first parameter;

[0081] S201: Determine the fault type and fault phase according to the fault distance measuring device, wherein the fault distance measuring device is installed at the head end of the line. When a single-phase grounding fault occurs in the line, the voltage sampling value and the current sampling value within a fixed time window before and after the fault occurs are recorded.

[0082] S300: constructing a distance measurement equation for a single-phase ground fault and a distance measurement equation for an inter-phase ground fault according to the second parameter;

[0083] S301: constructing a distance measurement equation for a single-phase grounding fault and a distance measurement equation for a phase-to-phase grounding fault according to the second parameter, wherein the construction process of the distance measurement equation for a single-phase grounding fault is as follows:

[0084] Assume that the fault occurs in phase A:

[0085] Construct a differential equation with fault distance as the unknown quantity as follows:

[0086]

[0087] Among them, Δi a1 (t), Δi a2 (t), Δi a0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase current variation, Δu f (t) is the voltage change at the fault point, R1 and L1 are the resistance and inductance of line 1 between the busbar and the fault point, R2 and L2 are the resistance and inductance of line 2 between the busbar and the fault point, R0 and L0 are the resistance and inductance of line 0 between the busbar and the fault point, Δu a (t) is the change of fault voltage of phase A;

[0088] Assuming that the line is uniform, that is, the line impedance per unit length is constant, then:

[0089] R1=r1·L,L1=l1·L;

[0090] R2=r2·L,L2=l2·L;

[0091] R0=r0·L,L0=l0·L;

[0092] Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0;

[0093] In addition, when a single-phase grounding fault occurs, the following conditions occur:

[0094]

[0095] Therefore, the distance measurement equation for single-phase ground fault is:

[0096]

[0097] r ∑ =r1+r2+r0,l ∑ =l1+l2+l0

[0098] Among them, Δi a (t) is the change of phase A fault current.

[0099] S302: constructing a distance measurement equation for a single-phase ground fault and a distance measurement equation for an inter-phase ground fault according to the second parameter;

[0100] The construction process of the phase-to-ground fault distance measurement equation is as follows:

[0101] Assume that the fault occurs between phases AB:

[0102] Construct a differential equation with fault distance as the unknown quantity, as follows:

[0103]

[0104] Among them, Δu f (t) is the voltage change at the fault point, Δi ab1 (t), Δi ab2 (t), Δi ab0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase-to-phase current variation, R1 and L1 are the 1-mode resistance and inductance of the line from the bus to the fault point, R2 and L2 are the 2-mode resistance and inductance of the line from the bus to the fault point, R0 and L0 are the 0-mode resistance and inductance of the line from the bus to the fault point, Δu ab (t) is the change of fault voltage between phases AB;

[0105] Assuming that the line is uniform, that is, the line impedance per unit length is constant, then:

[0106] R1=r1·L,L1=l1·L;

[0107] R2=r2·L,L2=l2·L;

[0108] R0=r0·L,L0=l0·L;

[0109] Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0;

[0110] Therefore, the distance equation for phase-to-ground fault is:

[0111]

[0112] Among them, Δi ab (t) Change in fault current between phases AB, r is the line resistance per unit length, l is the line inductance per unit length.

[0113] S400: setting initial values ​​of the voltage change at the fault point and the fault distance according to the first parameter and the second parameter;

[0114] S500: Correct the value of the voltage change at the fault point and the fault distance to obtain a first fault distance and a voltage change at the first fault point;

[0115] S600: Substitute the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance; substitute the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point;

[0116] S601: constructing a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to a second parameter;

[0117] The calculation process of the second fault distance is as follows:

[0118] Setting the initial values ​​of the voltage variation at the fault point and the fault distance according to the first parameter and the second parameter;

[0119] Correct the initial values ​​of the voltage change at the fault point and the fault distance to obtain the first fault distance and the voltage change at the first fault point, wherein the correction step length of the initial value of the fault distance is +0.1 km, and the correction step length of the initial value amplitude of the voltage change at the fault point is -0.01 kV;

[0120] Taking the fault distance as an unknown, substitute the voltage change at the first fault point into the distance measurement equation to find the second fault distance; Taking the voltage change at the fault point as an unknown, substitute the first fault distance into the distance measurement equation to find the voltage change at the second fault point;

[0121] When the second fault distance needs to be calculated again, the second fault point voltage change and the second fault distance are used as initial values ​​of the fault point voltage change and the fault distance.

[0122] S700: Determine whether the distance measurement result converges, if so, end the process, if not, return the value of the corrected fault point voltage change and fault distance.

[0123] S701: Determine whether the distance measurement result converges, if so, end the process, if not, return the value of the voltage change at the corrected fault point and the fault distance;

[0124] The basis for judging whether the ranging result is convergent is as follows:

[0125] LL′|≤ε

[0126]

[0127] Where L is the fault distance obtained in the previous calculation, L′ is the fault distance obtained in the next calculation, ε is the iterative calculation error, and L total is the total length of the line.

[0128] Furthermore, this embodiment also provides a distribution network short-circuit fault location measurement system based on fault point iterative correction, comprising:

[0129] A collection module collects the first parameters of each phase of the distribution network during normal operation and after a fault occurs;

[0130] A calculation module, which determines the fault type and the fault phase according to the fault distance measuring device, and calculates a second parameter corresponding to the fault phase according to the first parameter;

[0131] A construction module is used to construct a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to the second parameter;

[0132] A setting module, which sets the initial value of the voltage change at the fault point and the fault distance according to the first parameter and the second parameter;

[0133] A correction module, which corrects the value of the voltage change at the fault point and the fault distance to obtain a first fault distance and a voltage change at the first fault point;

[0134] An iteration module, substituting the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance, and substituting the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point;

[0135] The judgment module judges whether the distance measurement result converges. If so, the process ends; if not, the value of the voltage change at the corrected fault point and the fault distance is returned.

[0136] This embodiment also provides a computer device, which is applicable to the distribution network short-circuit fault distance measurement method based on iterative correction of fault points, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute computer-executable instructions to implement the distribution network short-circuit fault distance measurement method based on iterative correction of fault points as proposed in the above embodiment.

[0137] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0138] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for measuring the short-circuit fault location in a distribution network based on iterative correction of fault points as proposed in the above embodiment is implemented.

[0139] In summary, the parameters of the distribution network during normal operation and after a fault occurs are collected:

[0140] By collecting parameters such as voltage and current, we can fully understand the operating status of the distribution network and provide basic data support for subsequent fault location. This step lays the data foundation for the entire distance measurement process and helps improve the accuracy of subsequent analysis.

[0141] Determine the fault type and phase difference, and calculate related parameters:

[0142] The fault distance measuring device determines the fault type and phase difference, and calculates the corresponding voltage and current changes, thus achieving accurate identification of the fault situation. This step can quickly determine the nature of the fault, which is conducive to the subsequent adoption of targeted distance measurement strategies and improves the efficiency of fault handling.

[0143] Construct the ranging equation:

[0144] According to different fault types (single-phase grounding or phase-to-phase short circuit), corresponding distance measurement equations are constructed to achieve mathematical modeling of complex fault conditions. This step transforms physical problems into mathematical problems, provides a theoretical basis for accurately calculating fault distances, and helps improve the accuracy of distance measurement.

[0145] Set the initial value and make iterative corrections:

[0146] By setting the initial values ​​of the voltage change at the fault point and the fault distance and performing iterative correction, the distance measurement results are gradually optimized. This innovative iterative process can continuously correct the calculation error, significantly improve the accuracy of the distance measurement, and overcome the limitations of the traditional single calculation method.

[0147] Determine convergence and output the results:

[0148] By setting the convergence conditions and judging whether the distance measurement results meet the requirements, the distance measurement process is automated and intelligent. This step ensures the reliability of the calculation results and improves the efficiency of fault location.

[0149] Improve ranging accuracy:

[0150] By adopting the iterative correction method, the present invention can continuously optimize the calculation results and significantly improve the accuracy of fault distance measurement. Compared with the traditional method, the distance measurement error can be controlled within 0.4%, which is far better than the industry's accuracy requirement of 0.5%. This high-precision positioning can help operation and maintenance personnel find the fault point more quickly and accurately, greatly shorten the fault repair time, and improve power supply reliability.

[0151] Expand the scope of application:

[0152] The present invention is not only applicable to single-phase grounding faults, but also to phase-to-phase short-circuit grounding faults, significantly expanding the scope of application of the method. This versatility enables the method to cope with various fault types in the distribution network, improving the flexibility and efficiency of fault handling.

[0153] Simplify the calculation process:

[0154] By using the fault distance as the only variable to establish a simple distance differential equation, the complex simultaneous equations can be avoided and the calculation process can be greatly simplified. This simplification not only improves the calculation efficiency, but also reduces the demand for computing resources, making this method easier to apply and promote in practical engineering.

[0155] Eliminate the influence of load current:

[0156] The fault voltage change is used to calculate the distance measurement result, effectively eliminating the influence of load current on the distance measurement accuracy. This innovative processing method solves the problem of load current interference in traditional distance measurement methods and further improves the accuracy and reliability of distance measurement.

[0157] Realize intelligent fault location:

[0158] Through automated data collection, fault judgment and iterative calculation, intelligent positioning of distribution network short-circuit faults is achieved. This intelligent processing not only improves the efficiency of fault handling, but also reduces dependence on manual operations, helping to build a more intelligent and reliable distribution network operation and maintenance system.

[0159] Improve economic efficiency:

[0160] By quickly and accurately locating the fault point, the present invention can significantly shorten the fault repair time, reduce power outage losses, and improve power supply reliability. This can not only reduce the operation and maintenance costs of the power company, but also improve user satisfaction, bringing significant economic and social benefits.

[0161] In summary, the present invention realizes high-precision and intelligent positioning of short-circuit faults in distribution networks through an innovative iterative correction method combined with a number of technological innovations. Compared with the prior art, the present invention has significant improvements in ranging accuracy, scope of application, computational efficiency, and practicality, providing strong technical support for the safe and reliable operation of distribution networks. This unexpected high accuracy and wide applicability make the present invention have important application value and promotion prospects in the field of distribution network fault handling.

[0162] Example 2

[0163] Reference Figure 1 - Figure 2, which is the second embodiment of the present invention, and this embodiment provides a distribution network short-circuit fault location method based on fault point iterative correction. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0164] Test sample selection:

[0165] The 10kV distribution network is selected as the test sample, and its electrical parameters are shown in Table 1.

[0166] Table 1 10kV distribution network electrical parameters

[0167]

[0168]

[0169] Ranging results:

[0170] The A-phase ground faults at different distances were set and the distance measurement errors were obtained. The results are shown in Table 2.

[0171] Table 2 Ranging results

[0172] Fault setting distance / km Measuring distance / km Ranging error 4 3.97 0.03 6 6.02 0.02 8 7.96 0.04

[0173] It can be seen from Table 2 that the iterative method has a smaller ranging error and a higher ranging accuracy. This is because the iterative method gradually corrects the assumed fault point voltage through multiple calculations, making the ranging result more accurate.

[0174] In summary, this method is applied to the single-ended distance measurement of single-phase grounding fault in 10kV distribution network, and the average distance measurement error is less than 0.4%, meeting the accuracy requirement of 0.5%. The effectiveness of the iterative method is verified, and high-precision single-ended distance measurement of short-circuit fault in distribution network can be achieved.

[0175] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A distribution network short-circuit fault location method based on fault point iterative correction, characterized in that: include, Collect the first parameters of each phase of the distribution network during normal operation and after a fault occurs; Determine the fault type and the fault phase according to the fault distance measuring device, and calculate a second parameter corresponding to the fault phase according to the first parameter; Constructing a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to the second parameter; Setting the initial values ​​of the voltage variation at the fault point and the fault distance according to the first parameter and the second parameter; Correcting the values ​​of the voltage variation at the fault point and the fault distance to obtain a first fault distance and a voltage variation at the first fault point; Substitute the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance; substitute the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point; Determine whether the distance measurement result converges. If so, end the process. If not, return the value of the corrected fault point voltage change and fault distance.

2. The distribution network short-circuit fault location method based on fault point iterative correction according to claim 1, characterized in that: The first parameters of each phase of the distribution network are collected during normal operation and after a fault occurs. The first parameters include the voltage and current of each phase during normal operation of the circuit, the voltage and current of each phase after a single-phase ground short circuit fault occurs, and the voltage and current between each phase after a phase-to-phase ground short circuit fault occurs; the second parameters include the change in the fault phase voltage and the change in the fault phase current.

3. The distribution network short-circuit fault location method based on fault point iterative correction according to claim 2, characterized in that: The distance measurement equation for a single-phase ground fault and the distance measurement equation for a phase-to-phase ground fault are constructed according to the second parameter, wherein the construction process of the distance measurement equation for a single-phase ground fault is specifically as follows: Assume that the fault occurs in phase A: Construct a differential equation with fault distance as the unknown quantity as follows: Among them, Δi a1 (t), Δi a2 (t), Δi a0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase current variation, Δu f (t) is the voltage change at the fault point, R1 and L1 are the resistance and inductance of line 1 between the busbar and the fault point, R2 and L2 are the resistance and inductance of line 2 between the busbar and the fault point, R0 and L0 are the resistance and inductance of line 0 between the busbar and the fault point, Δu a (t) is the change of fault voltage of phase A; Assuming that the line is uniform, that is, the line impedance per unit length is constant, then: R1=r1·L,L1=l1·L; R2=r2·L,L2=l2·L; R0=r0·L,L0=l0·L; Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0; In addition, when a single-phase grounding fault occurs, the following conditions occur: Therefore, the distance measurement equation for single-phase ground fault is: r ∑ ＝r1+r2+r0，l ∑ ＝l1+l2+l0 Among them, Δi a (t) is the change of phase A fault current.

4. The distribution network short-circuit fault location method based on fault point iterative correction according to claim 3 is characterized in that: The method constructs a distance measurement equation for a single-phase ground fault and a distance measurement equation for an inter-phase ground fault according to the second parameter; The construction process of the phase-to-ground fault distance measurement equation is as follows: Assume that the fault occurs between phases AB: Construct a differential equation with fault distance as the unknown quantity, as follows: Among them, Δu f (t) is the voltage change at the fault point, Δi ab1 (t), Δi ab2 (t), Δi ab0 (t) are the 1-mode, 2-mode and 0-mode components of the fault phase-to-phase current variation, R1 and L1 are the 1-mode resistance and inductance of the line from the bus to the fault point, R2 and L2 are the 2-mode resistance and inductance of the line from the bus to the fault point, R0 and L0 are the 0-mode resistance and inductance of the line from the bus to the fault point, Δu ab (t) is the change of fault voltage between phases AB; Assuming that the line is uniform, that is, the line impedance per unit length is constant, then: R1=r1·L,L1=l1·L; R2=r2·L,L2=l2·L; R0=r0·L,L0=l0·L; Wherein, L represents the fault distance, r1 is the resistance per unit length of line 1, l1 is the inductance per unit length of line 1, r2 is the resistance per unit length of line 2, l2 is the inductance per unit length of line 2, r0 is the resistance per unit length of line 0, and l0 is the inductance per unit length of line 0; Therefore, the distance equation for phase-to-ground fault is: Among them, Δi ab (t) Change in fault current between phases AB, r is the line resistance per unit length, l is the line inductance per unit length.

5. The distribution network short-circuit fault location method based on fault point iterative correction according to claim 4, characterized in that: The method constructs a distance measurement equation for a single-phase ground fault and a distance measurement equation for an inter-phase ground fault according to the second parameter; The calculation process of the second fault distance is as follows: Setting the initial values ​​of the voltage variation at the fault point and the fault distance according to the first parameter and the second parameter; Correct the initial values ​​of the voltage change at the fault point and the fault distance to obtain the first fault distance and the voltage change at the first fault point, wherein the correction step length of the initial value of the fault distance is +0.1 km, and the correction step length of the initial value amplitude of the voltage change at the fault point is -0.01 kV; Taking the fault distance as an unknown, substitute the voltage change at the first fault point into the distance measurement equation to find the second fault distance; Taking the voltage change at the fault point as an unknown, substitute the first fault distance into the distance measurement equation to find the voltage change at the second fault point; When the second fault distance needs to be calculated again, the second fault point voltage change and the second fault distance are used as initial values ​​of the fault point voltage change and the fault distance.

6. The method for short-circuit fault location in distribution network based on iterative correction of fault points according to claim 5, characterized in that: Determine whether the distance measurement result converges, if so, end the process, if not, return the value of the voltage change at the corrected fault point and the fault distance; The basis for judging whether the ranging result is convergent is as follows: |LL′|≤ε Where L is the fault distance obtained in the previous calculation, L′ is the fault distance obtained in the next calculation, ε is the iterative calculation error, and L total is the total length of the line.

7. The distribution network short-circuit fault location method based on fault point iterative correction according to claim 6, characterized in that: The fault type and fault phase are determined according to the fault distance measuring device, wherein the fault distance measuring device is installed at the head end of the line. When a single-phase grounding fault occurs in the line, the voltage sampling value and the current sampling value in a fixed time window before and after the fault occurs are recorded.

8. A distribution network short-circuit fault location system based on fault point iterative correction, based on the distribution network short-circuit fault location method based on fault point iterative correction according to any one of claims 1 to 7, characterized in that: Also includes, A collection module collects the first parameters of each phase of the distribution network during normal operation and after a fault occurs; A calculation module, which determines the fault type and the fault phase according to the fault distance measuring device, and calculates a second parameter corresponding to the fault phase according to the first parameter; A construction module is used to construct a distance measurement equation for a single-phase ground fault and a distance measurement equation for a phase-to-phase ground fault according to the second parameter; A setting module, which sets the initial value of the voltage change at the fault point and the fault distance according to the first parameter and the second parameter; A correction module, which corrects the value of the voltage change at the fault point and the fault distance to obtain a first fault distance and a voltage change at the first fault point; An iteration module, substituting the voltage change at the first fault point into the distance measurement equation to obtain the second fault distance, and substituting the first fault distance into the distance measurement equation to obtain the voltage change at the second fault point; The judgment module judges whether the distance measurement result converges. If so, the process ends; if not, the value of the voltage change at the corrected fault point and the fault distance is returned.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the distribution network short-circuit fault location method based on fault point iterative correction according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the distribution network short-circuit fault location method based on fault point iterative correction according to any one of claims 1 to 7 are implemented.

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